n oo

The Uniden HR-251010 Meter SSB/CW/FM Transceiver

BY DAVE INGRAM", K4TWJ

Uniden's new HR-25 70 is a compact, all-mode 10 meter transceiver with a sensitivereceiver and 25 walt output transmitter.

""hat's this? A new 10 meter trans­ceiver that actually fits in tcdey's com­pact cars and sports an attractive pricetag to boot? Sure enough, and Unroen'snew HR-2510 is sure 10 capture thehearts and interest of 10 meter devoteeseverywhere . It is a genuine fun rig youcan mount in a ca r with its supplied brack­et. slide into an open corner at home, orslip into a small tote bag for traveling.

This 25 wall output transceiver covers28.000 10 29 .700 MHz witn 5SB. CW, AM ,and FM operations; built-in SWA bridge;semi-break-in CW: RIl ; noise bla nker ;and more. The receiver 's sensitivity of.25 uV is Quite adequate, and w hen 10 isopen as it has been recently .25 watts canwork plenty of Ox. In fact. my first week'sworth 01 050s while using the HR-2510was all OX! With sunspots increasingeve ry day , a lillie rig like the HR-251 0 isloads of fun.

I'm sure that many amateurs will re­cognize Unlden's name from their popu­lar Bearcat scanners , cellular tele­phones, and other electronic items. TheHR-2510 is their first serious entry intothe amateu r radio field. I would say theywill watch us prog ress as a measure ofconsideration in producing additionalamateur radio gear .

General OverviewThe compact HR-251 0 is enclosed in a

black and dark gray cabinet measuring2i?" H x 7Y." W x 11"0, and weighsroughly 4 POUnds . The front LCD readoutis amber color , with selectable bright ordim baCklighting. Its left side includesbar-graph metering, and the right side in­dicates frequencies, A stout internalspeaker is mounted on the bottom, and ahealthy heat sink on the rear is flanked byconnectors for antenna . power , and ac­cessor ies. Rather than using regular ~

inch phone jacks , Uniden's 2510 has onenine-pin Molex socket for connecting akey, external speaker , and aulo PAspeaker .Switching from internal toexter­nat speaker and/or connecting a key thus

' Eestwooa Vii/age No. 1201 So. , Rt. 11,Box 499, Birmingham, AL 35210

20 • CO • February 1989

involves replacing one " accessory" plugwith another (supplied) plug wired to yourspeaker and/or key.

The transceive r draws less than 1 ampof current during receive and only 4 to 5amps during transmit. Those low-powerconsumption ligures are appealing inseveral respects. You can enjoy somefairly long mobile operating stints whileparked in a shopping-mall lot, for exam­ple, wtthouttotauy draining a car's batte­ry. An inexpensive and low-current ACsupply also mates perfectly with the rigfor home or portable use.

The receiver 's overall sensitivity, se­lectivity, and audio quality strike me assu rprisingly good, especially conside ringits low cost. Its "S" meter is a bit on thestingy side , but that's not serious-onlytruthful , The AIT control covers roughly a6 kHz span, which is perfect. but newamateurs must remember to center-posi­tion the control for receiving and t rans­mitting on the same frequency . An RIT

" off" switch is not included I suggestplacing a small drop 01 red fingernail pol­Ishcn that knob's pointe r as a " mental re­minder." Addit ional HR-2510 detai ls andspecifications are shown in Table I-

Amateurs interested in self-containedportable operations can put togethersome clever systems using the HR-2510.Visualize, for example . home-fabricatinga slip-i n metal bracket for holding thetransceiver and a 5 amp rechargeableVCA-type battery , Add a carrying handleand Whip or ducky antenna plus a mikeclip, and you have a " midsize handheld"that will literally work the world. Imag ineusing that setup on a mountaintop orw hile relax ing ona warm southern beach.Now that's living!

We also understand KA8PGJ in Daytoninterconnected his HA-2510 and 2 metertransceiver for remote base operation on10 meter FM, A simple one-transistor in­terlace was used between each unit'ssquelch-voltage terminal and a basic

Say You Saw It In CO

Tab/e 1- Technical specifications of the Uniden HR-2510.

COR circuit. By now he has probablyworked all continents on a handheld .

A Front Panel TourA convenient means of familiarization

w ith any new transceiver involves trek­king through its front-panel controls andthe ir operation in a step-by-step manner.Using that technique, let's start at the2510's left top area and proceed to theright bOttom while pausing for a few de­scriptions along the way .

Fi rst, several " behind the panel" as­pects a re noteworthy in the transceiver 'smode swi tch. CW operations , for exam­ple, include a built-in sidetone that trackswith the rig 's volume control. Its semi­break-in operation is quite smooth (noclatt ering relays at all!), and the presetdelay time returns to receive mode aftert second of "key-up." If desired, the front" TX" button can override that functionfor manual T/R switching .

A group of nine pushbuttons is mountedon the front panel 's left side . One buttonsteps through the meter 's functions forselechng RF output. modulation, SWR,and ca libration modes. An adjacent frontcontrol is used in conjunct ion w ith theSWR function for calibrating and measur­ing SWR in the usual manner , Anotherpushbutton adjusts the rmcropnonegain-press it in for low or release it lorhigh. Tha t may initially seem a bit com­promising , but it is actually quite conveni­ent. Another interesting featu re is Ihe25 10's " Beep" button. When pressed, abrief lone is added at the end of each SSBtransm ission. You 've probably not icedmany operators using that toning methodduring contests. II's becoming quite pop­ular, and it maybe a real boon for Novices.

Frequency coverage is divided intofour band segments which are step-se­lected by the 2510's "band" pushbutton(see Table I for frequency ranges). Themain tun ing knob is also lightly detentedlor easy and positive mobile use, It thushas the " feel" of a 2 meter FM rig rathe rthan "free Wheel ing ." Three tuning ratesare step-selected via a front butlon-lOkHz. 1 kHz , and 100Hz. A small cursorappears under that selected digit in thetr ansceiver 's LCD readout. I found the 1kHz speed ideal for general band tuningand operating, and switched to the 100Hz speed only for f ine-tuning DX stat ions.I sncoe also mention the 2510's front" memo ry channel" buttons and mikeup/down switches likewise operate onlyin 10 kHz steps- not too good for SSB,but pe rfect for fast OSYs and operating10 meter FM . The international callingfrequency on 10 FM is 29.600 MHz, withother channels "stacking" up the band to29.700 MHz in 10 kHz increments . Popu­lar repeater outputs are every 20 kHz(29.620 , 640, 660, etc.). Their inputs areusually - 100 kHz (29 .520, 29.540,29,560, etc .). Transmit offsets are not in-

22 • CO • February 1989

GelleralFrequency Range

Microphone

SpeakerOperaling ModesDisplayDisplay Items

SizeWeight

TransmitterFrequency Stability

Output Power

Spurious Harmonic EmissionsCarrier SuppressionUnwanted Sideband SuppressionPower Consumption(No Modulation, PIT Depressed)

(Max Modulalion)Microphone InputCWKey VoltagelCunent

ReceiverSensiuvny for 10 dB SIN

SensitiVity for 20 ee SINAdlacent Channel SelectivityMax Audio OutputRF Gain RangeRll Range 1"S" Meter Sensillvify at S9Image Rejection RailaPower Consumption, No SignalPower Consumption, Max Audro

eluded in the 2510, so some fast buttonpresses fill the void . It works. I keyed sev­eral repeaters and then switched to theiroutput and heard my squelch tail. Honest!

Both RF and AF gain controls are in­c luded on the 2510's front panel. so re­ducing sensitivity when nearby stationsare exceptionally strong is a snap. Theunit's squelch also works on all modes.so you can leave the rig qu ietly monitor­ing for band opening and be pleasantlyalerted when DX conditions are good,The rig 's noise blanker is pushbutton-se­lectable and not level-adjustable, but itworks like a champ. Uniden really "hastheir act together" on that feature. It evenreduces power-line noises !

Wh ile the 2510 has an impressive­looking front panel with 20 controls, itsuse of muted colors is very beneficial formobile installations. Flashy rigs catchevil eyes. The 2510 blends with the dashin many modern cars, and it's smallenough to fit into those open tray areas inmany center consoles.

Band A-28.DOOO-284999 MHzBand B-28.5000-289999 MHzBandC-29.0000-294999 MHzBand 0-29.5000-296999 MHz500 ohms Dynamic, wlPIT and Channel

up and down8 ohms, 3WCWo USB, LSB. AM, FMBacklit LCDFrequency, Channel -, Meter, MeIer Mode

TX, Band, VFQ Span732-)( 103S"')( 2.44-410s30z

x 300 HZ Nominal, (aI2S"C. Sminutesatter power on)

CW 2S W NominalUSBILSB 2S W PEP NominalAMIFM 10W Nominal- SOdB Nominal, all modes- S5dB Nominal, USBILSB Modes- 45 dB Nominal, USBILSB ModesAMIFM 3 A Nomina!USBILSB 0 8 A NominalCWSA Nomina! (Key Down)AMIFMIUSBILSBI3 A Nominal1mVNominal for SO% AM Modulation8VOC,10mA

AM SI'V NominalCWIUSBfLSB 2S,.V Nom na tFM 5,.V Nommal70 dB Nominal (10kHZ Spacmg)4WNominaiSSdBNom nal:!: 3 kHz Nominall00".V Nommal6S dB Nominal500 mA Nominal1000 mA Nominal

CirCUitry OverviewBriefly studying any transceiver's

block diagram always reveals its innerbeauty, so ret's take a closer look insidethe HR-251 O. First, I will point out that f ig .1's diagram is Slightly simplif ied for dis­c ussion. The original filled two largepages. There is a substant ial amount ofcircuitry in th is littl e rig. Let's beg in withthe receive path .

An incoming signal from the antennamoves through the $WR detector and thelow-pass filter , and then " taps off ' andgoes up to the RF amplifier (a 2SC1647Ltransistor is used). It moves through the10 meter bandpass filter to the receivemixer. where it is oownconverted to10,69 MHz. Notice the noise blanker 'samplifier . detector , ALC. and gatingswitch above the IF filter section-im­pressive for a low-cost rig. The signalcontinues through the bandpass filter tothe IF amplifier (notice "takeoff' lor theAGC section), then continues to the AMor SSB detector. Finally, the detected sig-

Say You Saw It In CO

NB Ale

"' ''" F~

PLl

RX .... F''''' F FN F

""'''TF0.-

To IF.......,.

SSBDetf. n1AF Ampjl-l.J

lPF ,T-RS...

F'"Amp

Coo.. ,... ,

Votage AX RegReg.8V

')(Ale

Fig. 1- Simplified block diagram of the Uniden/Presidenr HR- 25 10. Light lines are rec eive paths, while dark lines are transmitpaths. See discussion in text .

Please MII(J all , eede r ,nQutroes a're<:l ly .

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nal moves through the AF amplifier andpower amplifier to the speaker.

The 251 D's transmit path begins at themicrophone, goes through the mike am­plifier , to the balance modulator , andthrough the bandpass filler. It then con­tinues "down" to the transmit mixer.through the bandpass filter and TX driv­ers , then to the final (a hefty MRF477transistor) through the low-pass filter,and to the ante nna. Notice the TX ALCsec tion " tapping off" the RF output and"going back " to the mike amp. This de­sign improves the average SSB output toincrease " talk power." The PlL syntne-

stzer block below the AX mixer containsthe HR-251 0 's microprocessor control ," divide by N," PLL. and digital rotary en­coder (main dial) sections. The rig's 50preprogrammed memories are stored inthe microprocessor and accessed by themike's up/down buttons. Each memory isspaced and fixed in 10 kHz steps (exam­pfe:28.500 = 1,28.510 = 2,etc,)Anyse­lecteo memory ca n be tuned (but not re­programmed)10 a desi red frequency (like28.503) with the main tuning knob.

Several of the HR-2510's transistortypes seem more "CB-oriented" than"KenYaeCom popular." However . I con-

steer that a natural design concept forthis 28 MHz rig. Ma ny of today's CB setsare impressive performers. Shaping fac­tor details on the bandpass filter were notavailable , but its on-the-air performanceis very good.

On-The-AirAlthough the Uniden 2510 is a 25 watt

output transceive r. it makes an impres­sive account of itself on the ai r. Indeed,my fi rst few days' contacts were allDX-even while mobile ! I started offworking northern Europeans on SSB, andthen switched to FM on 29.600 and con­tacted several southern Europeans. Fiveof the world's six continents were alsoheard and worked on CWoI even ran ast ring of JAs from my car parked in thedriveway. I used the HR-2510 duringthe 1988 CO DX contest and honestlycould not believe the super results . I evenworked a good bit of " rare DX" (and acouple of new countries) right throughpileups. What a blast ! Ten was flourish­ing with good equ inox-type exci tementand everyone was having a bal l. If youhave not been on 10 meters recently or ifyou are a new Novice hesitan t about op­erating HF bands, now's the time for ac­tion! Cycle 22 is doing great. and the nextfew years should be even better !

The 2510's selectable tuning ratestake some getting accustomed to, butthey are a snap to use afterwards. Onebutton press changes from "coarse" or 1kHz steps to "fine" 100 Hz steps. Twobutton pushes are then used to " jump

February 1969 • CO • 23

ConclusionAll aspects considered. Uniden has

done a good job on production of theHR-251 0.The t ranscelver is a neat t ravel­ing companion with an attractive pricetag rather than a lot of tr ttls. Combine itwith a mobile whip on the car and a shortwire antenna like Radio Works' new "int ree vertical" for portable use, and youare set for fun almost anywhere andanytime. For mo re information contactPresident, Amateu r Radio Division, 4700Amon Carter Blvd.. Fort Worth,TX 76155(telephone 317-842-2483). m.I

over" 10 kHz tuning and returning to 1kHz steps. The dial's cursor indicatesyour choice of steps to make selectioneasy and obvious.

Some of the 2510's favorable points areits good noise blanker, all-mode squelch,and SWR metering. These featu res areperfect for a "go anywhere" transceiver .It's easy to use, but I suggest new (Nov­ice-enchanced) amateurs ask an old­timer for some guidance in initial setup.Listen to your transmitted SSB siena! onanother transceiver and determine thebest speaking level for your voice. Checkto assure you are t ransmill ing and receiv­ing on the same frequency, and then notethat proper RII setting with red fingernailpolish. It makes a good "reminder" whenband action is hig h and you change theRIT setting, and forget to return it to cen­ter. If an old-timer is not available, con­tact an "aged" amateur on-the-air andask for honest-opinion assistance on howyour aud io sounds and its frequency.Amateurs are a friendly and helpfulgroup. After those getting-started steps,listen to others until you feel confident(anxious?) , and then get cracking onsome fun DXing . It's great!

A couple of the 2510's less favorablepoints also warrant mention. Firat. its ac­cessory plug with prest ripped wires foran external key and speaker should beconnected and/or cove red with tape toavoid accidental shorts (the wires are af­fixed to the 2510's accessory plug). Sec­ond, there is no speech processor or pro­visions for keying an external linearamplifier . The rig "gets out" fine withoutspeech processing, and problems of"overcornpression" are avoided. Youcan also rig your own mike-energizedswitching for a big amplifier, if desired.

As designed, however, the 2510 as­sures new amateurs/Novices make fewunnecessary mistakes-a very impor­tant consideration for first-time success.It is a clever approach to getting on the airand having fun . The 2510 is also an idealsecond rig for old-time amateurs. Youcan use it in the den or car wi th few reser­vations or problems. Uniden has a goodreputation for quality electronic equip­ment, and the 2510 is backed with a one­year limited warranty.

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