Hi All!
I am in the process of rebuilding a Central Electronics 20A and seem to
have an undocumented modification. As far as I can tell all of the mods
noted in the BAMA site are installed and complete. There are however two 5
amp diodes in series with the anode end grounded and the cathode tied to pin
1 of the 6AL5. The junction of the two diodes is connected thru a 33pf cap
to the junction of C42 & R77. None of this makes sense because the #1
cathode (pin 1) of the 6AL5 is only normally at -.5 volts and couldn't
provide enough voltage to forward bias the diodes. The junction of C42 & R77
is at -100 volts in stand-by and ground for transmit. Since the undocumented
33pf cap is polarized with the cathode end at the C42-R77 junction, I
suppose it could charge up to the -100 volts and serve some sort of spike
suppression when switched to transmit.

Anyone familure with this mod? Can you explain it?

Thanks
K3PID Ron H.