Re: Bitx V6 Modifications
There is an RC combination (0.01 uf and 1.8 K) that you solder between pins 5 and 8 of the LM386. It was listed as a BITX40 mod (that was the last HF Signals produced rig that used the LM386 until the v5 and then v6). I tried the mod on my v5, and it did reduce the high-frequency noise. Sounds much better without a signal present. Reduces some need for the AGC, though still would add it.
https://groups.io/g/BITX20/message/51572 was the starting point that lead me to the Norcal 40a http://www.n5dux.com/ham/files/pdf/NorCal%2040A%20Transceiver%20-%20Manual.pdf where I got the pin 5 to 8 connection. There is a capacitor between 1 and 8 in the Norcal 40a the same as in the v5 and v6 audio amp stage.
Ignore the comment that it would not work on the uBiTx, that was before HF Signals went back to the LM386 as the audio output amp.