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Simple QPR TX for the 40 meters

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ANTENTOP- 01- 2005, # 007  

Simple QPR TX for the 40 meters





Credit Line:

 “U- QRP- C. Reference Book- #3”  1991 year.



At QRP rubric at Antentop 01- 2005 I use stuff from old Soviet QRP magazine published by the U- QRP- C at 1991. It was named  “U- QRP- C. Reference Book- #3,”  you can see its cover at the right. The schematics, which were published there, are very interesting till now.


The simple QRP TX used two FETs was published at   “U- QRP- C. Reference Book- #3,”  page 4. I have done the TX, it worked pretty well! I have tried it in several ways. Pair low power FETs (300 MHz, 300 mWt) did very good job, near 200- 300 mWts output without problem. I put in parallel up to 5 the same transistors (instead output transistor), it gives near 1 watts, the transistors were without a heat sink. Of course, goog results were obtained at first FET (300 mWt, 300 MHz), second MOS, 300 MHz, 3 watts. I have near 2 watts at 24 Volts.


If instead C2  you use a variable capacitor, you can use quartz for 3500 or 1750 kHz. Of course, the transmitter works good at another bands, for 30, 20, 15 and 10 meters, however, the power is dropped. At 80 and 160 meters the TX has good power and clean tone. I did experiments with the TX and RF- generator, I removed the quartz, and put output of the generator to clips ‘VFO.’ So, I have got very nice small TX, that worked very good.


Data: L1= L2: diameter 30 mm, winding length 35 55, 15 turns, L2 tap from middle, L3 3 turns above center L2.

I strongly recommend you try the simple TX.

73/72! I. G.


First page of the

“U- QRP- C. Reference Book- #3’


Figures of the TX  are reproduced from  “U- QRP- C. Reference Book- #3.’

Page 64





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August 3, 2016 16:48

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