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$3.95

&FTAMATEURTELEVISIONQUARTERLYAPRIL 1989

VOL. 2 #2ISSN: 1042-198X

USPS 003-353

DEVOTED ENTIRELY TO AMATEUR TELEVISION

II

AMATEUR TELEVISIONCOLUMBUS, OHIO USAW80MR 439.2 MEGAHz

VISIT OUR BOOTH AT DAYTON, ORLANDO & BATCALL ABOUT THE ROSE PARADE ATV PUBLIC SERVICECROSSLINKING THE BALTIMORE AND WASHINGTON ATV REPEATERSBUILT IT: COMPLETE PLANS 300 WATT 2440 MHZ FM ATV MICROWAVE OVEN TRANSMITTER.BUILD IT: UNIVERSAL RDF WORKS ON ALL BANDS ALL MODES INCLUDING ATV!MORE OF EVERYTHING YOU EVER WANTED TO KNOW ABOUT HAM TV

a

N:MMIIIMMUNt

ATV op( 'abiding at the Pasadena Ro le

THE 1989 TOURNAMENT OF ROSES PARADE floe Angeles gimes

`If they didn't do what they do, * Tuesday, January 3, 1989

we couldn't get that parade downthe street-and that's the truth.'

-Delmer Beckhart, tournament official Story on Page 11

Ham Operators: Parade'sCommunications LifelineBy AMY PYLE, Times Staff Writer

APRIL 1989 AMATEUR TELEVISION QUARTERLY MAGAZINE VOLUME 2 #2ISSN # 1042-198X USPS # 003-353 92 PACKED PAGES!!

Amateur Television Quarterly Magazine is published four times a year by Henry R. Ruh KB9FO at 540 E. Oakton St., Des Plaines, Illinois60018-1950. Annual subscription rate for domestic delivery is $15 per year. Canadian delivery is $20 per year in US Funds sent first class mail.Delivery to other countries is $25 per year US funds and sent as air -mail, printed matter. Second Class Postage paid Des Plaines, Illinois and addi-

tional offices of entry. Second Class Mail Permit Number USPS 003-353. POSTMASTER: Send change of address to: Amateur Television QuarterlyMagazine, 1545 LEE ST. SUITE 73, Des Plaines, Illinois 60018. All inquiries, subscriptions and submittal should be sent to: Amateur TelevisionQuarterly Magazine, 1545 Lee St. Suite 73, Des Plains, Illinois 60018. The logo and trademark of Amateur Television Quarterly Magazine is ATVQas displayed on our front cover. The Business phone number is 312-298-2269. Note that the phone company will be changing the area code in January1990. Co -publisher is Bill Brown WB8ELK. Technical Editor is Tom O'Hara W6ORG. Editor is Sylvia Kurcz. Typist and word processing byLaurie Woisniewski. Editorial offices are located at 540 E. Oakton St., Des Plaines, IL 60018-1950. However, because of curb side delivery it

is preferred that all mail be addressed to 1545 Lee St. Suite 73, Des Plaines, IL 60018.

FRONT COVER PHOTOS: TOP LEFT - WB5JLZ ATV SHACK, TOP RIGHT - PHIL WB6LQP AT ROSE PARADE CONTROL HQ, BOTTOMLEFT - WB8ELK IN THE KB9FO ATV SHACK, BOTTOM RIGHT - ATV ID FROM BILL W8DMR. INSIDE FRONT COVER AND INSIDEBACK COVER: ROSE PARADE ATV STATIONS - STORY ON PAGE 11.

TABLE OF CONTENTSCOLOR PHOTOS OF HAM TV'S BIGGEST PUBLIC SERVICE EVENT, PASADENA ROSE PARADE INSIDE FRONT AND

BACK COVERS.

VIC 20/64 ATV RPT CONTROLLER BY Lyn Cyr W1NRE page 6

4 & 1/2 HOUR ROSE PARADE VIDEO TAPE page 9

VIDEO ID TIMER BY Bill WB8ELK page 10VIDEO LINK AND REPEATER SYSTEM FOR BALTIMORE/WASHINGTON ATV RPT BY Bob WB4APR page 12ATV OPERATING NEWS OF THE WORLD. ATVQ voyages, ENGLAND, BOSTON, CT, MN, IL, CA, VANCOUVER,

NY, TX, AUSTIN ATV RPT, LA, DENVER CLEAR LAKE, CA, MN, BC, BATC, HAWAII pages 14-20SUBSCRIPTION FORM page 21

ATV & ALL MODE RDF BY Paul W9DUU page 2210 uH INDUCTOR J. Cronk GW3MBO page 23HETRODYNE FM TV TRANSMITTER BY Dave WBOZJP page 24

ELECTRONIC COMPASS page 25POOR MAN'S SPECTRUM ANALYZER BY Murray Barlowe WA2PZO page 26UNDERSTANDING FM SIDEBANDS BY Warner Johnston page 32

A LIMITER FOR FM TV BY Klaus DJ700 page 33MICROWAVE OVEN 2.3GHZ 250 WATT FM TV TRANSMITTER Dave KA9BYI and Bill W8DMR page 34

54 PLACES TO BUY COPIES OF ATVQ!!! page 39

BLOOMING VIDEO BY Lyn Cyr W1NRE page 40ATV INTERDIGITAL FILTERS FOR 440, 900 & 1250 MHZ BY Lyn Cyr W1NRE page 41

LIVE ATV FROM THE EDGE OF SPACE BY WB8ELK page 45FULL COLOR PHOTOS 46, 47

ON THE ROAD WITH THE ELK . . . AN ATV TRAVELOGUE page 50FULL COLOR PHOTOS 48, 49

VIDEO PROC AMP BY WA6SVT page 53COMMODORE AMIGA FOR SSTV/FSTV John KDOLO page 56BACK TO BASICS KB9FO page 57

WB5JLZ ATV RPT page 58

CHEAP & SIMPLE HARDLINE CONNECTORS BY Bob WD5BJW page 59ATV COMBLINE DUPLEXERS AND FILTERS BY Jon WA2BTW page 60FINDING YOUR WAY THROUGH THE TV RESOLUTION MAZE BY Mario Orazio page 66ATVQ&A . . . READERS QUESTIONS ANSWERED ABOUT ATV BY Tom W6ORG page 68

ATVQ&A FEEDBACK . . . AMPLIFIER HEADROOM, POWER MODULES AND ATV BY Tom W6ORG page 74BASIC PROGRAM FOR ERP page 78KS8J ATV RPT CONTROLLER BY Earl KS8J with help from his XYL Tommy N7KBO page 80SNEAK PREVIEW OF THE AEA FSTV 430 ATV TRANSCEIVER . . . Ron NSIVN page 82WINTER CES SHOW BY WB8ELK page 87

APRIL 1989 VOL. 2 -2 PAGE 3

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BATC SPANS THE GLOBEThe BRITISH AMATEUR TELEVISION CLUB (founded in 1949), represents the

interests of amateur television enthusiasts throughout the world. With a

current membership of over 2,500, the BATC is the largest and oldest such

organisation in existence.

Amateur TV is an all -embracing hobby and includes such activities as:

TRANSMITTING TV - COMMUNICATION - HOME -CONSTRUCTION - VIDEO RECORDING -

SPECIAL EFFECTS - DIGITAL PICTURES - HOME TV STUDIOS - SLOW -SCAN TV -

AMATEUR PRODUCTIONS - SATELLITE TV - OUTSIDE BROADCAST - DX -TV - REPEATERS

etc. The list is endless.

As a member of the BATC you get a free quarterly magazine which is always

packed with up-to-date, practical information and designs. Printed circuit

boards and special components for projects are available from your U.S.

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TV, covering everything from starting new to the most advanced techniques.

Many other services and facilities are available to members, and practical

help is available on any TV related topic.

Find out about the BATC now -you won't regret it

Our agent for North America is Don Miller. W9NTP, who has full up-to-date

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boards.

All money - including annual subscriptionsin U.S. dollars, making it very easy to be

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(317) 525-6452

APRIL 1989 VOL. 2 -2PAGE 5

Prior to the advent of theinexpensive home computer, thedesign of repeater control circuitshad to be carefully thought outand allowances made for futuredevelopments and expansions. Oncethe hardware circuit design hadbeen frozen it could have beenfrustrating to implement revisions.

Many microprocessor controlcircuits appeared in magazines andon the market which simplified thedesign of repeater control func-tions. Most of the features, how-ever, were designed for voicegrade repeaters and while veryversatile they left a void for theATV repeater task. What was nee-ded for a viable ATV controllerwas the generation of video gra-phics and ease of programmabilitywithout resorting to machine lan-guages, eproms, as well as notbreaking the bank.

The following MV controlleruses a Commodore VIC-20 or C-64. The computers, as supplied,have an addresahle 8 -bit I/O portand two "el-cheapo" analog todigital converters in the form ofpaddle inputs. They also have theability to keep track of real timewhich can be used to advantage.

Our first attempts used a VIC-20 as an ATV controller but waslater changed to a C-64 becauseof the VIC's relatively poor per-formance at time keeping. I amtold there are ways to improve it,but the C-64 was chosen becauseof its greater memory and gra-phics capabilities. If time keepingis not vital to your operation theVIC-20 will perform nicely. Thefollowing discussion is orientatedto the C-64 but the material ap-plies equally as well to the VIC.The basic differences will bescreen size, for graphics, and thememory locations for the I/O portusage as well as reduced memoryspace. The C-64 used in theW1NRE ATV repeater has been de-veloped to provide a 32 -bit I/Oport, a 16 channel 8 -bit A/D con-verter, and touch tone decoder.Also contemplated and in progressis a spectrum, analyzer functionusing a defunct VHF -UHF varactortuner. Upon touch-tone command

VIC-20/C-64 ATV CONTROLLERLYN H. CYR, W1NRE

or prior to a transmitter key -up,a spectrum "snapshot" would betaken to be displayed through therepeater. The applications areendless.

Recognizing that machine lan-guage routines are much faster,the program was written in Basicnonetheless. As a controller, itoperates at more than adequatespeeds.

Enough chit-chat. Let's get tothe heart of the matter at hand.The key to using the C-64 as acontroller depends on the abilityto communicate with the I/O port.On the back of the C-64 is a userport connector to which the out-puts of a memory mapped 6526CIA (Complex Interface Adapter)chip is connected. The 6526 is in-deed a complex interface adapterchip and it is not the intention todiscuss all of its features andfunctions. Refer to the "Commo-dore 64 Programmer's ReferenceGuide" for further discussions onthis chip. For our purposes, onlythe 8 -bit I/O lines will be cliprus-sed. The lines of interest are PBOthrough PB7. These lines form an8 -bit parallel word which can beprogrammed as either input oroutput lines. Communicatingthrough these lines is done by acouple of memory locations.

There are two registers, eachwith its own address, which con-trols the flow of data. The firstregister is a Data Direction Regis-ter (DDR). This register dictateswhich of the eight lines will beused as inputs and which will beused as outputs. Once the direc-tions have been established, thedata flows in and out of the databus through another registerknown as the Data Register loca-ted at a separate address. Priorto using the Data Registers, theDDR has to be initialized or toldwhich direction data will flow. Ifa bit in the DDR is a 'T', thecorresponding line of the port willbe an output. If a bit is set to"0" then the corresponding linewill become an input. In Commo-dore basic, iqsaring a POKE com-mand allows you to write to mem-ory while a PEEK instruction lets

you read a memory location. Thegeneral format is <POKE (addre),-value> to enter data into a loca-tion and <PEEK (address)> to readthe data at the location. The ad-dress is in the decimal memorylocation and the value is also indecimal having a range of 0 -255. The chart on the next pagesummarizes the I/O lines, their pinnumbers, the decimal weights andtheir bit positions. The addressof the DDR on the C-64 is 56579and 37138 for the VIC, while theData Registers are located at56577 and 37136 for the C-64 andVIC respectively. Suppose we wan-ted our I/O port configured sothat liens PBO and PB1 act asoutputs and PB2 through PB7 asinput lines. The first order ofbusiness, early in the programinstructions, would be to informthe DDR of that fact. We wouldic-czie the instruction POKE(56579),3. The decimal value of 3would make bits PBO and PB1 logi-cal 'T' instructing the I/O portto have them become output lines.The remainder of the lines wouldbe inputs. This simple instructionis referred to as initializing theI/O port and must be done priorto using the port. Once initialized,data can be transferred throughthe I/O port at location 56577. Ifwe wished to make PB1 a logic "1"the instruction POKE (56577),2would suffice. PBO would be atlogic "0", PB1 at logic "1" and PB2through PB7 would take on thestates of the external signals. Ifwe wanted to know the state ofall the lines a PEEK (56577) wouldread the status of the I/O port.If all the inputs were at logic 'T'and PB1 were logic 'T and PBOlogic "0", reading the port wouldgive a decimal value of 254.Peeking a location, however, doesnot give us the value to workwith. It has to be stored in somevariable.For example:

10 PEEK (56577): Rem** Readthe port

20 C=PEEK (56577): Rem** Readthe port and store it as C.

Step 20 does both at the sametime. Now you can make decisions

PAGE 6 ATVQ DEVOTED ENTIRELY TO HAM TV

BIT/LINE NUMBERDECIMAL VALUEPIN NUMBER

ATV CONTROLLER continued . . .

I/O PORT (USER PORT)/0 PORTPB7 PB6 PB5 PB4 PB3 PB2128 64 32 16 8 4

L K J H F E

PB1 PBO2 1

D C

logic level

based on the value of C. In theexample given, if line 20 wereexecuted, C would have a valueof 254.

One more trick before lookingat a simple COR/Transmit routine.When reading the port, it is oftendesirable to determine the statusof only one bit. The AND instruc-tion is one method to achievethis. One way of looking at theAND instruction is as a binarymultiplication. That is 1 X 1 =1,1 X 0 =0 etc. For instance, as-sume that the port had a decimalvalue of 170. This would meanthat PB7(128), PB5(32), PB3(8) andPB1(2) would all be at logic 'T'and the remaining lines would belogic "0" (see chart above).

The decimal value comes from:lx128+0x64+1x32+0x16+1x8+0x4+1x2+0x1=170

If we had PEEKed this informa-tion, a decimal value of 170 wouldhave been returned. It would bea bit cumbersome to determine ifline PB6 were high or low. Byusing the AND instruction a pre-cise determination can be madevery quickly. If 64 were ANDedwith 170 it would effectively mul-tiply every bit by zero except PB6which would have been multipliedby 1. Remember that a 'T' at PB6has a decimal value of 64. Re-gardless of the status of the otherbits, the bit products would havebeen zero and the value of PB6would have been preserved be-cause it got multiplied by L So ifa value of 64 had been returnedas a result of Peeking the I/Oport the value of PB6 must havebeen at logic 'T' because lx1=1 and1x64=64. If on the other hand avalue of zero would have beenreturned, PB6 had to be at logic"0" because Ox1=0 and 0x64=0. Theinstruction to do this isC=PEEK (56577)AND64. If C=64 thenPB6 is high and if C=0 then PB6is sitting low. These I/O instruc-tions allow to control anything

APRIL 1989 VOL. 2 -2

1 0 1

from stepping motors to ATV con-trollers.

A few notes about the I/Oport. The PBO-PB7 lines have pas-sive as well as active pull-upsproviding both CMOS and TTL com-patibility. The port has a 2 TTLload drive (32ma) capability mak-ing it easy to interface. If loadrequirements exceed these limitsuse transistor drivers or digitalbuffers. Being of the "old school",I still like to hear relays click asshown in the interface circuit ofFigure 1. Relays also provide ahigh degree of isolation betweenthe computer and the outsideworld. In designing your interfacecircuits, keep in mind that whenthe computer is first turned on,all of the bits on the port aresitting in a high state and onceyou program the bits to becomeoutputs they switch to a lowstate. This can be handled byusing inverting buffers on all out-put lines, or using a switch todefeat the interface circuit whilebooting up the computer via alocal/repeat switch.

The interface circuit was builton a Radio Shack experimenter'sPC board (276-154) to which a12/24 pin edge card connector wassoldered to the fingers of theboard. The 12/24 -pin connectorsmight be hard to come by but youcan cut a 22/44 -pin connector tofit the I/O Port. For the UserPort, the pin spacing is .156 in-ches. A PC mounted terminalblock was used to interconnectthe transmitter keying line andCOR. Video connections were madeusing BNC jacks or you could useRCA phono jacks. I have includedLEDs which are helpful in debug-ging the software or simply lettingyou know the status of the port.

The schematic is simple enoughand doesn't warrant too muchexplanation except for the drivetransistors. The transistors can beany PNP type which will handle

1 0 1

the current requirements of therelays. In this configuration, thetransistors provide the neededlogic inversion thus preventingexternal circuits from being ener-gized at computer turn on. Itdoes, however, pose an aggrava-tion in the software since a "0"must be poked to turn on a func-tion. See Figure 1 for circuit de-tails.

A short program with its logicflow is provided in Table L Theprogram is functional as an ATVrepeater but meant to illustratethe principles cliscuPd. I am sureyou would want to develop theprogram beyond this. The programas described will provide a beaconmode, key a transmitter with key -up and drop -out delays and selectone of two video sources. The IDsand graphics are left to your ima-gination.

Program description:Line 10: InitializePBOPB1 as outputs, PB3through PB7 inputs.Line 20: Make sureoutputs are turned off(remember the logic isinverted)Line 100: Input the timeHHMMSS format)Line 120: Convert time(TI$) into a numericalvalue. TI$ is a clockwhich starts from 000000at turn on and incrementsevery second. It can beprogrammed to start froma specific count.Line 130:Check for timesto beacon. Any number oftime slots can be entered.If it's time to beaconthen go to line 4000, ifnot go to next line.Line 140:Read status ofCOR bitLine 150: If COR line islow go to 1000, if COR ishigh, go to next line.Line 160: Go back and wait

PAGE 7


1 REM2 REM s BASIC COR/TRANSMIT ROUTINE s3 REM s L.H.CYR, W1NRE4 REM5 REM10 POKE(56579),320 POKE(56577),360 REM100 INPUT'"DIelrUM.D11/1F1P1 ENTER THE TIME (HHMMSS)';TIS105 PRINT'O'111 PRINT'VDIPIelgele) WAITING FOR COR OR BEACON TIME'115 REM120 T=VAL(TIS)130 IF T=170000 OR T=173000 GOT04000140 C=PEEK(56577) AND4150 IF C=0 GOTO 1000160 GOT01151000 REM KEYING ROUTINE1001 PRINT'"1eIrleDIr91,11.1 KEY-UP DELAY'1002 FORX=1T0600:NEXTX1010 C=PEEK(56577)AND41020 IF C=0 THEN20001025 PRINT"0"1030 GOT01111040 REM2000 POKE(56577),22001 PRINT"-ItIrDlels1,1101 TRANSMITTER IS ON'2002 PRINT' AND RX VIDEO HAS BEEN SELETEO'3000 C=PEEK(56577)AND43010 IF C=0 THEN30003015 PRINT"nlrIDOlplopl DROP-OUT DELAY'3020 FORX=1T0600:NEXTX3030 C=PEEK(56577)AND43040 IF C=0 THEN 20013050 POKE(56577),33055 PRINT'O.3060 GOT01114000 REM BEACON MODE4010 PRINT'O'4015 POKE(56577),04020 PRINT"PIKFIrDIKeIrl INSERT BEACON GRAPHICS HERE'4030 FOR X=ITO 1000:NEXTX4040 POKE(56577),34045 PRINT'0"4050 GOT0111

Slf

By

TXKITING

COMPUTERVIDEO

RX VIDEO

0 CONNECTOR PIN

0 TERMINAL

INC

FUNCTION

START

INIT.PORT

TXOFF

INPUTTIM'

TXOFF

TXON

FLOW DIAGRAM

IXON

TXOFF

TERMINAL sLocKkftr4

PC ROARD

014USER PORT CONNECT

1EFL=1

BEND TERMINALS ANDSOLDER TO PC FINGERS

COMIWISRNIASVIIIW

PIN1,12,A,N GROUND2 3 VDCC PIO

rs 1I PB2

PE)P114

PISK PBSL P17

FIGURE 1. SCHEMATIC AND BOARD DETAILS



for beacon time or COR>Line 1000: Start of keyingroutine.Line 1002: Provides adelay before going on.Experiment with value ofx to suit your delaytimes .Line 1010: Recheck COR tosee if it is still there.If it is, go to line 2000.If it is not, go back andwait for beacon or COR>Line 2000: Key uptransmitter and selectreceived video.Line 3000: Check CORagain.Line 3010: If the COR isstill active go to 3000and keep transmitting. IfCOR is absent go to drop-out delay.Line 3015: Drop -out delayroutineLine 3020: Drop -out delaytimeLine 3030: Recheck COR tosee if it came back.Line 3040: If the COR wasstill present keeptransmitting, otherwise goto the next line.Line 3 0 5 0 : Unkeytransmitter and unselectvideo source.Line 3060: Go back andwait for beacon time orCOR.Line 4000:Start of beaconroutine.Line 4015: Key transmitterand select beacon video.Line 4030: Wait beforegoing on. Transmit time ofbeacon mode.Line 4 0 4 0 : UnkeytransmitterLine 4050: Go back andwait for next beacon timeor COR.

After you have built the inter-face card turn the computer offand plug it in the User Port. Loadthe program as shown and pressrun. You will be prompted to en-ter the time. As programmed, thebeacon time is 17:00:00 and 17:30-:00 hours. Enter 165955. The dis-play will show you that it is wai-ting for the beacon time or COR.After 5 seconds, the screen willdisplay the fact that it is in the


beacon mode. After a short timethe program will return to thewait state. If you ground the CORline, the screen will display thekey -up delay and then show youwhen the transmitter is keyed.Removing the ground from theCOR input, the screen will showyou the drop -out delay afterwhich it will return to the waitstate. A COR at beacon time willpresent it from going to the bea-con routine. As shown, the pro-gram is such that once the beaconroutine has started it cannot beinterrupted. If you wish to inter-rupt the beacon, PEEK the I/Oport and make a derision based onthe value of C.

The program at the W1NRE MVrepeater is a bit more involvedbut they are all further extensionsof the basic routines described.Many text to speech modules areavailable and the Simon Basiccartridge should not be overlookedfor high resolution graphics.

Attempts have not been madeto burn the program in an Eprombut there are a number of pro-ducts available that will allowyou to make an auto -boot basicprogram cartridge. The other al-ternative is to battery back upyour system.

Blow the dust off your unusedCommodore and enhance your ATVrepeater functions or use thetechniques to automate yourshack. Even if purchased new, theC -64c is still a cast effectiveway of getting a repeater control-ler which can be tailored to yourneeds.

If interest warrants it, signalreporting with bar graph routines,using the paddle ports as A/Dconverter can be disrussed. Happycontrolling.

THE ROSE PARADE HAM TVVIDEO TAPE

Now available is a limitedquantity (only 100 copies weremade and 20 were donated to theparticipants) of video tapes madeat the Pasadena Rose Parade. Thetape contains the following: Openlogo, "plea -GP pirate" notice andintroduction by Henry KB9F0.Followed by about 20 minutes ofbehind the scenes video shot at

THE ROSE PARADEHAM TV VIDEO TAPEthe Wrigley Mansion showing theTV feed control and beginning ofthe Satellite TV feed. Followedby the 2 hours sent via satellite,followed by 2 hours more of theATV public service effort to theparades conclusion. In total over4 1/2 hours.

The masters were shot on S -VHS and VHS HQ and 3/4" U -ma -tic. These were dubbed to 1" Cbroadcast format and assembleedited on C. Then the 1" com-pleted master was dubbed to 6 hrmode (SLP/EP) VHS using a$250,000 Ikegami mastering ma-chine used to make master refer-ence tapes for VHS alignment.The accuracy of these tapes is 1micron! The video quality from theVHS master making machine ishigher than any 2 HR mode indus-trial or home VHS machine! Themasters were FIRST GENERATIONas recorded at the Wrigley man-sion directly from the OFF -AIRATV receiver used to relay thesignals to the "end users" and thesatellite feed and were processedusing a frame synchronizer andcolor corrector as well as profes-sional Tektronix waveform/vectorscopes to get the best possibleimage from the 16 live ATV feedsall along the parade route. Inshort, you couldn't get a bettertape if you were there doing ityourself. The few video wiggleswere from the live feeds as recei-ved at parade HQ.

Henry KB9F0 pre -paid tohave the tapes edited and duplica-ted. We are offering them at cost,which includes the dubbing, edit-ing, tape stock, vinyl case withlabels, shipping box and shippingcosts. We are doing this so thatother groups can have a "show-case" program of ATV public ser-vice.

Your cost is $20 post paid.NO VISA, M/C or COD.

Send your order to ATVQ,Rose Parade, 1545 Lee St., Suite73, Des Plaines, IL 60018. Allowtwo weeks for postal delivery or1 week for UPS. If surface parcelpost is not fast enough for yourneeds, you are welcome to paythe freight for air delivery. Ship-ping weight is 2 pounds. FOB Chi-cago. This program is not availablefrom any other source.

PAGE 9

When showing long video tapesor retransmitting Space Shuttleflights a need for an automaticvideo identifier becomes necescary.During the last shuttle mission Iused this circuit to turn on andoff the VDG-1 video LD. board.Every 10 minutes the computerLD. would automatically come onfor 10 seconds. The only problemoccurred during the landing. Justas the shuttle was about totouch -down my LD. came up!! Ihaven't heard the last of that oneyet. The value of R1 determinesthe Relay On -time and R2 deter-mines the Off -time. Also by chan-ging the value of Cl differenttime delays can be obtained. Forexample by changing Cl to 33uFI was able to set up the balloonexperiment for 30 seconds of com-puter LD. and 2.5 minutes of livecamera. Use of a tantalum capaci-tor for Cl is recommended forbest accuracy.

VIDEO I.D. TIMER

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ERCOF

CFELCO BLDG)

10 GHZ

MOBILE 1

04:0

AIR 1

MOBILE 2 -J

419 1.1.J

CC SUB -REPEATER

/V.134 MHZ INPUT

"s

BLVD afo

CC3NVENTICN CENTER(SAFETY/SECURITY)

< 923.25 INM 434 OUT

CCccwi7)

ATV SYSTEM LAYOUT - 1989

ALL FIELD UNITS TRANSMIT VIDEO ON 434 MHZ.

PORTABLE REPEATER RETRANSMITS ON 1265 MHZ AMAND (2) 10 GHZ FM LINKS.

VIDEO AT TOURNAMENT HOUSE AND AT CONVENTION

CENTER IS CABLED TO ALL MONITORING LOCATIONS.

COORDINATION IS BY 2M FM


ROSE PARADE ATV COVERAGE UPLINKED VIA SATELLITEBill WB8ELK

An MV first occurred duringthe 100th Rose Parade on Jan. 2,1989. ATV'ers across North Ameri-ca were able to watch the cover-age of the parade by the AmateurTelevision Network (ATN) group ofSouthern California. Thanks to theefforts of Dave Steinfeld, WA6ZVE,a satellite uplink was provided onGalaxy 2, transponder 5 for twohours of live coverage. The paradelasts about 5 hours from srtartuntil the last float gets to theend of the route. Michael Landonstarted the activities rolling withan entertaining introduction toATV. Phil, WB6LQP described theAmateur Television Network andsome of the past events it hascovered. Ernie, WB6BAP then show-ed us his portable ATV repeaterand some of the equipment neces-sary to follow the parade alongits route. The extensive networkof portable and mobile ATV sta-tions along the 6 mile long paradeprovided detailed coverage of anyemergency or float breakdown toallow parade officials, police andmedical personnel an immediatetelevision view of the problem.Thirteen portable ATV stations on434 Mhz were situated at inter-sections along the route as wellas two Motorcycle Mobile ATV'ers(Mobile 1 and 2) and even a heli-copter piloted by Tom, W6ORGproviding spectacular aerial shotsof the parade. The heart of thesystem was the portable repeateron the roof of the six -story tele-phone company building. The re-peater received the signals fromthe remote camera positions andrelayed them to the emergencyservices area and the WrigleyMansion (Rose Parade Control Cen-ter) via microwave links on the10Ghz and 1.2 Ghz bands. Ernie,WB6BAP used a small beam on theroof of the telephone companybuilding to provide additional re-ceive gain when needed for dis-tant stations and the helicopter.Occasional glimpses of Ernie andthe repeater could be seen duringthe satellite uplink. Due to inter-vening buildings a sub -repeater(923.25Mhz in - 434 out) was lo-cated at Camera 12 to relay Cam-era 13 at the extreme end of the


parade. Hank, WB6MEU was locatedin the Wrigley Mansion controllingthe video levels for satellite up-link. He was asisted by HenryKB9F0. He also routed the signaldown to the Control Center wherePhil, WB6LQP coordinated all theremote camera video on two me-ters. A FORTEL video processorwas used to ensure a good qualityvideo signal for the uplink. Fromthe Wrigley Mansion the processedvideo was sent via optical cablephone lines and microwave linksto the satellite uplink site. Thesatellite downlink was monitoredat the Control Center by Dave,WA6ZVE using the portable TVROsystem in his RV. The downlinkwas also received directly by hun-dreds of ATV'ers across the coun-try. The Mt. Diablo ATV repeaternear San Francisco and the Metro -vision repeater near WashingtonD.C. relayed the downlink so theirmembers could watch the action.

The ATN group of SouthernCalifornia covers many such events

the year which demon-strate the incredible public servicecapabilities of ATV. Thanks to allthose in the ATN group for show-ing me the setup (although I coulduse a new pair of shoes afterwalking the entire parade route!).Special thanks to Louise Candage,our dedicated ATVQ photographerwho obtained the photos in thisissue even after being lassoed byMonty Montana and nearly beingeaten alive by a Chinese Dragon!

NET CONTROL:Phil, WB6LQP

REPEATER OPERATIONS:Ernie, WB6BAP Hugo, KA6CGD

SATELLITE UPLINK Monitor:Hank, WB6MEU, Henry, KB9F0

MEDIA MONITOR:Dave, WA6ZVE, Gary, N6LIE

INTERLINK MONITOR:Don, N6IXP

SAFETY MONITOR:Jim, N6JXIAMATEUR COMM. COORDINATOR:Fred WB60ITK

HELICOPTER Mobile (AIR 1):Tom, W6ORG Rick, N6UEM

MOBILE 1:

John, KB6MMF Bud KB6MID

MOBILE 2:Jim, N5COT

CAMERA 1:Bob, N6AZV, Dave, WA6PMX

CAMERA 2:Jim, N6PFP, Jan, WB6VRN

CAMERA 3:Ed, N6KCB, Bill, KA6TCL

CAMERA 4:Allen, KA6WG0, Rick, KA6DAN

CAMERA 5:Warner, N6HNR, Gordon, N6RGS

CAMERA 6:Joel, KB6RXE, Larry, N6QZI,Patty Ruple.

CAMERA 7:Hugh, K6TIJ, John, W6QMB, JeanKraus.

CAMERA 8:Jim, K6KOM, Jeff, KB6GSA

CAMERA 9:James, KB6WUM, Sean, KB6WUK

CAMERA 10:Bob, W6LUY, Mark, N6KES

CAMERA 11:Wes, WA6IPN Mark, KJ6H

CAMERA 12:Gary, WB6VVV, Doyalene,WB6FLG, Jerry, KB6AQD, Mike,WA6SVT

CAMERA 13:Rod, WB9KMO, Koichi, KB6ELMike, WA6ILQ

PAGE 11

VIDEO REPEATER AN

Several Washington DC areaindividuals pioneered the devel-opment of amateur video trans-mission in the US and have oper-ated the Metrovision MV repea-ter for more than 15 years. Simi-larly, the Baltimore Radio andTelevision Society (BRATS) hasinstalled an ATV repeater and isvery active in the Baltimore area.

An excellent repeater locationexists on top of the Naval Acad-emy water tower which providesexcellent coverage of the localarea and links to the existing ATVsystems in Washington DC andBaltimore as shown below. A threephase plan has been proposed toallow incremental operating capa-bility as construction proceeds.

PHASE I, RECEIVER LINK:This phase installs a remote

receiver on top of the water tow-er to relay both METROVISION andBRATS ATV signals at 426 MHzonto 923 MHz to the Annapolisarea.

PHASE II, LINK TRANSMITCAPABILITY

This phase adds a 1296 MHztransmitter at the water towerrepeater site to link Annapolisoriginated MV signals into theMETROVISION and BRATS repeatersin Washington DC and Baltimore:

COMPUTER CONTROL PORTS:The VIC-20 Computer issed

both as the character/ID generatoras well as the controller and sch-eduler for the system. It will usetouch tone controls for operatorinput and has a packet input forSYSOP control f unctions. The char-acter generator will display thecall sign of the repeater, its loca-tion and also the operating modeand status to users. The computeroperates from a battery back-upuninterruptahle supply and mostcharacteristics and timing func-tions are adjustable by the controloperator over the packet link. TheI/O port assignments are as fol-lows:

INPUTST/T ACCESS ENABLEDT/T SELECT CAMERAT/T SELECT MODEREC CYNC DETECTEDPACKET SERIAL CB1/CB2

PAGE 12

PORTJOYOJOY1JOY2FIRE

D LINK SYSTEM FOR ANNAPOLIS MARYLANDBOB BRUNINGA, WB4APR

OUTPUTSW RX TO BEAMSW RX BEAM TO BALTSW RX FREQ923 XMT ON1296 XMIT ON W/923SW TX BEAM TO BALTSWITCH IN CAMERAAVAIL

PORTPBOPB1PB2PB3PB4PB5PB6PB7

OP MODE IN RCV ANTLOCAL rpt 439 quasi omni

METRO rpt 426 beam to DC439 selectable

beam toBaltomn

SCREENS AND FUNCTIONS: beam toPRIMARY IDENTinCATION Wash

SCREEN beam toOn for 20 sec after each access BaltDisplay Call Sign, 4 39 selectableDisplay Present Repeater MODE OP MODEDisplay Camera Status OUT ANT LINK

LOCAL rpt923 omniSECONDARY IDENatICATION

SCREENOn for next 10 secLists Trustee InfoLists Supporting ClubsPR Information of Interest

TEST PATTERN AND COLOR BARSCREEN

Alternates w/screen 1

ANNOUNCEMENTS AND SCHEDULEAlternates w/screen 2

SYSOP PARAM}TFRSDuring SYSOP packet access

PHASE III, REMOTE CAMERA:This phasP adds a remote con-

trol camera on top of the watertower to provide views of the twoRiver Bridges, and principal streetsin town to support public serviceevents. The camera can be rotatedthrough about 300 degrees in azi-muth and will present video whilethe repeater is not receiving anyuplink video. The camera will beremote controllahlo using touch-tone control signals over a twometer link.REPEATER/LINK CONTROL SYSTEM:

The majority of the repeatersystem is under the control of theVIC-20 computer which also provi-des the character generator andgraphics for video identificationand status reporting to the controloperator. The user control mecha-nism will be touch-tone over atwo meter simplex frequency. Therepeater will operate in a numberof modes as follows:

BRATS rpt 426

439

CROSSLINK 426

4 26

METRO rpt923 omni923 omni 1296 beam

to DC

BRATS rpt923 omni923 omni 1296 to

Balt.CROSSLINK

923 omni 1296 toBalt

923 omni 1296 toDC

923 omni 1296select

TOUCHTONE CAMERA CONTROLS:Focus, aperture, zoom,

left/right, up/downDTMF PAD

1

LEFT2 3 A

UP RIGHT FOCUS

4 5ZOOM DOWN

IN

6ZOOM FOCUS

OUT

7 8 9 CSEL SEL RSVD CLOSEMODE CAMERA

0ACCESS OFF OPEN

ATVQ DEVOTED ENTIRELY TO HAM TV

MODE CONTROL ALGORITHM DEFINITIONS:STANDBY LOCAL METRO BRATS

State MODE MODE MODE MODE LINK

STBY

omni rcv

lsec Fscan

permanent

omni rcv

439 rcv

T/O 10 min

M rcv 10 s

lsec Fscan

T/O 30 min

B rcv 10 s

lsec Fscan

T/O 30 min

omni rcv

lsec Fscan

permanent

SYNCRCVD

stop Fscan

xmit 923

if 426 thenA scan & stop

stop Fscan

xmit 923

stop Fscan

xmit 923


if 439 thenxmt 1296 M

stop Fscan

xmit 923


if 439 thenxmt 1296 B

stop Fscan

xmit 923


if M, xmt Bif B, xmt M

LOSSof

SYNC

hold 923 30show ID

scan immed

hold 923 30show ID

scan immed

hold 923 30show ID

hold 1296 2then scan

hold 923 30show ID


hold 923 30show ID


CAMERA

hold ID 2

then camerafor 5 min

on 923

hold ID 2

then camerafor 5 minon 923

hold ID 2

then camerafor 5 minon 923

1296 for 1

hold ID 2


on 923

1296 for 1

hold ID 2


on 923

1296 for 1

Washington DCcross link

METROVISION

From Wash

from phase Ilink rcvrs

426CONVERTER RCVR

From Balt Equip-ment located at water tower

Baltimore*\ BRATS repeater

\

Cross \link \\

\\\*Annapolis

923XMTR

AT WATER TOWER SITE

1296 ANTRANSMITTER

PWRAMP

to Wash DC

IIIIIto Baltimore


ATV OPERATING NEWS

Response to our last issuewas overwhelming. The issue hada circulation of 3400 and in lessthan two weeks after its releasewe received over 450 additionalsul-Acribers and stores were re-porting SOLD OUT. We receivedseveral hundred well wishes fromreaders which are much apprecia-ted.

We would like to thank all theclubs, individuals and advertiserswho sent us their rosters, localATV op lists and mailing lists thatmade it possible. With all the kindsupport and help we received thecirculation of this issue is evenbigger which has allowed us torun the full color pages and ex-pand the issue. Using proportionalprinting has allowed us to fitwhat would have taken over 100pages into this 68 page issue.

Since the last issue ATVQhas traveled around the countryand received a lot of mail fromreaders. The extra copies held atour office for late subscriberswent quickly.

ATVQ staffers visited severalareas of the US to meet withATVers and participated in thePasadena Rose Parade. There is acomplete story about that laterin this issue.

The week of Nov 20th to 26thfound Henry and Sylvia travellingto central Florida. Along the wayusing a 120 watt ATV transmitterand a 20 element H/V circularpolarized beam antenna workingATV'ers in Indiana, Kentucky, Ohio,Georgia and Florida. Best mobileDX was 70-75 miles to fixed sta-tions in Ohio. This was whilemoving down I 75. We were ableto get an eye of the storm reporton Hurricane Keith which cameashore at Treasure Island, FLwhere we stayed the night! Videotape of that shows flooding, treesdowned and our car rocking in thewind even though it was parkedin the shelter of the 2nd floordeck. Seen from the "safety" ofour room on the third floor whichwas flooded to 1" made for someexciting times at 1 AM as I tried

to figure out what I would do ifthe patio door glass broke in thewind! The wind was blowing thedoor jamb more than an inchapart which let the wind and rainin. Soon the floor was covered inwater and we were on the lee-ward side of the hotel! The nextmorning debris filled the beachand pool on the Gulf side of thehoteL Two days later we were inDaytona Beach chatting with theATVers there and getting hamshack shots of Bob W3EFG and VicW3LGV. We met Vic's new YL,June N4DWF. They were marriedonly two weeks before we arriv-ed. They met via ham TV.

We are happy to report thattheir repeater is doing well andthe FM interference problems arebeing worked out now that theDBARA is handling central Florida450 Mhz FC.

Bill WB8ELK took off cresscountry in his ATV mobile withstops in St. Louis, Kansas City,Wichita, Tucson, and So. CaL pluspoints between. Bill reports abouthis excursion a little later. Billand Henry met again when Henryflew out to LA to pitch in withthe 50 ATVers involved in thePasadena Rose Parade.

Bill went to Las Vegas for theCES show the following weekwhile Henry flew back to Chica-go. Bill reports on goodies soonto be available in the marketplace which should be of interestto ATVers later this issue.

Bill is continuing up theCalifornia coast and will returnto the mid west through the south-western states.

ATVQ HAMFESTSATVQ will be in booth 361 at

Dayton so look for Henry, Sylviaand Rill. Henry has plans comple-ted to leave Dayton saturdaynight to fly to England to be atthe BATC convention which is onSunday coincident with Dayton.Look for a first hand report aboutthe BATC and hamfest "jet lag"in the next issue.

DAYTON ATV FORUM1445-1700 ROOM 3 SATURDAY

Topics: 70 cm full duplex orrepeat with 33,23 cm Tom W6ORG;

ATV from a 71b 100" long highpower rocket Bob Rau N8IYD;

250 watt ATV TX for 3.5 Ghzfor under $200, Dave PacholokKA9BYL

ORLANDO will also have anATVQ booth with Henry in atten-dence. Henry will also be aspeaker at the ATV forum at Or-lando Hamcation.

ARRL NATIONAL CONVENTIONARLINGTON, TEXAS

June 2-4 will have ATVQ technicaleditor Tom O'Hara W6ORG manningthe ATVQ booth.

The "crazy ATV'ers" at ATVQwill travel almost anywhere toreport on ATV activity. To inviteus to your ATV/hamfest just dropus a line with the details. We arecurrently drafting an agreementwith the York PA hamfest tosponsor an ATV forum. Positiveplans will appear here.

WB2OSZ John Langner ofChelmsford, MA wrote to say heis on SSTV using a homebrewinterface software for an AtariST Computer. Maybe we can getJohn to do an article about it forATVQ!

Bob Raynor W6LUY is Simi Val-ley, CA wrote to say he is on440,900 and 1250 ATV and alsooperates ATV from his Cessna182! We hope to get some pixsoon of his Aero ATV operation.

Sylvia chats with June & Vic about ATVin central Florida.


ATV OPERATING NEWS

ENGLANDAndy Emmerson 71 Falcutt

Way, Northampton, England NN28PH G8PTH is looking for testpatterns and station ID slidesfrom broadcast TV stations. Any-one out there with access tocast-offs? Andy would most ap-preciate being able to add anystations to his collection. Andywill pay postage or let him knowif you want anything from Eng-land. Had a very nice telco qsowith Andy which resulted in theinvite of ATVQ to England forthe BATC conference.

BOSTONIn the last issue we men-

tioned the TV guide articles aboutham TV. The August 27th iP-iestory was started by a phone callto Henry Ruh (Sr) who then putTV guide in touch with Henry Ruh(KB9F0) who then supplied muchinfo and leads to the other folksin the article. We received a verynice thank you note from Joan-marie Kalter the TV Guide staff

releases were sent by Henry toall the ham magazines. WorldRadio and at least 1 of the "bigfour" reprinted the pre. release.Copies were also sent to thecommercial network anchors atABC, NBC and CBS NYC, and localstation news departments of net-work stations in cities wherepeople in the article live. Thebest resunse was when NBC Nigh-tly News visited Ron K3ZKO inPhilly and ATV received a fewpriceless minutes on Brokaw's showon Nov. 3rd.

We mentioned in the last is-sue that TV Guide had also dida story about the WR4AAG (nowWA9GVK) ATV Repeater back in1974 when it became the firstATV repeater in the country. Nowthat is a long lead-in but nowthe real story.

Mel Dunbrack W1BHD (his callsince 1923) sent us copies of whatwe now believe to be the veryfirst mention of HAM TV in TVGuide Magazine. JULY 18, 1952features a story about Mel's beinga "Video Ham". The story tellsof Mel's ATV station and some of

his equipment of the day. Melsays he is still a "Tube" man butis trying to convert.

For those able to visit, Melhas a TV museum at home withthousands of items he has col-lected. These date back to 1900!Equipment from all era's and mod-es of scanning adorn his homemuch of which was featured inAPRIL 1951 QST! Mel's first ATVrig was a Scanning Disc in 1928-1929!! Can anyone top this?Thanks MeL

CONNECTICUTN1FHN and KA1KHZ in New

Haven report simples ATV activi-ty on 1285.25 every wed. 9 PM-10pm EST. They beam north from9-9:15, east 9:15-9:30, south 9:30-9:45 and west 9:45-10:00. Espe-cially looking for novices.

MINNESOTAJustin E. Spinier KOGNH of R2

Box 101 Owatonna, MN 55060 isin great need of a MC790P IC ora replacement. Can anyone help?

Roland Paulson KBOGL ofMinneapolis wrote to tell us thatATV got a boost in the twin ci-ties when the channel 5 10 PMnews crew visited his shack. Theygave his ATV operation 2 minuteson their newscast. He reportsthat lots of folks called him tosay, "saw your ATV on channel5!"

Roland works both 439.25and 910.25 ATV with a D1010amp on 439 and preamps on bothbands.

ILLINOISK9PDX has a new call, NZ9E.

Dave Miller of Niles is currentlya RX only ATV'er but has operat-ed SSTV for many years and regu-larly works Pitcarin island andother rare spots on SSTV. Davealso QSO's using a public accessVHF satellite which is used toprovide communications in thesouth Pacific islands which otherwise lack communications service.Dave's YL is Sue KA9UCK.NEW CHICAGO ATV RFT EFFORT

According to K9SUN, ACLRa club in Chicago has been an-nouncing its intentions to buildan ATV repeater using 439.25 Mhzinput and 910 Mhz output. Com-

plete plans are not available atthis time. However the ACLRgroup has FM repeaters on 10, 6,2, 220, 440 and 1296. The ATVrepeater will have a primary in-put on 1280 Mhz especially forNovices.

PEACOCK ATV CLUBAfter two and a half years

of trying PATC received its co-ordination from the Illinois Re-peater Association for its pro-posed ATV repeater in Chicagoutilizing 923 Mhz input and 427.25Mhz output. The group is nowlooking for its 6th site hav-inglost five due to the time de -laycaused by the IRA. PATC will co-operate with ACLR to providecrosslink operation and both willuse VERTICAL polarization on 900Mhz to be compatable. Both willhave HORIZONTAL on the 440 Mhzband.

ANECDOTE OF THE MONTHBill WB8ELK spent a week at

the ATVQ office and worked anumber of stations from HenryKB9FO's ham shack. ATV contactswere made to Madison, Milwau-kee, Davenport, several Ohio andMichigan stations up to 300 milesaway on average band conditionswith solid P3 -P4 pix. On the lastmorning while removing some ofthe equipment to go mobile wenoticed that the RX antenna leadfrom the down -converter hadbeen plugged into the earphonejack of the TV set. We can hard-ly wait to see what happenswhen we connect it to the AN-TENNA jack next time! Seems theJr. Op Chuck had been using theTV set for computer display andhad moved the cahlp for dad!

NZ9E


MORE ATV OPERATING NEWSCALIFORNIA

The last space shuttle launchand landing and Pasadena RoseParade was carried live on theW6NKF repeater on Mt. Diablo.Many comments on the Rose Par-ade program were heard on thelocal repeaters all of them con-gratulatory. Hats off to the So.Cal group (ATN) for a job welldone!

The Black mountain group inSouth Bay have been busy ontheir antenna system. An experi-ment at linking the Diablo ma-chine by picking up the 427.25Mhz output showed a better an-tenna may be needed at theirsite. Also a pasqiblp solutionmight be a 900 link to the southbay area.

Up in Sacramento, Jim N6HOSand Bill WA6QIX have come upwith a 900 machine on the airand at a fairly low level site.Jim has linked it to Diablo on1200 several times allowing someof the locals access to the moun-tain top. Coverage from the Dia-blo site continues to amaze view-ers. P-5 pictures at 100 milesaway with a D1010 amp pumpingout 80-90 watts on 427.25 andcable ready TV sets hooked to anoutdoor R/S corner reflector an-tenna. Tune to cable channel 58and you have pictures. Best DXinput to the repeater so far isBill WA6VZG coming in P5 on1264 from Pine Grove in the Si-erras some 80 air miles away.

Current plans are to improvethe 1264 receiver system on theDiablo machine and add a timebase corrector to the video chainto clean up the incoming signals.Currently in the works is themodification of the 30 watt com-mercial transmitter strip to fur-nish a separate aural transmitteron 431.75 with a combiner to usethe same antenna as the big boysdo. This will allow better picturepower and no sync buzz in theaudio channeL Also the separatetransmitter will increase the au-dio reception a bunch.

Coming up this spring a nonmilitary space shuttle launch willgive hours of shuttle video never

seen by the general public andlater the JPL Neptune flyby.Dates will be advertised as soonas we get them. 73 Don W6NKF.

Over 70 hams participatedin the 100 mile Angeles Crestrun. Last year ATV provided ex-cellent link coverage along theroute using low light cameras tofollow runners progress duringthe night. Starting at the Wright -wood ski area the race is atough one with a 19,000 footgain and 24,000 foot lass verti-cal change in the mountains withthe first 30 miles "at altitude"and the remainder over mountaintrails ending at the Rose BowLTemperatures in the 90's took itstoll as over half of the startingfield failed to complete the race.Eventually only 49 of the 107runners made it to the Rose Bowlwithin the 33 hour time limit.Many runners suffered from heatexhaustion causing stomach andmuscle cramps. Runners were sup-plied with food, water and me-dical aid at 15 checkpoints. Allrunners entry and exit times werepassed between adjacent checkpoints on 2 meters simplex toinsure none were lost or overdue.A remote base on 70cm FM loca-ted on Mt. Wilson (6000') relayedthe 2 meter reports and aid re-quests to the Sierra Madre Searchand Rescue HQ.

Excellent write up aboutthe ham radio and ATV publicservice was included in a writeup of the race in UltrarunningMagazine including a long poemby one grateful spouse who wasable to talk with and see herhusband at an inaccenoablP aidstation 6.6 miles away just aftermidnight 65 miles into the race.Fred K6KKD and Tom W6ORG op-erated full duplex ATV using 434and 1289.25.

PORTLANDFrom reports from WWATS,

Portland is about to get its firstATV repeater. Dennis Belles WA7-DRO is reported to be sponsoringthe repeater. Input is to be on434 and output on 1253.25Mhz.Location is yet to be determined.

VANCOUVERRobert Skegg VE7AII of Van-

couver B. C. has an ATV repea-ter that he has been testing.Robert is looking for a site. Themountains above Vancouver wouldprovide excellent coverage forATV providing international ser-vice. Not much else is availableat this time except that Bob hasan ATV station in his RV. A fewmonths ago he treated SeattleATV'ers with live video whiledriving his RV ATV.

Three or four stations are re-ported to be on the air in Yaki-ma according to WWATS.

VE7G0 in Victoria B. C. isalso active and providing SeattleATV'ers with DX from the "GreatWhite North". George often beamssouth on 434 Mhz and normallyworks 100 mi into the US. Georgewas at)10 to get equipment fromseveral WWATS members to getATV started in Victoria.

WWATS reports it is now in-corporated as a non-profit Cor-poration in Washington. The effortwas carried by Chuck W7SRZ,Dick W7TWU and Bob KG7E.

At their November meetingguest speaker was Dr. AlanChancl1Pr of AEA who spoke onATV equipment design.

Look for ATVers on 146.43,443.55 or 224.68 in the westernWashington area. Thanks WWATS.

Bob - W3EFG Full Color CQ.


MORE ATV OPERATING NEWS

NEW YORKCarmen DeVito WA2GYX is build-

ing an ATV repeater for easternLong Island. It is to operate on434 in and 421 out. He has beenexperimenting for two years onthe project. East -ern L.L hamsinterested in ATV should contactCarmen. He reports that hams inwestern L.L have been using theNYC ATV RPT but eastern L.Lhams ED W2WIA, Frank W2ORMand Carmen are trying to getactivity going in their end of theworld, closer to RI and CT thanNYC! Hams in the northeastshould tune down to 421 and lookfor the test videos. Carmen isvery interested in getting recep-tion reports. Carmen is retiredfrom broadcasting and buildsmuch of the equipment fromscratch.

NYC area AIV'ers are reportedto be on 147.45 for audio.

TEXASAustin Texas ATV RPT soon to

be on the air after a great ef-fort Approval for the antennasite on a tower is Westlake wasreceived January 9th. The toweris 100 feet high and sits on a1000'+ hi11. They report 7/8" and1 5/8" coax is already in place.Initial testing will be at the QTHof N5MHL A graphic ID board hasarrived with four W5VDS/R id's.Bob WA2TMD designed the EPROMstored graphics.

GETTING THE BUGS OUTAfter the site problem was

solved the group set about tosolve a desense problem in theATV equipment. The receiverworked superbly well but whenthe transmitter was keyed a P5signal became Pl. Obviously theRF did not know that the Ham-mond boxes were "RF tight". Thefirst approach was to make surethat the audio and video inter-connecting cables and coax tothe duplexer cavities was 100%shielded.

Frank Davis W5VDS assem-bled new cables using high gradeRG58 with BNC connectors foraudio/video and 9913 with N con-nectors for the RF lines. Also PatWA8PLR improved the by-passing

on the transmitter with betterground connections. This made aperceptible difference and if yousquinted at the monitor it wasalmost Pl. A couple stationscould see some hazy outlines onthe output frequency. After someserious head scratching aboutwhat to do next the observationwas made that when the videoline to the transmitter was dis-connected much of the "desense"would disappear. Did this meanthat RF was travelling from thetransmitter video input to thereceiver video output? A look atthe transmitter on Frank's spec-trum analyzer confirmed thatthere was indeed a lot of RFpresent on the video input.

Frank came to the rescue witha handful of filters of unknowntype. We looked at the output ofeach and found some that atten-uated the UHF RF and left thevideo untouched. Was this thesolution? Not yet. The followingweekend Glen Dawson WA5ZNTand Pat WA8PLR went into des-peration mode and tried everytechnique imaginable to isolatethe video line including using hisVCR as buffer amplifier, RF cho-kes, optical coupling by shootinga monitor with a camera. Frankreported from Wimperly that hehad found a bonafide 100 Mhz

filter and we jumped inthe car and met him half way topick it up.

None of these experimentseliminated the desense but theydid convince us that RF on thevideo line was not the primaryculprit.

The next weekend GLen, Frankand Pat set out to tighten upevery thing that could conceiv-ably allow RF from the trans-mitter to get into the receiver.New 500 pf feed -through capswere ordered express from Chica-go and installed.

An outboard box for the BNCand bypassing was attached tothe receiver, shielded power ca-bles, mini -hardline, connectors,lots of shielding tape and similaritems were added. Did it help?Yes! There was noticeably less

desense but still not adequate.As for color and sound.. don't

even ask. Pat's suspicion wasturned to the duplexer cavities.Were they just not doing the job?He called Beaumont, Steve GomesKE50 who has an ATV repeaterthere. Did he have any sugges-tions for the RX/TX isolation andconstruction techniques? It turnedout we had already tried all thestandard techniques. But he didsuggest looking for leaky spots inthe boxes and lines. We did trydifferent configurations and withthe interdigital filter between thetransmitter and amplifier the de -sense was totally gone!

The PC exciter is very wide -band to the point of being slop-py and filtering before the stuffreaches the amplifier is very im-portant.

Kenny Guillot WBSJLZ in BatonRouge was then called as he hadconstructed his ATV repeater withthe same TX/RX duplexer. Kennywas very eager to help and out-lined problems that he had en-countered with desense. He haddiscovered that the final trim capin the transmitter was very criti-cal and could giveth and takethaway the desense. An amazingdiscovery!

Finally on Jan 8, Jon PennerN5MHI and Pat worked on provid-ing shorter RF paths to the du-plexer and further tuning at hisQTH. With more tweaking andcursing! Finally we saw color onthe output. WOW! Bill WehlingKF5NB reported seeing a red blobon the image of the Corvette wewere shooting. More tweaking andhe could see it was a car. Sofar so good. Still barely detect-able, distorted audio. Ron PiersonKG5BZ ran the test with the au-dio and we found the right placefor the subcarrier injection leveland there was audio that soundedpretty good most of the time.

So a lot of progress hasbeen made but there are still abunch of bugs that must beworked out Thanks to everyone.From the Austin Amateur TV Clubnewsletter, "Camera Amateura"Joe Fisher K5EJL, editor.


STILL MORE ATV OPERATING NEWS

LOS ANGELES AREAAfter almost two years, the

Mt. Wilson ATV repeater K6KMNis back on the air. Doug Moonreports that many "old timers"are comming back on and gettingtheir rigs out of moth balls. Therepeater has been improved withnew racks, improved rx/tx equip-ment and new coax.

As of July 4, 1988 a newMonday night ATV net has beenstarted. So far the response hasbeen very encouraging. Time is8 PM through the Mt. Wilson 1241video and 146.43 FM. Typically15-20 video check -ins each nightplus several more 2 -meter onlystations.

Rose Parade video was airedwith excellent results. As wellas the NASA repeated video ofthe last shuttle landing.

Future plans include a link tothe high desert alternate frequ-encies and higher output. Sugges-tions and persons willing to helpshould contact Doug at PO Box40, Mt. Wilson, CA 91023. Phone818 440 1116 (work). The repeat-er input is 434 Mhz and requiresTV sync. Output is 1241 videowith +4.5 audio subcarrier. TheFM repeater is 449.30 Mhz (pl)and 146.43 audio is on the ATVID. TNX K6KMN.

DENVERNOIVN Ron Hranac reports

that the ATV'ers in his area gottogether and transmitted BTSC(Broadcast Television Stereo Com-mittee) stereo on FSTV. This isthe first effort we know of totransmit stereo TV audio on hamTV. Using CATV equipment theytransmitted morse code on theleft channel and voice on theright channel while full video wasalso being transmitted. They re-ceived some publicity for it incable TV industry publications.They are now experimenting withSSTV on the SAP (Second AudioProgram) to add a third audiochannel to their signal. Ron usesconverted cable TV equipment inparts of his station including amodified line extender to boosthis exciter to 1 watt on 450Mhz.Ron's DX record is 11 miles on

10 milli -watts!! Ron also worksSSTV.

CLEAR LAKE CALIFORNIAW6LOU Clear Lake California

100 miles north of San Franciscohas a new ATV repeater! Loca-ted at 2000' altitude with an in-put of 434.00, 911.250 and 1252Mhz and an output of 426.250.The location is near Mt. Konoctiand covers the Clear Lake, Sac-ramento area. They are limitedon output power because of USAFat Marysville, CA which causesinterference on UHF.

MINNESOTA ATV ACTIVITYMIKE HERTEL, KAOMIV

I would like to report on thenewest ATV activity in southcentral Minnesota. I am runninga P.C. Electronics TC70-1 into aMirage D24N with a 10 elementKLM beam antenna up 60 ft withgood 9913 coax all the way.Since first acquiring this equip-ment at the 88 Dayton Hamven-tion, I have used it during FieldDay activities with the MankatoArea Radio Club aone-way video link with the St.Peter Area Radio Club Field Daysite just 12 miles north. It work-ed great. I believe this was thefirst ATV activity of its kind totake place in south central Min-nesota. Since then another ATVstation has been put on the airby my friend Dave Miller, MBOKV.He is also running a P.C. elec-tronics TC70-1 into a MirageD24N with a 27 element KLMbeam at the other end, heightabout 40 D24N with a 27 elementKLM beam at the other endheight about 40 ft. So far theQS0's have been great, with anylocal hams now using cable readyVCR's and TV;'s for receivers toshare in the fun.

I'd also like to report that asa result of our local activity, asmall group of about 4 hams inWaseca, Minnesota, some 30 mileseast of Mankato have formed anATV group and have been re-transmitting NASA shuttle video,using a KPA5 from P.C. Electron-ics and Mirage amp. The group isspear headed by Denton Larson,WBOAUR of Waseca. I wished I

had more details, but we areworking towards establishing apermanent 2 way link from Man-kato to Waseca.

I should also mention that a-nother ham, Dale Cordes, WDOBWPof New Ulm, Minnesota, has join-ed the ranks with a TC70-1, Mir-age D24N and 10 elements. NewUlm is 30 miles west of ManKatoand some P1 to P2 pictures havebeen exchanged between KBOKVand WDOBWP. We are still work-ing on improving that one.

That's the report from here,except to say that the challengeis out to the Minneapolis ATVgroup to establish a 2 way ATVQSO with anyone down here insouth central Minnesota. After allit is only 70 air miles from Man-kato to the Twin Cities. Any ta-kers up there??? We will do allwe can at this end, so let usknow.

BRITISH COLUMBIAORIN BEEBE VE7BEE

In South Central British Col-umbia, aboutwest of Spokane, Washington, liesthe Okanagan Valley, home of anew group of ATVers, based inPenticton and Summerland, B.C..This group has been on ATV onlyjust over a year, but they areadding new members at the rateof about one per month! That'spretty good for this area of Can-ada where the total ham popula-tion of Penticton and Summer -land --maybe 40 hams. We haveabout tweleve amateurs active insome capacity on ATV, mostly onreceive and with a few, ofcourse, with transmitters andcameras, etc. Typical terrain ismountainous region with softpeaks common; some are 7000 ft.Due to the Okanagan Valley run-ning north and south, we havesent pictures about 20 miles withonly 10 watts and small yagis ateither end. The gorup hopes tohave a 70 cm in 33 cm out ATVrepeater (crcIss band on the airsoon) operational in June of thisyear. This will allow more ama-teurs to join in the fun. Our sys-tem which we will be using isunique in some respects and I


STILL MORE ATV OPERATING NEWS

thought that we should pass alongthe information. The reason forus as a group for coming out on33 cm is two fold. 1) To allowthe use of full duplexing of sig-nals, in and out can be seen atsome time, 2) to allow for thecontinued use of our very lowcost down converters. I discover-ed that by using a 2 MitisumiSatellite Receiver Block DownConverter, the type that used tobe found in the older receivers,that we could tune the 439.25Mhz ATV channel and the 911.25Mhz ATV channel with one con-verter. How, you ask? Simple. The"old stuff" satellite downconver-ters such as those used in Ander-son and other makes tuned a 500Mhz wide frequency range from420 Mhz to 920 Mhz or from 450Mhz to 950 Mhz. (The secondrange can be converted by squee-zing the first oscillator coils to-gether lowering the frequencyrange.) The new satellite downconverters in the new receivers,

70 cm but willwork from 33 cm up to and in-cluding 23 cm. I have tried thelatest ones which tune from 950Mhz to 1450 Mhz and it worksgreat on 23 cm with a two pre -amp for extra gain. Our typicalreceive set-up here in this areais as follows: (see fig.) Workedup to 10 miles snow free from 10w transmitter with color. Thissystem has worked great. It isnot the most sensitive systemsfor receive, but it is one of thecheapest. Since most of the planswanted to keep the initial costdown of setting up to receive,we thought we would go thisroute: Approx. Total Cost as Fol-lows: 1 -Radio Shack Corner Re-flector for UHF or antenna craft:$15 Soft coax R659 foam withconnectors $10. One Radio Shackor surplus satellite coax preamp$15. One surplus Mitsumi D.con-verter: $20. ATV Receive TotalCost $60. (you supply box forD/converter and 12 VDC). $60 fora dual Band ATV receive set upthat works good. Seems like awinner to me! Anyway in cluingif there is enough interest, I can

supply additional source materialsfor D/converters / pre -amps,write me directly.

As for 23 cm TX goes, othersand I have been using P.C. Elec-tronics transmitters and Tom'sstuff works good for us up here.Hope this information will help.Some hams out there that go toflea markets and surplus housesget on the ATV mode. 73's. Seeyou on ATV. VE7BEE ORIN.

BATC CONVENTION 1989NEW VENTURE

The BATC Convention will beheld on Sunday April 30 between10am and 4pm at the COVENTRYCREST HOTEL. The hotel is loca-ted adjacent to JUNCTION 2 ofthe M6 (Coventry South). The clubhas booked the entire FOUNDERSSUITE, which is a custom builtconference center. One advantageof this venue is that the suite isseparate from the main concourseof the hotel, thus our 'activities'will not cause any disruption tothe normal running of the hotel(at least that's the theory!). Ano-ther advantage is that there is agreat deal more parking space,which should help alleviate someof the problems we have had atCrick. Due to the nature and sizeof the venue we shall not be us-ing a marquee this year. The ho-tel management have agreed thatthe usual impromptu car boot salemay take place in the car park.A full lecture program is intendedand this will be held in a separ-ate room within the hotel. Pleasenote that the doors will not openuntil 10am.

Owing to problems with theSunday trading laws that havebeen looming over the club in thepast, we are having to introduceentrance by program only thisyear. The programs will only beavailable at the door and willcost the vast price of 50p. Thiswill allow us to ensure that allattending thee rally are membersfor the day at least, thus anysales/purchases are then cla'nedas 'mutual trading', which is al-lowable on Sundays. Families willonly need to purchase one pro-gram, as will adults accompanied

by children under fourteen. Con-sequently, this change will meanthat people will be required toman the doors throughout theday, so all volunteers will begratefully welcomed.

The now standard feature ofthe "Bring -and -Buy" stall run bythe GB3RT Repeater group willagain be present, creating theusual state of mayhem around thestall. There will be a slightchange to the B&B this year, inas much that there will be a no-minal registration fee of 50p peritem, refundable upon sale. Thisis due to the amount of aban-doned equipment that the grouphas had to contend with afterthe show in the past! The com-mission will remain the same at5% or 50p.m, whichever is thegreater.

Another new feature, or atleast a revival of an old one, isthat we would like an exhibitionof home-brew equipment If youhave anything associated withamateur TV which you would likethe rest of the club to see,please bring it along. The clubshall award a price for the bestexhibit and this shall be judgedby members of the committee.

A 'surgery' will be held wheretechnically qualified members willbe on hand to answer your ques-tions and help with any problems.Again volunteers will be welcome.

Finally, and I offer no apolo-gies for repeating myself, pleasedon't leave it all to the commit-tee; there are only 22 of us! Or-ganizing and running a conventionthe seize of ours requires a greatdeal of forward planning and agreat deal of work on the day.We need VOLUNTEERS to help manthe doors and generally assistwherever necessary. We don't ex-pect anyone to offer a whole day(unlike the committee does ofcourse!), but a couple of hourswould be ideal. PLEASE do notleave it to the other guy; offera little help. Your committee willbe forever grateful. (See fig.)

If travelling to the conventionby rail, journey to Coventry sta-tion. From there a regular bus


service to the central terminusoperates. Then take a bus tot heWalsgrave area.

If travelling by boat, the Ox-ford Canal (Northern section) pas-ses through Ansty three miles outof Coventry on the A46.

If arriving by air, BirminghamInternational Airport is 12 milesaway to the north on the M6.

A talk -in station will again beoperating, provided this year bythe Coventry Amateur Radio Soci-ety, to whom we offer our grate-ful thanks. The station will beoperating on $22 (2m) and possib-ly SUB (70cm) and will be usingthe special call sign GBOTV.

ATV IN PARADISEHAWAII'S FIRST ATV RPT

AH6I0 Richard is putting togethera434 in 421.25 out ATV repeaterfor the Honolulu area. It is in-tended to go up on Diamond Heador atop one of the high rise Wai-kiki area hotels. So if you everplan a vacation among the palmtrees and hula girls, take yourATV gear along and check withthe gang at Honolulu Electronics.

FOR SALELarge collection of broadcast ty-pe audio and video equipment.Unless otherwise specified equip-ment is like new. Most of themicrophones are flat black or nonglare finish. Price for all equip-ment is best offer or swap forcertain ham gear or broadcastgear. WANTED: LARGE HF AMP,160-10 FULL LEGAL POWER, NOJUNK, OR HIGH CHANNEL TVTRANSLATOR, MINIMUM 100 WATTSOR C BAND UPLINK HARDWAREOR 2 GHZ COMMERCIAL ICR TVRELAY TRANSMITIER/RECENER,ENG viewfinder for Sharp XC-820P pro camera. Also battery orAC supply for camera. (12 volt -15 volt, type 7700 battery).FOR SALE OR SWAP: Prices indi-cated are asking price or swapvalue.

. Panasonic 200 3/4"Canhasin -OK.make

tnew ma

ies for QCD not6 months. $350.

TBC,edit. Videobut works

Used tod in

EVEN MORE ATV NEWS!

2. CBS model 1602 stereo audioDA 600 Ohm Z, 1 x 8. Veryclean. Works fine. $2003. CBS 4440 mono Audimax.Very clean, works fine. $2004. Ward Beck M605A audio DAand DA tray. Like new. 600 ohmin/out 1 x 6. $1505. International Nuclear Inc.Video DA. 8 units, 3 are 1 x 4and 5 are 1 x 8 All are loopthrough input (bridging) All havepulse/video select, gain and eqcontrols. All working OK. $50each.6. NLS (Non -Linear Systems)miniscope, model 215, dual trace,15 Mhz. Fine portable scope.Runs on ni-cads, with chargerand probes. X -Y and usual dis-plays. $250.7. Cetec Vega wireless mictransmitter, receiver, Sony elec-tret mic, ant, (Pro/R33) completeon 170 Mhz. Like new retail over$2200, Asking $1000.8. Sony ECM55B mini lavaliermic, black, like new, $100.9. Neuman BS945 phanthom pow-er supply for mic, like new, $7510. Neuman N452 fet 80 dualpower supply, like new, $10011. Shure FP32 stereo mixer,like new, $600.12 Shure FP12 headphone bridingamp and "IFB" type talent ear-phone. like new, $150,13. Shure FP11, mic to line levelamp, like new, $150.14. Shure 512 mic/headset, minorcosmetic scratches $5015. Audio Technica 4071 capaci-tor shotgun mic with windscreen$1200 list, asking $600 like new.16. Audio Technica 835 electretshotgun with windscreen, $700list, asking $400.17. Audio Technica AT 4073shotgun with windscreen, $300.18 Sennheiser ME80/3KU/MZW30shotgun, power supply, wind-screen. $300.19. Sennheiser MKE2-2R microlavalier, black. $150.20. Porta-Brace bag, modelcc505P, slight wear, holds proENG camera or other goodies.$10021. Collection of Audio Technicamic cables. $50 for lot.

22. Tektronix 529 rack mountbroadcast waveform scope (asreceived back from QCD) wasworking when I lent it to him,came back missing fns'. $75.23. Whiteway Sign computer/con-trol terminal. $50Items 7-21 are owned by Chicagopro video shooter getting out ofbusiness. For any/all above, con-tact: Henry KB9F0, 540 E. Oak -ton, Des Plaines, IL 60018 312298 2269.CLASSIFIED ADS IN ATVQ AREFREE TO SUBSCRIBERS.

KB9FO ARRAY.

DAYTON ATV PARTYATV operators are invited to enjoy

and enter a Home Brew Contest andcasual QSO party while at the DaytonHAMVENTION and win prizes forHome Brew ATV projects.

Amateur Television QuarterlyMagazine (ATVQ) is sponsoring a Fri-day night, from 7:00 p.m. to midnight,ATV OSO party and Home Brew Con-test at the Travel Lodge Motel (former-ly La Quinta). The Home Brew Contestis open to Ham TV projects and prizeswill be awarded including $100.00 firstprize.Free coffee, soft drinks and snacks

as well as display tablesfor Home Brew Contest entries.

Entries must be accompanied by a short write-up not to exceed two typewritten double-spaced pages. Other prizes to be announced.


A NEW HAM TV MAGAZINE

Amateur Television Quarterly. A high quality technically oriented ham TV magazine.

PROFESSIONAL STAFF FOR EDITINGIn the tradition of the BATC, CO -TV, Ham TV in the US needs a technically oriented ATV magazine. Amateur TelevisionQuarterly is being started to fill this need. Each issue will cover technical subjects, build -it projects, equipment reviews,theory articles and operating news. Each issue will have virtually no editorial content except for FCC and operatingnews. Each edition will be edited by a professional staff of technical and journalistic experts. Not every item submit-ted will get published unless it passes our editorial and technical staff.

VALUABLE CONTENTThe first issue is expected to be out in January of 1989. Each Issue should be at least 48 easy to read pages. That's48 pages of useful information not 12 pages of ads for in house products and promotions.I Areas covered will beFSTV, SSTV, video and related subjects. Our internal text paste up is done on daisy wheel and laserjet printers . . . no

hard to read dot matrix fonts!

YOUR INPUT NEEDEDIn order to succeed we encourage your input. This can be In the form of articles, operating news, subscription orcomments. Amateur TV Quarterly will PAY for your technical articles. You won't get rich but it will keep you in typewriterribbons. Our initial distribution of 4,000 copies will make you famous! This may mean even more issues per year ifresponse is large enough! Well known ATV'ers have already submitted prime material for the debut issue.

YOUR RESPONSE PLEASE

I don't want to miss out and my subscrip-tion is enclosed.

Optional Info

DEVOTED ENTIRELY TO AMATEUR TELEVISIONoperate: FSTV SSTV FAX other

US Delivery Canada Elsewhere ATV/SSTV bands

$25

$45Phone (kept confidential)

$55 (all US Funds) Best ATV or SSTV DX$65

$70 Grid locator or Lat/Lon.

Call: Name: ATV RPT7 0TH

Address: Station Equipment

City:

State/Prov: ZIP: Country: Comments:

Gift? From: Call: Name:

1 YR $15 S20

2 YR $25 $40

3 YR S35 $55

4 YR $45 $65

5 YR $50 $70

Amateur Television Quarterly.1545 Lee St., Suite 73Des Plaines, IL 60018

One last advantage, a business phone you can call: 312 298.2269


FOX HUNT RADIO DIRECTION FINDERPaul Bohrer W9DUU

How often have you wishedfor a simple RDF which couldwork on just about any band andprovide you with both an auraland visual means of determiningthe direction of a signal? Youmay have wanted to find an er-rant transmitter, QRM source orjust have fun finding the "FOX"or more seriously search and res-cue or recovery. Now you can doit. The author is chief engineerfor WTTV channel 4 in Indianapol-is. He and several other ATV'ersin the area have built and usethe unit described here. Successin finding transmitters is easywith the unit. Recovery of WB8-ELK's balloon ATV transmitterswas done with these units. Con-struction is not critical just usegood construction techniques. Youwill undoubtedly want to build itin a rugged manner to survivethe environs of mobile/portableoperation and trekking throughthe wilds.

NOTES: Battery voltage =8when readings were taken. V onLM339 pins 1, 2, 4, 5, 6, 7, 13,14 depends on setting of VR 1 &2. Battery drain = 7 ma with nosignal and about 13 ma with sig-nal with either LED lit. Antennaand receiver jacks should bemounted as close together aspossible. Use short leads on thetwo .001 caps and the 4.7k resis-tor. Mount the 4.7k resistor atthe antenna jack. The length ofthe coax between the antennaand the switching diodes is notcritical however, they should beEXACTLY the same length. Withno signal, adjust the meter ZEROpot for zero meter reading thenadjust VR 1 and 2 so that theLED's just extinguish. With signalapplied rotate the antenna formax meter deflection. Adjust thereceiver audio level to just pro-duce full scale meter deflection.The size of the cap between pins2,6 of the 741 can be picked fordesired sensitivity. For example,a .05uF cap will require a highervolume setting on the receiver

for a full scale deflection thanwill a .001uF. Adjust the oscfrequency for equal left -rightmeter deflection with signal sup-plied. Use S4 in the "A" positionfor averaging meter flutter whenin high multipath areas and in"B" position to store LED left -right readings when DF-ing ker-chunkers. Leave the switch in thecenter off position for normalDF-ing.

PARTS LISTQuantity R/S P/N1 276-1718 555 timer1 276-007 741 op amp1 276-1712 LM339 cmos 5

276-1603 2N3904 or eqiv.2 276-1604 2113906 or egiv.1 276-041 red led1 276-002 green led1 276-168 pcb1 270-286 box (user choice)2 274-253 mini jack1 274-286 mini plug1 274-1565 coax jack2 278-239 SO -239 jack1 40-245 2" speaker2 270-325 bat snap conn.2 23-126 9V nicad bat2 270-326 9V bat holder1 272-1434 lmF 35v taut.2 272-158 / 272-135 .1mF1 272-157 / 272-134 .047mF6 272-126 .001mF use 3=.0033 272-156 / 272-131. OlmF1 272-957 470 mF 16V1 272-998 4.7 mF 50v nonpol2 272-1028 100mF 33v ele.2 271-339 500K min pot1 271-217 5K pc pot1 270-047 8 ohm spkr vc1 271-338 100K min pot3 275-625 mini spilt switch1 275-325 spilt center off1 271-019 470 ohm3 271-1330 4.7K2 271-1312 150 ohm3 271-1321 1K1 267-565 5.1V zener2 271-1335 10K4 271-1332 47K7 271-1347 100K2 271-1356 1 meg2 276-1122 1N9142 ecg 553 pin diode

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HETERODYNE FM TELEVISION TRANSMITTERBY DAVE WILLIAMS WBOZJP

This approach to FM Televi-sion as certainly not the onlyway nor is it neceocarily thecheapest way but it does make anice modular transmitter andserves as a building block tousing the same technique for the900, 1200 and 2300 MHZ amateurtelevision bands.

The transmitter consists offive modules. 1. A video amplifierusing an NE592 differential videoamplifier ic, the second module isthe FM60-70 MHZ modulator. Thismodule is based around the NE564 phase locked loop ic. Thethird module is the FM soundmodulator at 6 MHZ . The fourthmodule is a wideband IF amplifierusing the Motorola MWA120 wide -band RF amplifier module. Thefifth module is the heart of thetransmitter. It consists of thelocal oscillator, the double bal-anced mixer and RF amplifiers.

The idea of this transmitter isto build a high quality FM TVtransmitter complete with pre -emphasis network, FM sound gen-erator and FM video modulatoroperating at an IF frequency andthen up convert or heterodynevia a mixer and local oscillatorto the final operating frequency.In this way you can use onecommon IF FM transmitter tofeed various transmit mixers on400, 900, 1200, 2300 MHZ orhigher.

The first module is the videoamplifier. It uses an NE 592differential video amplifier chip.This has a band width of at least100 MHZ and an adjustable gainof 0-400. I used this choice be-cause it provides a good termina-tion for the video and has suffi-cient gain to drive the pre -em-phasis network. Frequency re-sponse was very good, showing nodisc-ernable high frequency roll -off.

The second module consists ofthe pre -emphasis network, whichconfirms to CCIR recommendation405-I for 525 line U.S. standardsand correctly matches the re-sponse needed for the de -empha-sis network used in the satellite

receiver used to receive the FMTV signal. The FM modulator hasseparate inputs for video and the6 MHZ audio subcarrier. Inde-pendent input pots are used toset the levels. A 10PF variablecapacitor is used to set theoperating frequency. This shouldbe set with no video and no sub -carrier audio signals applied.The range is roughly 40 to 80MHZ. I use mine around 60 MHZ.The output is very low, around-16 DBM. This design came fromC.Q. TV magazine.

The third module is the 6 MHZsound subcarrier generator thiscircuit was found in CQ-TV mag-azine and is by far the nicestcircuit I have found. It is quoteinvolved and a P.C. board layoutwould be nice, but I build mineon PERF board and it works fine.It is based around the RCA CA -3046 D.I.P. chip transistor array.

TR-1 and TR-3 from an emit-ter coupled oscillator. A portionof throughTR-2 and L-1 and frequencymodulate the oscillator. TheLM747 dual OPAMP is used as anaudio amplifier and is used as anaudio filter. Frequency responseis 60 Hz to around 10Khz. Inputimpedance is 10K OHMS and is atline leveL

The fourth module is a wide -band amplifier used to amplifythe modulator output to an ac-ceptable level to drive the dou-ble balanced mixer. The MWA120 is Motorola's equivalent tothe MMICS marketed by Avantekand Mini Circuits Labs. The 1DBcompression point is +8 DBM sorunning at 0 DBM is well belowthe compression point of the de-vice. It is class A device andrequires only an input and outputcoupling capacitor, bias resistorand bypass capacitor for the D.C.line. It is unconditionally stableand has around 14 DB of gain. Isee no reason why one of theAvantek or Mini Circuits MMICSwouldn't work just as well.

So now we have a 60-70 MHZFM TV transmitter with 6 MHZsubcarrier audio operating at

about 1 MW out. We now needto take this and drive a mixer toHeterodyne up to the frequencyof choice.

On 400 MHZ, I use a Hamtron-ics XV 4-9 transmitting conver-ter. This uses a local oscillatoroperating at 378 MHZ, an SBBL-1Mini Circuits doubly balancedmixer, and three stages of RFamplification. This unit worksvery nice and is also what i useon AM TV simply by replacing theFM modulator with a Dynair TX4AAM TV modulator.

On 900 MHZ, I use a localoscillator board developed by theR.S.G.B. (Radio Society of GreatBritain). This was featured inFebruary 1983 QST and is in theRSGB VHF, UHF manual. This op-erates with an overtone XTAL inthe 90 too 110 MHZ range. Theoutput is filtered to use a har-monic. This is fed to the mixer,and the output is filtered andfed to a Toshiba SAU-15 which

an SAU-11 900 MHZ powermodule.

I see no reason why a com-mercial trans-verter for 900,1200, or 2300 MHZ would notwork just as well.

So, this should give you abasis for a Heterodyne FM TVsystem. Hope you have as muchfun building it as I did. See youon FM TV.

COPYRIGHT NOTICEATVQ Amateur Television Quarterly. Copyright1989. All rights reserved. No portion of AmateurTelevision Quarterly in whole or in part may bereprinted without written permission of the copyrightholder. Publications in foreign countries mayreproduce portions of a current issue provided sourcecredit is printed in the heading of any such reproduc-tion and a copy of the publication containing thereproduction is sent to ATVQ.ATVQ editorial policy is to provide technicalmaterial of interest to those interested in visual com-munications. We invite contributions which are aboutany aspect of amateur television. ATVQ evaluatesall material published for accuracy, Constructionprojects are evaluated for likelihood of repeatabili-ty by another builder. Because of variance in con-struction technique exact results may vary depen-ding on the critical nature of some signals but aworking unit must have been built or demonstratedprior to our publication of an article. ATVQ makesno guarantee of a builders success. When additionalinformation is needed the article will indicate thatthe reader should contact the author prior to con-struction for additional information.


FM TRANSMITTER continued . . .

I.SK 12. VDc

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ELECTRONIC COMPASSBill WB8ELK

For those involved in T -hunt-ing, the Flux -Gate Electronic Com-pass model 63-641 sold by RadioShack should come in handy. Justmount the remote sensor on yourdirection finding loop or beam.The electronic compass mounts onyour dashboard and provides areadout of the true antenna bear-ing independent of your vehicle'sheading. You will have to extendthe cable between the sensor andthe readout unit however. Thisshould save invaluable time whentracking down those hidden sig-nals. Thanks to Scott Bovitz, N6 MI,of the LA T -Hunters for this info.

cMi-12- Avon rn1

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Continued on page 40

APRIL 1989 VOL. 2 -2MA- 120 ttlia.B,44 ZF

PAGE 25

POOR MAN'S SPECTRUMANALYZER/MONITOR RECEIVER &

TRACKING GENERATORImagine if you will, a single

piece of equipment that couldprovide you with the ability tobe able to: Check your transmit-ter output for "spurs". See if theband is "open" at a glance, orfind a quite spot on the band.Monitor ALL the local repeatersSIMULTANEOUSLY! Receive "on -carrier" or "sub -carrier" ATVsound. Examine Satellite TV sig-nals and their sub -carriers. (Cur-ious about those "secret" signalson the Cable?) Meal:lire the ampli-tude and frequency of RFT gener-ated by your computer, electricalappliances, etc. and instantlyevaluate the results of filteringor shielding. Orient and tune an-tennas (and antenna tuners) formaximum re:2111-s across a band offrequencies. Sweep an area forillegal "bugs". Identify modulationmodes such as AM, FM, SSB, FSK,PC M etc. Signal trace transmittersand receivers, check "gain perstage" when building or trouble-shooting and test for harmonic orintermodulation distortion. Tuneantenna dupiexers or diplexers,make VSWR measurements, mea-sure insertion loss and tune RFfilters. Make field strength mea-surements. Act as a continuoustuning AM FM, VHF/UHF soundreceiver. These are only a fewof the applications for the NewScience Workshop Spectrum Analy-zer/Receiver. With "RF-Vision" youwill have a new monitoring mode,with rapid signal detection, modu-lation analysis and band conditionand activity information constant-ly available at your finger tips!Through its many applications, thisnew instrument provides informa-tion and operating techniques notavailable in any other way.

SOME HISTORYBack in 1978, I assembled a

few pieces of surplus electronicgear into what I affectionatelycalled "The Poor Man's SpectrumAnalyzer". I demonstrated it atthe Dayton Hamfest and sold outon the first day. One of the key

MURRAY BARLOWE, WA2PZOitems was a surplus TV IF stripwhich I had narrowbanded forthis application. I found a fewmore, sold out again and then wewere out of the Spectrum Analy-zer business! The excitement cre-ated by this extremely low-costapproach to spectrum analysis anddisplay inspired me to see if Icould design a simple circuit thatcould do all that the originalpackage did, and maybe a bitmore.

Well, we've done it! The newdesign is simpler, more stable andhas greater dynamic range. Howcould we do all this and stillcome up with a package thatmeets the economical goal ofbeing called the "Poor Man'sSpectrum Analyzer"? Simple. Care-ful compromise! We would all loveto have an instrument whichwould have all of the featuresof the $30,000 machine or evensettle for the features and accur-acy of the $5,000 machine. Butwe also realize that it's not inthe cards for under $100. Howabout a machine that would doAL MOST everything the professio-nal models do, but one that wouldrequire a little more effort andingenuity on our part when itcame to making precise measure-ments? Isn't half a loaf betterthan none? Many times it is andI believe this is one of thosetimes. The original kit was basedon these assumptions, and wemade lots of friends with it! Theresults both in performance andeducational value are impressive.Once you've had the opportunityto use it and appreciate its po-tential you will probably findapplications that we haven't evendreamed of! (see Fig 1)

HOW DOES rr WORK?Basically, the "Poor Man's

Spectrum Analyzer" sweeps a vol-tage tuned front end over a rangeof frequencies in synchronism withthe horizontal sweep of a scope.The received signal is passedthrough a narrow band filter and

the detected signal is applied tothe vertical amplifier of thescope. No signal, no vertical de-flection. The deflection producedby the signal is proportional tothe received signal's strength.Resolution is approximately 200Khz, which is determined by thebandwidth of the filter.

Since the output of the analy-zer is audio, it can use ANYSCOPE for the display! If youdon't have one pick up the cheap-est "flea market special" thatproduces a horizontal line! Theanalyzer functions as a TUNABLERF VOLTMETER with "eyes" and"ears". This makes it a natural forsignal tracing receivers and trans-mitters, making relative gain -per -stage measurements, tuning trans-mitters, receivers, antennas andduplPxers, locating and identifyingsources of RFT, checking receiverlocal oscillator radiation, trans-mitter spurs, remote off -the -airrepeater transmitter monitoring,etc. Using the analyzer on atransmitter, provides a display ofthe frequency, amplitude, andpurity of the oscillator, frequencymultiplier, and final signals. Whilea watt meter indicates the totalpower output of a transmitter,the analyzer will tell you howmuch of that power is the desiredoutput signal and how much of itis garbage. Have you ever "peak-ed -up" on a spur? How would youknow? Wouldn't you like to seethe level of the synthesizer side -bands? The harmonics?

The high sensitivity of theinstrument permits signal tracingreceiver circuits from the antennathrough the low-level RF stages.If the output of an RF amplifierstage contains signals not visibleon the input, the RF stage isgenerating distortion products asa result of either overload, incor-rect bias, etc. A conventional RFvoltmeter (or scope) simply sumsall of the voltages with no indi-cation of the individual frequencycomponents. Not so with the

PAGE 26SCIENCE WORKSHOP BOX 310 BETHPAGE, NY 11714


SPECTRUM ANALYZER continued . . .

HOW DOES IT WORK?

SYSTEM DIAGRAM

SW -6007DIGITAL

FREQ.CK'T

SCOPEHOR.

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SCOPEVEITT-1

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FIG.1

SCIENCE WORKSHOPBOX 310

BETHPAGE, NY 11714

Spectrum Analyzer! In addition,the analyzer displays the presenceof the local oscillator signal, aswell as its frequency and injec-tion leveL

The Science Workshop "PoorMan'sSpectrum Analyzer/Receiver"may not provide you with thel -ii It -in calibration convenienceof its bigger brothers, but it willprovide you with a basic, instru-ment that will teach you how aSpectrum Analyzer works, do allthe good things we've described,provide you with a continuoustuning A m/F M, U HF/VH F soundreceiver and best of all, its priceGUARANTEES NOT to make YOU A"POOR MAN"!

WHAT DOES IT COST?The "Poor Man's Spectrum Ana-

lyzer/Receiver" has been designedand packaged as a semi -kit toprovide the cost-conscious Ham/ -Experimenter the opportunity toaqsemlale this unit at the lowestpossible ccet. The heart of theinstrument is what we call the"Main Board Ac.ci.m bly". It containsthe converter, IF filter, amplifier -/detector and audio amplifiersections. All on a 3" X 4 1/2" PCboard. Complete kit of parts forthe "Main Board Assembly" is $30.We can also supply this boardascemblPd and tested for $20m ore.

WHAT ELSE DO I NEED?A sawtooth horizontal sweep

voltage is required to deflect thebeam horizontally across thescreen of the scope, and at thesame time, causes the varactortuner to scan across the RF band.Many scopes provide access to theinternal horizontal sawtooth vol-tage. If your scope does, that'sall you need. Our instructionsshow you how to use it. If yourscope doesn't, we've providedanother kit which uses a singleLM -3900 chip to do the job. Italso provides a voltage regulatorand the circuitry necessary tointegrate the controls for "width","sweep rate" and "center frequen-cy". Makes it a lot easier to as-sem hie your analyzer even if yourscope provides the horizontalsweep voltage. Order Ramp Board


SPECTRUM ANALYZER continued

RF VISION FROM SCIENCE WORKSHOP771E VIEW FROAI THE AN7FNAI4 AfERE BETNP,46' NY

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itSW-6001. Kit $20; assembled $10more. To finish the project, youwill have to provide a box, con-trols, knobs, speaker and powersupply.WE GET LETTERS, LOTS & LOTSOF LETTERS...

"Recently purchased yourSpectrum Analyzer kit. It wasassembled in a few hours andworked perfectly the first timeout. I am delighted with yourunit that compares in many as-pects with Hewlett Packard, AV-COM and Tektronix spectrum ana-lyzers costing many thousands ofdollars more. We use it for look-ing for 6 meter openings andidentifying the type of scramblingbeing used on Satellite TV signals.It is a real pleasnre using yourSpectrum Analyzer, compared totrying to guess looking at a stan-dard TV display. There are onlyso many different ways a satelliteTV programmer can scramble asignal and "all" of them are ra-ther obvious when one looks atthe audio and video on a Spec-trum Analyzer. Also pick up the

123-136 Mhz aircraft band, 2meter band and weather bureaufrom Toronto, 130 miles away. "Robert M. Richardson, W4UCH,noted author of "The GunnplexerCookbook", "Disassembled Hand-book for TRS-80", and "Synchro-nous Packet Software Aprroach",

SEVERAL MONTHS AFTER WERECEIVED HIS UNSOLICITED LET-TER, HAM RADIO MAGAZINE (SEPT.'86) PUBLISHED HIS ARTICLE TIT-LED "LOW-COST SPECTRUM ANA-LYZER WITH KILOBUCK FEATURES".WE QUOTE...

"Although laboratory -gradespectrum analyzers cost $4,500or more, you can build a spectrumanalyzer offering many featuresof its costlier cousins for about$50 (Main Board & Tuner). Howcan such amazing capabilities behad at such incredibly low cost?Through the use of a commerciallymass produced varactor TV tuners.Through the use of consumergrade integrated circuits in theascillator/mixer, dual ceramicfilter, IF amplifiers/detector, andaudio amplifier (offering audio as

well as scope output, it is reallya spectrum monitor). Through theuse of your own oscilloscope. Justabout any scope may be used. Iused a 1951 Heathkit Model OL-1 with its original cathode raytube".AND ANOTHER...

"I was very fortunate to havepurchased your "RF VISION" kit.I originally used it for listeningto signals and just seeing whatwas on the band... My real interestwas in using it as a spectrumanalyzer. It has done this remark-ably well. Another area of inter-est to me is antenna measiire-ments. I have used a PalomarNoise Bridge for several years,and with the help of a computer,I have been able to calculatesome good data on my antennas.The final data being convertedmanually from tabular form tographs. It occurred to me to useyour unit as the detector in placeof the normal receiver. You canwell imagine my excitement inseeing my antenna graphs appearon the CRT without any laboriousdata gathering or calculations! Iam so pleased with this projectthat I have recommended it toseveral friends and plan to de-monstrate it at a club meeting inthe near future. It is hard tobelieve an electronic tool couldgenerate so much pleasure, butthis one did. Thanks again formany hours of pleasure". TerryGood, WB2PFB, Hillsdale, NJAND FROM JOE CARR'S "PRACTI-CALLY SPEAKING" COLUMN IN THEMAR. '87 ISSUE OF HAM RADIOMAGAZINE.

"Sheer genius!...WA2PZO deser-ves accolades and our businessbecause of the Poor Man's Spec-trum Analyzer project, which of-fers opportunity for experimenta-tion in areas previously closed toamateurs solely for reasons ofcost I plan to buy the TrackingOscillator Kit if and when it be-comes available."NOW, ZERO TO 500 MHZ IN ONECONTINUOUS SWEEP!!!

We have acquired a quantityof NEW cable tuners (with pre-scalers) which we have modified

PAGE 28SCIENCE WORKSHOP

ATVQBOX 310 BETHPAGE, NY 11714

DEVOTED ENTIRELY TO HAM TV

SPECTRUM ANALYZER continued

for our application. They nowprovide continuous tuning fromapproximately 0 to 600 Mhz. Thedrawing on the back of this pageillustrates what we see (and hear)when we connect this tuner to anantenna here in Bethpage. Addinga UHF tuner gives us the abilityto tune from approximately 0 to900 MHz! Since the resolution ofthe analyzer is approximately 200KHZ, it is difficult to resolvesignals at the low end. It shouldbe possible to improve this withcrystal filters. The pre -scalersmakes it possible to add additio-nal circuits to provide a direct,digital read-out of the centerfrequency.SW -6900 TRACKING GENERATOR

The addition of a trackinggenerator to the spectrum analy-zer provides a powerful receiversystem for stimulus -response m e a-sur ements. A tracking generatoris a signal source whose RF out-put follows (tracks) the tuning ofthe spectrum analyzer. Since theinstantaneous output frequencyof the SW -5900 matches the in-stantaneous input frequency ofthe analyzer, this swept frequencytest system acts as a very sensi-tive synchronous detector. Thismakes it the ideal set-up formeasuring the frequency responseof active and passive devices suchas amplifiers, mixers, couplers,attenuators, transmission lines,and even antennas when usedwith an external bridge. Its out-put signal is generated by mixingtwo or more riscillators. Physical-ly, the tracking generator consistsof another modified cable tuner,designed to operate in conjunctionwith the SW -5800 modified cabletuner.

Figure 1 is a simplified blockdiagram of the system. The in-coming signal to the spectrumanalyzer mixes with the LO, andwhen the mixing product equalsthe IF, this signal passes throughto the detector. The detectoroutput is amplified and producesa vertical deflection on the CRTdisplay. The sweep (ramp) genera-tor drives the horizontal CRTdeflection and tunes the LO. The

tracking generator uses the sweptLO from the spectrum analyzerand mixes that LO with a fixedIF oscillator. The sweep of thetwo instruments are matched andsynchronous, and precise trackingbetween the two is assured.

TYPICAL APPLICATION.The RF output from the tracking

generator is connected to theinput of the Device Under Test(DUT) and the output of the DUTis connected to the input of thespectrum analyzer, as in Figure1. The resulting display is aninstantaneous plot of the frequen-cy response of the DUT. If youwere adjusting a bandpass filter,you would immediately see theresult of your tweaking. The tun-ed (sweeping) receive bandwidthof the analyzer assures that youare not peaking on a harmonic orany other spurious energy.

ANOTHER APPLICATION.Connect a piece of coax in placeof the DUT (in parallel). Tuneacres the spectrum for a notchin the response curve. An open1/4 wave line reflects a short,acting as a trap at the notchfrequency. Clip 1/4" lengths fromthe open end with different val-ues of resistance and watch thenotch move up in frequency.Terminate in different values ofresistance until the notch disap-pears. The value of resistancerepresents the characteristic im-pedance of the line at that fre-quency. Connect the transmissionline from your antenna in itsplace. You may be in for a sur-prise! The SW -5900 Tracking Gen-erator is NOT a kit. It is a fullyassembled and tested module,ready to be installed. Best of all,it is priced at $50 and is avail-able from stock!NEW!!! CENTER FREQUENCY READ-OUT CIRCUIT KIT FOR THE "POORMAN'S SPECTRUM ANALYZER"

This new kit uses a uniquecombination of Analog and Digitalcircuitry to accomplish a relative-ly complex task. The conventionalapproach to this problem has al-ways been purely digital, requiringanywhere from 10 to 20 digitalchips. In keeping with the philo-

sophy demonstrated by the designof the "Poor Man's Spectrum Ana-lyzer", I felt that there had tobe a simpler, more economicalway. Since we are looking at aCRT display, covering anywherefrom a few Mhz to several hun-dred, all we needed was a 3 -digitread-out that could display 0 to500 MHz directly.

PREVIOUS SOLUTIONS.Most frequency read-out circuits

use the local oscillator signal togenerate the display. This signalis offset from the incoming RFsignal by an amount equal to theIF frequency. A little arithmeticmust be performed to either addor subtract the IF signal to getback to the received frequency.This has required the use of het -r odyne oscillators, pre-setablecounters, or to somehow playgames with the time base to ac-complish the same result. Thesemethods provide a relatively in-flexible solution.

A NEW APPROACH.Rather than using the conventio-

nal all digital circuit, I decidedto use a Precision Frequency -to -Voltage converter IC, along withthe output of the prescaler IC inthe SW -5800 tuner. A bit of Ana-log Computer circuitry took careof the remaining math. Althoughthis circuit was designed to workwith the SW -5800 tuner, it pro-vides experimenters with a simplelow-cost solution for directlydisplaying the received frequencyof almost ANY receiver. A simpleadjustment of a potentiometer isall that is required to accommo-date any IF frequency from 0 tohundreds of MHz. For the firsttime, a TRULY UNIVERSAL DIRECTDIGITAL FREQUENCY READOUT!

DISPLAY OPTIONS.To keep costs down, I designed

the circuit so that it could useyour Digital Voltmeter as thedisplay. With the meter set on the20 volt scale, 0 to 500 MHzwould be displayed as 0.00 to5.00 volts. At first I found thedecimal point annoying, but itdidn't take too long before I wasignoring it. Later, when I foundtime, I bought a $29 DVM, disa-


bled the decimal point and dedi-cated that meter display to mySpectrum Analyzer. Now it readsdirectly in Mhz. However, we nowhave 2 miniature digital panelmeter modules available that areideal for this application. Theymeasure approximately 1" x 2" x.5" and easily mount into a rec-tangular front panel cut-out. Theyare state-of-the-art, surfacemount technology assemblieseither LCD or LED. These are notkits. The LCD version sells for$59, the lED version is $3 more.We also have an LET version KITthat is slightly larger for only$39.

OTHER APPLICATIONSFOR THE SW -6007.

There should be many other "fre-quency meter" applications forthis unique circuit. Since thiscircuit could be used with ANYLF., it represents a real break-through. Adjusting the LF. offsetwith the simple setting of a sin-gle control has been unheard ofuntil now!

PC BOARD.The SW -6007 Kit is built up on

zO

-

a double -sided epoxy glass board,approximately 2" X 4.5", screenedwith the component parts layout.All parts and instructions aresupplied. As usual, NO test equip-ment is required!

PRICE.Best of all, it is priced in the

tradition of the "Poor Man's Spec-trum Analyzer", GUARANTEED NOTTO MAKE YOU POOR! Only $39 +$4 S/H. Available from stock!

OPTIONAL FILTER KIT FK-1001SPECIAL PURCHASE!

The 2 ceramic filters sup-plied with the SW6006 main boardkit are approximately 200 Khzwide. These filters are quite ade-quate for most applications. How-ever, there are times when itwould be desireable to be able toseparate signals that are closerthan 200 Khz apart. Ideally, wewould like to be able to conveni-ently switch between narrow andwide band filters. The presentboard design is not set up toaccommodate more than one setof filters at a time. The FK-1001filter kit provides you with theopportunity to experiment with anarrower IF bandwidth. It contains

one 15 Khz crystal filter and twomatching tuneable transformers.Installing the 15 Khz crystal filteris a bit more difficult than the2 ceramic filters. The mechanicalconfiguration is completely dif-ferent. Fortunately, there isenough space on the SW -6006main board after the crystal fil-ters and related components areremoved. The 2 coils and thecrystal filter can be mounted ona 5/16" x 1" piece of perf board.Two input and two output leads,plus a ground lead are then drop-ped down through the holes onthe main board that were usedfor the 200 Khz filters and thensoldered. You may have seen thisarrangement at our display at ahamfest.

These filters were purchasedas a one -shot -deal. I have notbeen able to locate a source thatwould allow me to make themavailable at a low price on acontinuing basis. So while theylast they are $25 for the kit.Order part # FK1001.

Murray Barlowe WA2PZOTEL. 516 731 7628

SCIENCE WORKSHOPBOX 310

BETHPAGE, NY 11714516-731-7628

VISIT US AT BOOTH 326

April 28, 29, 30, 1989


****RUSH ORDER FORM****

SHIP TO:Name Tel.#Addr.City St. Zip _.

A Spectrum Analyzer consisists of a Basic Kit, &

your choice of one or more tuners which determinethe frequency ranges to be covered.

Description Quan Price Total

BASIC KIT(Main & Ramp Boards)SW -6006K (Main Board Kit)

or SW -6006W (Main Board Wired)SW -6001K (Ramp Board Kit)

or SW -6001W (Ramp Board Wired)

30.0050.00E0.0030.00

TUNERS:a.) 0-500 Mhz (Modified cable

tuner, w/prescaler) SW-5800b.) 420-900 Mhz (UHF ONLY

tuner) SW -5810

35.00

15.00

TRACKING GENERATOR SW -5900 50.00

DIGITAL FREQ.READOUT KIT SW -60078or, same as above, WIRED SW-6007W

39.0059.00

LCD DIGITAL DISPLAY, WIRED LCDDVMLED DIGITAL DISPLAY, WIRED LEDDVMLED DIGITAL DISPLAY, KIT LEDKIT

59.0062.0039.00

UPS Shipping & Handling* 4.00

NYS Residents add Sales Tax

TOTAL AMOUNT ENCLOSED

* OVERSEAS, ADD $25 FOR AIR SHIPMENT, US FUNDS.Personal checks require 7-10 days to clear.We are not set up to handle credit cards.

MAIL TO: SCIENCE WORKSHOPBOX 310 BETHPAGE, NY 11714

How did you learn of us?


New York, NY... For thosewho are not mathematically inclin-ed, I do attempt to explain thepurpose of the Bevel Null as usedby the broadcaster so that youmay follow discussions of use.You may remember from AM that

all information is contained in theupper and lower sidebands. Infact, the amplitude of the carrierdoes not change.

The information in the uppersideband is the same as that inthe lower, and (assiming a distor-tionless system) only two sidebandsexist. In fact, either of the side -bands and/or the carrier may besuppressed.

Equation 5A is a minor butquite justifiable variation on abasic equation of FM, which I willuse for this tutoriaL

In Equation 5A, the instantane-ous voltage ec is dependent uponthe sine of the sum of two quan-tities. One of these quantities isthe carrier frequency and theother is the modulating informa-tion, itself a sine wave for ourpurposes.

While I will not show proofhere, Equation 5A may be rewrit-ten in a different and more com-plex form (Equation 9), which isyet very usefuL

A Useful EquationAs can be seen at once, this

equation now consists of an in-definite number of terms, eachof which is multiplied by somefactor Jx'

Except for the first term (cor-resizmding to Jo), each term con-sists of two sinusoid, one with afrequency below the carrier (X,the other with a frequency thesame amount above the carrier.(See Fig.)

These two frequencies differfrom the carrier by an integermultiple of the modulating fre-quency, and the integer corres-ponds to the subscript associatedwith J. Thus all the terms (exceptfor the J0 th) exactly describe thefrequency of a pair of sidebands.

The amplitude of the uppersideband and the lower sidebandis identical (although possibly op-posite in sign) and dependent uponthe Bessel Function Jx(m).

UNDERSTANDING FM SIDEBANDSWARNER W. JOHNSTONThe first term, the 30th term,

contains only one frequency com-ponent, which happens to be thecarrier frequency. Again, the am-plitude of this component, thecarrier, is dependent only uponthe Besgel Function 30(m).

Thus we have a complete des-cription of a sinusoidal carrier,which is frequency modulated bya sinusoid of lower frequency. Wecan write an exact value for eachsingle sideband and the carrieronce we can describe m, which weknow to be the modulation index,and Jx(m),which we know nothingabout.Besse' Functions

Friedrich Wilhelm Besse' (1784-1846) was an early 19th centuryastronomer and mathematician whowas largely self -strained. His doc-torate was awarded for work al-ready done, not as a result ofuniversity training.

In addition to devising theform of analysis involving theBessel Functions, he was also thefirst person to measure the dis-tance of a star by the method ofparallax, and also predicated thedark companions of Sirius andPr oclon.

The Bessel Function (specifical-ly the Bessel Function of the FirstKind) is usually written in thenotation Jy(m), where the subscriptx designaes the order of theBessel Function, and m is the var-iable (see Fig.)

As with a sinusoidal function,values of Bessel Functions can befound in tables in standard mathe-matical reference works. Becauseof their use in FM broadcasting,these tables are often found inbroadcasting handbooks as well.Reference Data for Radio Engi-neers from Howara74. Sams is oneexample; it contains values forBessel Functions of the first fiveorders.

Figure 1 is a graph of theBessel Functions of orders zerothrough five for values of m lessthan 25. Figure 2 is the same fororders six through 15.

While a Bessel Function of anyorder (for broadcasting purposes,the order of Bessel Functions islimited to positive integers) can

be calculated, it is unlikely thatsidebands beyond the 15th needto be calculated. However, doremember that a 50 Hz signal canhave up to 1500 sidebands in astandard FM signaL

Equation 6 and its minor vari-ant Equation 6A relate the modu-lation index (m), the modulatingfrequency ( ) and the frequencydeviation ( ). We also know, byregulation, that the maximum fre-quency deviation is 75 kHz, in theFM band.

If we examine the graph of theBessel Function of the 0th orderfJo(m)}, we find that there aremany values of m where the Bes-sel Function has a value of 0: m= 2.4048, m = 5.5201, m = 8.6537are only the first three values.

If we frequency modulate ourcarrier with a sinusoid of an amp-litude such that the modulationindex is equal to one of thesevalues (m = 8.6537 as an example),then the value of the Bessel Func-tion J0 (8 6537) = 0.00.

In another fashion, with amodulation index of 8.6537 theamplitude of the carrier will be0.00. Furthermore, from Equation6 we can relate the modulationindex, the modulating frequencyand the frequency deviation: Wefind that with a modulation indexof 8.6537, we need a modulatingfrequency of 8666 Hz to achievea frequency deviation of 75 kHz(8.6537 X 8666 = 75,000).

We know, directly, by theequations of the FM system thatwe can determine frequency devi-ation. Figure 3 shows an FM sys-tem being modulated with 8666 Hzat some modulation index otherthan 8.6537.

The carrier frequency compo-nents can be seen in the figure.As the modulation index is chang-ed to the third Bessel Null levelof 8.6537, the amplitude of thecarrier has changed to 0 (Figure4). It can also be seen that thefrequency deviation is 75 kHz.

This particular frequency andmodulation index combination areof course not the only ones whichcan be used for setting frequencydeviation. The second carrier nullJ0 (5 5201) will cause 75 kHz devi-


FM SIDEBANDSation at a frequency of 13,587 Hz.

It is also possible to null oneof the sidebands. Again, choosethe modulation index where thatparticular Bessel function (of thesame order as the sideband num-ber) is qual to 0.

A second example of the useof the Bessel Null method withmore application for televisionfollows.

C -band satellite televisiontransmission calls for audio fre-quency division of 185 kHz (370kHz peak -to -peak). In choosing afrequency, you should take intoconsideration the maximum audiofrequency usable by the system.

Since in television the maxi-mum audio frequency is 15 kHz,we should stay well away fromthis and not exceed 14 kHz formost testing. Taking this into con-sideration we find that the lowestfrequency we can use is 12.413kHz at the 5th Carrier Bessel NullJ0 (14 903) 'This null is shown in Figure 5.

It should be pointed out thatadjusting deviation using the Bes-sel Null technique requires anaccurate, stable oscillator whichcan be adjusted in steps of notmore than 0.05 dB (0.01 dB isbetter), and has the ability togenerate a signal at a level below-80 dBm.

When making a Bessel Nulladjustment, be very careful count-ing nulls. It is very easy to skipone.Reprinted with permission fromTV Technology Jan 89.

,

Figure 1.

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Equation 5A.ec = Asin (wct +msinip)

Equation 6.m =Acoh,/,

Equation 6A.mi. = Aw

Equation 9.ec = A { (Jo(m)sirbyt) +Ji(m) Icos(wc -10) t - cos(wc + 1 tk)t] +J2(m) Isin(wc -20) t + sin(wc+24)tj +J3(m) (cos(wc-30)t -cos(wc+30)t]+. }

Figure 3.

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10 11 1 2 iu1111 1 2H1 ST 51.11 .sec

A LIMITER FOR FM -TVKLAUS HIRSCHELMAN DJ700

This article first appeared inTV -Amateur 62/1986 and we thankthe editors for their permission toreproduce it here.

The phase -lock -loop integratedcircuit type NE564N, which is usedextensively by amateurs for thedemodulation of FM ATV signals,is easily over driven by stronginput signals Although a limitingarrangement is built into the de-vice, frequency rejections andsignal distortions can still occur.To remedy this problem it must beensured that the input level ofthe NE564 is not too high. Thiscan be accomplished by using ex-ternal signal limiters, and for thisthe Motorola MC10116 device isvery suitable.

The MC 10116 line receiver isused in this application as a limit-ing broad -band amplifier, withapproximately 20dB of IF gain, itdelivers a stable output of ap-proximately 0.8 volts. The circuitof this simple unit is shown inFig. 1 and can easily be arrInm bledusing a small piece of Vero -board.The connection between the outputof the last IF amplifier and theinput to the NE564 on the demod-ulator is broken and the circuitinserted. The input and outputconnections to the limiter must beas short as possible. Power re-quirements for this modificationare provided by the 78L05 regula-tor shown in the circuit, which isfed from the supply to the demod-ulator.

This improvement for the NE564demodulator can be carried outeasily and quickly, and is non-critical, in that no further adjust-ments to the system need bemade. It leads to a noted im-provement of the receive qualitiesand should therefore be part ofany such equipment. (see Fig.)from BATC-CQ-TV with permission.


THE MICROWAVE OVEN FM ATV 250 WATT 2.4 GHZ TRANSMITTERa review by Bill Parker W8DMR

with editorial comment by Henry KB9FO

At the Indianapolis MV meet-ing in January, Dave Pacholok*KA9BYI from Sleepy Hollow, IL de-monstrated and spoke about a mi-crowave oven he had convertedto an FM ATV transmitter for 2.4Ghz with a power output of 250watts! The project had been donein an effort to win an award fromanother publication. In our lastissue we told ATVQ readers aboutthe project from material we re-ceived prior to the demonstration.This article is based upon thepresentation by Dave at the In-diana UHF -ATV meeting, from handout material with some addedcomments and considerations byBill Parker W8DMR. The buildermay find numerous ways to modifyand improve on the design and wewould appreciate any reader/build-er feedback.

Tom O'Hara W6ORG who is chai-ring the Dayton ATV forum hasin formed us that Dave will bringthe unusual transmitter to theDayton Ham vention and speak atthe forum.

The lure of high power atlow cost for this band is great.However, before starting this pro-ject bear in mind that seriousprecautions need to be taken sothat you and others are not injur-ed. A microwave oven is designedto cook food. If the RF is locsein your ham shack it can cookYOU.

WARNING WARNING WARNING

DO NOT UNDERTAKE THIS PROJECTWITHOUT TAKING PRECAUTIONS.HIGH POWER MICROWAVE ENERGYCAN DAMAGE ANY LIVING TISSUEAND EVEN KILL. BE SURE TO AL-WAYS HAVE A MICROWAVE OVENLEAKAGE DETECTOR ON WHENWORKING ON THE OVEN. NEVERAPPLY POWER WITH SHIELD PLATESAND CABINET OFF. DO NOT WEARCONTACT LENSES WHILE OPERAT-ING. NEVER POINT THE ANTENNAAT ANY PERSON OR ANIMAL. REG-ULAR COAX CABLE CANNOT BE

USED FOR THIS PROJECT. HIGHPOWER AT THESE FREQUENCIESREQUIRES THE USE OF SPECIALSILVER PLATE COAX AND TEFLON

INSULATION. REGULAR COAX WILLMELT AND LEAK RF. DO NOT BY-PASS ANY SAFETY FEATURES. DONOT DEVIATE FROM THE RF DESIGNUNLESS YOU ARE EXPERT IN MI-CROWAVE AND HIGH POWER RF.THIS PROJECT CAN BE DANGEROUSAND SHOULD NOT BE UNDERTAKENBY A NEOPHYTE IN HIGH POWERMICROWAVE. TURN OFF ALL POWERIF YOU FEEL ANY WARMING OFBODY PARTS. NEVER LOOK INTOWAVE GUIDE OR STAND IN FRONTOF THE ANTENNA WHEN OPERAT-ING. FAILURE TO HEED THESEWARNINGS MAY RESULT IN INJURYOR DEATH.

Review by Rill ParkerGENERAL DESCRIPTION

A new microwave oven can bepurchased for about $45 to $65.Typically a 450 watt oven deliversabout 250 watts of RF at a fre-quency of 2450 Mhz. A video mod-ulator must be added and somepower supply changes made. Theestimated cost of adding thesecomponents is less than $225.Many of the parts are availableat Radio Shack and hamfests. Toreceive 23cm MDS (Multi -pointdistribution system) down -conver-ters can be utilized with goodresults and at a very reasonablecost. The cast of many units ad-vertised in major electronics mag-azines is usually $89 to $149. TheMDS units include a 20 inch dishantenna with about 40 db gain(includes preamp gain). The down -converter tunes roughly 1.9 to 2.7Ghz remotely from its base powersupply.

A microwave oven magnetronis a self contained cross fieldpower oscillator. Built-in cavitiesprimarily determine the oscillatorfrequency. However, the amountof plate voltage and strength ofthe magnetic field around themagnetron does determine thequiescent operating frequency. Byexperiment and analysis the bestoperating mode is FM video.Ed. Comment: The oscilla-

tor is a basic tank cir-cuit, as with any oscilla-tor connected to a load,the load acts as a "tap"

across part of the tankcircuit, thus affectingthe resonant frequency. Inthe case of this projectthe external circuit istuned by placement of thewave guide to coax probeand by the impedance andreactance of the load. A

frequency counter must beused to measure the outputfrequency of the unit whenin use to avoid out -of -band operation. WARNING:The CIA operates satellitespy video on adjacent fre-quencies and they take avery DIM VIEW of your op-erating on THEIR frequen-cies!. END

Experimental tests by Daveindicate that a maximum useablefrequency swing is about 20 Mhz.The coefficient of frequencychange is about .1 Mhz/ma ofMagnetron current

The video modulator is a bitunusual as shown in the blockdiagram. It functions as a highvoltage current source of highopen -loop gain that can set themagnetron current to a knownvalue. This establishes the oper-ating frequency and power output

The unit of transconductance isthe Siemen (formerly MHOS).Transconductance is the reciprocalof resistance. For volts in, themodulator provides a current out.It is essentially Ohm's law inver-ted or upside down. MHOS= cur-rent/voltage. The video modulatorhas a transconductance of 0.2Siemens.

The transconductance ampli-fier must provide enough band-width to amplify all the videomodulation components. If an audiosubcarrier is used the bandwidthrequirement is 6 Mhz. A capacitorand resistor (C6, R27) is used toextend the high frequency re-sponse from approximately 4.5 to6.0 Mhz. A video pre -emphasiscircuit is still required for FMusage.

ED NOTE: see the ARRLHandbook, FM Video, CCIRvideo pre -emphasis network


MICROWAVE OVEN continued .

by Bruce Brown W9GVW. END.The screen supply for the two

sweep tubes must float aboveground. Only the Magnetron platecurrent must be allowed to enterthe current source control loop asthe controlled variable. The screencurrent should not be included.

The wave guide must be modi-fied by adding a shorting partitionor plate. This is analogous to a1/2 wave coaxial stub or a 1/4wave when reflected path providestwice the distance. Wave frontsin either case, are phase shiftedby 180 degrees. The shorting platecauses the reflected wave to bein phase with the incident wavefrom the magnetron. The E fieldprobe is inserted where the RFvoltage maximum occurs.

Normally the length of an out-put probe is 1/4 wave for maxi-mum power output. Shorting theoutput probe introduces a reactivecomponent to the output port ofthe magnetron. After undeterminednumber of degrees of rotationwithin the magnetron feed struc-tire back to the magnetron cavi-ties causes the operating frequen-cy to be lowered by about 25Mhz.This helps insure operation in thelegal amateur 23 cm band.

CIRCUIT DESCRIPTIONThe +5 volt regulator, U2 pro-

vides a voltage reference. It isdivided by R5 and R6 and connec-ted to the non inverting input ofwide band op -amp Ul establishinga current reference. The outputof Ul feeds the gate of Ql.The output of the source follower

Q1 is sent to R9 and through R7providing negative feedback to theinverting input of Ul. THe feed-back ratio is calculated as fol-lows:

FEEDBACK RATIO =

470 + 100 570

R9+R7

R7

100 100- 5.7

At equilibrium, Ql's drain tosource current produces a dropacross R 11 that is 5.7 times Ul'snon inverting input voltage. PotR6 sets a drain current in Q11that is proportional to the non -


inverting input of Ul. The plateand cathode current of V1 and V2in parallel are one in the same ifscreen current is not consideredat this time.

The voltage on the drain ofQ11 increases or decreases untilthe control grid of V1, V2 changesthe cathode bias until Ik = Id =Is. V1 and V2 are a grounded gridvoltage amplifier with unity cur-rent gain. V1 and V2 have suffi-cient current capacity to serve asa current source for the magne-tron.

Actually a transconductanceamplifier is formed with the highvalue of 220,000 micrnsiemens (0.2Siemens). The value can be calcu-lated by solving:

R9 +R7S = I/V = (

R7

1 1

(

R11 R9 + R7Transformer T3 provides a non -grounded +100 V screen supply forV1, V2. R 28 limits the screendissipation. The screen floats a-bove ground because only theplate current ak = Im) shouldenter the control loop by way ofVI and V2 cathode and is thecontrol parameter the screencurrent).

Components R 14 and R15 helpprovide current sharing in V1, V2.Zener diode D3 protects powerFET Ql. Resistors R16 -R27 serveas voltage equalizing as well asbleeders for the supply.

Regulators U3 and U4 provide+15 and -15 V for the op -amp.Magnetron current is monitored bymeter Ml.

CONSTRUCTION DETAILSDepending on the exact brand

and model microwave that is tobe modified certain general infor-mation applies.

First, inside the oven, cut offthe wave guide that connects tothe cooking cavity matchingflange.

Second, a wave guide shortingcover needs to be fabricated tocover the feed port to the ovenchamber. The size of this port istypically about 1.5 inches by 3.5inches. A piece of COPPER approx-

- .22 S

imately 3 x 5 inches, 18-22 gaugewill do nicely. Drill. 16 to 22 holesaround the outer edge for mount-ing holes. Of course, an equalnumber of holes will need to bedrilled around the oven waveguide port. Sheet metal screwsor machine screws with nuts willprovide a good shorting partitionfor the open wave guide end.

Third, an E -field probe needsto be constructed. Using a TEFLONN connector solder apiece ofabout 0.175 diameter 5/8" longbrass tubing to the connector,.Solder a brass nut to the otherend of the brass tubing. Insert a1/2 inch brass screw into the nut.This forms a tuning adjustment forthe probe. Have the screw fullyinserted and snug tight.

Fourth, a hole must be madein the wave guide to accept theprobe. The hole is placed in theop of the wave guide from theoutside of the oven. It mounts 1and 5/16th inch from where thewave guide cavity shorting parti-tion was added. It should also becentered in the wave guide.

Fifth, the filament leads of themagnetron are bypassed by feed -through capacitors. The groundside of each feedthrough capacitormust be opened. Care must betaken not to damage the insulationon the filament wiring. The capa-citors are white oval shaped cer-amic. By drilling out four rivetsthe ground is removed. The capa-citors are about 2000 pf. Push thecapacitors back into the tubehousing about 1/8" or so, so thatthe ground is broken and it willnot slip back when in use.

Sixth, inside the microwave ovencooking chamber it is necemoryto remove the radome (food splat-ter cover). Remove the dielectricRF energy dispersal unit (stirrer)also. Next remove the feed guideto the multimode cavity Z -match-ing plate is removed. The match-ing plate is removed by cutting orsawing. The magnetron cooling airis discharged into the oven cham-ber. If the video modulator tubesare mounted inside the chamberthey too are cooled.

Retention of the oven door andinterlock switches provide a sAfeway to disable the high voltage

PAGE 35

BLOC PC ID I A - - M I C R CI LA11 A V la A -T- V x M -r

MAG.CURRENTADJUST 1

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GROUNDED GRIDSWEEP TUBES'

NOTES:

1. FOR 2M1B9A MAGNETRON.

2. CAVITY MODIFIED W/SHORT.

3. Z = 50 + JOLOAD

4. SEE TEXT FOR SHORT INFO.

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whenever the oven door is opened.The outer cabinet cover furtherincreases safety and is drilled toaccept and allow the output Nconnector to exit when the coveris later reinstalled.

SAFETY PrecautionsRadiant energy above a certain

level can be harmfuL Use an inex-pensive microwave leakage detec-tor to verify the safety of thefinished transmitter. Readings from

any surface of the transmitter inthe unsafe or red some indicatea leak that MUST be corrected.

Do not point a microwave an-tenna emitting RF power levelsin the class of this transmitter atpeople, buildings, residential areas.use common sense and don't testit on your pets. Currently a levelof more than 5 milliwatts persquare centimeter at 2400 Mhz isconsidered hazardous.

F' in%FZTS

ITEM QTY.

L I S - NI _ O _ t.." X r -1 -1 -

DESCRIPTION

1. 1 EA. MICROWAVE OVEN, 40e-500 WATTWITH 2M1B9A OR 2M226A MAGNETRON

2. 2 EA. TV SWEEP TUBE, 6JE6C/6L06CEA. CAPACITOR. ELECTROLYTIC. 100 MFD/400V

4. 1 EA. DIODE, HI. V. RECTIFIER. le EV, 250 MA.5. 12 EA. RESISTORS. 470 K OHMS. 1 OR 2 WATTCp. 1 EA. TRANSFORMER, 12.6 VAC. 3.0 AMPS.7. 1 EA. TRANSFORMER, 12.6 VAC. 450 MA.8. 1 EA. METER. 0-200 MA. USED OR SURPLUS9. 1 EA. CONNECTOR. N -TYPE. FEMALE. CHASSIS MNT.

10. 2 EA. CONNECTOR, F -TYPE, FEMALE, CHASSIS MNT.11. 1 EA. IC. LF357. WIDE BAND OP -AMP12. 1 EA. IC, REGULATOR. 781513. 1 EA. IC. REGULATOR. 791514. 1 EA. IC, REGULATOR, 780515. 1 EA. TRANSISTOR. POWER FET. IRF-51116. 2 EA. DOIDE, LOW V. RECTIFIER, 200 V., 1 AMF.17. 1 EA. DIODE, BRIDGE ASSY., 400 V.. 1 AMP18. 1 EA. DIODE, ZENER, 68 VOLT, 1 WATT19. 1 EA. CAPACITOR. CERAMIC, 0.001 MFD.20. 1 EA. CAPACITOR, ELECTRO., 10 MFD., 25 VOLT21. 2 EA. CAPACITOR. ELECTRO., 100 MFD., 10 VOLT22. 1 EA. CAPACITOR, ELECTRO., 330 MFD., 10 VOLT

1 EA. CAPACITOR. POLY., 1200 PFD., 100 VOLT24. 1 EA. CAPACITOR, CERAMIC, 0.1 MFD., 50 VOLT25. 2 EA. CAPACITOR. ELECTRO.. 47 MFD., 160 VOLT

EA. CAPACITOR, ELECTRO., 470 MFD., 25 VOLTS27. 1 EA. RESISTOR. :90 OHM. 1/4 WATT28. 1 EA. RESISTOR, 100 OHM, VARIABLE, PANEL MOUNT29. EA. RESISTOR. 470 OHM. 1/4 WATT30. 2 EA. RESISTOR, 3.3 K OHM, 1/4 WATT31. 1 EA. RESISTOR. 1.0 K OHM, VARIABLE. PC BRD.32. 1 EA. RESISTOR, 100 OHM, 1/4 WATT

1 EA. RESISTOR. 22 OHM. 1/4 WATT. 5 %34. 1 EA. RESISTOR, 27 OHM, 1.0 WATT. t-5. 2 EA. RESISTOR. 120 OHM. 1.0 WATT, 5 %36. 2 EA. RESISTOR, 100 OHM, 1.0 WATT, 5 %37. EA. RESISTOR. 470 OHM. 1.0 WATT. 5 X38. 1 EA. SWITCH, POWER, 125 VAC, 0.5 AMP.

REFERENCES:A photo copy package of 40 or sopages with multiple photos andnotes is avaiahlp for $6 from:1.* Dave Pacholok KA9BYI

Creative Electronics1815 W. Higgins Rd.Sleepy Hollow, IL 60118

312 428 56762. RF Deisgn Magazine, Design

Award, Dave Pacholok, Pages24,25, July 1988.

3. Microwave Oven ATV Transmitter D. Pacholok, Indiana UHFand ATV Meeting, 14 Jan 1989.

EST. COST

70.00

-4.00'6.0012.506.00

$ 4.015.00

. 50$ . oo$ 1.0($ 1.50$ 1.00$ 2. 00

$ 1.00$

^.00. 50. 501.00.50.50.501.50-7.00. 10

-s.00. 30

.^01.00. 10

.10

. 50

.50

.50

ESTIMATED TOTAL $19e3.55


ATVQ

The following stores sup-port ATVQ by stockingissues for sale. Kindlyrefer local ATV'ers tothe store nearest you toget the latest copy ofATVQ. Your support helpsinsure our continuedsuccess in bringing youthe best in ATV. 73KB9FO/WB8ELK

Rivendell Electronics8 Londonderry Rd.Derry NH 03038

EGE224 BroadwaySalem NH 03079

Hatry Electronics500 Ledyard St. SouthHartford CT 06114

KJI Electronics66 Skytop Rd.Cedar Grove NJ 07009

Abaris Systems227 Stuyvesant Ave.Lyndenhurst NJ 07071

Gilfer Shortwave52 Park AvenuePark Ridge NJ 07656

VHF Communications915 North Main St.Jamestown NY 14701

Hamtronics4033 Brownsville Rd.Trevose PA 19047

Delaware Amateur 71Meadow Rd.New Castle DE 19720

Amateur Advanced Corn.3208 Concord PikeWilmington DE 19803

Maryland Radio Center8576 Laureldale Dr.Laurel MD 20707

EEB516 Mill St. NEVienna VA 22180

IS AVAILABLE AT THESE FINE HAM STORES

EGE Bldg. B14803 Build America Dr.Woodbridge VA 22191

F&M Electronics3520 RockinghamGreensboro NC 27407

H RO6071 Buford HwyAtlanta GA 30340

Doc's Communications702 Chickamauga Ave.Rossville GA 30741

AES621 Commonwealth Ave.Orlando FL 32803

AES1898 Drew St.Clearwater FL 33575

Radio Shack / Cotronics2200 SE Federal HgwyStuart FL 34994

Universal ARC1 280 Aida Dr.Reynoldsburg OH 43068

Doug Hall Electronics815 E. Hudson St.Columbus OH 43211

AES28940 Euclid Ave.Wickliffe OH 44092

Ham StationPO Box 6522Evansville IN 47719

Michigan Radio Service1 5000 Nine Mile Rd.East Detroit MI 48021

AES4828 W. Fond du LacMilwaukee WI 53216

Burghardt Amateur Ctr182 N. Maple PO Box 73Watertown SD 57201

C&S Sales1 245 RosewoodDeerfield IL 60015

Erickson Communications5456 N. MaiwaukeeChicago IL 60630

Gateway Electronics8123 Page Blvd.St. Louis MO 63130

Missouri Radio Center102 NW Business ParkKansas City MO 64150

Associated Radio8012 Conser Box 4327Overland Park KA 66204

Inland Software510 Oregon St.Hiawatha KS 66434

Dandy's124 S. WashingtonWellington KS 67152

Electronic Center Inc.2809 Rags Ave.Dallas TX 75201

Madison Elec. Supply3621 FanninHouston TX 77004

Gateway Electronics9890 Westoark Dr.Houston TX 77063

Mission Communications11903 Aleif Clodne #500Houston TX 77082

Allied Appliance & Radio4 253 South BroadwayEnglewood CO 80110

Gateway Electronics5115 N. Federal #32Denver CO 80221

Gateway Electronics9222 Chesapeake Dr.San Diego CA 80221

Colorado Comm Center525 E 70th Av. Suite 1WDenver CO 80229

Ross Distributing Co78 S State St. POB 234Preston ID 83263

HRO1702 W. Camelback Rd.Phoenix AZ 85015

AES1072 N. Rancho Dr.Las Vegas NV 89106

Henry Radio2050 S. Bundy Dr.Los Angeles CA 90025

Jun's Electronics3919 Sepulveda Blvd.Culver City CA 90230

H RO6265 Sepulveda Blvd.Van Nuys CA 91411

A -Tech Electronics1033 Holywood WayBurbank CA 91505

H RO5375 Kearney Villa Rd.San Diego CA 92123

HRO2620 W. La PalmaAnaheim CA 92801

H RO2210 Livingston St.Oakland CA 94010

H RO999 Howard Ave.Burlingame CA 94010

Honolulu Electronics819 Keeaumoku Ave.Honolulu HI 96814

MoTron Electronics695 W 21st Ave.Eugene OR 97405

IF YOUR LOCAL HAMSTORE IS NOT LISTEDLET US KNOW SO WECAN CONTACT THEM TOCARRY AMATEUR TELE-VISION QUARTERLY TOSUPPORT YOUR LOCALMV ACIWITY.


Some of the video transmittersin use display a "blooming" effectand the audio is distorted for theinitial 1 or 2 seconds after firstkeying up the transmitter. Haveno fear, the solution is near.

The solution lies in keyingmethod and its effect on the vi-deo modulator circuit. A popularkeying method in low power tra-nsmitters is to key the entirepower supply voltage to the tra-nsmitter since the current drainisn't much. This is the culprit!

Upon examining the video mod-ulator you will probably find alarge coupling capacitor (about100Mfd - C1) from the video gaincontrol to the base of the firstvideo amplifier (See fig.1). The

"BLOOMING" VIDEOLYN H. CYR, W1NRE

value of capacitance at the inputstage establishes the low frequen-cy and is determined by the inputimpedance of the amplifier. Thehigher the input impedance of thestage, the lower the input capaci-tance can be to maintain goodlow frequency response. Since thecapacitor can and will charge upthrough the biasing network, howsoon the base voltage will stabil-ize will depend on the RC timeconstant of the network. Whenthe transmitter has been off forsome time the capacitor will havebeen diceharged but upon appli-cation of power the cap will mo-mentarily look like a short circuitand charge up to the bias voltagevalue provided by the resistive

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divider network (R1, R2). As thebase voltage is increasing becauseof Cl, the correct bias voltagewill be ut as well as the blan-king level The result will be anin -correct video setup for thatperiod of time.

The solution is simple. Keyonly the transmitter not the vi-deo modulator. With minor sur-gery find the line that feeds+VCC to your modulator and con-nect it to an unkeyed source. Inthis way when you key transmit-ter the modulator and hence theinput coupling cap will have al-ready been charged up puttingthe bias of the first stage into astahili7ed operating point. Happyno "blooming" key ups.

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Prior to the publication of"Computer Aided Interdigital Band-pass Filter Design" written byJerry Hinshaw, N6JH, which ap-peared in the January iccue ofHam Radio magazine, the subjectof high performance filters wasrelegated to the professional pub-lications. Wideband filters, whichmight have had ATV repeater ap-plications, were constructional innature and did not offer anychoice of parameter modifications.Most of the previous designs wereof the squared rod type and limi-ted in the number of poles. Con-struction of these filters was sim-ple enough but test results werea little disappointing. The band-widths were either too narrow orbroad and the insertion lcsees nottoo desirable. Out of frustration,the subject of filters was put onthe back burner.

Thanks to Jerry and his excel-lent article, the hair pulling wasover. The technical discussionswhich had appeared in the profes-sional journals with their manyformulas were now a thing of thepast. Jerry had compiled anMS/DOS Basic program written forthe IBM PC which was promptlytranslated to a Commodore C-64format. We were now free tomodify and try several designswithout expending precious timeand materials.

The original design goals ofthe filter were: 1. Minimum in-sertion loss, 2. Enough out ofband isolation to permit duplexing,3. Sufficient bandwidth to passthe video, color burst, and 4.5Mhz sound subcarrier. The firstfilter was designed and built fora 5MHz bandwidth. Subsequenttesting on a network analyzerwas met with mixed emotions.While the response curve wasclose tot he computer's predictedresults, the actual bandwidth wasa little narrower than expected.We tend to speak of ATV band-widths in terms of 4-5Mhz and Ihad overlooked the basic defini-tion of the term which places thebandwidth at the -3db points. Asa consequence, the color burstand sound subcarrier informationwas rolled off a bit too early.


ATV INTERDIGITAL FILTERSLYN H. CYR, W1NRE

After trying several other soft-ware designs a 7 MHz bandwidthseemed to meet the requirementsnicely. Several number of poleswere also tried and the results ofthe response curve plotted in Fig-ure 1. As might be expected fromthis graph, a 7 -pole, 7Mhz widefilter was chosen because of itssteeper skirts. Filters were calcu-lated for 426.25Mhz and 439.25-Mhz and plotted on the samegraph to determine the amount ofisolation to be expected from thefilters in a duplex configuration(see Fig. 2). As shown in thegraph, the amount of isolationbetween the transmitter videocarrier and the receiver videocarrier is about 60 db. Since wewere planning to use separateantennas and additional 30-40dbof isolation could be expected.Taking into account the receiver'sIF frequency response, filter re-sponse and antenna separation,over 120db of isolation could rea-sonably be expected. Everythingseemed to fall into place and theconstruction of the filters wasbegun.

The final mechanical designdictated that a ground plane spa-cing of 2" with a rod diameteror 3/8" would meet all of ourrequirements. The sides of thefilter were made out of 2x1/4"aluminum bar sock and 3/8" alu-minum rod. The rods were avail-able in most hardware storeswhich carry Reynolds Aluminum.The rods come in 6 foot sections.The 2x1/4" bar stock was a bitmore troublesome to obtain as noone seemed to have any in stockor there was a minimum purchaserequirement. Fortunately, a "littleole" sheet metal shop was willingto order a piece of bar stock forme if i was willing to have the12 ft piece cut in half so that itcould be shipped UPS thus savingtrucking costs. The ground planeor covers were made of 1/16"aluminum sheet. Other than usinga lathe to cut the ends of therods square and mounting holescentered, the entire ambly wasmade with nothing more than atable saw with a metal cuttingblade and a drill press. I have to

thank Joe Adeli7zi, formerKN1AFO, for" his extreme patiencewith my demands on accuracy andputting up with me. Joe is sort ofour "mechanical wizard" with allof our club's repeater projectsand without his support, many ofour projects would have incurredheavy financial expenditures formechanical work. The total costof the materials was under $80.00which was enough material toconstruct two filters.

The filter dimensions werethose shown in Figure 3. The 910and 1296 designs have not beentried but enough confidence canbe had by the excellent resultswe had from the 450Mhz versions.The critical dimensions are theelement lengths and their center -to -center spacing. The perfor-mance of these filters will bedependent on how closely the di-mensions can be held. For a givenmechanical design, changing fre-quency by more than 1Mhz or somay not be possible even thoughtuning screws are provided. Thetuning screws allow for fine ad-justments only. Particular atten-tion should also be given to thetap distances on the outer ele-ments. These dimensions are for50 ohm terminations and devia-tions from these will alter theresponse of the filter.

Not all of the dimensions aregiven in the sketch of Fig. 4, asthe cover sizes and location ofmounting holes will be dependenton the frequency. The coverscrews, however, should be loca-ted at the center line of the ele-ments and more added if desired.A good ground contact betweenthe covers and the side walls isesentiaL

The four sides were cut tosize and assembled to ensuresquareness as well as to providea template from which the coverscould be made. The sides werethen taken apart and the twolong pieces scribed to mark theelement locations. The sides wereclamped together and drilled atthe same time to ensure alignmentof the tuning screws with theelement ends. The holes were firstdrilled for an 8-32 tap size and

PAGE 41

then those holes securing the ele-ments enlarged to an 8-32 clear-ance hole. Note that a tap holemust be opposite a clearancehole. The end pieces were treatedin the same manner. The centerhole for the connector should bethe same distance from the insidewall as the 50 ohm tap distance.The mounting holes for the typeN connector were tapped for 4-40 screws. The length of thescrews securing the connectorshould not protrude into the en-cicsure. After the covers werecut to size they were also clamp-ed to the enclosure where themounting holes were drilled againto ensure alignment of the coverscrew holes to the sidewall holes.Mount the end rods so that the

z0

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-60

F-70

INTERDIGITAL FILTERStapped hole can be accessed

from either the top or bottomside (see Detail A, Fig. 4). Usinga piece of #12 AWG wire pass oneend of the wire through theelement hole so that it can besoldered to the center conductorof the connector. Once solderedin place tighten the recessedAllen head screw securely on theelement and trim any excessexposure beyond the rod.

The filter is best aligned usinga sweep generator or networkanalyzer, if you are fortunateenough to have access to one.Not having either, you could usea MV transmitter with color baror multiburst modulation. Usingyour off the air RF sampler adjustthe filter for best response. One

VC CS SC

word of caution, however, mostRF line samplers work fine whenlooking at your signals on TVmonitor but the high frequencyroll off can sometimes be exces-sive. (Good topic for another ar-ticle).

While these filters are not in-tended to be true vestigial side -band filters they do reasonablywell in that respect. As duplexersthey have done remarkably wellat the W1NRE ATV repeater witha transmitter power of 100 wattsPEP.

I hope that the computer aidedfilter designs can offer you a so-lution to your repeater or duplex-ing problems and that they willprovide the needed push to getthat ATV repeater on the air.

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PAGE 42

.100/ANT 55555 ATION

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ATV INTERDIGITAL FILTERS

CARRIER FREQ. (MH2) 421.25 426.25

CENTER FREQ. 423.50 428.50

LOWER CUTOFF (-308) 420.00 425.00

UPPER CUTOFF (-308) 427.00 432.00

INSERTION LOSS (DB) .824 .829

DIMENSIONS (INCHES)

INSIDE HEIGHT 2.000 2.000

INSIDE LENGHT 18.543 18.587

INSIDE DEPTH 6.967 6.886

INSIDE ELEMENTS 6.539 6.458

END ELEMENTS 6.649 6.567

ROD DIAMETER .375 .375

TAP FROM GROUND END .568 .558

7 -POLE ATV INTERDIGITAL FILTERS********************************

434.00 439.25

436.50 441.5

433.00 438.00

440.00 445.00

.837 .842

2.000 2.000

18.658 18.702

6.760 6.683

6.331 6.254

6.439 6.361

.375 .375

.542 .533

CENTER TO CENTER SPACING FROM INSIDE WALL (INCHES)

WALL TO ELE. #1 .500 .500 .500

ELE. #1 TC ELE. #2 2.524 2.532 2.543

ELE. #2 TO ELE. #3 3.048 3.056 3.068

ELE. *3 TO ELE. #4 3.199 3.206 3.218

ELE. #4 TO ELE. #5 3.199 3.206 3.218

ELE. 445 TO ELE. #6 3.048 3.056 3.068

ELE. #6 TO ELE. #7 2.524 2.532 2.543

ELE. #7 TO OTHER WALL .500 .500 .500

.500

2.551

3.075

3.225

3.225

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910.25 911.25 923.25 1241.25 1289.25

912.50 913.50 925.50 1243.50 1291.50

909.00 910.00 922.00 1240.00 1288.00

916.00 917.00 929.00 1247.00 1295.00

1.210 1.210 1.128 1.42 1.44

2.000 2.000 2.000 2.000 2.000

21.475 21.470 21.529 22.657 22.801

3.234 3.230 3.188 2.373 2.285

2.815 2.812 2.770 1.962 1.874

2.891 2.887 2.845 2.037 1.949

.375 .375 .375 .375 .375

.179 .179 .175 .113 .106

.500 .500 .500 .500 .500

3.013 3.013 3.022 3.210 3.234

3.537 3.538 3.546 3.734 3.758

3.687 3.688 3.696 3.884 3.909

3.687 3.688 3.696 3.884 3.909

3.537 3.538 3.546 3.734 3.758

3.013 3.013 3.022 3.210 3.234

.500 .500 .500 .500 .500

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Balch Springs, Texas 75180

HMAY ASSOCIATION

OF MESQUITE

Andrew D. Carstarphen12904 Elam Road, Apt. 402


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LIVE TV CAMERA TAKEN TO EDGE OF SPACE

if

On Jan.21, 1989 a 7 foot Heli-um Balloon carrying a live TVcamera was launched by Bin, WB8-ELK from Hesperia, CA in theMojave Desert. The package con-sisted of a 100 mW 2M FM trans-mitter on 144.34 Mhz sending outa CW meocage and a P.C. Elec-tronics KPA5 1 watt ATV transmit-ter on 434 Mhz. The video alter-nated between two computer LD.screens on an Elktronics VDG-1and a live TV camera pointingdown at the earth below. Russ,W8VKR donated a miniature SONYB/W camera (model HVM-302) forthis flight This camera onlyweighs 6 ozs. and even has anauto iris and microphone. Two inchthick styrofoam was used for insu-lation which housed the electron-ics and the 7.5 Ah Lithium cells(SAFT LX3457). A two meter verti-cal ground plane antenna wasmounted to the top of the pack-age. Mike, WA6SVT built a 1/4wave GP for 434 Mhz which dan-gled 4 feet below the package inorder to keep RF away from thecamera.

The balloon was launched fromthe parking lot of Mark Fischer'scommunications business (WB7AJC)at 9:48am. The camera videoshowed us all cheering and wavingbon -voyage as the balloon headedup at over 850 feet/minute. Wes,WA6IPN, had set up a ground sta-tion so we could watch the spec-tacular views of the desert floorand the town of Hesperia. Drama-mine is recommended when viewingthe video tape as the packagespun around once every few sec-onds! Future flights will have someform of stahili7ation to preventspinning. Ernie, WB6BAP and Bob,N6AZV used telescopes to triangu-late the balloon's position opticallyduring the first few minutes. Thepicture of the balloon in flightwas taken by Ernie through histelescope when it was over 10,000feet high. At 20,000 feet the bal7loon went through a cloud layerand only the tops of the cloudscould be seen for the rest of theflight. After nearly 2 hours theballoon achieved its maximum al-titude of about 105,000 feet. Atthis point the ATV signal could beviewed all over southern California


and was seen as far away asPhoenix, Arizona (300+ milesdistance!) by KD7HH, KS£3J, WV7Kand others at nearly P5 levels.Since the package was now in anear vacuum the spinning hadnearly stopped. A peaceful viewof the clouds far below could beseen as the package slowly driftedback and forth. The ATV antennacould be seen hanging straightdown. Suddenly the balloon burst,the antenna swung abruptly to oneside and the package began itswild gyrating return to the desertfloor below. As the package tumb-led, twisted and spun it's wayback we were all treated to viewsof the horizon which reminded usof Space Shuttle flights. Eventhough it was noon the blacknessof space could be seen against thecurvature of the earth (At leastwe proved that the Earth isround!).After the balloon burst the trac-

king and recovery team spranginto action. An extensive teamwas assembled consisting of six T -hunt vehicles, a chase plane andeven a chase helicopter! Membersof the Los Angeles T -Hunt clubwere tracking the balloon through-out the flight with direction find-ing equipment. One of their mem-bers was located on top of anearby mountain and provided avery accurate triangulation of theballoon's position. Tracking becamedifficult when the two meter sig-nal faded away after the firsthour of flight It was later dis-covered that the VHF Engineeringtransmitter output dropped to onlya few milliwatts when the internaltemperature fell below 49 degrees.Also the violent return caused theATV antenna on the end of theRG-58 coax to tear off at thepackage. Still minutes from impactall signals had ceased from thepackage! The Be]lanca chase planeflew towards the best estimatethe T -Hunters could provide of thepackage's location. Suddenly Mike,WA6SVT, monitoring the ATV signalin N6ESW's airplane shouted outthat he could see the video. Thesignal grew stronger and housescould be seen on one side of theopen desert. Then he saw a glim-pse of an airplane wing and look-

ed out the window to see a whitestreak as the package zipped byonly a few hundred feet away!The desert floor could be seenrising up quickly and then thesignal faded away. Fortunately thetwo meter signal reactivated asthe package warmed shortly afterimpact and allowed the two clos-est chase vehicles, N6MI and KB6-MMF, to point their beams towardthe package. Tom, W6ORG, simplyflew his helicopter over the chasevehicles and headed in the direc-tion they indicated. After only a10 minute search Rick, N6UEM,flying with Tom in the helicopterspotted the package on the desertfloor. They landed next to it andhelped the chase vehicles find thelocation. The balloon had travelled22 miles north of the launch siteto land near the small town ofHelendale.

Upon examination it was foundthat the parachute had ripped toshreds when the balloon had burstand the package had made a totalfree -fall from 20 miles up! How-ever the package sustained onlyminor damage and the camera andATV transmitter were still sendingout a picture of an upside downmesquite bush!

Thanks to all who participatedand especially to Rod, WB9K MO,for his invaluable help in con-struction of the package. Moreflights are planned for the upcom-ing year including a balloon ATVRepeater!

K6KMN

PAGE 45

-rw

KDOFWf.r.":77.45 (ITT MISSOURI

/iTfPil 144235 SS114/045 Fm

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In mid -December a cross-coun-try ATV adventure was startedleading from Ohio to California.Piling my mobile TV system intomy station wagon, my co-pilotLouise and I set out to contactATV'ers in as many corners of thecountry as we could.

OHIOHome RasP, Findlay.

In northwestern Ohio there aredozens of ATV'ers active. Thefollowing stations can be workedjust about any night in the localarea: Joe, WESMSJ - Jeff, KA8WLV- Dick, WB8VNC - George, WA8-HDX - Harold, WA8HDY - Dick,K8LZG - Jan, WM8W - Bob, W8RSK- Dan, W8PXU - Paul, W8ZD -Mark, N8GVF - Mel, KA8LWR -Lou, KZ8P - Lowell, K8PYQ - Jim,W9AZO - Brian, KA8IGU - Rill,WB8URI - Harold, KA8MDT - Mike,NM8E - Bud, KA8A'II - and Dave,WB8RTZ. The 2 meter talk frequen-cy is usually 147.45 Mhz for localactivity although 144.34 Mhz isalso monitored quite a bit for DXcontacts. A lot of activity occursduring the evenings hours howeverKA8LWR, KZ8P, K8PYQ, and W9AZOusually keep the airwaves warmedup from midnight till 3am everynight. Starting out on our trip wewere able to watch my dad, WB8-MSJ and my brother, KA8WLV forabout 30 miles. The first ATVrepeater system was encounteredin Lima, Ohio 35 miles from Find-lay. Dave, WB8RTZ has put toge-ther a vertically polarized systemwith 439.25 Mhz input and 421.25Mhz output. The WB8ULC repeateris located in the center of Limaon top of a 200' tall bank build-ing. The Lima machine was one ofthe first systems to gain permis-sion to send out the Kavorousweather radar feeds. A touchtoneaccess on two meters will bringup the Ft. Wayne radar which islinked in from a remote site at acommercial radio station. Talkfrequency is on 147.45 althougha call on the 146.67/.07 repeaterwill usually net you one of thelocal ATV'ers.100 miles down the road the Day-ton ATV repeater was seen on426.25 Mhz (W8BI/r). This systemalso is vertically polarized al -

ON THE ROAD WITH THE ELKBill WB8ELK

though most simplex contacts arehorizontal in the midwest. Most ofthe locals have some way of flip-ping their antennas from horizon-tal to vertical through some rath-er ingenious methods. My particu-lar favorite is W8RVH's Rube Gold-berg system of pulleys and motorsto twist his huge collinear overon its side. The Dayton machinehas a 439.25 Mhz input as well asa weather radar link from theairport on 923.25 Mhz. Bruce,WB8UGV has been taking care ofthe repeater for the last 8 yearsand is usually monitoring 147.45Mhz during the weekends. Onenice feature that will help to findthe signal when driving through isthat any signal on 147.45 Mhz willbring up a computer LD. on theoutput for several seconds. Lookfor this one when attending theDayton Ham vention as it put's ina healthy signal over the entireDayton area. Simplex activity isguaranteed every morning on 439.-25 Mhz between 7:30am and 8:00-am as W8RVH, W8BLN, W8EHW,WA8KQQ and WB8UGV have a sche-dule with W9NTP and W9PRD inIndiana on 144.34 Mhz.

INDIANANo trip to Indiana is complete

without a visit to the "Wild West"farm of Don Miller, W9NTP in Wal-dron. Don and Sue, W9YL, operateWYMAN RESEARCH from their farmsoutheast of Indianapolis. Don isa true pioneer in both SSTV andATV and has developed a completeline of ATV gear over the years.He recently has been offering FMATV equipment for the 1200 Mhzband. Don also is quite an arche-ologist and has an amazing displayof Indian artifacts in his museum.Don has a daily schedule with theATV'ers in Dayton and Springfieldbetween 7:30 am and 8:00 am on144.34 and his 500 watt ATV sig-nal usually can be seen as faraway as Findlay, Ohio (160 miles)every day. He quite often can befound as net control for the SSTVnet every Saturday on 14.233 Mhz.

Fifteen miles away in Greens-burg can be found another veryactive ATV'er. Bob, W9PRD hasbeen responsible for organizingtwo balloon launches from Indiana

during the past year attainingheights over 110,000 feet. A visitwith Bob and Michelle is alwaysa pleasant experience.

Indianapolis is home to the K9-LPW ATV repeater. This machinehas an input on 439.25 Mhz (Lowersideband to minimize FM repeaterinterference) and an output on425.25 Mhz and is vertically pola-rized. A touchtone access on 2meters will bring up a few min-utes of weather radar and colorbars. The repeater is located onthe east side of Indianapolis andcould be seen over 30 miles awayin my car. Lots of activity existsin the area just about any night.Talk frequencies are 144.34 Mhzand the 146.76/.16 repeater.

It's impossible to escape Indianawithout running across severalmore ATV types. In Lafayette youwill find a whopping signal fromJeff, KA9TGX. With his Henry amp-lifier and 100 foot tower Jeff isreb-punsible for stirring up manyDX contacts. If you receive hispicture you will be treated withsome amazing AMIGA graphics andspecial effects. His impressivedisplay of monitors all tuned tovarious satellite feeds, test pat-terns and the like rivals that ofa network newsroom. Further downthe road in Hebron you most likelywill run across Garry, K9WZB andTobi, KA9MMY. Even though 200miles away from my home QTHGarry and I work each other sev-eral times a year. Both Garry andJeff monitor 145.01 packet andcan be alerted of a band openingvia a packet connect immediately.This system has resulted in manysuccessful TV contacts when evena direct voice transmission contactcouldn't make it.

ILLINOISAs you pass through the Cham-

paign -Urbana area you will enc-ounter Mark, KA9SZX and Tim,KA9SZY. Local contacts are fewand far between but several QSO'shave been made with KA9TGX inLafayette and the Springfieldgroup. Mark has been active intracking the balloon flights thisyear and may try a balloon flightfrom Champaign sometime thisyear.


ELK ON THE ROAD continued .In Springfield contacts can be example of cubism art I had just

made with Gene, WB9LHD and Bill, bought. Finally reaching the topK9KKL. Nearing the St. Louis, Mo. of the 600 foot arch we werearea Scotty, K9SM in Hillsboro is presented with 6 inch high win -also quite active. dows which although providing a

MISSOURI (St. Louis) fantastic panorama of the St.A visit with Dave, WI302JP and Louis area was virtually impossible

John, KDOLO will put you in ex- to fit a quad into. It also turnedperimenter heaven! Dave and John out that with it's tons of thickhave both made DX ATV contacts stainless steel the Arch was ain excess of 400- 500 miles sever- very effective RF shield! Evenal times over the past few years. with all of the obstacles contactsThey have most recently been de- were made with several of thesigning an 910 Mhz FM ATV trans- local ATV'ers out to over 25 milesmitter as well as trying contacts distance. We looked sufficientlyon every microwave frequency wierd trying to stick the antennaimaginable. I particularly enjoyed out the window that a punk rock -their story of tracking down a er actually said "FAR OUT" andstrange interference on the 2300 took our picture.Mhz band. It seemed that the in- After an enjoyable visit, we setterference only occurred between outtowardsthelndependence/Kan-5-7pm and llpm to midnight. It sas City area. There we visitedturned out to be microwave oven Mike, KDOFW, who is putting toge-leakage from the neighborhood as ther the Kansas City ATV repea-everyone cooked dinner or warmed ter. Input is 439.25 Mhz with anup a quick midnight snack! We had output on 426.25 Mhz (Horizontalquite an enjoyable weekend work- polarization). Several ATV'ers areing all the local ATV'ers. Give a active in the area and monitor thecall on 144.34 Mhz when in the 147.045 repeater. The ATV repea-area and you will most likely raise ter will be located 27 stories highone of the group. Some of the in a skyscraper in the downtownmore active ATV'ers that can be area and should have quite a cov-worked are John - KDOLO, Dave - erage area. Already the 4 wattWBOZJP, Dale - NIOD, Everett - test signal has been seen regularly

KBOWG, Jim - WB000L, Earl - 50 miles away at a P3 leveLWDOFCH, and Earl - WODDZ. KANSAS (Wichita)

After having lived back in the The Wichita ATV group has aflat lands of the mid west the past vertically polarized repeater loca-four years I started getting the ted in the north part of town.urge to do some mountain -topping. It's input is 434 Mhz and outputsI searched St. Louis for the high- on 421.25 Mhz. We were able toest spot to operate from and fi- receive KOLXO's picture quite wellnally found it. You guessed it...the over 30 miles away in the car."Gateway to the West" itself, the While in Wichita we visited Bob,gleaming Arch of St. Louis! Taking NOHKI who has checked into thean ATV station up to the top of ATV HF net many times. The Wich-the Arch is no easy feat. Although ita area is fairly isolated froma TV camera, a small ATV trans- other ATV groups but there maymitter and battery pack are fairly be a chance that contacts can beunobtrusive, a 2 element quad on made with the Kansas City anda mag-mount definitely attracts Tulsa, OK groups eventually.a lot of attention! It probably NEW MEXICOwould have been easier to scale Anybody out there? If there arethe outside of the Arch than to any ATV'ers in the state pleaseanswer all of the question posed, let us know as rd like to workby the numerous park rangers, you on my return acres country!ticket takers and elevator opera- ARIZONA - (Tucson)tors who kept a wary eye on me Just one lonely ATV'ers wasand Louise. We both felt like Arch found. Roy, N4ABY would like toTerrorists! I finally fended off the become active again on TV ifsuspicious looks by explaining that anyone else is interested in thethe quad was actually a great area. Roy occasionally does work

. .at the Multiple Mirror Telescopeon 8000 foot Mt. Hopkins and alsoKitt Peak observatory. On his lasttrip to Mt. Hopkins we gave hima Kreepie-Peepie and the infamousquad. Except for the three inchesof snow that accumulated on hisparka his picture was snow -freeinto Tucson 50 miles away. It wasquite a treat to get a privatetour of one of the largest tele-scopes in the world as Roy showedus around the facility on MV.(Phoenix) As Louise put it; "We'veseen pockets of ATV'ers so far butnow we're in the midst of a wholeNEST of them!!" Dozens of veryactive ATV'ers abound in the Pho-enix area. Several days were spenttouring around visiting the mem-bers of the AAA5 club with Earl,KS&T and Tommy, N7KBO. The KS8Jrepeater is located in the centerof Phoenix on top of 1000' ShawButte. The input is on 434 Mhzand an output on 421.25 Mhz andis vertically polarized. Also ano-ther repeater is currently locatedat WA7TSD's QTH and will have a434 Mhz input and output on1253.25 Mhz. Earl, KS8J, is mostnoted for his aeronautical ATVadventures from 30,000 feet in ajet while testing FAA equipmentover Minnesota and Wisconsin.

Last November, a real ATV firstoccurred during the ThunderbirdHot Air Balloon Race. On boardone of the 160 balloons Earl andTommy were married high overPhoenix. Area ATV'ers and onlook-ers at the launch site witnenrr,dthe ceremony televised via the onboard 434 Mhz transmitter. Al-though the camera slipped partwayduring the proceedings, (a wonder-ful view of their feet could beobserved!) the wedding vows couldbe clearly heard via the subcar-rier. From a nearby balloon Norm,WV7K and Wayne, N7MAO sentback pictures of the ceremonyfrom yet another camera angle.Not only that, they were able toestablish a two-way balloon toballoon ATV QSO with the newly-weds. The happy couple have beenfloating on air every since!

Mountain -topping and motileATV are popular activities in Pho-enix. It didn't take much encour-agement to spark a round of DX -


ELK ON THE ROAD continuedpeditions to some of the localhigh spots. Louise and I decidedto try some contacts from 2000'South Mountain on the outskirtsof town. The panoramic view ofthe entire area provided numerousP5 contacts with many of theATV'ers below. Shortly after arriv-ing a beat up van pulled up besideus. Expecting a bunch of partyingrowdies to emerge we were quitesurprised when the doors flewopen. Four ambitious teens poppedout to set up antennas, cameras,and a generator. Inside was a ATVstation complete with a 50 wattamp and an AMIGA computer forgraphics! With N7LWO, KB7EXUand KB7EXY on the AMIGA graph-ics keyboard and Chris, KA7SMImanning the camera we were ableto work them two-way mobilewhile driving back. The next dayNorm, WV7K went on an expeditionto the top of 9000' Mt. Lemmon120 miles to the southeast nearTucson. With 50 watts from histruck he was seen P4 -P5 back inPhoenix.

Lou, W7LNX is one of the pio-neer spirits that got ATV rollingin the area many years ago. Louwill always go out of his way tohelp newcomers get started onATV. If you would like to ex-change pictures with the AAA5group you might be able to do sovia SSTV if you contact Bob, WB7-CAM. Bob can be found on theSSTV net on 20 meters and canrelay some of the local ATV sig-nals by way of slow scan TV.NOTE: If there is interest in link-ing ATV groups together via a20m SSTV network please writeto ATVQ with suggestions of timeand frequency.

The ATV calling frequency inPhoenix is 145.17 Mhz and thereis a net every Wednesday nightat 7:30 pm on the 147.28/88 re-peater.

CALIFORNIA (Los Angeles)After a week of meeting with

some of the 200+ ATV'ers in theLA area and having seen the RoseParade activities, Louise was con-vinced that I had taken her froma NEST of ATV'ers and thrown herinto a whole SWARM of them!!With all of the tall mountainssurrounding the LA basin an ex-

tensive network of ATV repeatershave sprung up over the years.The ATN group (Amateur TelevisionNetwork) has been busily liking upthese repeaters with plans to cov-er virtually all of southern Cali-fornia. The furthest east of theseis on SANTIAGO Peak. With analtitude of over 5500' this repea-ter cover-, most of the LA basin.Input is on 434 Mhz with an out-put on 1253.25 Mhz verticallypolarized. Mike, WA6SVT has beeninstrumental in maintaining thismachine and has eventual plans tolink up to the Phoenix, AZ group.

The OAT Mountain repeater,NU6X/r, covers the San FernandoValley and links into the SANTIA-GO repeater. It's input is 434 Mhzand outputs on 923.25 Mhz. Bymeans of a 1253.25 alternate in-put, this machine can link up withthe output of Santiago Peak tobetter cover the San FernandoValley.On top of 5000' MT. WILSON a-

bove Pasadena you will find theK6K MN ATV repeater with an inputon 434 Mhz and output on 1241.25Mhz.

In SAN DIEGO there will soonbe a repeater (WA6VLF/r) with434 Mhz input and output on1277.25 Mhz located on Mt. SanMiguel

LOOP CANYON north of theSan Fernando valley has a repea-ter (WA6ZVE/r) with 434 Mhz INand 1277.25 Mhz OUT. Simi Valleyand the Ventura area are coveredby the SULPHUR Mtn. machine 434IN - 1253.25 OUT.

In SANTA BARBARA the WB9-KMO repeater is located at 2600'on Gibraltar Peak. It has an inputon 434 Mhz and outputs on 1277.-25 Mhz (10 watts). This machinewill be linked soon to the otherrepeaters. Rod, WB9K MO, alsoplans to link up eventually withthe northern California group.

The Los Angeles area is thehome of P.C. Electronics. Tom,W6ORG, has been offering a com-plete line of ATV receiver andtransmitter modules and transceiv-ers for many years. As a result ofTom's efforts, getting started inATV is far easier than it used tobe and has been a major influencein the current popularity of the

mode. Tom really enjoys the mo-bile capabilities of ATV. He hascarried systems on board every-thing from Motorcycles, Airplanesto Helicopters.

The two meter calling frequen-cy in Southern California is 146.43Mhz. There are three weekly nets.The Mt. Wilson net chaired byK6K MN meets Monday night at8pm. Tuesday night at 8pm San-tiago Peak and Oat Mtn. have anet chaired by Phil WB6LQP, ErnieWB6BAP or Mike WA6SVT. Also onTuesday at 8:30pm the SulphurMountain Net meets in the SimiValley area on the 146.88/.28repeater.

The Roving "ELK" will be visit-ing groups in other corners of thecountry during the year. Next onthe list is the Northern Californiagroup and possibly Texas and Ok-lahoma. 73's and CU on the Road. -..Rill - WB8ELK

Henry KB9FO ATV Mobile. 20 elementGP YAGI, 200 W AMP, = 12 KW ERP.Wind tested to 100 MPH & 96,000 miles!

SAY YOU SAW

IT IN ATVQ!


WA6SVT VIDEO PROCESSORIn some older ATV transmitters

high frequency roll -off and synccompression can become a prob-lem. Also if driving solid stateamplifiers for that extra wattsync compression can be quitepronounced. This Video Processorcircuit will compensate for thesesituations and has four controls:1) Sync Level, 2) White ClippingLevel, 3) High Frequency Equali7a-don, and 4) Composite Video Le-veL The input impedance is 75ohms so no termination is needed.The module can be built into aseparate box and placed in thevideo line leading into your ATVtransmitter. Also you could mountit directly inside the transmitterif room permits. 47 OF tantalum

vofo 940

75

19 K

Al 1,110V

4.7 K970

1K

11011

capacitors are used although theycan be substituted with 100 uFelectrolytic caps.

ADJUSTMENTS:1) Set the controls of the pro-

cessor as follows, Sync Level --fully counter clock wise, High Freq.Equalisation --center, White Clip-ping --fully counter clockwise,Composite Video Level --center.

2) Apply power with video signalinput and a 75 ohm load on theoutput.

3) Connect an oscilloscope tothe output and adjust the Com-posite Level for 1 V p -p.

4) While monitoring the demodu-lated output of your ATV trans-mitter set the Sync Level for 1/3sync to 2/3 video. For those

FREQUENCY

EOUALIZATtON

39 p1

2H2222

10091.1

10 K

1,7 K

10 K

1 map

2/422221-4.03 ut

330 K

0

10 K

2N2222

2742229

Two Video InputsSPDT Toggle

Switch

100

without a line sampler, have adistant station look for the moststable signal while adjusting thesync.

5) Adjust the High Freq. Equali-zation control for a flat videoresponse and best color burst le-vel.

6) Adjust the white clippinglevel so any video above 100 EIAare clipped. This will keep theMV transmitter from whiting out(flat topping) on very bright ob-jects.

The following will be availablefrom ELKTRONICS, 12536 T.R. 771Findlay, OH 45840:Blank Circuit Board - $7, Kit(blank board and parts) - $29.Assi.mbled/fiested - $39.

GO/APOltrif V1040 (EVIL

+147ut10V

0 K 00+147 lot

T

4.7 K

WHITE C1.11111140 LEY91.

?KUREGULATOR

11.0

To Video Input VP -18 Inch Max Length

Video 1

Video 2

0+t2 V'

LC:

VDEG OLIT0

F I G

1

FIG3

Remove the 75 ohm re-sistor from the VP -1and replace with a330 ohm +W resistor.

DAK corp. is offering a close-out sale on a device known asthe Cyberex ANSWER BACK. It wasdesigned to record your voicedigitally and play it back as atelephone message. It digitizes up

DIGITAL VOICE LD.Bill WB8ELK

to 15 seconds of voice and storesit as long as power is applied. Theoutput is good quality and couldbe used as a voice I.D. for repea-ters and hidden transmitters. Thesecan be purchased for $15.90 direct

from DAK Industries. To ordercall (800) 325-0800 and ask forcat. #4859. For more informationcall (800) 888-7808 and refer toeither the Backtalk Plus or GoneFishing Plus.


MICROWAVE MODULES EQUIPMENTUse your existing HF or 2M rig on other VHF or UHF bands.

RECEIVECONVERTERS

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MMI 1296-144G 499 00MM, 1268.144 395 00MMI 432.28(S) 370 00MMI 144.26(R) 499.00MMI 144.28 265 00MMI 435-211(S) 390 00

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PSF 900.3 890.940

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pass filters are a 3 pole, The bandwidth Interdigital design.The 0.1 dB ripple Tchebyscheff characteristic has a 30dB shape factor of 4:1. They are intended for receiver pre -selector and transmitter applications. The very low lossis realised by using an air dielectric transmission linedesign.Technical DateGeneral: Ripple

ImpedanceVSWR, typPower, nom

Size:

Material:

WidthThicknessBrassHardware

CN1 S,, 1 U FS 24 I". 117 0

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0.1 dB50 Ohms1 25100 W (BNC)250 W (Type N)4.0 ins approx

1 inchPlates, Rods 8 BarsStainless Steel

419041 I. Tad. AN

SPAN 10. coo am 4.44

General Information: All prices are NET, FOB Concord, Mass. USA. Our trams are "Payment with Order" or C.O.D. Your personal cheque is welcome; MasterCard and VISA are available for your convenience. On foreign orders, U.S. Dollar cheques drawn on a New York bank and Irrevocable Letters of Credit areacceptable From Canada only, Postal Money Orders in U.S. Funds are convenient. Prices subject to change without notice.Delivery Information: Domestic U.S.A. delivery is by U.P.S. or the Postal Service. Small parcels are sent U.P.S. Blue Label (air) where theservice is available.Overnight express delivery via Federal Express or U.P.S. is available, n request, at increased charge.

Foreign delivery is by Registeres (or Insured) Air Mail for small items. Large items and high value shipments are sent Air Freight, from Boston Inel Airport,to your local airport for Customs clearance and collection. Air freight charges, etc. are payable in your local currency at time of collection of goods. Pro -formainvoices are available (if required) prior to placing your order. All facilities for Export Documentation are available.Returns: All crystals are "non -returnable". Please request authorization before returning any item for check-out, repair or other reason. A re-stocking/re-testingcharge of up to 15% of item list price will be levied on returns, plus a cancellation charge on cancelled orders.Massachusetts residents add 5% SALES TAX to item cost.Spectrum International. Inc, qualifies as a SMALL BUSINESS under Federal Procurement Regulation I 1 702 and other govt. regulations.

WORLD CLASS COMPONENTS AND ANTENNAS. . .FOR THOSE WHO ARE SERIOUS ABOUT GETTING THE MOST OUT OF THE. VHF, UHF

AntennasW.137 (137 MHz Weather) $ 9010P -21A 83

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PMH/2C70cm aerial,2 way prising harness for circular 12964waT ("tine)polarisation for two 2m aerials 1891- 1 Komblnell

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PRICES SUBJECT TO CHANGE WITHOUT PRIOR NOTICE

SPECTRUM INTERNATIONAL, INC.Post Office Box 1084

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Just when you think you've seenabout everything, someone willcome along with a new widgetthat proves you wrong. So it iswith Commodore's relatively newoffering the Amiga (500, 2000).Although this computer has beenaround for several years, it 'isjust now coming into its own asfar as ATV'rs are concerned.

The Amiga 500 and 2000 arebasically the same machines, how-ever the 2000 is easier to expand(i.e ram,hard disks etc.) The 2000also comes packaged more like astandard P.C. Clone in a metalcabinet with internal expansionslots and built in power supply.The 500 comes with 512k ram andthe 2000 comes with 1 meg ram.The 500 requires a rather involvedprocess to expand beyond 1 megof ram including an outboard ex-pansion chassis while the 2000can easily be expanded to 8 megof ram with the addition of aninternal "plug-in" ram board whichcan be added increments of 1meg.

While the Amiga is hailed asthe video enthusiasts computer itdoes have a voracious appetitefor memory. The machine is a mu-ltitasking computer able to runseveral programs simultaneously inaddition to supporting 2, 3 1/2inch 880 kb disk drives. It canalso be fitted with a bridge boardwhich will allow full compatibilitywith PC software. That's right,add an optional 5 1/4 disk driveand all your PC software will bo-ot and run. The video display isavailable in either NTSC or PALbut will not run both simultane-ously. The video display is ableto present 4096 colors on its RGBanalog monitor and has up to 512kb of ram dedicated to its videomemory wow! At the expense ofgoing on with system specs, suf-fice it to say that this is THEpremier computer for video appli-cations.

The big news on 14.2 mhzthese days is the new offeringfrom Black Belt Systems 406 367--5509. Imagine a SSTV system th-at supports ALL Robot modes,weather fax, news fax, Volker-Wrass.e line sequential and has its

COMMODORE AMIGA AND AMATEUR SSTV/FSTVby John Spaeth KDOLO

own mode to boot. The AVT hardsoftware from black belt does allthis and more for under $200.

The hardware consists of a3x5 inch circuit board which youmust enclose and power with 12volts D.C. A cable is providedwhich connects this board to theparallel port of the computer. Thereceive audio must be routed tothe board through any cable con-nector you choose. The transmitaudio comes directly from thecomputer at line leveL

After booting the program thecrt goes black and an attractiveand colorful switch panel fadesonto the screen. This panel lookslike the membrane keyboard foundon the 1200C. Functions are sele-cted by moving the mouse con-trolled cursor over the top of thefunction button on the screen and"clicking" the mouse control but-ton. This procedure is used fortransmitting, receiving, processingetc. The computer keyboard neverreally has to come into playwhich is good news for poor ty-pists like myself.

To receive Robot 36 sec com-posite color simply move the cur-sor to the 36 button, then thecomposite button then the receivebutton, clicking on each as yougo. The image will be retained ina buffer area as it is receivedand although you will be able tosee the image as it comes in --theprogram will have to process itafter reception. This process takesabout 10 sec. The composite colorpicture is then displayed. A com-puter with more than 1 meg ofram will hold up to sixteen suchimages in its current buffer andeach one is immediately accessiblewith a keystroke, much like flipp-ing through a photo album. Theseimages may be saved to disk atany time. The image on the frontmost screen can be sent out inany Robot mode by selecting thetransmit speed, synthesizing theimage and clicking on the trans-mit button. Of course the frontscreen can be changed at anytime to any of the sixteen im-ages in the buffer or any of theimages stored on disk. The imagecan be modified by adding a col-

orbar or grey scale strip to it orby writing text over the top ofit. Both of these functions areincluded as program functions andthe available text fonts are thosesupplied with the computer.

Additionally, the program pro-vides options for color correctionto the received image as well asline correction which allows theuser to correct the image line byline. This enhancement actuallyallows you to remove any hits youmay have received and make thepicture appear noise free or cor-rect the hue of a picture receiv-ed off frequency.

Once satisfied that the progr-am worked well with Robot imag-es I moved to another mode ofthe program called the AVT modeor Synchronous Line Phase mode.This mode is unique to Amiga use-rs with the Black -Belt system andboasts better color accuracy, po-sitioning, and narrower bandwidthrequirement. This mode also hasa QRM option which will take animage ordinarily received with50% noise and make it 99% cor-rect due largely to narrowerbandwidth requirement.

My initial reaction to thismode is positive having receivedimages through impossible QRM.The color register was perfectand the image was correct yetthe tones were just audible overthe noise on the band. With over400 registered users of this pro-duct I expect this mode will drawsome attention on the bands andcatch on rapidly.

Although I haven't tried anyof the fax operations the programis capable 120 or 60 1pm rates in16 grey levels with up to 1024 by1200 resolution. Also included arefull auto -start for transmit andreceive with an "unattendedauto -start" function. Fax imagescan be panned, flipped, rotatedand of course saved to disk.

The author tells me the fu-ture will bring enhanced video(3-D capability) as well as thePanasonic 5 sec mode which isused with consumer telephoneunits. I was also told that anyfurther updates including any newmodes which might become avail -


able to the ham community wouldbe sent to me. As of this writingI have already received one soft-ware update at no charge!

This program is not a substi-tute for the Robot 1200C as itwill not do some of the thingsthat the Robot unit will (live vid-eo frame grab for instance) butit is certainly compatible with itand brings to SSTV the new andexciting mode of AVT mode. Morecomplete information can be ob-tained by calling Black -Belt atthe number above or through theAmiga Ham Radio Users Net at14.345 Mhz on sundays at 5:00PM central, net control WB3KRN(Kathy). Next issue, a look at theAmiga and FSTV applications. 73'sKDOLO.

BACK TO BASICSHENRY KB9FO

Last issue we threw you acurve by giving a wrong answerto an Ohm's law problem. In our"survey" either no one knows Oh-m's law, or no one was readingmy column (pout). In either caseno one wrote in to tell us, trickyaren't I?As I write this we have 4 broad-

cast equipment maintenance en-gineer openings and 4 duplicatortech openings. Anyone looking fora job?

By the time you read this wewill have a FAX number and acomputer MODEM for direct deli-very of your material! Watch forthe announcement in the nextissue of ATVQ.

Video Sidebands! Where do theycome from and what do they do?Our topic. Video is composed oftwo basic forms of information,AC and DC. When ever the signalis steady state, unchanging, itrepresents a DC voltage level. Thiscould be the sync pulse, blankingarea or and flat video area in thepicture. The AC components aregenerated by any TRANSITION inthe signaL This could be the riseand fall of the sync pulses, orsmall changes in the video fromobject to object. The rate ofchange produces a characteristicfrequency. The faster the rate of

change, the higher the characte-ristic frequency. The greater thechange in level the more energyis generated at the characteristicfrequency. The highest frequencywe are interested in is 4.2 Mhz.This is the limit of NTSC broad-cast video bandwidth. From DC(video carrier) to 4.2 Mhz at mul-tiples of the horizontal frequency(15,734 Hz) you will have side -bands. The sideband energy at anyof these points will be directlyproportional to the energy repre-sented by the magnitude of thesignal change in the picture atthat frequency.

If you remember good old AM,then you know that the sidebandscannot have more than 50% of thepower of the carrier. With videoyou have sidebands at multiples ofthe sync frequency (mostly) so theenergy is centered around 274sidebands. Simple arithmetic willtell you that 25% of your powerdivided into 274 sidebands meanseach sideband has very little en-ergy. In fact you would have ahard time generating such a sig-nal. In real life the sideband en-ergy is typically 40 to 50db belowyour carrier power at frequenciesof .5 Mhz to 4.2 Mhz removedfrom your carrier. More than halfof the sideband power is usuallyin the first .5 Mhz area from yourcarrier.

With vestigial sideband trans-mission the lower sideband, from1.25 Mhz out, is thrown away, butthis represents less than 10% ofyour power! A color signal willhave a number of strong sidebandscentered at +3.579545 and thesesidebands fall in between yourluminance signal sidebands becausethe color carrier is 455 times theH rate (an odd number) and isthus interleaved. Even in full sat-uration though, the color signalamounts to about 10% to 15% ofyour total sideband energy and thecolor sidebands are insignifidantafter more than .5 Mhz from thecolor subcarrier.

This is why it takes about 50db more signal to get a "perfect"tv signal than your typical NBFM,and why a weak NBFM signal 40db below your desired signal willwipe out the received picture!

73 KB9F0

A TV Q HUMOR TESTYou say you never have any-

thing to write us about? You saylife is dull and you can't take itanymore? Well listen up bunky! Itis time for a national A TV QHumor test.1. You say you got the Januaryissue and you didn't suhcrribe?A) You were too shocked at theamount of good stuff in 1 maga-zine about ATV and thought it wasa fluke.B) You are too cheap to subscribeand steal your ATV buddies copy!(Yeah, we know, ham's are cheap!)C) You believe the "other mag"will get better. (We like theBATC's CQ-TV)D) You were on your way to theham store to get a copy and gotcaught in a tornado, flood, earth-quake.E) Your local ham store was soldout so you couldn't find the ad-dress to mail in your suhsrription.F) Your tower blew down and youdecided it wasn't worth puttingit backup so why buy a magazinetoo.G) You can't read! (then how comeyou can read this??)H) You don't print any risque pic-tures! (This isn't Playboy!!)I) There are too many pages andI can't spend three days readingonly one magazine. (Well you gotyour money's worth didn't you?)J) DX was in and the band wasopen for 48 hours and the lackof sleep caused you to have amental lapse. (Yeah, DX of 3

blocks)K) I've already got too many

d -it projects. (Buy two solder-ing irons!)

THIS IS YOUR OPPORTUNITY TOSUBSCRIBE TODAY AND AVOIDTHESE EXCUSES IN THE FUTURE.

AMATEUR TELEVISION QUARTERLY1545 LEE ST. SUITE 73DES PLAINES, IL 60018

SUBSCRIPTION FORM ON PAGE 21(ITS OLD ENOUGH TO VOTE)


F

L

TER

TXRX

DownConverter

Receiver I

Video Out

AUDIOMIXER

425.75 M ZEXCITER

REPETER

TEL

atiosaIsWB5JLZ/R

D-24POWER AMP Tuned

-Cavity_

D-100

POWER AMP

Ant.

GRAPHICE.O.

IGRAPHICE.Q.

2MTR. TX. I


A few simple plumbing andhobby shop components can pro-vide a considerable savings whenyou are in need of a connectorfor 1/2 inch Heliax such as An-drew LDF-50. With a 3/8 inchcopper sleeve and hose clampfrom your local plumbing supply,along with copper tubing sold atmcst hobby shops, you can assem-ble an effective RF coax connec-tor. Using other plumbing transi-tions for different sizes of cable,you can easily adapt standardconnectors to any size Heliax.

To begin, strip back 1 inch ofthe plastic covering and 1/4 inchof copper shield and foam expos-ing the center conductor. Next,slot the end of a 3/8 inch coppersleeve in an 'X' pattern; solder

1/2" HELIAXLDF4-50

INEXPENSIVE HELIAXCONNECTORS

BOB - WD5BJWthe other end approximately 1/4

inch over the rear of A type 'N'or P1-259 connector. Slip the hoseclamp over the sleeve and spreadthe slotted end open slightly.

Next, assemhie the center tap-er. Your local hobby shop carriesvarious sizes of brass tubing thatnest in one another tightly withthree or fours sizes. This will al-low you to taper down from theHeliax center conductor to thecenter pin of the coax connectoryou are using. Start with 7/32tubing and cut a piece 1/2 inlong. Next, cut 1/4 inch lengthsof the next three smaller sizesand nest each piece inside of theother 1/8 inch. Solder this assem-bly together. Slide the taper overthe center conductor of the Heli

3/8" HOSE CLAMPOVER SLOTTED END

OF SLEVE

3/8" COPPER SLEVESOLDERED OVER PL -259

OR TYPE 'N'

ax and solder using the minimumamount of heat so as not to meltthe foam. In the case of the Type'N' connector, measure and cutthe correct length for the smal-lest tubing and solder the centerpin to it. For a PL -259 use apiece of wire long enough to gothrough the center pin and solderthe tip after assembly and cut offthe excess.

Slide the sleeve and hoseclamp assembly over the Heliax,stopping when the center pin rea-ches its correct position. Clampthe sleeve to the Heliax by tight-ening the hose clamp until it isfirm, being careful not to crushthe Heliax. The entire assemblycan be water -proofed by wrappingit with rubber tape. (see Fig. 1).

CENTER CONDUCTOR TRANSITIONMADE FROM SHORT PIECES OF HOBBYBRASS TUBING NESTED AND SOLDERED

MPer

"May I have the mouse back, please?"


ATV COMBLINE DUPLEXERS AND FILTERSBY JON C. HENNING

WA2BTW

A duplexer, designed for usein amateur television, is quite astep away from a narrow pass -band FM duplexer. The bandwidthor range of frequencies passed ismuch greater. The rejection bandwidth must also be very broad.

If a pseudo band-pass circuit(narrow pass -band broad reject)were used, the end result wouldbe a much too narrow pass -band.If the approach taken was the useof notch -filters (broad pass -band,narrow rejection), the pass -bandwould be wide enough but therejection notches would be toonarrow. Therefore, the logical ap-proach would be the band-passcircuit. The proper number ofcavities must be determined forthe required selectivity and eachmust be calibrated for a specific3 dB bandwidth. Interconnect ca-ble lengths have to be determin-ed, since these are also a part ofshaping the pass -band. This designworks very well. However, thereis a better alternative; the useof combline filters.

Combline filters eliminate in-terconnecting cables and connec-tors, which in turn results in alcoc distorted pass -band and shar-per rejection roll off. Open aircoupling is used in place of inter-connecting cables. Figures 1 showsa cutaway view of a single comb -line filter. Shown here are sixresonators and five coupling ad-justments probes. In the lowerleft and right corners are band-pass loops located just under thefirst and last resonator. They arecoupling in the current area ofthe filter and may be rotated inthe field to increase or decreasecoupling. The filter has a symme-trical pass -band, which meansthat either port may look towardthe receiver or transmitter to theantenna (all ports 50 OHMS).

The coupling of each resonatoris optimized to form the 6 MHzpass -band. Fine adjustments of thepass -band width can be made byslightly interacting with the vol-tage field between resonators.

This is done by the coupling ad-justors (Figure 1).

Problems with Full Duplex ATVSystems Using Two Antennas

If a station is going to "fullduplex", the first thing to con-sider is the amount of isolationneeded. Secondly, how that isola-tion is obtained. One way wouldbe to vertically separate the TXand TX antennas. Twenty feet willproduce about 55 dB of isolationin the UHF band. However, thereare other variables involved, suchas a tower coupling, where energyfrom the antenna actually couplesto the other antenna via the tow-er itself. To determine the bestplacement of the antennas youcould use a spectrum analyzer andsignal generator. Inject a signalfrom the generator into the inputof the analyzer and obtain aknown reference level at thefrequency you are working with.Next, inject this signal into oneantenna and detect at the otherwith the analyzer (Figure 2).

Simply read the differencebetween your reference level andthe new level. The 3 dB pads atthe output of the signal generatorand input to the analyzer areused to force the equipment tobe a "true 50 OHMS." Move theantennas vertically apart untilmaximum isolation is obtained.Chances are additional isolationwill be required to operate fullduplex. Another drawback to atwo antenna system is each an-tenna will see the environmentsome w hat different, making cover-age uneven. The additional costof the hard line and extra anten-na should also be considered.

A single cornialine filter willwork very well to suppress un-wanted sidebands in a simplexATV station. However, there aretwo RF paths to be dealt with ina repeater system. Obviously twocorn bline filters must be used. Andif a single antenna is to be con-sidered, a harness must be design-ed to tie the filters together.While the procedure for this is

simple, the equipment involved isreacting complex.

Using a network analyzer,'sweep either the low or highfrequency. For example, we aregoing to determine the cablelength to be attached at the lowfrequency filter and the antennajunction tee, by connection aprecalculated cable length (about1/2 wavelength) to the low fre-quency filter. At the other endof the cable connect an "n" tee.Looking through the "tee", readthe return lass at the high fre-quency. (Reference Figure 3). Thebest match condition over thatfrequency bandwidth (6 MHz) iswhat we are concerned with. Ifthe best match seems to high infrequency, a longer cable is tired;if too low, a shorter cable istired and so on. The same proce-dure is done using the high fre-quency filter. When both cableshave been determined and theantenna "N" tee connected, eachfilter sees 50 OHMS to the anten-na and a high impedance reflec-tion to its adjacent channel., al-lowing simultaneous operation ofthe transmitter and receiver. Thetwo filters now form a duplexer(Ref. Figure 4). With each sidepretuned, some small adjustmentsmay be required to each pass -band after the antenna junctionhas been connected.

Figure 5 shows the electricalresponse for the ATV duplexer. Itwas measiired on a HewlettPackard 8754A network analyzer.If you are accustomed to readinga spectrum analyzer, this shouldbe easy to interpret. The verticalscale is read in either 1 db or 10db per division increments. Thescale left to right reads frequen-cy (Low to high). Curve A shows1 this means that the curve reads1 db for each vertical division.The same curve has 1.0 this showseach division horizontal is 1 Mhz.

The top two curve responsesrepresent the pass -band, the mid-dle two are isolation (rejectionabove and below the pass band)


COMBLINE FILTERS continued . . .

and the single curve at the bot-tom is the between -channel isola-tion. Between channel isolation isread by injecting a signal into theTX port, loading the antenna portwith a 50 ohm load and detectingat the RX port. Between -channelisolation helps protect the recei-ver from white noise generatedby the transmitter. Should thetransmitter have energies awayfrom its own carrier frequency,toward the receiver, it will stillbe suppressed by the amountshown at any point on that curve.If you look at a straight notchduplexer, the between channelisolation is so low, usually lessthan 15 db, that it does not offerthis type of additional protection.(ref figure 6). Again a notchduplexer would not work for theATV applications: however, it's agood "rule of thumb" when eitherbuilding buying any duplexer thatit have sufficient amount ofcenter isolation. The circuits thatbest offer this are band-pass andpseudo band-pass. The ATVcombline duplexer shown here hasa straight band-pass response, of-fering high isolation betweenchannels as well as out of bandprotection.

In order to form a pass -bandwith low ripple and maintain anacceptable VSWR over such awide range, the coupling must begreater on the outside resonatorsand be decreased moving towardthe inside of the filter. If thecoupling were greater on theinside resonators the pass -bandcould not be tuned.

As important, is the number ofresonators needed to accomplishthe selectivity required above andbelow the passband. Figure 7shows a four section corn bline vsa six section version. Additionalresonators could be worked intoa filter design or two comblinescould be cascaded in series,should additional selectivity berequired. This is usually not re-quired if the minimum transmitterto receiver frequency spacing iskept at 6 Mhz or more and thepass -band is kept at 6 Mhz orless. This is also true of the

band-pass preselector mentionedearlier. In a four cavity preselec-tor (ref. fig. 8) the two outsidecavities would each be set at a3 db band width of about 8.5 Mhzwhile the two inside cavitieswould be set at a 7 Mhz 3 dbband width.

Additional isolation may beobtained in close to the pass -bandby using notch cavity filters. THisis possible because this circuitstyle, as mentioned, has a broadpass -band. It must of course beable to pass the full 6 Mhz. If anotch cavity filter is set to re-ject 1 Mhz above the high end ofthe pass -band and connected inseries with 1/2 of the corn blineduplexer, the total increase wouldnot only be the sum of the two,but rather the sum of the twoplus 5 to 6 db if the proper cablelength is determined. By using theproper 1/4 wave -length cable, theenergy from filter to filter willarrive in phase thus giving a 5 to6 db addition to the total isola-tion. Determining such a cablelength without proper equipmentsuch as a network analyzer wouldbe very difficult. If you were tomeasure the interconnect cable,you would see that it is somewhatless than a 1/4 wavelength be-cause you must take into consi-deration the length of the loopsin each filter (subtracted fromthe cable length). There are noset formulas for subtracting theselengths. One would start with a1/4 wave cable to hunt thelength. If the interconnect shouldbe physically to short to reach,1/2 wavelength of cable can beadded thus electrically repeatingyour initial point. More than onenotch filter may be used to rejectabove or below the pass -band, ifadditional protection is needed.Fig. 9A and 9B show a comblinefilter in the UHF commercialband, with six sections and three1.25 x 2 inch notch filters. Thissystem is set for a 4 Mhz win-dow. One Mhz off the low side(notched side) the isolation is 45db down and on the high side itis down 21 db. The amount ofinsertion lass added is about 1.2

db on the low side, 0.4 db at Foand about .85 db on the highside.

POWER HANDLING CAPABILITYThe power rating for this MV

duplexer design has been testedup to 100 watts continuous opera-tion. At 100 watts there was noheating evident in either filterunder test. Test cycle was 15 muion, 15 min off. Internal parts areexamined closely to make surethat all components in high vol-tage areas have no sharp edgeswhere corona could occur. Thecontact area of the resonators(current area) to the filter chassis(high current area) is very impor-tant. To maintain high Q theremust be as close to a 100% con-tact area as possible. In addition,all resonators, tuning rods,coupling adjustors, loops and con-nectors are silver plated for bet-ter RF conductivity.

Figure 10 shows a grid usedfor calculation of power 1c1ssPsirVout vs insertion lcss. This canbe useful in determining pass lossnot only in duplexers but in mostRF paths. However it should beremembered that the field accura-cy of a wattmeter reading issubject to considerable variancedue to RF connector VSWR andbasic wattmeter accuracy, par-ticularly at low end scale read-ings. Allowing for these variances,this graph should prove to be avery useful reference. Lets saywe have a 100 watt ATV trans-mitter and we know that theduplexer has a .9 db lnss at itsfrequency. We should see, accord-ing to the graph, about 85 wattsout. The scale is set from 50 to500 watts. For lower power levelsdivide both scales by 10 (5-50watts).

COMPARING CURVE RESPONSESFig. 11 shows the comparison

of pseudo band-pass, band-pass,notch and the ATV corn bline fil-ters. Even though these curvesare hypothetical, they still repre-sent the typical of responses eachcircuit will produce.


SIX SECTION UHF COMBLINE FILTER

FREQUENCYADJUSTMENT

RESONATOR

BAND-PASSLOOP(ROTATABLE)

REFERENCE

3 dB 3d8

PAD PAD

SIGNALGENERATOR

FIGURE 2

Ill leISO leSO 1111ON III

SPECTRUMANALYZER

CURRENTAREA

SINGLE FILTER SPECIFICATIONSSIX MHz PASSBANC

VSWR (ma L 1.35:1INSERTION LOSS 1.0 CB ma, 0 BandsegasNOISE L CARRIER SUPPRESSION 70 OB ream se MHz on 15.7.1.e&..POWER RATING 100 wan.CONNECTORS WI maleMECHANICAL 9.5. H x 10.75' Do 7.25' ve

COUPLINGADJUSTMENT

VOLTAGEAREA

FIGURE 1

PROCEDURE FOR DETERMINING ANTENNAJUNCTION CABLE LENGTHS

N NEPNORKANALYZER

DETECTOR LOOKING AT RETURN LOSS AT

TRANSMISSIONREFLECTION

TEST SET

SIGNAL OUTON HIGH FREQ. rib'

TRANSMITTEROR

RECEIVER -O.INPUT

FIGURE 4

LEAD

11111111111I COMB-

LIN E 50 OHMLOW FREQ. TERM.

'N TEE'

TUNING ROOS

HIGH FREO.

ATV UHF INTERDIGITALCOMBLINE DUPLEXER

111 INCHRACK

MOUNT BAR

ANTENNAPORT


Return LossKt)

SWR Return Loss(co)

SW11 Return Loss(co)

swn

9.5 2.008:1 13.7 1320:1 17.9 1.292:19.6 1.990:1 13.8 1313:1 18.0 1.288:19.7 1.973:1 13.9 1506:1 18.1 1.284:19.8 1.957:1 14.0 1.498:1 18.2 1.280:19.9 1.941:1 14.1 1.491:1 18.3 1.277:110.0 1.925:1 14.2 1.484:1 18.4 1.273:110.1 1.910:1 14.3 1.478:1 18.5 1.270:110.2 1.894:1 14.4 1.471:1 18.6 1.266:110.3 1.880:1 14.5 1.46-4:1 18.7 1.263:110.4 1.865:1 14.6 1.458:1 18.8 1.259:1103 1.851:1 14.7 1.451:1 18.9 1.256:110.6 1.837:1 14.8 1.445:1 19.0 1253:110.7 1.824:1 14.9 1.439:1 19.1 1249:110.8 1.810:1 15.0 1.432:1 19.2 1.246:110.9 1.798:1 15.1 1.426:1 19.3 1.243:111.0 1.785:1 15.2 1.421:1 19.4 1.240:111.1 1.772:1 15.3 1.415:1 193 1.237:111.2 1.760:1 15.4 1.409:1 19.6 1.234:111.3 1.748:1 15.5 1.404:1 19.7 1231:111.4 1.737:1 15.6 1.398:1 19.8 1.228:111.5 1.725:1 15.7 1.393:1 19.9 1.225:111.6 1.714:1 15.8 1.387:1 20.0 1.222:111.7 1.703:1 15.9 1.382:1 203 1208:111.8 1.692:1 16.0 1.377:1 21.0 1.196:111.9 1.681:1 16.1 1.3721 21.5 1.184:112.0 1.671:1 16.2 1.3661 22.0 1.172:112.1 1.661:1 16.3 1.3621 22.5 1.162:112.2 1.651:1 16.4 1.357:1 23.0 1.152:112.3 1.641:1 16.5 1.3521 233 1.143:112.4 1.631:1 16.6 1.3471 24.0 1.135:1123 1.622:1 16.7 1.3421 24.5 1.127:112.6 1.612:1 16.8 1.338:1 25.0 1.119:112.7 1.603:1 16.9 1.333:1 25.5 1.112:112.8 1394:1 17.0 1.329:1 26.0 1.105:112.9 1586:1 17.1 1.324:1 26.5 1.099:113.0 1577:1 17.2 1.320:1 27.0 1.094:113.1 1.5681 17.3 1.3161 27.5 1.088:113.2 1560:1 17.4 1.312:1 28.0 1.083:113.3 1.552:1 173 1.3081 283 1.078:113.4 13441 17.6 1.3041 29.0 1.074:113.5 1_536:1 17.7 1.3001 29_5 1.069:113.6 1528:1 17.8 1.296:1 30.0 1.061:1

IN VAR TUNING ROD(CONNECTED TO

MOVEABLE PROBE)

TEMPERATURECOMPENSATION

LOCK DOWN POINT n_

LOOP ASSEMBLY TOCOUPLE ENERGY IN

CIRCULATING CURRENTAREA

AREA OF HIGHCIRCULATING

CURRENTS

ABOUT THE AUTHORJon C. Henning is currently

employed by TX-RX Systems, INc.of Angola, NY. TX-RX is a multi -coupler and duplexer manufactur-er. He started his employment asa production technician in 1979and worked in that capacity forsix years. During the past fouryears Jon has worked in the salesand marketing department. He isan avid ham radio operator andhas had his license since 1969.

FOUR -CAVITY UHF BAND-PASS FILTERCUT -AWAY VIEW

//

//

/

END CAP AWAY FROM HIGH CIRCULAT NGCURRENTS. DOES NOT REQUIRE WELDING.

WEDDEDEND CAP

STATIONARY

MOVEABLEPROBE

CAVITYVSHELL

FIGURE 8APRIL 1989 VOL. 2 -2 PAGE 63

COMBUNE ATV DUPLEXER MODEL 26-66-87072

0t1.0

1.0-11.-

0f 1.0

1 011.--0 i H\AINSERTION

LOSSJ- r

0t10

1.0-lir-

0410

1.0--lb-

0RETU

LOSS

I

426 MHz 432 MHz 438 MHz 444 MHz

0t 10

5.0

IISOLATION

I 0t 10

XRESPONSE,-

'

0t--to-

t--II.-

)429 MHz 441 MHz

BETWEEN CHANNEL ISOLATIONOF A NOTCH DUPLEXEFI I

1.0

t

4 Section

Fill;URE 6

00

10

(Di

0t 10

50-10-

0BETWEENt

--..-CHANNELISOLATION

6 Section

429 1,.4117

CURVE KEY

- Vertical sensitivity in dB/div.

- Horizontal sensitivity in Mliz/cfrv.

Zero reference line is at the top otdisplay for curve A, and horizontalcenterline for B.

SEE FIGURE 3 FORRETURN LOSS TO VSWRCONVERSION.

FIGURE 5

0t 10

10

tc,

FIGUI E 7


0

10

20

30

40

C

10

20

30

40

C

10

20

30

40

INTERDIGITAL PLUS0 3 EA_ SERIES NOTCH

tonnwor

1 MHzidiv. 468

FIGURE 9A

0

10

20

30

40

50

60

70

80

TYPICAL FILTER RESPONSE CURVES(RESPONSES ARE HYPOTHETICAL)

0 PSEUDO BAND-PASS

A)

B)

1 KHzldiv.

0 NOTCH

ul

0

10

20

30

40

50 10

60 20

70 30

80 40

0

10

20

30

40

50 10

60 20

70 30

80 40

COM8LINE DUPLEXERWITH NOTCH FILTERS

NOTCI1

ALTERSTX 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0RX

0 BAND-PASS

500

400

300

250

200

150

125

100

75

soso

FIGURE 10

FIGURE 98

INSERTIONLOSS (00)

O

1 MHz/div.

0 COMBUNE LINE(BAND-PASS)

V

43

0

10

20

30

40

50

60

70

80

0

10

20

30

40

50

60

70

80

75- .100 125 150 200 250 300 400 500

CURVE A:CURVE B:

OUTPUT POWER (WATTS)

ISOLATION RESPONSE'RETURN LOSS RESPONSE

'SEE CONVERSION CHART - RETURN LOSS TO VSWRFOR CURVE B RESPONSES.

1 KHz/dry. 2 MHz/div.

FIGURE 11


FINDING THE WAY THROUGH TV'S RESOLUTION MAZEMARIO ORAZIO

Somewhere Out There...Youmight not have noticed that reso-lution seems to be the least un-derstood aspect of television equi-pment specifications. I have. -

It's ridiculous! Resolution is,specified in terms of lines, linepairs, bandwidth, pixels and/ornancseconds. Sometimes it's speci-fied across a picture's width andsometimes from top to bottom,even when dealing with horizontalresolution.

Besides horizontal resolution,there are vertical resolution anddiagonal resolution, each of whichhas static resolution and dynamicresolution. There's also temporalresolution.

For each of these resolutions,there are both luminance resolu-tion and chrominance resolution,and even different chrominanceresolutions for different colors.

And, even with all of that, acamera specified at 700 lines ofresolutions looks better than acamera specified at 500 lines ofresolution, even when both areviewed through a broadcast chan-nel restricted to just 330 lines.

Now, rm not saying I am theworld's greatest expert on resolu-tion, but rn give you a few de-tails that should help clarify mat-ters a bit.

Clarifying Resolution. First,here are the most basic facts ofhorizontal resolution.

We broadcast 525 scanninglines per frame at about 30frames per second. That meansthere are 15,734.26 scanning linesper second or about 63.5 us perscanning line. Take away about11 us for the horizontal blankinginterval, and you've got 52.5 usof active line time.

Looked at in video terms, eve-ry cycle of a sine wave can besaid to consist of a bright line(the positive going peak) and adark line (the negative going peak)and the transitions between them.Those two lines are referred to astwo "T" lines of horizontal resolu-tion.

There is exactly one cycle ofa 1 MHz signal in 1 us. Therefore,there are 52.5 cycles of a 1 MHz

signal in the active line time.Since there are two TV lines ofresolution per cycle, there are 105TV lines of resolution per MHz peractive scanning line.

Television pictures are 0.75times as high as they are wide,and it would be nice to measureresolution the same way in boththe vertical and horizontal direc-tions. Therefore, there are 78.75(105X.75) TV lines of resolutionper MHz per picture height in anactive scanning line.

We are allowed to broadcastonly 4.2 MHz. Therefore, thereare a maximum of 330.75 TV linesof horizontal resolution per pic-ture height for US broadcast tele-vision.

If you look at a properly scan-ned resolution chart, you won't beable to make out more than 330lines on the vertical wedges. Yes,horizontal resolution is measuredwith vertical lines.

The Vertical Picture.Now for vertical resolution.We still have 525 scanning

lines, but 41.5 go to the verticalblanking intervals, so we are leftwith 483.5 active scanning lines.Here is where it gets tricky.

Even analog television signalsare sampled vertically by thescanning lines. In a sampled sys-tem, the highest recoverable fre-quency is no more than one halfthe sampling rate, less filter los-ses.

The filters in an analog televi-sion system include the shape ofthe electron beam spot, whichstraddles more than one scanningline at a time.

We're lucky to have this filter-ing. If we didn't, and you shot agrid of 483.5 alternating whiteand black horizontal lines, youmight see the lines when the cam-era was pointed a certain way,but you'd see nothing but grey ifit titled up or down, by half ascanning line. Without filtering,the lines would flash on and offas the camera tilted.

If the Kell Factor is 0.684(somewhere around the generallyaccepted range), then verticalresolution is 330.75 lines, exactly

the same as horizontal resolution,which is a good idea, since studieshave shown that human vision hasa hard time dealing with unmatch-ed horizontal and vertical resolu-tions.

Unfortunately, besides the KellFactor, there is another less invertical resolution caused by thefact that we broadcast interlacedscanning liens. The interlace coef-ficient seems to be in the rangeof 0.6 to 0.7, yielding a verticalresolution (if the Kell Factor is0.68) of only 200 to 230 lines.

That is where vertical andhorizontal static (unmoving image)resolution figures come from, andthey are both correctly measuredin TV lines per picture height.rve already explained the rela-tionship between bandwidth and TVlines PPH (78.75 TV lines PH/MHz).Now rll tackle nancseconds, pixelsand line pairs.

Pixels and Line PairsIn a 4.2 MHz signal, each cycle

lasts 238 ns. Since each cyclecontains a bright line and a darkline, each line lasts just 119 ns.Looked at another way, the fast-est a signal can rise from dark tolight is 119 ns. This can be calledthe fastest rise time.

Two hundred thirty-eight nano-seconds goes into 52.5 us (activeline time) 441 times, so some saythere are 441 pixels (picture ele-ments, also sometimes ceLs) acrossthe screen. That's exactly consis-tent with diving a resolution of330.75 TVL/PPH by 0.75 (the as-pect ratio).

Computers claim resolutions of640 pixels across the screen, sothey might, at first glance, seemto have much greater resolutionthan television pictures. Yet goodTV character generators makebetter looking characters thancomputers.

TV character generators specifytheir resolutions in figures muchlower than 119 ns Quantel'sCypher specifies better than 1 nsedge resolution, the seeming equi-valent of over 1 GHz of band-width, or more than 238 4.2 MHzTV signals.

The secret is positioning. Corn -


puters are stuck with fixed posi-tions for their 640 pixels. TVmight have only 441, but theycan be placed anywhere along theline.

Quantel's 1 ns edge resolutionmeans that a character edge canbe positioned accurately to anyof 52,500 different positions on aline, but its rise time will stillbe no faster than 119 ns (it bet-ter not be; if it is, your viewersmight hear sync buzz).

That's why TV characters lookbetter than computer characters.They can be positioned (or shaped)up to 82 times better. (Not everycharacter generator offers 1 nsresolution, but even 35 ns resolu-tion is more than twice as goodas a computer's 82 ns).

Line pairs are used to measurefilm (and sometimes lens) resolu-tion. They are an indication ofhow cicse together a pair of linescan get before they cannot bedistinguished as individual lines.That is exactly what you look atwhen you read resolution off a TVchart, except that TV cheats byclaiming a white line and a blackline as two lines, whereas for TVlines equals two film line pairs.

Film cheats, too. Its resolutionis usually measured off a station-ary piece of film, so it suffersnone of the unsteadiness of atypical projection gate.DYNAMIC RESOLUTION

That brings me to dynamicresolution, which is resolution inspace (horizontal, vertical anddiagonal resolution) when thingsare moving.

Outerlaced scanning takes alot away from our dynamic resolu-tion. Look at the output of acharacter generator when it's ina roll mode; the characters haveonly half the vertical resolution.That's interlaced scanning.

You can also freeze a frameof horizontal motion to see whatinterlaced scanning does to that.Some TV devices have even worse,dynamic resolution problems, how-ever, including a log of theschemes that compress high defini-tion signals into narrow channels.Shutters are added to cameras toimprove their dynamic resolution.

Spatial resolution, whether it

RESOLUTION continued . . .

is dynamic or static, includes notonly horizontal and vertical reso-lution, but also diagonal.

Since diagonal resolution is aresult (in NTSC, anyway) of hori-zontal and vertical resolution, itis actually 1.4 times greater thanits parents (derived from Pytha-goras' law of hypotenuses).

Thus, 330.75 lines becomes467.75 lines diagonally. The funnything is that human vision seemsto work exactly the opposite way.To match 331 lines of vertical orhorizontal resolution, we seem toneed only 234 lines of diagonalresolution --half of what we havenow. Several advanced televisionschemes take advantage of thisdiscrepancy.TEMPORAL RESOLUTION

Then there's temporal resolu-tion, not to be confused withdynamic resolution, which is spa-tiaL Again, even analog televisionsignals are sampled in time (bythee field and frame rates)1 andtherefore, again, they need to befiltered.

Unfortunately, the only tem-poral filter we have is poor dyna-mic resolution. Film rarely offerseven that, which ,is why you getto see wagon wheels and aircraftpropellers moving backwards (e-xamples of a temporal alias).

Drs. Bill and Karen Glenn ofNew York Tech in Florida haveshown that we cannot simultane-ously perceive high temporal andhigh spatial resolution, a factorused in their and other HDTV sys-tems.

Finally (for this article), there'scolor. Human vision requires lessdetail in color than it does inbrightness, which is why FCC reg-ulations call for 1.3 MHz of band-width in the I component and 0.6MHz in the Q, translating to 102and 47 TV lines per picture heightof static horizontal resolution,respectively.MINDING YOUR I'S AND Q'S

We need more resolution in I(and the I axis is rotated 33 deg.from R -y) because we see detailin reddish colors along the I axissomewhat better than we do inblues. Yet, the number of TV mo-dels that offered full I resolutionin the 35 -year history of NTSC

color can be counted on the fin-gers of one hand.

Vertical chroma resolution isanother matter. To avoid interfer-ence between chrominance andluminance signals, we need filter-ing.

A simple luminance ow -passfilter restricts horizontal resolu-tion to 3 MHz or 236 lines (that'swhere the 240 line resolution ofcolor -under recorders comes from).

To get more luminance resolu-tion, we use comb filters, butthese restrict vertical chrominanceresolution --not nece-n-n-ily a badidea, considering the desire tocome cicse to matching verticaland horizontal resolutions.

None of this explains why a700 line camera looks better thana 500 line camera looks betterthan a 500 line camera through a330 line transmitter. That's be-cause everything rve explainedto this point refers only to maxi-mum or limiting resolution, whichis a number.

Real -world resolution is a fun-ction, which can be graphed ascontrast versus detail. This "modu-lation transfer function" falls offfrom zero detail in a curve witha Gaussian or sine X/X shape;,depending on the devices beingused.

Either way, the farther outthe limiting resolution, the greaterthe contrast at 330 lines thandoes a 500 line camera, eventhough both will be restlicted to330 lines by your transmitter'sroofing filter.

Understand it all? Of courseyou do. Horizontal resolution ismeasured with vertical lines andvice versa. Diagonal resolutionmight be twice what it has tobe. Computers sometimes havebetter resolution than TV andsometimes don't.

Dynamic resolution allows sharpstill frames but makes wagonwheels turn backwards. Red lipsneed more detail than blue eyes.And 330 lines still lets 700 lineslook better than 500 lines. It's allperfectly clear.Reprinted with permission fromTV Technology Jan. 89.

APRIL 1989 VOL. 2 -2 P GE (7

Thanks for your calls and letterswith questions and comments fromthe first issue of ATVQ - keep themcoming. The only dumb question isthe one you didn't ask!

This quarters emphasis will be onreceiving ATV. However, thecomments and further questionsgenerated by the last issuesemphasis on transmitting and addinglinear amps will be covered at the endunder "Q & A Feedback".

HOW FAR DOES ATVGO AND CAN I GET AGOOD PICTURE FROMTHE REPEATER X MILESAWAY?

This is the most asked questionby those thinking about getting intoATV and are considering just gettinga downconverter to try it out. I

suspect all you long time ATVers alsohear it when you talk about ATV tonewcomers on the air or radio club.

There is no pat answer since eachcondition has so many variables. Theline of sight DX can be calculated ifeasily measured parameters areknown. See the path loss Basicprogram in this issue. With the nonline of sight condition, there are somany unmeasurable variables thatone just has to try it to find out.

As to "how far does ATV go" it ismore of a question of how muchenergy is left at the end of a non lineof sight path, and your receivesystems noise figure and bandwidth.

Unless you can cut down all thetrees, level the hills, etc. to give you aline of sight path, I suggest puttingyour money and time in the best andhighest antenna and feedline systemyou can afford. This will pay off bothin receive and transmit.

If you had a perfectly flat groundpath, and your antenna was at 50 ft.,your RF horizon would be at 10 miles.Therefore you would have a near freespace path to another station alsowith a 50 ft. antenna height up to 20miles.

So you could put in a snow freepicture to this station with just 1 wattalso assuming 3 dB loss in coax, 14dBd beams, 3 dB system noise figureand TV luminance bandwidth of 3MHz. I am defining snow free as 40

ATV Q & ABy Tom O'Hara, W6ORG

dB signal to noise ratio which is allabout what our home entertainmentcameras and VCR's can do anyway.Peak sync in most TV sets for snowfree is around 200 microvolts.Broadcast calls 55 dB snow free, butthat is like the case of the super $$$digital stereo audio system beingplayed into a small portable transistorradio speaker.

IF ONE PREAMP ISGOOD THEN 2 HAS TOBE EVEN BETTER,RIGHT?

Not always true intermod breath!Front end gain should only determinethe system noise figure, not it's gain.Preamps are usually designed forlowest noise figure and sufficient gain(12 - 15 dB) so that the noise figureof the following stage contributes littleto the total system noise figure.

These preamps usually have verybroad bandwidth and as such amplifynot only the desired ATV signal butstrong FM amateur and commercialrepeaters, and worst of all, UHF TVstations. If any ot'the signal levelsreach the dynamic range limits of anyof the receiver stages, they will mixand their products may fall right in thedesired ATV passband.

The best rule of thumb whenselecting devices for preamps withgood noise figure for high intermodareas is the 1 dB compression point.Generally with devices designed forvery low noise figures (<2 dB), bipolartransistor 1 dB compression pointsare about -20 dBm, dual gat eGaAsfets 0 dBm, and single gateGaAsfets +12 dBm. 0 dBm = 1 mW.

UHF TV stations can h av eeffective radiated powers of up to 5Megawatts. Most preamps,downconverters, and TV tunersprobably won't have the selectivity tosufficiently reject the undesiredsignal. Adding a preamp to anexisting IM interference situationwithout also adding some selectivitywill only aggravate the situation.

You can add selectivity with lowinsertion loss bandpass or notchfilters just after the first preampwithout noticeable change insensitivity. If that doesn't do it, youneed more selectivity or your preamp

is being hit too hard past it's 1 dBcompression point and the filteringwill have to be put in the antenna line.In this case the insertion loss willdirettly affect the sensitivity.

A very simple low insertion lossmethod with a single known IM sourcesuch as a strong UHF TV station is anabsorption notch filter at the preampor downconverter antenna input.

2 pF

Rec 0Antennainput

1.5"#18

The absorption notch filter shownhere has a 25 dB notch when tunedto channel 14 (471 MHz) and only .5dB loss at 439 MHz. It consists of a 1-5 pF variable cap tuning a parallel 1.5 "long hair pin loop .5" wide of #18buss, and coupled to the 50 ohmreceive coax antenna input with a 2pF cap. 1 pF gives a 10 dB notch.

Set the cap to minimum capacity.Tune in the ATV frequency that hasthe interference. Then slowlyincrease the variable capacitor tuningto the point that minimizes t heinterference from the strong UHF TVchannel.

Do not put this in the transmit lineas mistuning could cause problemswith your transmitter. You can put itright on the downconverter boardantenna input or receive output of theRF T/R relay board. The 2 pF capmust have leads no longer than 1/8".

Other causes of intermods can becontaminated coax and connectors,rusted antenna joints, and othertransmitters in the area.

HOW THEN DO I KNOW IFI HAVE ENOUGH OR TOOMUCH GAIN?

The right amount of gain is thatwhich just starts to pump up the videoIF's AGC on noise. The gain andbandwidth are going to vary from TVto TV as well as the addeddownconverter/preamp combo. Theprice, manufacturer or model of TV isnot always a good indicator. You cancheck this out by putting a voltmeter(isolated from the AC line to prevent


ATV Q & A continuedshock from a hot chassis TV - batterytype VOM suggested) on the VideoIF AGC test point. Make sure it is thevideo IF TP and not the RF or delayedAGC TP. You might want to leave aninexpensive voltmeter connected asan S -meter.

With the ATV downconverterconnected but turned off, fine tune tochannel 3 or the open channel youare using for all snow or minimumadjacent channel interference. This isthe no signal IF AGC voltage. Thenturn on the downconverter. Tune thedownconverter frequency also to a nosignal point with the ATV antennadisconnected or input shorted. If theAGC voltage changes then your gainmay be a little too high.

If the downconverter does notcontain a low noise preamp stage(<1.5 dB), you can try adding a goodquality preamp as long as it does notpump up the AGC voltage. If it doespump it up you might considerreplacing the downconverter with onecontaining a better preamp device. If

you are not in an area with highintermod possibilities you can add apreamp even though the AGC mightget pumped up a bit, but keep in mindthat the amount of extra gain abovethe noise floor will cut into your strongsignal handling capability.

Antenna mounting a goodpreamp is always preferred for bestsensitivity since it eliminates thefeedline loss, again assuming youhave enough system gain to just getyou to the noise floor (the video IFAGC test again). I suggest runningBelden 9913 coax (2.5 dB/100' loss)for up to 75' and hard line after that. If

your feedline loss exceeds 2 dB, andnew preamps noise figure is better bymore than 1 dB, then with theantenna mounted preamp you willsee a difference.

Most TV sets I have tested need15 to 25 dB at most to get to it'sbandwidth noise floor. Addinganother 15 dB gain preamp at theshack to a downconverter with 15-25dB gain will start pumping up the TVAGC on noise. But mounting thesame preamp at the antenna willactually improve the dynamic range bydecreasing the added preamp gain asseen at the downconverter input dueto the coax loss.

I have tested the AdvancedReceiver Research (call 203-5840776 for info) RF switchedantenna mounted MML432VDGAPRIL 1989 VOL. 2 -2

preamp with good results. There areothers on the market now that shoulddo as well. However make sure theywill handle the RF transmit power ofyour transmitter at it's output. TheMML432VDG handles up to 160watts and has a noise figure of <.6 dB.The SP432VDG takes up to 25 watts.

OK I'M JUST BARELYPUMPING UP THE AGCON THE NOISE FLOORWITH MY ANTENNAMOUNTED PREAMP, BUTI WANT A LITTLE BITMORE SENSITIVITY FORTHE DX OPENINGS. ISTHERE ANYTHING I CANDO WITHOUT ALSOINCREASING THEPROBABILITY OFINTERFERENCE FROMSTRONG SIGNALS?

Yes there are two things you cando. One trick is to reduce thebandwidth, thereby lowering thenoise floor. Given standardtemperature, system bandwidth,noise figure and sufficient gain to getyou there, the noise floor can becalculated. For a 3 MHz bandwidthand a total system noise figure ofaround 2 dB the noise floor is goingto be about 1 microvolt (-107 dBm).The luminance 3 dB bandwidth in theaverage TV set is around 3 MHz.

To lower the noise floor, yousimply reduce the bandwidth. It is adirect power relationship. In otherwords if you reduce the bandwidth bya factor of 10 to 300 KHz, you alsoreduce the noise floor 10 dB. So ifyou put a 300 KHz wide channel 3bandpass filter followed by an in -lineamp to make up hr the 10 dB lowernoise floor and the filter insertion loss,you can gain 10 dB more sensitivity.

Ah Ha you say, what happens tothe video? You do end up with little orno color and sound subcarriers andlow resolution black and white video.But for DX and seeing the call lettercard what's the difference, it will bringit out of the snow. 300 KHz roll off isnot too low to affect the horizontalsync lock up.

But you want it all? Well you canalso do the same thing with a 75 ohmlow pass 300 KHz filter between yourprimary color TV set, if it also has avideo output jack, and a video

monitor. That way you can see theweak snowy video or sync bars toidentify and peak the antenna on withthe black and white monitor, and thensee the stronger signals on the colorTV.

75 Ohm 300 KHz Low Pass Fil ter

Monitorvideoin

The other thing you can do iswhat weak signal contesters haveknown for along time and that is thatstacked antenna gain seems to workbetter than a single long antenna ofthe same gain. Theoretically you canget 3 dB more gain every time youdouble the size of your antennasystem. In practice you can expect 2to 2.5 if everything is right. So thissays that running a pair of KLM 440-6X antennas would have about thesame total gain as a single 440-10X.The dual antenna seems to suck inthe signals better however. Goingfrom one antenna to a stacked pair willincrease your DX up to a factor of 1.4times for the same picture.

It could be that it is better to havetwo points in space receiving thesignal rather than one. We do knowthat with a single antenna in amultipath ghost condition, moving theantenna a few inches one way or theother puts you in or out of the null.So with the dual antenna, if one ofthem is going through a null, theother one may not be.

Stacking the two antennas oneabove the other gives you theincreased gain but does not narrowthe horizontal beamwidth or antennarotation sharpness. If you stack sideby side it does make it sharper. This isregardless of the antenna polarity.Spacing for the KLM440-27's is 5' - 6"for one above the other, and 6' - 2"side by side.

WHAT IS THE BESTANTENNA FOR ATV, ANDDO I MOUNT IT VERTICALOR HORIZONTAL?

A U.S. Army study showed thatabove 300 MHz a case could not bemade for one polarity always beingsuperior to another. Polarity is aregional decision usually made bythose who are first on and what they

PAGE 69

ATV 0 & A continued .. .

already have up. For newcomers Isuggest finding out from thosearound you before bolting yours in31ace. Cross polarity can cost you 20dB. One way around it is to usecircular polarization as the satelliteaeople do so that you cancommunicate with either polarity andany other mode in the band. Mostrepeaters are vertical and most DXersare horizontal.

Antennas are always a subject ofdiscussion because there are againso many variables and conditions.Besides high gain you also need thebandwidth for the frequency(s) andupper vestigial side band to gothrough without rolling off. Worstcase on 70cm is an area with a 439.25in/ 421.25 out repeater. The antennathen must cover 420- 444 MHz withreasonably flat gain, and low VSWR atyour transmitters frequency.

Most high gain Yagi typeantennas are not wideband (1% bandwidth) unless the designer doessome thing like making the elementslarge in diameter or driving multipleelements at a sacrifice of a littleoptimum gain. The 15 element Quagiin the ARRL Handbook is an excellenthome brew antenna if the material andlengths are followed to the letter.Bandwidth is about 15 MHz andshould be cut or scaled for yourtransmit frequency. The roll off at thebottom end of the band to receive therepeater is of less importance thanhaving radiation from VSWR gettinginto things.

The most popular commercialantennas designed for good gain andfull 70 cm wide bandwidth suitable forATV are the 88 element J Beam andthe 27 element KLM. Both are 12 ftlong. The J beam gets it's bandwidthwith a Quagi type driven element and4 director elements in an X pattern ateach boom location. The KLM 440-27 has 4 driven elements. I haveseen both of these measure 14 dBdat antenna measuring contests.

I encourage more participation byATVers in the VHF/UHF antennameasuring contests that are held atDayton and the regional VHF/UHFconferences in the spring andsummer every year. This is a chanceto see what different antennas reallydo and to talk directly with the buildersand designers.

This year at Dayton the antennameasuring contest will again be run byJoe Burke, WA8OGS, on Sunday

PAGE 70

morning. All antenna's, home brewand commercial, are welcome. Sobring yours from home, buy oneSaturday and put it together in yourroom that night, or just show up tokibitz. Joe will also be the moderatorfor the VHF/UHF Forum Saturdaymorning, 0900-1230 in room 5,which will include preamp measuring.

At the antenna measuringcontests you will see smiles on thosethat get near their expected gain, andtears and sour grapes from those thatdon't. These events are usually runby knowledgeable people withequipment and locations that giveresults within a dB or so. Most usethe NBS Yagi for a reference which isa very repeatably built antenna ofknown gain.

But even if you might nit pick (it'sexpected from the aficionado's) at theactual gain figures and set up, thereare enough well known antennasmeasured that good comparisons canbe made. And if your particularantenna doesn't live up to yourexpectations, there will be at least 10self styled experts on hand to tell youhow to make it better. It's really a lot of

There are some unusual typestoo that might surprise you. I oncesaw at the West. \ Coast UHFConference a guy throw one togetherwith a metal fish pale and quarter wave23 cm spike inside. He made twomeasurements: 8 dBd without and 7dBd with the fish in it. Another useda trash can lid as a reflector and didsurprisingly well.

Come prepared to mate to a TypeN male coax connector or take theloss of their adaptors. Frequency isusually at the weak signal part of theband: 432, 903, 1296, 2304, etc.This should not be a problem with ourbroad band ATV antennas eventhough a little off. Gain bandwidth isusually much wider than VSWRbandwidth, and it is your built i nexcuse if you are off a few dB's.

MY TV HAS TO BETUNED FOR EITHERBEST PICTURE OR BESTSOUND, BUT ANOTHERATVER RECEIVING THESAME SIGNAL DOESNOT, HOW COME?

article supposed it was caused by thedouble sideband pushing the AFC offto one side. But this doesn't makesense to me since these same TV'shave the problem with the AFC off,and the AFC's discriminators I amfamiliar with are less than 1 MHz wideand are sync keyed.

I would like to hear from those thatconsistently have this problem from anumber of ATV transmitters with adescription of the signal strengthsinvolved and a copy of their TV'sschematic. Maybe we can come upwith a good repeatable scientificanswer.

None of my TV sets have theproblem so I have never been able torecreate the situation. But I suspectthe problem is a poor IF bandpass orlittle or no sound IF limiting. If that isthe case then both subcarriersidebands are arriving at the FMdetector with about the sameamplitude and canceling. Detuning toone side decreases the amplitude ofone of the sidebands and the soundreturns at the expense of the video.

One way to prove this out andsolve the problem in these sets is tosuck out the lower sideband soundsubcarrier. This can be done with anabsorption trap in the channel 3output 75 ohm coax tuned toattenuate 56.75 MHz (ch3 - 4.5). Thesimple filter shown has an 18 dBnotch and 3 dB down +/- 1 MHz.Insertion loss is negligible +4.5 MHz.

Even if you do not have the bestsound or best picture situation thistrap can help suck out strong adjacentchannel VHF TV signals, amateur FMrepeaters, links, etc.

The 8.5 turn coil is made bywinding the #18 buss wire around a1/4-20 screw as a form, and thenunscrewing it. The 2 turn link iswrapped around the coil withinsulated #24 hook-up wire.Paralleling a 2-18 pF tuning cap with a33 pF (40 pF total) will tune thru theresonant frequency with so meresolution. All should be mounted ina small shielded box with F

connectors no more than 2" apart.Set the cap for maximum capacity.

Tune in an ATV station with a color orP3 or better signal for best picture.With the transmitting station givingyou a test count, slowly decrease thetuning capacitor to the point where

I keep hearing this from time to the sound improves, then peak it.time, and it was mentioned in a recent For just outside of the ATVHam Radio Magazine article. The channel interference, tune in the


desired ATV station with thedownconverter, and then tune thetrap cap to the point where theinterference is minimized.

CHANNEL 2-4 NOTCH FILTER2-18 pF

33 pF

Cony

8.5 T#18

2T#24

TV

MY TWO METER TRANS-MITTER WIPES OUT THE70CM VIDEO, CAN IT BEFILTERED OUT?

The 2 meter interference can befrom two different causes. If the 3rdharmonic of your 2 meter rig falls inthe passband of the ATV signal, it ismost difficult to get rid of. You canfilter it but your downconverter and ortwo meter transmitter may not beshielded enough. The best thing todo is to select your local ATVcoordination frequency on twometers -to not have a 3rd harmonic inthe passband. 144.34 is fine for439.25 but not for 434.0, and146.430 is vice -versa.

A low pass filter in the 2 meterantenna coax line will kill the 3rdharmonic before it's radiated. The lowpass filters are available fromSpectrum International or use one ofthe low cost mobile antennaduplexers used with one of the 2antenna output dual band FM rigs.

Actually I run my 50 watt 434 ATVand 25 watt 146.43 transceivers tothe Kenwood MA700 duplexer anddual band mobile antenna system onmy Motorhome. I can transmit oneither of them with no trace of theother in the receiver. The antennagives 3 dB on 2 meters and 5.5 dB on70cm. I recommend this for publicservice work to minimize the numberof antennas and coax you need andat the same time have the filtering.Larson and NCG Co. also have 2m/70cm duplexers for under $60.

The duplexers have hardly anyinsertion loss as they arehighpass/lowpass filters with about 50dB of isolation. The 70 cm high passsection also cuts the amount of frontend overload from the two meters into

ATV Q & A continued .. .

the ATV downconverter or preamp.You can do the same thing withantenna separation. I suggest at least10 ft driven element end to endseparation between antennas for 10watt 2 meter rigs and add a foot foreach watt above 10.

Do not bundle all your coaxes as itincreases crosstalk coupling from anyleakage or VSWR . Tape them toopposite sides of the tower.

HOW MUCH ANTENNASEPARATION AND/ORFILTERING DO I NEED TORUN DUPLEX ATV WITHMY 70 CM RIG AND ONEON 33 OR 23 CM?

Again, watch the harmonicrelationships. There should be noproblem with 434.0 and 439.25, but426.25 can wipe out 1277.25 andmaybe 1289.25. I suggest 10 ftdriven element end to end separationbetween 70 and 33 cm antennasminimum, and 7 ft 70 cm and 23 cm.

The nice thing about crossbandduplex or repeat is that it does nottake any additional filtering if attentionis paid to antenna positioning. If youare running higher power or seeingsome desense, you can try movingone of the antennas back and forthon the mast to find the "magic point"nulls and then clamp it in place.

This trick is often done onemergency vehicles with multipletransceivers and antennas. Aspectrum analyzer or communicationsmonitor is connected to the coax fromthe antenna to be added but tuned toreceive the existing transmittersfrequency. A sig gen on the existingtransmitter frequency is thentransmitted out on the old antenna.The new antenna is then movedaround on top of the roof until theminimum pick up point is found.

FULL DUPLEX AUDIO ONATV WITH THESUBCARRIER AND TWOMETERS OR ANOTHERATV STATION ON 33 OR23 CM IS GREAT BUTHOW DO YOU PREVENTTHE AUDIO FEEDBACK?

Most camera mics and lowimpedance dynamic mics are omnidirectional. They pick up the kidsfighting in the next room as well as

yourself and your two meter or TVsets speaker. If you turn the gain upon the speaker to hear the otherstations or your mic gain to be heard,feedback will result.

In these cases you could turn themic gain down low and close talk themic or use ear phones. But thisseems to negate the advantage of fullduplex audio, and you sure would notdo it with the public when doing apublic service event like a remoteSanta Claus at childrens hospitals,etc.

I use a Radio Shack 33-986Aunidirectional mic with phone t cminijack adaptor plugged into myTX23 transmitter for duplex operationat public service events. As long as I

don't point it directly at the TV or 2meter speaker I don't get feedback. It

you place the TV set and 2 meter rigor it's remote speaker behind thecamera, you will be seen as talkingand listening directly to the personyou are facing. The directional miccan be fastened to the camera with it'srear toward the TV speaker, or if handheld you just have to remember not toaim it directly at the camera.

Give me a call or drop a note with yourtechnical questions, or let us knowsome of the solutions you have fountso they can be passed on to the restof the gang. Come by booth 358 atDayton and say hi - the 11th year lotMaryAnn and I- and we will be 'tinningfull duplex ATV with Bill, WB8ELK inthe ATVQ booth, 361.

The Dayton ATV Forum will startSaturday at 2:45 in room 3. I'll begiving the ATV basics and 0 & A forthe newcomers plus what seems tobe the trends in ATV...duplex,repeaters and linking.

We have Bob Rau, N8IYD, who wiltshow and tell about running ATV fromhis high powered 100" long 7 LbRocket - matches will be confiscatedat the door.

Also David Pacholok, KA9BYI, wildemonstrate his 250 watt ATVtransmitter he put together for under$200 using a microwave oven.

CU AT DAYTON, TOM, W6ORGy2522 Paxson LaneArcadia CA 91006(818) 447-4565

PAGE 71APRIL 1989 VOL. 2 -2

ELECTRONICS

P.C. ELECTRONICS 2522 PAXSON LANE ARCADIA CA 91006-8537 USATOM (W6ORG) & MARYANN (WB6YSS) O'HARA (818) 447-4565

THE "KREEPIE PEEPIE" ATV TRANSMITTER1. 1.5 watts typical output on sync tip (@13.8 vdc) matches 15 & 50 watt amps for full linear output.2. Now you can see your own transmitted video with the on -board RF detector/monitor 1 v output.3. Final RF output test point for setting up blanking pedistal with a DC voltmeter.4. Improved lower distortion subcarrier sound generator for cleaner audio and 4.5 mHz stability.5. All this at no increase in price! Single freq. KPA5-E board still $159*delivered*. Two freq. $174.TX70-1 READY TO GO ATV TRANSMITTER contains the KPA5E & TR-10 T/R relay in a small6x5.2x2.5" shielded cabinet. Same xmit functions as the TC70-1 including both the 10 pin "VHS"camera & RCA phono jack video/audio inputs. If you are one of those who started with just adownconverter, saw some pictures and was bitten by the ATV bug, then this ATV transmitter is foryou - just connect its input to the downconverter BNC connector on the back of the TX70-1.

/41.TX70-1 $239 DELIVERED

KPA5 70CM ATV XMTR BOARD FEATURES:>1 WATT P.E.P. RF OUTPUT ON SYNC TIP.Run barefoot for portable. Output properly matches MirageD15N, RFC4-32 15 watt or D26N-ATV 50 watt linear amp forfull output and the Mirage D1010N-ATV to over 50 wattsFULL COLOR AND SOUND on a small 3.25x4" boardWired and tested board runs on external 13.8vdc @300 ma. supply or 12 V batteryAccepts composite video from cameras, camcorders,VCRs, computers, etc.2 audid inputs, one for low Z dynamic mic, & one linelevel from most cameras & VCRsSupplied with one xtal on 426.25, 434.0, or 439.25.2nd xtal add $15. Specify freq. when ordering, check withlocal ATVers, ARRL Repeater Directory or call us. Only 2channels available in any given area due to video bandwidthof 9.1 mHz.Price still 1159 delivered via UPS surface incontiguous USA. Transmitters sold only to licensedTechnician class or higher amateurs for legal purposes.We verify name, call letters, & QTH in the Callbook. Ifrecently licensed or upgraded send a copy with order.

KPA5-Eboardstillonly$ 1 5 9

14 %Ayres. MAY eipRices &pup 4

KPA5 APPLICATIONS:PORTABLE CORDLESS TV CAMERA. Think of it as avideo HT. Place the KPA5 in one of the Hammond Dicastaluminum boxes, AEA HR -4 half wave "hot rod" on top orat the end of 500 coax attached to a headset. Plug into a12-14 v source such as the Radio Shack 12v 5Ah batterypower pack (23-182). Depending on terrain & receivingantenna DX is typically over 1 mile. With KLM 440-27s atboth ends DX is 22 miles snow -free line -of -sight.

Transmit the video to a remote VCR rather than lug it.Great for public service events: marathons, parades,damage accessment, search & rescue, CAP, etc.Mount in a R/C airplane, rocket, balloon, or robot toenable remote control when the vehicle is out of sight.Put it in your own cabinet for base, portable or mobile.When more power is needed, connect to one of theMirage or RF Concepts amps listed below.Put a KPA5 in a dicast box with a VOR (video operatedrelay) to make a hill -top video repeater . Repeat otherATVers, weather radar or Space Shuttle video.

WHAT IS REQUIRED FOR A COMPLETE OPERATING SYSTEM? A TVC-2G, TVC-4G or TVCX-70downconverter connected to any TV set or VCR tuner tuned to an open channel of 2, 3 or 4, and coax cable to a good70cm antenna to receive. Connect up the TX70-1 or package up the KPA5, add 12 to 14 vdc, antenna, and any homevideo camera, camcorder, VCR, or computer with composite video output and you are on the air. IT'S THAT EASY!

ACCESSORIES:TVC-2G GaAsfet downconv. board wired & tested $49

varicap tuned, 420-450 MHZ to ch3. Req 12vdcTVC-4G (TVC-2G in cabinet with 120vac supply) $89TVCX-70 crystal controlled GaAsfet downconv $99

specify in freq. & out on ch 3 or 45mhz IF. 2 freq $114Hammond 1590D Use for KPA5. 7.3x4.7x2" $17

1590C 4.6x3.6x2" aluminum box. Fits TVCX-70 $11800J 10 pin VHS color camera chassis connector $10VOR Video (horiz sync) operated relay board $25

PAGE 72

MIRAGE D15N-ATV 1in /15 out all mode amp.....$149RF CONCEPTS rfc4-32 15w + GaAsfet preamp.$155MIRAGE D26N-ATV1 in / 50 out all mode amp....$209AEA HR -4 "Hot Rod" half -wave portable antenna $23450 ISOPOLE omni 4dDd vert. gain antenna $65KLM 440-6X 8.9dDd ant., 28" boom, >50 deg BW $51KLM 440-10X 11.2dDd, antenna, 64" boom $65KLM 440-27 14dDd, 36 deg. BW antenna $107UG21 type N male connector for larger ID coax $5

ViPtATVQ DEVOTED ENTIRELY TO HAM TV

P.C. ELECTRONICS 2522 PAXSON LANE ARCADIA CA 91006-8537 USATOM (W6ORG) & MARYANN (WB6YSS) O'HARA (818) 447-4565

ELECTRONICS NEW FROM P.C.SEE THEM ALL AT OUR BOOTH, #358, AT DAYTON

Crossband full duplex with 70 cm or repeat using 33 or 23 cm is the nextadvancement in ATV, and we have made it easy for you. It's as simple as addinganother downconverter or transmitter and antenna to transmit and receivesimultaneously. Besides seeing and talking to each other at the same time, you canalso use one of the other bands for your own remote link or repeater as is done atthe Rose Parade. Make a crossband repeater with 2 antennas, bandpass filters,select one of the ATVR receivers and RTX transmitters, add VOR board and 13.8 V.

MEMO. 1140SMITTEAK.t3

U sT1,31e a RTI.ro

Y ATE.fuNpm

tilECMOIOCE.1522 PAXSON 1 MitARCAINA e IMODOat

NEW 1 WATT ATV TRANSMITTERS:TX -33 910.25 MHz $299TX -23 1289.25 MHz $299

Both models have a > 1 watt p.e.p. output with adjustableblanking pedestal for proper adjustment when driving theDowneast 18 watt or other amps. Built-in T/R relay with BNCoutput to companion TVC-xG down -cony. Independentvolume controls for mic and line audio. Push -to -look. 10 pinVHS camera jack plus video & audio input RCA phono jackson back for any other camera, camcorder, VCR or computerswitch selectable from the front panel. Video monitor outputhas actual detected modulation in transmit for accurateadjustment of video gain, & camera video in receive.

Requires 13.8 Vdc @ .5 amps + camera current.

RTX-33 923.25 MHz $299RTX-23 1253.25 MHz $299

Same transmitter board as the TX -33 and TX -23 put in a1590D Hammond Diecast aluminum box without T/R relayand VHS camera connector for dedicated repeater and linkapplications.

NEW ATV RECEIVERS AND CRYSTAL CONTROLLED DOWNCONVERTERSNow you have your choice of TV set or video monitor output of ATV from 70, 33, or 23 cm. We

have added a crystal downconverter for the 23 cm band to our line and put it or the 33 or 70 cmversions in a 1590D box with our VRC45 receiver. This makes the other half of building a repeateror dedicated link easier. All our downconverters have a GaAsfet preamp and mixer for best noisefigure and dynamic range. Conversion gain 25 dB.

TVCX-70 3x3.8"

3/89

Wired and tested xtal cony. boards:TVCX-70 Specify 70cm input freq to ch3 or 1F...$ 99TVCX-33 Specify 33cm input freq to ch 3 or 1F.$109TVCX-23 Specify 23cm input freq to ch 8 or 1F.$129Ready to go in 1590C aluminum box add $30

Tuneable downconverters ready to go:TVC-4G 420-450 MHz to ch 2, 3 or 4 $89TVC-9G 902-928 MHz to ch 2, 3 or 4 $99TVC-12G 1240-1300 MHz to ch 7 or 8 $109

COMPLETE RECEIVERSTwo composite video outputs, one for local monitor,

the other to plug into VCR or transmitter. 8 ohmspeaker and 1 volt into 10K line audio outputs.Adjustable audio squelch. Req. 13.8 Vdc @ 300 mA.ATVR-4 Specify 70cm input freq $299ATVR-9 Specify 33cm input freq $309ATVR-23 Specify 23cm input freq $319

PAGE 73APRIL 1989 VOL. 2 -2

ATV Q & A FEEDBACKBy Tom O'Hara, W6ORG

100 WATT 70 cm AMPSMany of you tried the upgrade

and power increase changes in yourMirage D1010N-ATV's from the lastissue with good results.

One ham suggested putting ashort coax jumper in place of the 22ohm resistor instead of one longerone from the amp PC board inputstripline. I don't see why not, but becareful soldering the braid at bothends to the board and the centerconductor lead lengths. The extracoax does put 2 more smallimpedance bumps in the line.

What to do about other ampssuch as the older KLM, TE Systems,Tokyo Hi -power, and new RFConcepts 100 watt amps? I mighthave something for these people inthe next issue.

I have tested the TE Systemsand the RF Concepts. Both do nothave the bias and B+ feed stiffnessrequired to pass an AM videomodulated signal without majordistortion and roll off. I have beenworking on the RF Concepts andhope to have some design changesfed back to the company in time forDayton. The TE Systems wanted togo into oscillation with any capsadded on the bias and B+ lines. It iscritical to have the right combinationsof inductors and caps that keep a lowsource impedance up to 5 MHz butdon't allow the two stages to go intoa low frequency oscillation o nfrequencies a little higher.

I don't know about the Tokyo Hi -power 100 watt amp but would like tocheck one out. I need yourfeedback. The problem usuallyshows up as unstable sync, colorshift or smearing especially with peaksyncs over 50 watts.

WATT'S THAT YOU SAY?There is still a lot of confusion as

to watt I mean when I say the D1010is a 100 watt amp, D24 a 50, etc.,when we hear someone on the airsaying he is getting something farless with his.

We all want a little more out of ouramps than the next guy, but with anAM modulated complex waveform, itis difficult to compare Bird wattmeterreadings with any real meaning

unless all use the same standard.The FCC a few years ago changedthe rules to give power limitations inpeak envelope power so that eachmode would not need a separatelydefined value.

The p.e.p. is easily measuredwith most all modes. With ATV it isthe power read on a Bird wattmeterwith no video plugged in and theblanking pedestal pot cranked tomaximum power out. This CW poweris the maximum peak power yoursystem is capable of. It will occur onthe sync tip no matter where yourblanking pedestal is set, video gainlevel, or relative amount of black orwhite in the picture.

To get the proper video to syncratio necessary for a stable picture atthe other end, the blanking pedestalmust be set, with no video pluggedin, to 56% of the peak sync power.During modulation, even though itwill not show on the Bird wattmeter,the sync tip and blanking power in aproperly operating ATV transmitterwill still be those same power levelsyou read.

Many ATVers erroneously givetheir power out as that read on a Birdwattmeter under video modulation as"average power". The standard Birdwattmeter with slugs that most of ushave does not read true averagepower with a complex AM waveformhaving components over 50 KHz. Soto compare one stations power toanother this way is very inaccurate,not only from the power meter, butbecause of where each person setthe blanking pedestal, depth of videomodulation, and what is in thepicture. A scene that ispredominantly black will read higherthan one mostly white.

MAX HEADROOMUnfortunately, the gain of many

of the amps year by year has goneup. What, you say? Don't we alwayswant more? That's OK with CW andFM modes but with ATV you have tostay just within the amps linearregion. When I first tested theD1010N the blanking pedestal on myTC-1 was running about 7 watts.Now it's down to 4. The TXA5 + PA5basic modules back then peak sync

was typically 11 to 12 watts. It

matched the amp real close. Nowwith the Toshiba SAU4 brick we aregetting 15 watts p.e.p. when drivenby the TXA5-5 (all with 13.8 Vdc).

The result is that the peak syncinput to the 100 watt amp drives itinto complete saturation (110-120watts). With no headroom, thesuperimposed sound subcarrier getssquashed on the sync tip, the top ofthe color burst is compressed, andreduces the dynamic range - affectsgrey scale, especially the white end.I suggest 12 dB as the minimumdynamic range for ATV systems.

For the black and white call plateDXer's it is probably no big deal, butfor public service work, and thoseinterested in video quality, you mightconsider setting your max drive synctip power to 90% ( only 1 dB) of thesaturated amplifier power level.

Loss from a long length ofinterconnecting coax can do thateasily, but it's loss will also affect thereceive if you don't have an antennamounted preamp or one in the amp.Or you could put a coiled up lengthof small RG174 50 ohm coax (Belden8216) in place of the coax betweenthe amps first stage input and T/Rrelay as a 50 ohm attenuator with noaffect on receive. At 70cm you getabout 3 dB loss per 17 ft.

I prefer coax attenuators forpowers between 1 and 15 watts overresistor networks at UHF becausethey are naturally 50 ohms, havevirtually no VSWR except if thecenter conductor or braid leads arelong, and have greater attenuation ofharmonics.

Coax Attenuation /100 ft:Belden 8216 9203

70cm33 cm23cm

RG-17418 dB28.5 dB36 dB

RG-5811.5 dB20 dB26 dB


ATV Q & A FEEDBACK continued . . .

You can use a pi resistivenetwork but the lead lengths becomesignificant inductors as frequencygoes up. The resistor must be noninductive types (no wirewounds) andtheir wattage rating should be twicethat of the power dropped throughthem. Keep leads extremely short.

Rs

50 Ohm Resistor Pi attenuatornetwork to closest 5% values:

1 dB 3 dB 6 dB 10dBRp 820 300 150 91Rs 5.6 18 36 68

POWER MODULESI got a lot of questions about

proper feeding of power modulesfrom different transmitters. The 1watt transmitters can blow out any ofthe 70cm bricks - Motorola MHW-710,MHW-720, Amprex BGY-41B,Toshiba SAU4, and the older RCAand TRW units. Max power input tothese is 250 mW. They are made for50-100 mW nominal drive.

Some with the 1 watt rigs foundout the hard way thinking that if thepedestal pot could be cranked downfar enough or the transmitter variablecaps detuned, it would work withoutan attenuator. They forgot that thesync stretcher still pulls the sync upto around 1.5 watts, or that detuningthe transmitter changes thefrequency response, linearity, andcould be come unstable. Anattenuator at the brick's input is theproper way to go.

Others have also popped the firststage in the 50 watt D24's - max input4 watts - by adjusting down their 10watt transmitters in like mannerwithout an attenuator. Mirage haschanged the model number of theD24 to D26. It is the same amp withthe ATV mods I gave them a fewyears back, but they finally ran out ofprinted labels and literature with D24on it. The 4 stood for 40 watts. Themods also increased the max powerto 60 watts.

On the other bands, I havetested the Motorola, NEC andToshiba 900 MHz and the Toshiba

1200 MHz power modules. The 900MHz "cellular" FM modules weredisappointing. The dynamic rangewas only 6-8 dB (full on to full offoutput power with varying drive)since these, designed for the highlycompetitive cellular market, units didnot have any internal bias on the firststage. Low drive levels usuallyrequire a small amount of bias on thetransistor so that the RF waveformswings above the .7 Volt base -

emitter turn on point.Since the blanking is set to

almost 3 dB down from peak sync,that left only 3 to 5 dB of range forthe video. You would like at least 7dB of range for good grey scale plusa few dB of headroom, or in this casebottom room for whites. White levelis almost 10 dB down from peak syncin a proper system. While viewablepictures could be seen with thisnarrow modulation range, it tookconstant adjustment of video gainand pedestal as the modules warmedup and their RF gains changed or ifthe power supply voltage waschanged a little.

The sound subcarrier had muchmore buzz due to no head room -sound subcarrier was cut off at synctips and white limiting. A 10 dBattenuator was put on the modulesinput to drop the 1 watt output fromthe TXA5-33 to the required 100mW. Max power into the modules is400 mW before possible destruction.

Unlike their 70cm counterparts, Idon't recommend the 33 cm powermodules for AM ATV unless one ismade for linear multimode rigs in thefuture.

The Toshiba M57762 23 cmmodule worked great. It is designedfor multimode rigs, so it had greatlinearity and dynamic range. It startedto compress at about 12 watts.Maximum input is 1 watt. For ATVusing the TX23 1 watt transmitter, 4dB's of RG 174 dropped the inputpower to the best linear range. Withpeak sync at 13 watts, I set thepedestal at 7.5 watts. This took .3watts at the module input after theattenuator.

A good source of any of thesepower modules plus a wide stock oftransistors for transmitting andreceiving is RF Parts, 1320-16 GrandAve, San Marcos CA 92069 (619-7440728). Get their catalog and seetheir ads in QST.

I have tested the DowneastMicrowave 18 watt amps for 33 and23 cm found that they are very linearand do a great job connected directlyto the 1 watt transmitters. For moreinfo contact Bill Olson at Box 2310RR1, Troy ME 04987 (207-9483741). He also has some nicelow noise preamps and long loopYagi's for 33 and 23 cm.

FILTERS - VSB - REPEATERSI have been getting about twice

the calls about putting up a repeaterthis year compared to last. It variesbetween inband and crossbandwhere it used to be exclusivelyinband.

Some repeaters using the TX-RX70 cm inband duplexer to one goodantenna report some desense andsome did not. This is after going backand making sure everything wasdouble shielded, etc. The problemseems to be the differences inintermod in the transmitters andamps.

The sideband harmonics andtheir intermods before filtering canbe anywhere from 40 to 80 dB down12 - 18 MHz away on the repeaterreceiver frequency. But 40 dB downfrom 50 - 100 watts is very significantwhen you figure the repeaterreceivers noise floor is 150 dB belowthe transmitters peak power output.If you take the 80 or more attenuationof the duplexer plus the worst case of40 dB down sidebands, you still canhave have as much as 30 dB abovethe noise interference.

Reducing the IM in thetransmitter and amp can help, as wellas putting in another VSB filter, suchas the Spectrum International PSF-421-ATV, between the exciter andamp, or putting notch filters in thetransmitters line. Attention shoulcalso be paid to proper linear drivelevels, since the unwanted sidebandharmonics and IM increase veryquickly as you get into amplifiercompression. The higher the amppower, the more important.

I did some experimenting withthe KPA5 looking at reducing the IMand found that a little base bias of theMRF555 could cut it down 10-20 dE.I put a 680 ohm resistor from theMRF555 base to the +13.8. If you tryit, make sure the base to groundresistor is 22 ohms, and connect thebody of the 680 ohm resistor direct yto the base with no more than 1/4"



lead. Sleeve the other lead andconnect to a + 13.8 V trace next tothe 2N3734 modulator collector. Onolder units using a MRF628 and / or a47 ohm resistor to ground on thebase, run a 1.5K resistor in likemanner to +.

The advantage of running aduplexer rather than two antennas isnot only the cost savings of oneantenna and hardline, but also thereceive and transmit point in space isthe same. You can get higherisolation however with 2 antennas byfinding the magic null point as

previously discussed in the Q & Asection.

TX-RX now has a 33 cm VSB filteravailable. Spectrum International justcame out with the PSF-1253-ATVVSB filter for 23 cm. It has 2.8 dBinsertion loss and goes for $182.

1/2 WAVE CAVITY BANDPASS FILTER BY KEN GUILLOT, WB5JLZ

KA06

,ASR Pleces

i" O. D. coPPER pier

M/) co/WA w't(

(--2Y; --->

SEPARATE SOUND XMTRWB5JLZ's Baton Rouge ATV

Repeater uses a separate FM soundtransmitter at 425.75 MHz in order tomake the sound come out better withweak signals. When subcarrier ismixed with the video you are limitedto about -18 dBc depending onheadroom, but you can go to -7 dBcwith a separate transmitter andantenna for sound.

He had some problems gettingenough deviation and proper pre -emphasis for which I marked up hisschematic with changes to try. Thisworked fine on the bench but whenconnected to the antenna at therepeater site, it interfered with thereceive video.

The FM transmitter strip he usedstarts with a 12 MHz crystal which isgoing to have some small amount ofenergy plus noise on multiples of thecrystal. Also the final transistor willgenerate intermods with any othertransmitters, in the area which may fallin the receiver passband. I suggestthat any repeater transmitter have abandpass filter on it's output toprevent IM interference to it'sneighbors.

C6V/Ty RESON6 TOR125.75

Nor DX,ctiv,s/ TD SC4 z

ALA< /Liar w.assz z..e' t; .441.

r -

To get rid of the problem he builthis own bandpass filter using some3" and 5/8" O.D. Copper tubing youcan get at a hardware or plumbingsupply store. This filter is similar tothe half wave filter in the ARRLHandbook which uses a 10" Bud boxbut is 100% shielded. Ken,WB5JLZ, says that it is a half wavefilter but half wave would be about13.1" by my calculations instead of14".

I suspect the tuning was broadenough that it passed enough of thesignal at 425 even though it wouldhave peaked lower. He told me hedidn't take time to check the insertionloss closely or tuning range becausehe wanted to get the machine up onthe air asap....and it worked.

I would like to hear back fromsomeone that intends to try it withsome test data on insertion loss andbandpass. I would experiment with ashorter length also to narrow thebandpass and move up the tuningrange for the whole band.

I experimented with an AlincoALR-72T 25 watt 70cm FMtransceiver for use as a separatesound transmitter. The conversion to

3" coPPEP-P

ircoNt.

con/4/-Z-pa,eS

25 KHz deviation and 75 us pre -emphasis was as easy as parallelingone resistor in the pre -emphasisnetwork. All I did was put a 22Kresistor in parallel with the 180Kresistor R50. This resistor isconnected to the wiper of thedeviation pot VR2. The frequencyrange of the synthesizer can bechanged by solder jumpers on thecontrol board for 430-440 MHz. I

have not had time to see if I can makeit go down to 420.

FREQUENCY COORDINATIONLots of calls on this one also.

The time has come for FM repeatercoordination councils to become areaSpectrum Managers. While thesecouncils have evolved out of thenecessity to coordinate FM repeatersto prevent interference, there arenow more and more other modesusing the bands above 70cm thatmust also be fit in.

The volunteers who do thisthankless job naturally came from theFM repeater group. Now we asATVers are pounding on them forcoordination and interferenceprotection asking for big chunks of



the spectrum. You cannot expectthem to be familiar with thecharacteristics and operatingpractices of ATV. So don't besurprised if you get a flat NO, goaway, or why don't you go to a higherunused band.

Even the well intentioned or wellknown and respected in one modecannot do a proper job of local bandplanning and spectrum management.I suggest your ATV community gettogether and get the bestcommunicator and the besttechnically competent, and thenthese two people volunteer tobecome members of the spectrummanagement technical committeerepresenting ATV.

The technical committee shouldalso be made up of two people fromall other modes - packet, satellites,weak signal as well as FM repeatersand control links. I think this is theonly intelligent way to come up with alocal workable bandplan that all canagree to. This has been workinghere in Southern California since1972 when our technical committeewas first formed. If it works in thehighest communications density areain the USA it should work anywhereelse.

Going by the crystal orders thepast few years the shift does seem tonow be from 439.25 to 434.0 due toincreases in FM repeaters between440 and 444 MHz. Although manyorder combinations of single and twofreq transmitters, I used to use equalnumbers of crystals among 426.25,434.0 and 439.25. Now it is shiftingto more 434 and less 439.

The big decision in your areamust be made sooner than you think!You can stay on 439.25 for a longtime if you can get your coordinationcouncil to fill up 444-445 MHz withFM repeaters first before going below444 MHz. This gives 40 FMrepeaters in any given area beforefull. But when that day comes, andpush comes to shove, you may nothave 434.0 to go to. It may be filledwith packet or links from 433 to 435MHz.

All the 220 people who will bedisplaced if the bottom 2 MHz isactually removed are looking to 70cmfor a home. If a no code license goesthrough, one of the possibilities is 70cm privileges. 70cm may fill in yourarea like two meters. In my area itfilled 8 years ago.

No matter if you want to fight for439.25 or 434.0, the time is now tolet your coordination council knowthere are a lot of ATVers out thereand growing. The packet andsatellite people have a lot ofappearance to coordination councilsand the League because they arevocal and write articles. Get youractivity known by volunteering tohelp your local coordination councilget into spectrum managementintelligently, and anytime you do apublic service event with ATV, give aradio club talk, etc. as a minimum dropa note to your ARRL SCM so it getsprinted in QST.

Get positive about your modeand promote it, stay away from thename calling and negative responsesto others who probably just have thesame zeal for their main interest in thehobby. Cooperation and help cango a long way. There is room foreveryone in the 30 MHz of spectrumbetween 420 and 450 MHz.

REPEATER ANTENNASFor horizontal polarization you will

have to build your own. I know of nocommercially made horizontal omniswhich have proven out with decentgain that are not in the thousands ofdollars. I suggest contacting the twobest known amateurs who have beenperfecting the Alford slot (MerleReynolds, W9DNT, 710 25th Ave Ct.Moline IL 61265) and Rib Cage slot(Gerald Cromer, K4NHN, 1014Summerland Dr., Cayce SC 29033)for their latest constructioninformation and advise. Measuredgains have been in the 4 to 7 dBdrange on 70cm. I don't know if thebandwidth has ever been measuredbut the antenna should be scaled tofavor the transmitter.

There are a number ofcommercially made vertical omni'smade for FM communications thatgive 6 to 11 dBd gain. Anotherconsideration is that repeaterssharing a commercial site may berequired not to have a homemadeantenna do to the owners fear a hamantenna might come down or causedamage under heavy or windconditions. Most popular are theexposed multiple dipole types.

They cover 406 to 512 MHz andcan be placed on a mast for a cardioidpattern or omni. The 4 bay types get6 dBd omni or 9 dBd cardioid.Another bay can be added for up to

11 dBd. Sources are: DB Products(214-6310310), Sinclair (716-8743682), and Telewave (415-9684400). Celwave makes thefiberglass stick type (904-7879200).

CMC Distributing in Van Nuys CA(818-9944455) reps a number ofthese commercial and amateurantenna manufacturers and couldhelp in your selection, ask for BobWB6CLG.

There are some amateur stickand dipole types that are less ruggedand less cost. Cushcraft (603-6277877) and Max-Rad (312-5953933) make the multiple dipoletypes, and NCG Co. (714-6304541)has the fiberglass transposed coaxsection "sticks".

NCG Co. also has quite aninteresting variety of multiband UHFantennas and duplexers. Their gainclaims are very exaggerated but stillhave good real gains over a dipole.They have 10 dBd sticks for 33 and23 cm that most of us use on the ATVand FM repeater outputs here.

COLOR LOSS SOLUTIONSome repeaters and ATVers who

put their system together withmodules report color loss. This couldbe due to too many RF bypass capson the video line. For 75 ohmterminations there should be nomore than 220 pF total. If you used a500 ohm or higher video gain potwith 100 ohm across it, make sureany bypass on the wiper is no morethan 100 pF. I have ordered a stockof good quality 100 ohm panel pots.

HAM TV SIGN LANGUAGEJOHN RUCKERT WB6ZPN

Sign language communicationscan be done on ham TV. Yourquick inquiry or interest of pos-.:it-Op future support is needed.The number one goal is to do liveMV sending demos for leadingorganizations helping the deafcommunity. Send a note with along SASE to HAM TV SIGNERS,c/o John Ruckert WB6ZPN, 953South Beacon Ave., Los Angeles,CA 90015. Note: John is a memberof GLAD --Greater Los AngelesCouncil on Deafness.


BASIC PROGRAM TO FIGURE EXPECTED SIGNAL STRENGTH IN FREE SPACEThis is written in Microsoft Basic for the Radio Shack TRS-80 Model Ill but has remarks to enable adapting to any other

computer. Given the measurable variables it will give the peak carrier to noise ratio as well as the distance to the RF horizon

given a flat surface. It is a good starting point to figure repeater coverage area. The program also lets you change thevariables one at a time. Any ham is free to use it in his computer except for profit, reprint, copy or sale. Tom O'Hara,EXAMPLE:

RF TRANSMISSION PATH LOSS. BY TOM O'HARA, W6ORG.

FREQUENCY 434 MHZ

DISTANCE 22 MILES

TRANSMITTER POWER 1.5 WATTS

TRANSMIT ANTENNA GAIN 14 DB

TRANSMIT COAX LINE LOSS 3 DB

FREE SPACE PATH LOSS 116.2 DB

SIGNAL STRENGTH ARRIVING AT RECEIVE SITE -75.6 DBM 37.2 uVRECEIVER ANTENNA GAIN 14 DB

RECEIVER COAX LOSS 3 DB

SIGNAL STRENGTH AT RECEIVER INPUT -66.7 DBM 103.1 uVMINIMUM RECEIVER SENSITIVITY IS -106.2 DBM

(SYSTEM NF= 3 DB WITH 3000 KHZ BW) 1.1 MICROVOLTSCARRIER TO NOISE RATIO IN THIS CASE IS 39.5 DB.

TRANSMIT ANT HEIGTH 70 FT, RF HORIZON IS. 11.8 MILES.RECEIVE ANT HEIGTH 50 FT, RF HORIZON IS. 10 MILES.

1 POKE 16427,75:REM TRS80 III, SETS PRINTER LINE WIDTH LIMIT.2 REM CLS CLEARS SCREEN3 REM TV VIDEO IF BANDWIDTH IS TYP 3 MHZ, SOUND IS 200 KHZ, AND NBFM IS 15 KH

Z. SNOW FREE ATV PICTURE IS ABOUT 40 DB CARRIER TO NOISE RATIO.10 CLS:PRINT"RF TRANSMISSION PATH LOSS & CARRIER TO NOISE RATIO.":PRINT" BY

TOM O'HARA W6ORG (C) 7/81"100 PRINT:INPUT"ENTER FREQUENCY IN MHZ ";F

110 INPUT"ENTER DISTANCE IN MILES120 INPUT"ENTER TRANSMITTER OUTPUT POWER IN WATTS ";X

130 INPUT"ENTER TRANSMITTER COAX LOSS IN DB "*L1

140 INPUTHENTER TRANSMIT ANTENNA GAIN IN DB OVER A DIPOLE ";Al

142 INPUT"ENTER TRANSMIT ANTENNA HEIGTH ABOVE GROUND IN FT ";H1

150 INPUT"ENTER RECEIVE ANTENNA GAIN IN DB OVER A DIPOLE "A2152 INPUT"ENTER RECEIVE ANTENNA HEIGTH ABOVE GROUND IN FT ";H2

160 INPUT"ENTER RECEIVE COAX LOSS IN DB ";L2

170 INPUT"ENTER PREAMP TRANSISTOR NOISE FIGURE IN DB "N180 INPUT"ENTER RECEIVER BANDWIDTH IN KHZ (TV IS 3000) .;B

190 PRINT200 GOSUB 400210 GOSUB 500220 INPUT"ENTER C FOR CHANGES,N FOR ALL NEW, OR P FOR PRINTOUT";C$230 IF C$="C" GOSUB 700240 IF C$="P" GOSUB 900250 IF C$="N" GOTO 10 ELSE 220400 L=36.6+20*(LOG(F)/LOG(10))+20*(LOG(D)/LOG(10)):REM PATH LOSS410 W=30+10*(LOG(X)/LOG(10)):REM XMTR POWER TO DBM420 RI=W+A1-2.15-L1-L:REM DBM AT REC SITE430 M1=10[(.05*(107+R1)):REM DBM TO MICROVOLTS440 R2=R1+A2-2.15-L2:REM ADD ANT GAIN LESS COAX LOSS450 M2=10[(.05*(107+R2)):REM DBM TO MICROVOLTS, L IS EXPONENT460 S=-174+10*(LOG(B*1000)/LOG(10))+N+1:REM -DBM MIN SENSITIVITY470 S1=10[(.05*(107+S)):REM -DBM TO MICROVOLTS480 S2=R2-S490 H3=1.415*SQR(H1):H4=1.415*SQR(H2):REM RF HORIZON499 RETURN500 CLS


510 PRINT"FREQUENCY520 PRINT"DISTANCE530 PRINT"TRANSMITTER POWER540 PRINT"TRANSMIT ANTENNA GAIN550 PRINT"TRANSMIT COAX LINE LOSS560 PRINT"FREE SPACE PATH LOSS

570 PRINT"SIGNAL STRENGTH ARRIVING AT RECEIVEM";INT(M1*10+.5)/10;"uV"600 PRINT"RECEIVER ANTENNA GAIN610 PRINT"RECEIVER COAX LOSS620 PRINT"SIGNAL STRENGTH AT RECEIVER INPUTM";INT(M2*10+.5)/10;"uV"640 PRINT"MINIMUM RECEIVER SENSITIVITYM

650 PRINT" (SYSTEM NF=";N+1;"DB WITH";B;"KHZ BW)";TAB(45)INT(S1*10+.5)/10;"MICROVOLTS":REM 1 DB ADDED TO TOTAL SYSTEM NOISE FIGURE TO ACCOUNT FOR 2ND STAGE NF.660 PRINT"CARRIER TO NOISE RATIO IN THIS CASE IS ";INT(S2*10+.5)/10;" D

SITE....

";F;" MHZ"";D;" MILES"";X;" WATTS"";Al;" DB"";Ll;" DB"";INT(L*10+.5)/10;" DB

B

670 PRINT"TRANSMIT ANT HEIGTH";H1;"FT,"TAB(28)"RF HORIZON IS....";INT(H3*10+.5)/10;"MILES."680 PRINT"RECEIVE ANT HEIGTH";H2;"FT,"TAB(28)"RF HORIZON IS....";INT(H4*10+.5)/10;"MILES."690 RETURN700 CLS:PRINT"SELECT CHANGE:":PRINT:PRINT"1. FREQUENCY.":PRINT"2. DISTANCE.":PRINT"3. TRANSMITTER POWER."710 PRINT"4. TRANSMITTER COAX LOSS.":PRINT"5. TRANSMIT ANTENNA GAIN.":PRINT"6. RECEIVE ANTENNA GAIN."720 PRINT"7. RECEIVE COAX LOSS.":PRINT"8. PREAMP TRANSISTOR NOISE FIGURE.":PRINT"9. RECEIVER BANDWIDTH IN KHZ."725 PRINT"10. TRANSMIT ANTENNA HEIGTH":PRINT"11.730 INPUT C:INPUT"ENTER NEW VALUE...";V740 IF C=1 THEN F=V:GOTO 200741 IF C=2 THEN D=V:GOTO 200742 IF C=3 THEN X=V:GOTO 200743 IF C=4 THEN L1=V:GOTO 200744 IF C=5 THEN A1=V:GOTO 200745 IF C=6 THEN A2=V:GOTO 200746 IF C=7 THEN L2=V:GOTO 200747 IF C=8 THEN N=V:GOTO 200748 IF C=9 THEN B=V:GOTO 200749 IF C=10 THEN H1=V:GOTO 200750 IF C=11 THEN H2=V:GOTO 200 ELSE 700900 CMD"Z":REM THIS COMMAND ON TRS80 III SENDS ALL SCREEN PRINTING ALSO TO PRINTER. IT IS A TOGGLE COMMAND, YOU MAY HAVE TO USE LPRINT INSTEAD WITH ANOTHER COMPUTER OR PROPER COMMAND.910 CLS:PRINT:PRINT"RF TRANSMISSION PATH LOSS. BY TOM O'HARA, W6ORG.":PRINT:GOSUB 500920 PRINT:PRINT:CMD"Z":REM TOGGLES SCREEN TO PRINTER OFF.990 RETURN

";INT(R1*10+.5)/10;"DB

";A2;" DB"";L2;" DB"";INT(R2*10+.5)/107"DB

IS ";INT(S*10+.5)/10;" DB

RECEIVE ANTENNA HEIGHT."

ATVQ AT THE HAMFESTSWe would like to thank the folks who stopped by our booth at the Davenport, Iowa hamfest. We

quickly sold out of copies of ATVQ we brought and gathered in more than 20 new stihscribers. While therewe were invited to do the ATV talk and have a booth at Peoria, IL, Des Moines, Iowa, and Cedar Rapids,Iowa hamfests, which we expect to be ah1 to do. We also were invited to the Galesburg, IL ham clubmeeting to give a talk on ATV there. The date has not been set at this time but will be in the nearfuture.

On March 3, Henry gave a talk at the Tri-town Radio club on ATV. The club has the distinction ofgiving a demonstration of LIVE ATV at the Chicago Worlds Fair in 1933!!! KA9TAP hosted the address byHenry which included part of the Rose Paradevideo tape. The talk covered public service, DX and localoperations on ATV, basic how, to, how much, where to get info. The "show and tell" generated quite a lotof interest especially with the news of the ACLR ATV RPT.


KS8J ATV REPEATER CONTROLERBy Earl Campbell KS8J3713 W. Charleston Ave.,

Glendale, AZ 85308 Phone (602) 978-9037

Publication Editor - Tommy Campbell N7KBO

This repeater controller projectwas inspired by the need for aprogrammable control circuit. The8052 AH Basic micro -controller ICturned out to be ideally suited forthis project. This chip has an 8Kcontrol basis language as well asI/O built right into the chip. Sinceyou can program this controllerusing the basic language, imple-menting different operating needsand conditions are a snap.

I have broken the circuit downinto 3 major areas as follows:1. CPU and optional RS -232 inter-face2. Memory and I/O3. Video and audio controlThe circuit may be constructed

using standard wire wrap or pointto point construction techniquesor a circuit board may be fabri-cated.

Figure 1 shows a MAX 233RS -232 interface while Figure lAshows a MAX 232 RS -232 interfaceas well as Figure 1B that showsthe discrete component RS -232interface. All 3 circuits ut-ili7e asingle +5 VDC supply voltage todevelop the + - 12VDC RS -232voltages. The only difference beingcomponent availability, complexityand cost.

Figure 2 shows the layout forthe 32K RAM and 8K EEPROM wir-ing. I chose 32K of RAM for de-velopment work although only 2Kof RAM is needed. You maychange the RAM/EEPROM/EPROM toany size convenient, (greater than2K). The INTEL 8052 Basic Manualgives many suggestions and circuitalterations. The 8255 PPI chip isused for I/O to the audio, video,VOR, relay keying circuits.

Figure 3 is the audio videorelay keying circuit diagram. Notethe touch tone decoder +5 VDCsupply pin must be well by-passedfor proper operation.

Figure 3A shows a similar in-terface using the much less ex-pensive 4066 IC's instead of theMAX 455 multiplexer at a cost ofa much more complex circuit andadditional parts consisting of 2

74138s and 4 4066 IC's. The relaydriver transistor may be any lowvoltage NPN switching transistorwith a diode across the relay coilto prevent back EMF from des-troying the transistor. The relayis a low current 5 VDC type fromRadio Shack. The N/O contactsmay be used to key a larger relaythat in turn switches on thetransmitter and amplifier. PPI out-puts CO and Cl may be used toselect 1 of 4 video screens of theWB8ELK video ID unit (see lasti spa le).

THEORY OF OPERATIONThe controller is a stand alone

computer system not requiring theRS -232 interface for normal oper-ation. When power is applied, thesystem executes the pre-program-med basic program in EPROM. Thisprogram detects input from thetouch tone decoder and the VORinputs. If only one VOR input isused, the unused input should begrounded.

As you can see there are 8video and 8 audio inputs to themultiplexer. Two of the audioinputs are used via the basic pro-gram for CW ID and to feed theTT audio to the ATV repeateraudio channel. At the KS8J Repea-ter, we use 1 audio video pair forthe 910 MHZ input, 1 pair for the434 MHZ input, 1 pair for thelocal camera, and 1 video inputfor the Radio Shack color com-puter bulletin board video.

By touch tone control, we canroute the touch tone audio to theATV transmitter audio. Many pos-sible combinations of touch tonecontrol are available via program-ming. By reading the basic pro-gram listing, you can see that allthe necessary repeater ID timingand control is accomplished viasoftware timing as the 8052 chiphas a timer built in!

This project has been fun aswell as educational and could beadapted for control of all youraudio video and keying needs inthe shack. With the advent ofcomputer interfaces on most mod-

ern HAM rigs, total control of theshack is possible limited only byyour imagination. I have used thisbasic circuit for controlling myYaesu 767 rig remotely via 2 me-ters. If you come up with anyunique and useful applications,please drop me a note. I hopethat this project is as much funfor you as it was for me.

I am at the present time work-ing on a new project that will bea repeater controller with a soft-ware programmable video ID unitwith live video and graphics over-lays using an INTEL 82786 videochip.

I would like to thank BillBrown WB8ELK for the encourage-ment he gave me to write thisarticle and my wife Tommy N7KBOfor her patience while I wasworking on the project and forher editing help. If anyone hasany questions or comments, pleasefeel free to contact me.

PARTS LTSTSUPPLIER NUMBER PART

R 2 IC's 78L05 or 7805 3terminal voltage regulatorsJ 1 8052AH Basic CPU

($24.95)J 1 2865A or 2764 EEPROM/

EPROMJ 1 42256 32K RAMJ 1 8255 PPI chip

M 1 MAX 233 or MAX 232M 2 MAX 455 MultiplexerR 1 SSI 202 R/S 276-1303 T/T

DecoderJ 1 74373J 1 7408J 1 74138J 1 11.0592MHZ crystal (see

notes)R 1 3.58MHZ crystalR 1 5VDC relay R/S 275-240J 1 10K OHM Sit' resistor

PAC (see notes)7 LED's1 1 MEG 1/4 W resistor7 470 OHM 1/4 W resistors12 .1 MFD capacitors1 10 MFD electrolytic capa

citor


KS8J REPEATER CONTROLLER continued . . .

1 10K 1/4 W resistor desired CW ID call letters; I will 5102 1N914 diodes program the EPROM/EEPROM. XBY(0E001H)=128.0R.IDV.OR1 2N2222 NPN transistor2 20 PF capacitors ADDRESSES OF SUPPLIERS:

OPTIONAL PARTS for MAX 232Interface

5 10 MFD 15 VDCcapacitorsOPTIONAL PARTS for DiscreteRS232 Interface

J= Jamco Electronics1355 Shoreway RdHP1mont1 CA 94002(415) 592 8097

M= MAXIM Integrated ProductsInc,

1 1.8K resistor 510 N Pastoria Ave.4 4.7K resistor Sunnyvale, CA 940861 NPN transistor (408) 737 76001 PNP transistor2 1N914 diodes R= Radio Shack1 10 MFD 15 VDC

capacitorNOTES:

1. Instead of the 10K OHM SIPyou may use 8 10K 1/4W resistorsstood up on end with all the topleads connected together and tiedto 5 VDC or if you are breadboarding the circuit, you maychoose to use a 10K resistor DIP.2. The 78L05/7805 3 terminalsvoltage regulator is used to con-vert the normal 12 VDC out ofthe video operated relay circuit(horizontal sweep detector) to a+5 VDC level for the PPI chip.3. The 11.0592MHZ crystal may beany value between 9 to 11.5MHZ.If you use a crystal other thanthe 11.0592MHZ specified, add aline in the program near the be-ginning that reads:1 xtal=11059200Substitute your crystal value inHZ for the 11059200 number.4. The 8052 Basic Manual may beobtained from Intel, PublicationNumber 270010-003.5. The RS -232 computer or ter-minal interface is ootional andonly needed if you wish tochange, develop or otherwise mod-ify the program.6. The printed circuit board layoutis for an RS -232 less stand aloneoperation with MAX 455 multiplex-er 32K RAM and an EEPROM 8K orEPROM 8K with provisions for 2VOR inputs. If anyone makes aprinted circuit board for this pro-ject, let our readers know aboutthe availability as I bread boardedthis project.7. If you send me a blank 2764 or2865A, your crystal frequency,APRIL 1989 VOL. 2 -2

Intel Corp.3065 Bowers Ave.Santa Clara, CA 95051

PROGRAM1 REM2 AUXA=33 AUXV=164 TMA=25 KU=06 IDV=07 FFV=88 IDA=09 FFA=110 TIME=020 XBY(0E003H)=91H30 CLOCK 140 DDLY=350 IDT=355 MTD=60060 FOR X=1 TO 2470 PRINT80 NEXT X85 XBY(0E001H)=090 PRINT "Drop out

delay ",DDLY95 PRINT "ID Time

",IDT100 TIME=0 : GOSUB

1000105 PRINT "RKU =

,RKU," DV = ",DV,"TTD = ",TTD," KeyUp's = ",KU, CR ,

106 IF DV=16.AND.TTD=11THEN IDT=30

110 IF DV=16.AND.TTD=11THEN GOTO 4000

120 IF RKU=128 THENGOTO 3000

130 IF DV=16.AND.TTD=15THEN GOTO 500

199 GOTO 100500 IDKU=TIME

.IDA520 GOSUB 6000530XBY(0E001H)=128.0R.AUXV.0R.TMA540 IF TIME>IDKU+600

THEN GOTO 580550 GOSUB 1000560 IF DV=16.AND.TTD=12

THEN GOTO 3050565 IF DV=16.AND.TTD=13

THENXBY(0E001H)=128.0R.AUXV.0R.TMA566 IF DV=16.AND.TTD=15

THENXBY(0E001H)=128.0R.AUXV.0R.AUXA570 GOTO 540580XBY(0E001H)=128.0R.IDV.OR.IDA590 GOTO 40991000 D=XBY(0E000H)1010 RKU=D.AND.1281020 DV=D.AND.161030 TTD=D.AND.151040 RETURN3000 KU=KU+13005 PRINT3010XBY(0E001H)=128.0R.IDV.OR.IDA3015 GOSUB 60003020 IDKU=TIME3030 IF TIME<IDKU+IDTTHEN GOTO 30303035 ATV=FFA3040 GOSUB 10003045 IF DV=16.AND.TTD=13

THEN ATV=TMA3046 IF DV=16.AND.TTD=14

THEN ATV=FFA3047DV=XBY(0E000H).AND.163048 IF DV=16 THEN GOTO

30473049 IF TTD=11

THEN GOTO 40003050 IF RKU=0 THEN GOTO

33003055 IF TTD=15 THEN

GOTO 5303060XBY(0E001H)=128.0R.FFV.OR.ATV3065 IF TIME>IDKU+MTD

THEN GOTO 35003066 PRINT "Time to time

out",(IDKU+MTD)-TIME,CR ,

PAGE 81

33403500XBY(0E001H)=128.0R.IDV.OR. I DA351035113520

3080 GOTO 30403300 DDY=TIME3310 IF TIME>DDY+DDLY

THEN GOTO 35003320 GOSUB 10003330 IF RKU=0 THEN GOTO

3310GOTO 3040

IDKU=TIMEIDT=1IF TIME<IDKU+IDTTHEN GOTO 3520

3530 IDT=33999 GOTO 40994000 IDKU=TIME4010 GOSUB 10004015 IF TTD=11 THEN

GOTO 40004020 IFDV=0.AND.TIME>IDKU+3

THEN GOTO 40994030 IF DV=0 THEN GOTO40104040 PRINT : KU=KU+14050 IDT=TTD*604060XBY(OE001H)=128.0R.IDV.OR. IDA4065 GOSUB 60004070 GOSUB 10004080 IF DV=16.AND.TTD=12

THENXBY(0E001H)=128.0R.IDV.OR. IDA : GOTO 40994082 IF DV=16.AND.TTD=13

THENXBY(0E001H)=128.0R.IDV.OR.TMA4083 IF DV=16.AND.TTD=14

THENXBY(0E001H)=128.0R.IDV.OR. IDA4085 PRINTIDKU+IDT-TIME, CR , 4086PWM 400,400,200 :

PWM 600,600,2004087 OT=TIME4088 GOSUB 1000 :

IF DV=16THEN GOTO 4080

4089 IF TIME<OT+2THEN GOTO 4088

4090 IF TIME<IDKU+IDTTHEN GOTO 40704099 GOTO 5605000 IDT=35010 FOR T=1 TO 1000 :

NEXT T5020 XBY(0E001H)=05030 FOR T=1 TO 1000 :

PAGE 82

KS8J REPEATER CONTROLLER continuedSNEAK PREVIEW OF THE AEA

430 FSTV TRANSCEIVERRon Hranac NOIVN

Western Vision Network had theopportunity to evaluate a proto-type of the new AEA FSTV trans-ceiver in February. The rig is a70 cm vestigial sideband transcei-ver with 1 watt output and fea-tures a GasFET front end in thereceiver. The prototype differedsomewhat from the unit in AEA'sadvertisements due mainly to anew front panel layout and addedfeatures since those original pho-

NEXT T5040 GOTO 606000 GOSUB 7000 : GOSUB

8000 : GOSUB 8000GOSUB 9000GOSUB 8000GOSUB 9000GOSUB 9000 : GOSUB9000GOSUB 7000 : GOSUB8000 : GOSUB 7000GOSUB 9000GOSUB 8000 : GOSUB8000 : GOSUB 8000GOSUB 9000GOSUB 7000 : GOSUB7000 : GOSUB 7000: GOSUB 8000 :

GOSUB 8000GOSUB 9000GOSUB 8000 : GOSUB7000 : GOSUB 7000

GOSUB 7000GOSUB 9000GOSUB 7000 :

GOSUB 7000GOSUB 8000 :

GOSUB 8000GOSUB 7000 :

GOSUB 7000GOSUB 9000GOSUB 8000 :

GOSUB 7000 :

GOSUB 8000RETURNPWM 300,300,200FOR T=1 TO 40NEXT TRETURNPWM 300,300,100FOR T=1 TO 40NEXT TRETURNFOR T=1 TO 100NEXT TRETURN

6001600260036004

6005

60106020

60306040

60506060

60706080

6082

6084

60906100

611070007010702070308000801080208030900090109020READY

tographs were taken.The production unit will be

nearly identical to the prototypewe tested. The transmitter includ-es a class A output power amplifi-er stage, SAW filtering, one crys-tal is included with two frequen-cies an option. The camera videoappears at the TV output jack onchanel 3 or 4 in transmit. The TVoutput from the downconvertergoes through a selectable channel3 or 4 SAW filter also.

If the prototype is any indica-tion of the quality of productionunits, AEA will have a real winnerhere. Overall receiver noise figuremeasured 2.6 to 3.1 db dependingon the frequency tuned to, usinga Hewlett Packard 8970B noisefigure meter. Power consumptionat 13.8 VDC was .41 amps onreceive and 1.03 amps on transmit.With a camera attached to thefront panel connector (10 pin) thetransmit power was 1.25 amps.

Transmitter power output was+28 dbm (0.631 watt) on sync tipswith 1 volt p -p video input and62% visual depth of modulation. Atthis output level, the sound car-rier was 19 db below the videocarrier and -33 db on the lowersideband. Transmitter video fre-quency response was +- 1 db to4.5 Mhz. The downconverter con-version gain averaged 6 to 7 dbacross the band.

We exhibited the FSTV 430 ata local swapfest and commentsabout its appearance were verypositive. During Western VisionNetwork's weekly net, the AEAtransceiver was used to simulcastNET activity and on -air pictureand sound quality was reportedquite good.

A complete evaluation of aproduction model will be in thenext issue of ATVQ along with acomparison to other productionATV transceivers on the market.By the time you read this theAEA FSTV 430 will be availableat local AEA dealers.

About the author, Ron is anavid ATV'er and also is technicaleditor and contributor to severalCAW industry publications and isa professional engineer specializingin CATV RF and video equipment.


KSBJ REPEATER CONTROLLER continued . . .

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P2.6P1.0/T2 P2.7P1.1/T2XP1.2 5iP1.3P1.4P1.5 ArmP1.6 TXDP1.7 RXD

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ATVQ AT THE HAMFESTSIs Indianapolis the next "Dayton"?

ATVQ attended the Indianapolishamfest March 12th and the crowdwas bigger than ever. Both com-mercial and flea market (bothINDOORS) were sold out well inadvance. The crowd was huge allday and didn't start to thin outuntil 2 PM. Contingents of ATVerswere present from 5 states withgroups from central Illinois, Bloo-mington, IN and Dayton/Cincinnatiwell represented. Our thanks toBob W9PRD and Paul W9DUU whofound us a tablP to share as wewere too late in getting our re-quest in for our own tahle. Ourthanks to Larry WB8YAJ and DaveN9EFC who shared their tahlp withATVQ and who locals can contactfor ATVQ stihscriptions. Both workin broadcast TV in Indianapolis andquite active on MV. The hamfestis held in the State Fair Groundsin central Indianapolis and parkingwas FREE and abundant. Despite

TOP PCB the large crowd, we were able topark cicse enough for a comfort-ahlP walk to the hamfestCommercial vendors included sev-eral of the large ham stores andall remarked that sales were brisk.Although we didn't arrive until 10and didn't set up on the tahlPuntil almost 11, we sold out of allthe goodies we brought and alsogathered several new subscriberswhile having pleasant chats withATV'ers. ATVQ will be there nextyear!

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YORK PA ATV CONFERENCEPlans have been agreed to

between ATVQ and York Hamfestfor a satixday night ATV confere-nce. Speakers will include MurrayBarlow of Science Workshop andJohn Beanland of Spectrum Inter-national and Henry KB9F0. Othersto be annmounced. Free snackscourtesy of ATVQ will be providedand a live ATV demo will followfrom the York ATVers. Full detailsthe July ATVQ.

PAGE 86

BOTTOM PCB


January found us in Las Vegasattending the Winter ConsumerElectronics Show. The Las Vegasconvention center was jammedfull of the latest new electronictoys to be introduced this year.It takes days in order to fullycover the entire show. Two ofthe most unusual items found dur-ing the event were the electronicbarking dog burglar alarm and theFishiba TV. The Fishiba is an fishaquarium made up to look like aTV complete with a VHF/UHF Tuna.I understand that 'Herring'boneinterference is particularly pro-nounced with this unit.

There are a number of interest-ing new video devices on display.Unfortunately, although they arecurrently available in Japan, therewere no immediate plans to intro-duce some of the most interestingitems into the U.S. Guess they justbrought them along to tease us!SANYO and Toshiba had a numberof excellent portable color LCDTV's on display. These may showup near the end of the year. Thequality of the picture is a definitestep above current models of colorLCD sets. Panasonic had an ultraminiature color LCD Camera whichcame in two units. The controlbox which plugs into the side ofthe VCR is about the size of apack of cigarettes. The CCD andlens unit detaches from the boxand is about the size of mythumb. This camera could easilymount right on your hat! The com-panion VCR (S VHS -C format andHi-Fi stereo) is very lightweightand even has a color LCD monitorbuilt into it. There were no plansto introduce these into the U.S.immediately but you might trycontacting Panasonic and askingfor info on the Model NV -V1 re-corder and Model VZ-Cl camera.

There were several items ofinterest to the ATV'ers that arecurrently available. Several smallB/W CCD cameras were on display.These could be of real interest forthose of you thinking of R/C air-craft ATV. The GBC Model CCD-500 weighs under a pound anddraws 250mA at 12 V. DC. Thissolid state CCD B/W camera isvery compact and will produce a

WINTER CES SHOWBill WB8ELK

usable picture under very lowlight levels (.02 lux). Elmo Mfg.Corp has a very similar camera(Model 8700A) and has an externalsync input. Elmo also has a micro-miniature color CCD camera headwith a separate control box. Thisis a commercial quality unit thathas interesting possibilities al-though it's near $3000 price tagkeeps it out of range of mostATV'ers.

While on the subject of compactB/W CCD cameras, AMPEREX hasintroduced a module that has beenused by several ATV'ers. This is amodule made by Phillips (Model #56471 for EIA U.S standard - Mo-del #56470 for CCIR European)with two small circuit boards at-tached to a C -mount lens holder.This module can be configured ina standard configuration with thecircuit boards pointing straightback or spread out horizontally tomake a very thin camera perfectfor telescope mounting. This cam-era is ideally suited for astronomyuse as the gain can be externallycontrolled as -well as a gammaadjustment from 0.45-1.0. Comingin at 0.02 lux light sensitivity, itis so sensitive that it will providequite watchable video with illumi-nation from a single match. It'svery sensitive in the IR spectrumand can actually see the hot tipof a soldering iron. Ernie, WB6BAPand Roy, N4ABY have both usedthis camera hooked up to theirtelescopes with excellent results.Even without a telescope youshould be able to point it at anight sky and see stars clear downto 4th magnitude.

Another camera that is startingto become available in some storesis the SONY WATCHCAM. This isthe same B/W camera used in thelast helium balloon launch. Notonly is it lightweight but it hasa built-in fixed lens, auto iris andmicrophone. Although it is not aCCD camera, it produces a finepicture and apparently can handleextreme environments. Currentlyit is being sold in a completesecurity system and can't bebought separately. For around $700you get two of the SONY WATCH -CAMS, cables and a small monitor.

The other B/W cameras mentionedabove range in price from $500 -$700. There usually is a price

break when more than 10 unitsare ordered, therefore if there isenough interest in these itemscontact me and we could put to-gether some group orders.

Finally an item that impreedme with it's quality constructionand operation is the STATPOWERPC -100+ power inverter. If you'veever been out in the field runningmobile, covering public events andmountain -topping you'll find plentyof use for convenient 110 v. ACpower. This very small unit isbuilt into a well -shielded case andactually produces a modified sinewave which is much superior tothe square wave produced by manyother inverters. You can use itto power small motor -driven ap-pliances, sensitive radio equipmentand computers. I plan to run mySSTV converter mobile with myinverter. Rod, WB9KMO, mountedhis inverter into a small backpackwith a 5 Ah 12V battery and op-erated a R-7000 receiver with nodetectable interference or noise.The inverter will handle 100 Wloads continuously and will actual-ly handle 200 W loads for a fewminutes until the built-in overtemperature circuit kicks in. Thisinverter will also drop out whenthe battery drops below 10 voltswhich prevents a complete dis-charge of the battery. An low -battery alarm will sound when theinput voltage goes below 10.7volts. I liked this inverter so muchI decided to carry them in theU.S. for $139. If interested con-tact me at ELKTRONICS, 12536T.R. 77, Findlay, OH 45840. 73's:ill - WB8ELK.

AMPEREX, Providence Pike, Sla-tersville, R.L 02917 (401) 762-3800.(Ask for Carol Ethier)GBC, CCTV Corp, 315 Hudson St.N.Y., N.Y. 10013 (800) 221-2240.ELMO, 70 Hyde Park Rd. New HydePark, N.Y. 11040 (516) 775-3200.


CES SHOW

CCD-500LOW LIGHT CCD CAMERA

WATCHCAMSONYModel 8700A


ThE RadioAmatEurs Journa

ON THE COVER: With his retirement from the U.S Senate,Barry Goldwater, K7UGA, finds more time available for his life-long hobby of AmateurRadio from his home OTH In Scottsdale. Arizona.

FEBRUARY 1989 VOL. 45, NO. 2

FEATURES

POLAR BRIDGE EXPEDITION Wade Luce, N7KQU 11

BUILD A COAX.ANTENNA SWITCH FOR YOUR STATIONLew McCoy, W11CP 18

CO REVIEWS: THE UNIDEN HR -2510 10 METER SSB/CW/FMTRANSCEIVER Dave Ingram, K4TWJ 20

THE WNZ AWARD: YOU CAN DO IT! Patty Winters, N6BIS 26

A MAG-MOUNT CONVERSION FOR UNDER A BUCKJohn R. Somers, KC3YB 32

CRAZY ANTENNAS I HAVE USED Jeff Lackey, K8CQ 34

HAROLD S. BRIDE, HEROIC TELEGRAPHER OF THE R.M.S.TITANIC David 0. Norris, N8HKV 36

CQ SHOWCASE: NEW AMATEUR PRODUCTS 40

AND BLESSED BE THE XYL Kristi Jenkins -Smith, VK9NL 42

CQ REVIEWS: CODEMASTER 100 Jonathan L. Mayo, KR3T 44

THE EVOLUTION OF AN HF SUITCASE STATIONJohn J. Schultz, W4FA/SV0DX 52

ANNOUNCING THE 1989 CQ WW WPX CONTEST 56

BILL'S BASICS: POTPOURRI 1989 Bill Welsh, W6DDB 60

Dave Ingram, K4TWJ 64

THE PACKET USER'S NOTEBOOK: PACKET DUPLEXINGBuck Rogers, K4ABT 72

WASHINGTON READOUT: ENTRY INTO THE AMATEUR RADIOSERVICE-IS IT TIME FOR A CHANGE?

Frederick 0. Maia, W5YI 79

ANTENNAS AND ACCESSORIES: READER FORUM, PART IIKarl T. Thurber, Jr., W8FX 82

WORLD OF IDEAS: MORE KEYS REVISITED

DEPARTMENTSAWARDS: STORY OF THE MONTH-JOHN R. SPARK, W4LHP

Dorothy Johnson, WB9RCY 76

CONTEST CALENDAR: CONTESTS FOR FEBRUARY ANDEARLY MARCH, NA RESULTS OF THE DUTCH PACCCONTEST Frank Anzalone, W1WY 88

PROPAGATION: CONDITIONS DURING 1988 WW DX PHONECONTEST, FEBRUARY VHF OPENINGS

George Jacobs, W3ASK 93

DX: NEWS, VIEWS, TIDBITS, AND LORE FROM THE WORLDOF DX Hugh Cassidy, WA6AUD 96

ZERO BIAS 4 OUR READERS SAY 8

ANNOUNCEMENTS 6 HAM SHOP 104

ThE Radio AmatEur's Journal76 North Broadway, Hicksville, NY 11801


Tune in with

The Ham's Magazine

All year long CQ bringsyou the best writers ...the best reading inAmateur Radio. Writtenand edited to be enjoyedas much as you enjoyHam Radio itself. Notjust good. It's the best!

Subscribe andSAVE!

SAVE 36%OR MORE ONYOUR COPIES OFSubscribe now and save $10 a year ormore over the cost of buying your issueson the newsstand.

Yes! I want every issue of CO delivered tomy door, so sign me up.

1 year 12 issues $19.95(Save $10.05)

C 2 years 24 issues -$38.00(Save $22.00)

3 years 36 issues $57.00(Save $33.00)

Canada/Mexico-One year $22.00. two years 542.00,three years 583.00; Foreign-one year $24.00, two years&MOO, three years $89.00. Foreign Air Mail-one year$77.00, two years St52,00, three years $228 00

(Please print clearly)

Name

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L Check or Money Order enclosed

Bill to Mastercard Visa =My account number Is:

Expiration date'

Nole: Allow 8-6 weeks for delivery of first Issue.

PAGE 89

WYMAN RESEARCH NEW ATV TRANSCEIVER

VISIT BOOTH 275 AT DAYTON HAMVENTIONNE tv

WYMAN RESEARCH INC. WILL BE SHOWING NEWLY DESIGNED FM AND AM VIDEOTRANSMITTERS, TRANSCEIVERS AND RECEIVERS. SEE THE NEW TRIDON ATV LINE OFTRANSCEIVERS AND OTHER RELATED EQUIPMENT. THIS EQUIPMENT HAS BEEN PACKAGED INMODERN ALL ALUMINUM CABINETS WITH STYLIZED DECORATIVE PANELS. ALL CIRCUITRY HASBEEN UPDATED TO INCLUDE THE LATEST IMPROVEMENTS IN DESIGN. EQUIPMENT WILL BEAVAILABLE FOR THE 450, 900 AND 1200 MHZ BANDS

THE WR-450 TRANSCEIVER HAS BEEN UPDATED WITH A CRYSTAL CONTROLLED RECEIVERTHAT WILL PERMIT THE RECEPTION OF TWO INDEPENDENT AUDIO SIGNALS WHILE RECEIVINGATV PICTURES. THE RECEIVER INCLUDED IN THE CABINET WILL MAKE IT POSSIBLE TORECEIVE EITHER THE SUB -CARRIER AUDIO SIGNAL (EITHER SIDE OF THE CARRIER) OR THEON -CARRIER AUDIO SIGNAL INDEPENDENT OF THE TUNING OF THE ATV DOWNCONVERTER. ITIS ALSO POSSIBLE TO SET THE CRYSTAL CONTROLLED RECEIVER TO A 2 METER FREQUENCY SUCHAS 144.34 MHZ FOR AUDIO RECEPTION ON THAT BAND. MOST EXCITING IS TO USE THE ON -CARRIER RECEIVER TO RECEIVE SSTV PICTURES WHILE TUNING THE DOWN CONVERTER TO BRINGTHAT WEAK SET OF CALL LETTERS OUT OF THE SNOW ON FSTV. THIS TYPE OF ATVTRANSCEIVER HAS NEVER BEEN OFFERED COMMERCIALLY. IN ADDITION THE UPDATED WR-450INCLUDES ALL THE NEW CIRCUITRY OF THE TRIDON 2000 450 TRANSCEIVER PLUS THE REGULARPOWER SUPPLY. NO OTHER COMPANY PRODUCES AN ATV TRANSCEIVER WITH ALL THESEFEATURES.

THE PRICE OF THE NEWLY DESIGNED TRIDON LINE IS THE LOWEST EVER.BE SURE TO ATTEND THE SSTV FRIDAY NIGHT GET-TOGETHER AT THE HOLIDAY INN NORTH.

(advertisement)

WIN $10000 AT DAYTON WINATVQ HOME BREW ATV CONTEST & PARTY

1st PRIZE $100!

other prizes from AEA, PLE, WYMAN7 p.m. - MIDNIGHT TRAVEL LODGE MOTEL FRIDAY NIGHT

(Next to Denny's - Across 1-75 from Holiday Inn)ROOM 202

EYEBALL QSO MEET - GREET - EAT!

FREE COFFEE, POP, SNACKS FREE

DISPLAY TABLES FOR CONTEST ENTRIES

BRING YOUR HOME BREW ATV PROJECT & SHORT WRITE-UPNOT TO EXCEED 2 TYPEWRITTEN PAGES TO ENTER


E SAVINGS,PA ERICA

aATV operations at the Pasadena Rose Parade

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FSTV-430Fast Scan Thlevision Transceiver

Advanced ElectronicAPPIlcallons, Inc

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Fastscan TV Transceiver

In the last ten years AEA has become one of thebest known names in amateur radio digital communi-cations. With our multi -mode data controllers you cansend and receive data in several digital modes fromMorse Code to Packet.

Now AEA joins another growing segment of Ama-teur Radio....Amateur Television.

The new FSTV 430 fast scan television trans-ceiver from AEA makes getting on ATV easy andinexpensive. Almost any video camera (including mostcamcorders) can be used. Plug the camera into theFSTV 430, and connect to your 70cm antenna. Use astandard television for display of received signals,and you're on the air. Of course, using an amplifier willadd range to your signal.

The AEA engineering standards of high performanceare evident in this new transceiver. The FSTV 430has a sensitive UHF GaAsfet preamp with a crystalcontrolled downconverter and IF filter (channel 3 or

4) for signal reception. The transmitter in the FSTV 430uses a VSB (Vestigial Side Band) design to mini-mize adjacent channel interference. Two frequenciescan be selected for transmission, one crystal isincluded.

Signal output is one watt p.e.p..Any amateur with a technician class (or higher)

license can join the fun of ATV. The FSTV 430 cantransmit in either black and white or color. Theportable, lightweight FSTV 430 transceiver can be usedfor in station or on the go operation. You can evenconnect your VCR for transmission of video tapes.

If you own a video camera, you should be on ama-teur television. Why not use your amateur radio andvideo skills together. The FSTV 430 makes puttingtwo hobbies together easy and fun. Contact your localAEA dealer today for more information about theFSTV 430 from AEA.

ADVANCED ELECTRONIC APPLICATIONS, INC.P.O. Box 2160

Lynnwood, Washington 98036 USA

$3.95 amateur - americanradiohistory.com · 2019-07-17 · $3.95 &ft amateur television...

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