Erhard Haertel DF3FY comments, “There are a lot of proposals for addressing the RX-TX audio pop with the uBITX, but none of them really works”.
Erhard has come up with his own pop-fix that involves muting the TDA amplifier during TX, turning the IC on with the 12V RX line (to prevent SSB noise in headphones during transmit) and additional decoupling for the 12V line.
Erhard says, “This fix cures all the issues”. Write and tell us if you have tried this fix.
Erhard.
if I see correctly in CW transmit you are driving the speaker
(8 to 16 ohms) through a series of resistors that total 13K.
Can you still hear the sidetone with that 1625 to 1 divider?