[Heathkit] SB-104 agc problem

[Ulrich Graf]

Hi to the list,

the last weeks I was involved in the upgrade of an SB-104 to the SB-104A
version. After integration of most of the mods I detected a strange effect:
Every time I release the PTT on the mic, the receiver agc gets some sort of
pulse, the s-meter pegs to maximum and the receiver is blocked, at least as
long as the slow time constant determins. It is no rf pulse, I can shortcut
the rx input or the if input without effect. It is no effect of the relay
voltage or the relay action - even without swithing of the transmit/receive
relay the effect remains. Meanwhile I'm running out of ideas about this
strange functionality. Anybody any ideas?

vy 73, Uli, DK4SX