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A simple soundcard interface for digital modes By J.B.Randall, W1ZE

If you are new to the HF bands or a seasoned veteran thinking of trying your hand at TTY, PSK, MFSK and the other digital modes you may already know you need a way to connect your PC or laptop to your HF transceiver. The device needed is called a soundcard interface and there are a lot on them in the Ham Radio marketplace with names like Signa-Link, MFJ, Little Rascal, West Mountain, etc. They are all good and will do the job. Some have a lot of bells and whistles but they all do the same thing.

As you may know I am a DIY person and like to build things. Over the past dozen years I have assembled several types on soundcard interface devices, from very simple to complex. All worked as designed and help me enjoy the digital modes. In fact I think I have put article into past Squelch Tales newsletters describing several types I have built and used. These days, I appreciate building things using the KISS (Keep It Simple Stupid) design method.

Since I own several YAESU and ICOM transceivers I wanted a simple interface that would work with both makes and most models without disrupting the rigs microphone and speaker circuits. So I went to the Internet and started to see what others had built. Most of the designs used rig keying functions from data provided by the computers serial output connection. Problem one, my PC and laptop(s) no longer provide a serial port, only USB and printer outputs. Technology marches on, I guess. If you have one of these computers and want to use an interface device that needs serial port data to do your PTT keying, you need to buy a serial to USB interface adaptor. I didn’t want to spend the money for one, so back to the Internet I went looking for more ideas.

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What I came up with was a tone keying circuit that used the data (audio) voltage from the computers audio output (or line out) to drive a keying circuit. Using that found information I bread-boarded a audio rectifier circuit using two 1N914 switching diodes to produce a small DC voltage to drive a single NPN transistor (like a 2N2222) and it in turn would take the transceivers + key-line voltage to ground keying the transceiver. The little circuit worked well.

Now to build a hard copy. With two very small 600/600-ohm audio isolation transformers, salvaged from a few junk PC soundcard boards I started to assemble the small circuit board. I highly recommend using the transformers to isolate the electrical system in the PC from the electrical and audio circuits in the transceiver to keep hum and hash out of your transmitted signal.

As you can see in the above diagram, audio signal is sampled from the secondary of the isolation transformer on the incoming PC audio/data line through a resistor and coupling capacitor feeding the rectifying diodes. After some experimenting I found out that a 1 uF electrolytic capacitor at the base input of the 2N2222 giving me about a second and a half keying hang-time, good for PSK and RTTY. If you want more hang time increase the capacitor value to 10 to 22uF. For less hang time try a .47 uF cap. I housed the entire circuit board into a 1x2x5 inch black plastic project box.

This circuit will work with most all HF transceivers. My ICOM & Yaesu rigs have a rear apron 6-pin mini-DIN data jack that can be used for digital modes. Fortunately the pin-out on the DIN jack was the same for both manufacturers. Data-in, Data-out, PTT and ground pin-out connections are the same configuration..

I salvaged a 6-pin Mini Din plug & cable off an old busted computer keyboard and wired it to the interface circuit. I can plug the interface into the ICOM or Yaesu transceivers and it functions well and no need to unplug the transceivers microphone or external speaker to do digital modes.

As a final note: Some Yaesu rigs like the FT-450D, FT-897D, FT-857D and others with the rear apron Mini-DIN data ports, also have a programmable “Digital VOX” command setting that when the rig sees audio/data on the data input circuit the Digital VOX keys up the rig, thus eliminating the need for an external audio/data keying circuit. All that is needed for these rigs is an interface assembly consisting of two small Isolation transformers a few resistors, a capacitor and a 1K

linear taper mic/data-line level pot. 73 W1ZE

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The Cordermans,W3ZD/W2ZD & K2CML Members of the MARA

Roy’s Corderman, W3ZD’s two sons followed in their father’s footsteps by becoming ham radio

operators. During WWII Roy helped develop radio and recording devices for the War Department.

Oldest brother Sidney ‘Sid’ K2CML became one of the founding engineers for McIntosh Corp, the Audio

recording, HiFi and Stereo developers. Sid now in his early 90s and until last year lived in Five Islands,

Georgetown, Maine during the summer and wintered in Scottsdale, Arizona, where he now resides full

time. The Youngest son Allan ‘Al’ now holds his father’s call of W3ZD. Al is a Naval Academy

Graduate and Navy Pilot. He went on to earn a MBA from Harvard Business School. Al was also with

RCA Communications in Palo Alto, California. Later in life he and his wife started a publishing

company here in Maine. Al now lives at the Highlands in Topsham but still attends MARA meetings and

activities when he can. Both Sid and Al are long time members of the MARA.

Above is a photo of Roy Corderman, the original W3ZD standing next to a prototype VHF transmitter with the brass tube

wave-meter. The meter is now in the possession of Bob Oxton, W1RSO. Roy was a mover and shaker in the early days of

Ham Radio and radio communications. During WWII Roy worked in the Washington Physics lab working on electronic

equipment to help in the war effort. He was given special recognition by President FDR shown in the following photo.

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Roy W3ZD at his station in Roy with son Sidney having Field Day Al operating a solar power station

the early 30s in the 30s during Field Day 2009 in Topsham

A FAMILY OF ACCOMPLISHED HAMS

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Field Day 2016, a ho-hum

event due to a blank sun

Again this year the MARA’s KS1R Field Day

team set up operations at the Topsham Red

Cross facility during Field Day weekend.

Weather was good but

the HF bands to say the

least were not

accomidating. The folks

who attended had fun

and some QSOs were

made with several folks got their first chance to

try out PSK and RTTY.

The major reason for the low QSO total was that

Old Sol had no spots, just a blank sun. Tad

Cook, K7RA who does the propagation forecasts

for the ARRL wrote:

There were no sunspots during all of

Field Day weekend.

The last time we saw a blank Sun

(before June 2016) was 2014. Just one

day, on July 17, 2014. Sunspot number

was 0, and only for one day. Prior to

that, there were just two days in

2011, on January 27,and on August 14.

Prior to that there were 51 days with

a blank Sun in 2010, with 12 periods

ranging from 1 to 13 days. The longest

periods were 11 days beginning on May

9, 2010 and 13 days beginning on April

1, 2010.

These recent periods of no sunspot

activity are a surprise to me, even

though we are in a declining half of

the solar cycle.

Rich, AB1YX & Norm, W1MKD doing PSK & RTTY

Jim McIrvin, N1IPA setting up the Sat-Comm antenna in hopes

of a contact

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ARRL’s New England Divison Director Tom Frenay,

K1KI stopped by to show League interest in the MARA’s

Field Day effort

Rich, AB1YX holds a training session on the Raspberry-Pi

and its usefulness in Ham Radio

Here is our submitted report to the ARRL:

Call Used: KS1R

GOTA Station Call: none

ARRL/RAC Section: ME Class: 1F

Participants: 26 Club/Group Name: Merrymeeting Amateur

Radio Association (MARA)

Power Source(s): Commercial, Battery, Solar

Power Multiplier: 2X

Bonus Points:

100% Emergency power 100

Media Publicity 100

Public Location 100

Public Information Table 100

Formal message to ARRL SM/SEC 100

W1AW Field Day Message 100

Formal messages handled - No.=10 100

Natural power QSOs completed 100

Site Visit by invited elected official 100

Site Visit by invited served agency official 100

Submitted via the Web 50

Educational activity 100

Total Bonus Points 1,150

Score Summary:

CW Digital Phone Total

Total QSOs 5 40 8

Total Points 10 80 8 98 Claimed Score = 196

Submitted by:

Donald Wakeman, KA1WAL

Comments:

(blank)

Band/Mode QSO Breakdown:

CW Digital Phone

QSOs Pwr(W) QSOs Pwr(W) QSOs Pwr(W)

160m

80m

40m 5 100 7 50 5 100

20m 33 50 3 100

15m

10m

6m

2m

1.25

Other

Satellite

GOTA

TOTAL 5 40 8

As you can see by the above QSO tally the bands

did not cooperate for our 1F effort. But all in all,

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those that came out to the KS1R Field Day had

fun and maybe learned something too.

DXWATCH a useful

tool in the shack

By W1ZE

Chasing DX , looking for that new grid on six

meters or a VHF/UHF weak signal station is a lot

of fun and every little advantage helps land a

good contact. To this end I rely heavily on the

Internet based DX spotting services. The one I

use the most is a direct connection to one of the

various Telnet DX spotting nodes. Check out

http://www.ng3k.com/misc/cluster.html for more

info on the Telnet system. With Telnet you have

to make your PC or laptop emulate a dumb

terminal using a free program such as PuTTY.

The spotting service works well and is fast and

interactive.

The other day the Telnet spotting system went

down for hours while I was looking for six meter

spots out of Europe. Bummer Dude! I quick

went on a Google search for DX spotting sites

and came across a free access site called

DXWATCH at http://www.dxwatch.com/ so I

logged onto the site and set up an account.

It appeared to have the same spotting listings as

the Telnet system and I think maybe it is getting

its feed from the worldwide DX spotting Telnet

system. The graphics are good and easy to read.

It is also interactive and you can post spots and

set your own spotting filters. It is not as fast as

the direct Telnet system which has instant input

postings. DXWATCH updates new postings

about every 60 seconds but I can live with that,

plus I don’t have to use a dumb terminal

program to access it. Another thing it does do,

when you put your curser on the spotted call sign

the DX stations data appears on the screen like

country, zone, etc. a nice added feature.

Try it, you may like it, and it is FREE.

JULY 2016, A GOOD MONTH

FOR SIX METERS

The first part of July found some increased

sporadic-E and enhanced F layer DX activity on

the old six meter band. Even those of us up here

in Maine were experiencing some good band

openings across the pond into Europe, North

Africa with an occasional signal out of the near

east (i.e., Israel & Jorden). In addition there was

some double hop propagation to the west with

stations from the Pacific northwest making it out

to the northeast. Mid month evening openings

would last into the late hours with midwest and

Rocky Mountain region stations pounding into

Maine and Atlantic Canada.

The evening of the July 13th had wall to wall

signals throughout the SSB portion of the band

and a lot of CW activity between 50.075 and

50.105 MHz. Stations with high power and big

beams as would be expected were easy to work

but even stations running 100 watts or less into

dipoles and halos could be worked with ease.

If you have not tried your hand at six meter SSB

and/or CW, string up a dipole (9 ¼ feet long) and

give the band a try. You may enjoy it.

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BOXBORO By Bob DeMattia, K1IW

Boxboro! is less than two months away, so our

event planning is in full swing. We are close to

publishing our forum schedule - look for another

announcement in a few weeks.

In the meantime, take a look at our Friday and

Saturday evening programs. At our Friday

DXCC/Contesting dinner, David Collingham,

K3LP, will brief us on the recently completed

VP8S DXepdition. On Saturday, noted radio

historian Donna Halper will treat us to "Heroes

of Amateur Radio: Past, Present, and Future".

Visit our website for more info. While you are

there, you can sign up a friend for a license class

or VE Exam. You can also reserve yourself

an operating slot at our W1A special event

station.

We still have opportunities for those that would

like to volunteer a few hours of them time at the

convention. Volunteers will receive a voucher

for a free lunch.

Finally, we've published a "Guide to Quick

Entry" on our website to learn how to avoid

those entry lines.

Visit our website today to find more and

purchase tickets!

http://www.boxboro.org

73,

Bob DeMattia

Chairman, Boxboro Convention 2016 Committee

P.S. Even if you've already ordered tickets, please

be sure to check our website for program updates.

ARE YOU UP TO DATE?

If you can not remember the last time you

plunked down $10 for your MARA yearly

membership, most likely you need to get in touch

with Marjorie Turner, KX1I kxxx1i@gmail.com

and bring your membership up to date.

If you are not a member and would like to

become a member of the Merrymeeting Amateur

Radio Association (MARA) you can get all the

membership information needed from the

Association’s website at www.ks1r.org. We

would love to have you join us.

Rockwell Collins to

End Mechanical Filter

Production

As more and more communications equipment

designs have adopted digital signal processing

techniques, Rockwell Collins has announced that

it will stop manufacturing its renowned

mechanical filters. It did not provide a specific

date.

“Over the past several years, we have seen a

dramatic reduction in demand for narrowband

analog filters,” the company said on its website.

“Due to this and other economic reasons,

[Rockwell Collins] Filter Products will be

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discontinuing its mechanical filter products in

the near

future.”

Rockwell Collins makes two different types of

mechanical filters, many of which have found

their way into Amateur Radio products and

applications. In a mechanical filter, input and

output transducers convert the electrical signal

to and from resonant mechanical vibrations,

respectively.

“For frequencies between 100 kHz and 700 kHz,

we create filters made from rods resonating in a

torsion mode,” the company explained on its

website. “For frequencies below 100 kHz, we use

flexure code bar resonators.”

Collins has made mechanical filters for more han

6 decades, and their initial application was in

telephone circuits. The filters gained favor for

Amateur Radio use because of their excellent

selectivity, especially in IF applications. It is said

to take about 12 weeks to manufacture a single

unit.

Art Collins, W0CXX (SK), founded Collins

Radio Company in 1933 in Cedar Rapids, Iowa.

That same year Collins supplied the equipment

to establish communication with the Byrd South

Pole expedition. Over the years, Collins

produced a line of Amateur Radio equipment,

and its products remain popular among radio

amateurs and collectors. Rockwell International

purchased the company in 1973, and Rockwell

Collins was spun off in 2001. Today, the

company has focused its market on electronic

communications, avionics, and in-flight

entertainment systems.

Thanks to Mike Morris, WA6ILQ;

Rockwell Collins