[R-390] IF Gain Problem

[n4buq at knology.net]

I'm having some "strange?" problems with the IF gain in my R390A.  If I 
crank it too far CCW (towards max gain) the radio will suddenly go silent 
and the diode load reading will spike.  In order to get the radio to play 
again, I have to turn the control to about 1/2 position and then increase 
it back to a more normal setting.

Any ideas what's causing this?  It occurrs whether in MGC or AGC mode and 
can be triggered by a strong signal on the antenna input or switching the 
bandwith position.  Switching the BFO on and off will also sometimes bring 
the radio back but sometimes it won't and I have to resort to backing down 
on the IF gain to get it working again.

I know the IF gain doesn't need to be too "hot" and I can actually run the 
radio with the IF gain at about 50% and it works fine, but I'm wondering if 
this "swamping" effect is seen in other radios?  I need to align the IF 
deck properly and set the IF gain control properly, but am thinking I might 
have issues with this deck.  I've recapped it and replaced an resistor or 
two that were high but haven't found anything else that seemed off with it.

Thanks,

Barry - N4BUQ