Audio pop on CW

K4LXY
 

I think I solved the audio pop problem on CW based on the VE1BWV muting circuit (see uBitx.net)

Earlier I tried this muting circuit, which mutes the audio during transmit, but it also muted the sidetone.

The solution was to use his muting circuit but insert the sidetone on the top side of the volume control, after the muting circuit, instead of earlier in the audio circuit as it was originally.
 
The idea was suggested earlier by Philip as part of his AGC solution (though he incorrectly identified the resistor involved as R235 rather than R253).
 
Here is what I did
Removed R253.
To the end of R235 that was also connected to C252, I added in series a 1K resistor and .1 microfarad capacitor, then going to the yellow wire on the volume control (top).
 
There are two things about my setup that make it different than Philip’s but it should work as suggested above.
 
1) I have a Hi-Per-Mite SCAF after the volume control, and it may provide some amplification.
 
2) Earlier I had replaced R250 with a variable resistor so that I could control the sidetone volume, so I have the option of fine-tuning sidetone volume.
 
73 Howard K4LXY

Join BITX20@groups.io to automatically receive all group messages.