Re: Spurious RF at beginning of CW transmission in the uBitx

Arv Evans


Interesting.  Maybe that indicates that the solution by Allison is still best...?
Actively pulling the RX power line to ground when switching to transmit mode
seems productive.  Could solve the receive Click problem but may need something
similar for the TX power line to stop the 20 ms RF burst at beginning of transmission. 

Thanks for the attempt. 


On Tue, Jul 31, 2018 at 1:14 PM <n1kw@...> wrote:

I tried my earlier suggestion about putting a diode in series with R66 and it causes another problem. The energy stored in C64 keeps the mic amplifier running for about a half a second after releasing PTT, feeding mic audio into the audio output stages resulting in feedback and a nice squeal in the audio output! Maybe all (or half) of N3GO's solution would be better, at least for clamping the TX line. 

Bob N1KW

Join to automatically receive all group messages.