Since I have been doing a few tweaks on my BITX40 lately, I have started wondering about using a difference scheme for?
injecting CW sidetone to prevent the "sidetone surging" issue that is inherent with the current scheme of sidetone injection at the?
speaker.? I did previously try injecting it before that LM386 audio amp, that was before I realized that the supply voltage to the LM386
gets yanked on TX, making all but the first bit of the sidetone inaudible.?
What I am wondering is whether anyone has tried leaving the LM386 powered all of the time? This would make earlier injection of sidetone
practical and I suspect it would do wonders for the remaining minor thump that I am seeing on the transition from TX -> RX (I am using one of the
anti-thump mods that grounds the input to the audio amp on TX)).? It seems to me that providing a permanent supply voltage to pin 6 of the LM386
could easily be accomplished by tombstoning? ?R111 and feeding the top end of it with 12V. Has anyone tried this ??
Michael VE3WMB?
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