Seems like all this work on muting the Tx to Rx pop situation may be an attempt to
treat the symptom instead of fixing the actual problem.?
This infamous BITX Click and the 20 ms Tx carrier burst is caused by charging and
discharging of C-64, C-68, C-69, C-70, C-73, and to a lesser extent other capacitors that
charge or discharge during short time periods when changing from Tx to Rx and from
Rx to Tx.? The Tx carrier burst happens when the BFO mixer diodes are held in
conduction while these capacitors discharge or charge to normal operating potential for
Tx mode.? The BITX Click on change from Tx to Rx is caused by these capacitors
charging or discharging to normal Rx operating potential when changing from Tx to Rx
mode.?
Might it be possible to move these capacitors so that they connect prior to switched
voltages for Tx and Rx modes?? While it would be difficult to make these changes on
the present BITX-40 PCB, maybe someone who is building a BITX-40 from scratch
and using ugly-construction method could make the changes and evaluate results.
Arv? K7HKL
_._
