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Simon,

This hack does not address the sound in the BITX40 speaker. This is entirely a different issue.

In my unit the power meter would deflect to more than 500mW when the PTT is pressed. IF I listened to my commercial RX I could hear a
"clonk/tong" sound. After the mod the meter barely moves.

What I am trying to do is not allow the C122 to charge via the diode. C122 BLOCKS the DC from getting to the diode but the cap charge current goes through to the diode when PTT is pressed. You need to put a 1K resistor parallel to C107 to route this current to ground.

If the mic amp had 2 stages and if the second stage is always powered on then there will be no problem.

AFAIK in a 4 diode mixer this wont happen as there are two diodes that will conduct and cancel any carrier leak in the trifilar transformer.

The amp pop would have not been there if it was left powered on but the audio was muted in a stage before it. Farhan has kept BITX40
as simple as possible. We can make it more elaborate in design if we wish.

If the audio pop is to be removed then keep the amp powered on and use a 2n7000 across the volume control and mute it on TX.