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Number 7 on your Feedback e.rd Build Your Own 20 Meter Transceiver Work the world with this easy-to-build rig. by Gordon Young WB6NKJ T his project is perfect for the low-power enthusiast who wants full break-i n (QSK), sidetone and diode antenna switching features. The parts for this project are common and even a first-time builder should have little or no trouble assembling a complete transceiver. You will be surprised at the results and happy with the simple features this rig provides. I have already logged many stations and have put on many hours of use, talking across the states and around the world with just a few watts. An advanced builder may consider adding RIT, audio filtering, a frequency counter, a drive control, or other features. The power output will easily drive a pair of high-power transistors to a level greater than 100 watts, but alone it is enough power to work almost any station you can receive. .,. ," ---- - • - •• " "- - "-- 't. - - -. • • - I • • •• • - - -- -- If::. • -- • • • ~ Figure J. Transceiver block diagram. _. - With some tinkering. you can bri ng the MRF-433 transistor to its full tz-wan capability. I am always surprised at the performance of simple direct-conversion rigs. and this one is no exception. The circuit is simple. construction is easy, and normal operation is a pleasure considering that rhe transceiver is so simple. I' ve worked all states before with j ust 5 watts; this rig should do the same for you. The Circuit Figure I shows the block diagram of the transceiver and it is readily apparent that it contains the basics: a signal input, a detector. VFO. audio amplifier and RF PA. This started as only a weekend project, but I wanted to make sure that it had some ofthe nice features Igrew to depend on. such as a sidetone, diode antenna switching, and audio output to drive a speaker (headphones begin to get uncomfortable after hours of operation on Field Day). The other annoying aspect of fu ll QSK is the " thumping" you normally get switching from transmit to receive. The cause of this is the DC dumping of the audio stage. To help overcome this problem I used a simple transistor switch betweenthe detector and AF preamp. This switch doesn't really tackle the mismatchofimpedances at this point; an FET would be better. Another objective was that the power amplifier have enough guts to drive a linear stage 10 later follow rhe transceiver project. Ifyou have a pair of 8O-watt devices. they will require at least 5 watts ofdrive. and pushing the MRF4 33 to 12 watts would mean that an attenuator would likely be needed somewhere in between. The outcome ofthe entire effo rt is shown in the figures. In my prototype, each part ofthe rig was originally air-wired on plates of PCB board. However.etched and drilled are available to case your construction efforts (see the Parts LiM). Starting with the receiver PCB. the frontend bandpass fi lter helps a 101 to reduce the foreign broadcast interference that would overpower receivers such as this. To make up for the few dB lost in the filter and to add ........... w.o:;!'; ~.. • PhOIO A. The completed WB6NKJ transceiver. 26 73Amateur Radio Today . June, 1992 Photo B. Inside view ofthe transceiver.
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Page 1 and 2: JUNE 1992 ISSUE #381 USA $2.95 CAN
Page 3 and 4: ONG LE~ Greatly I Is" AMlSSB Signal
Page 5 and 6: THETEAM PUBLISHERIEDITOR Wayne Gree
Page 7: their PC to discover the "ell' visu
Page 10 and 11: LETTERS Dave KD8VI, Lakewood OH I j
Page 12 and 13: Number 4 onyourFeedbeclI CIII'd 8,0
Page 14 and 15: inary address is input to the devic
Page 16 and 17: make it easier to remove, you can m
Page 18 and 19: !'Unbet' 5 on yovr FeedbKk card VE3
Page 20 and 21: Figure 2. The wire beam for /5 and
Page 22 and 23: Number . on r- F..ll'Mc~ ~ Touch-To
Page 24 and 25: Pin 17 is the GT (guard time) contr
Page 26 and 27: output and charged up C I). If the
Page 30 and 31: •• ,. ,.,..,. " " .. :.~'" ,.-
Page 32 and 33: help reduce the " thump" problem. F
Page 34 and 35: You may elect to tinker with the in
Page 36 and 37: VE3CYC's Wire Beam Colltitlued/rom
Page 38 and 39: G S.',"m,,, ,.. ,""", , " Ol 'us,
Page 40 and 41: . ICOM'" R7000 SWEEl'lNG : 1300 CHA
Page 42 and 43: 73 Review by Bill Brown WB8ELK Numb
Page 44 and 45: 73 Review by Mike Baker WSCM The He
Page 46 and 47: planned to use. This top shelf is n
Page 48 and 49: HAMSATS Number 10 on your Feedback
Page 50 and 51: y Bill Clarke WA4BLC ELNEC Version
Page 52 and 53: _ «r • .,. .. "" lIea. .....- I"
Page 54 and 55: SANELLI TECHNOLOGY Sanelli Technolo
Page 56 and 57: Arv Number 13 on your Feedback card
Page 58 and 59: .. . - ' .,. "" . ', , -------,-"-
Page 60 and 61: SPECIAL EVENT;,m..",,"",,,..db,,k,,
Page 62 and 63: VE eeeme. Vendors need to reserve s
Page 64 and 65: QRP Number 16 on your Feedback card
Page 66 and 67: ABOVE & BE"YOND~F-- k ~" C. L Hough
Page 68 and 69: 73 INTERNATIONAL Numbet 19 011 y(U'
Page 70 and 71: TALK WITH THE KNOWLEDGEABLE PEOPLE
Page 72 and 73: ASKKABOOM MichaelJ. Geier KBfUM do
Page 74 and 75: Natural Voice Playback Board Datavu
Page 76 and 77: Joe Moel/, PE., KOOV PO. Box 2508 F
Page 78 and 79:
NEVER SAY DIE Continu8(/ from page
Page 80 and 81:
RTTY LOOP Marc I. Leavey, M.D., WAJ
Page 82 and 83:
Carole Perry WB2MGP Madia Mentors.
Page 84 and 85:
BARTER Tum your old ham and compeer
Page 86 and 87:
PROPAGATiiiN'''....''''~ FCC Enforc
Page 88 and 89:
WNlOI Ellel'Yday Electronics Dl tl
Page 90 and 91:
YAESU FT-1000 FT-912R FT·747GX FT
Page 92:
• 100 Watts on all nine Amateur b
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