[R-390] R-390 AGC Question, SLOW MED FAST

[David Wise]

> From: r-390-bounces at mailman.qth.net
> [mailto:r-390-bounces at mailman.qth.net]On Behalf Of Tom M.
> 
> My 390 IF deck seems to have an AGC problem in that it has 
> low AGC action on
> FAST (when no timing capacitors are engaged) but good AGC on 
> MED and SLOW (when
> the timing caps are engaged).

 
It's counterintuitive, as you said.  The only thing that comes
to mind is unlikely.  If C547 and C548 were both open, the
AGC line would have next to no filtering, and would vary with
the envelope, reducing it to a small value.  If you have a
scope, put it on the line.  If nothing else, put on a high-impedance
DC voltmeter and tabulate voltage vs signal input.

73,
Dave Wise (SWL in Portland OR)