[R-390] Gain drift

[Jacques Fortin]

Hello Dave,

Two ideas:
1_ What can be seen if you monitor the AGC line when this happens ??
Say by connecting a meter to TB102, screws 3 or 4 vs GND ?
In which AGC mode this happens ? In all or only Med and Slow ?
Have you changed C551 ??
2_ Possible self-oscillation of the RF stage....
This was a trouble in the early Collins RF decks, especially when the 6DC6
is "hot" - meaning high in transconductance.
>From the Moto '56 and up this was solved by the addition of E212, E213 and
C267 around the 6DC6.
I do not know which vintage your RF deck is, so this one is purely a shot in
the dark....

Let's us know about anything found...

73, Jacques, VE2JFE