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Sunday, July 7, 2019

The Fish Soup 7 QRP Rig -- On the Air on 40 Meters (video)

I don't know why, but this weekend I got the urge to get on the air with a very low power homebrew QRP rig.   I reached for my Tuna Tin 2 -- Herring Aid 5 combo.  I call it the Fish Soup 7 (seven transistors in total). 

I first tried to turn this rig into a transceiver by taking the VFO signal from the receiver (it is direct conversion) and using it to excite the Tuna Tin 2, but it just didn't work out.  The oscillator in the Herring Air 5 is very bare bones -- no buffering and an LC circuit that is mostly L (10 uH).  It became very difficult to get a stable amount of CW offset.  So I went back to crystal control for the transmitter.  I did replace the 5K tuning pot in the RX with a 10k 10 turn pot (thanks to W8NSA).  Tuning is now very smooth.  I used my old UK freq counter to monitor my receive freq. (Thanks to Tony Fishpool G4WIF-- back in 2009 he sent me the CMOS chip that brought this counter back to life.) 

I was putting out about 750 milliwatts.  

I had a very quick contest-like contact with K2D -- one of the "13 Colony" stations.  Then a longer chat with Hank K1PUG (see video above).  

I had lost my 7050 crystal, but this morning it re-appeared.  TRGHS. 

As you can see in the video I am using the beautiful VU3XVR  key that Farhan brought me from India. 

This was fun.   I may try to put a VFO of some sort into the TT2, just to get more agility.  But I want to keep things simple.  

Look for me on 7050.  


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  2. Now that is how its done!! Manual T/R switch and all!!
    Love it!


  3. Bravo Bill!! Way to go!! 750 milliwatts, and no amp, WOW!!!

    Ed KC8SBV


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