[R-390] Signal Increases With Limiter Switch

[ToddRoberts2001 at aol.com]

In a message dated 1/6/2007 10:57:16 AM Eastern Standard Time, 
kellerfamily01 at charter.net writes:
Some time ago, someone on the net suggested that if a nearly dead R-390A  
showed an increase in signal strength by turning on and increasing the limiter 
switch, it was indicative of a specific problem that's easily corrected - a 
specific capacitor or something else that simple.  Does anyone recall that advice 
and what was it?
Thanks to all.
WB5KXO 

Nine times out of ten that problem was traced to a bad capacitor in the 
limiter circuit, either C532 or C537. These are both small molded silver mica caps 
that tend to get leaky and short with age, taking the audio out with them. 
These are in the schematic between Detector tube V506B and Limiter tube V507. 
C532 is a 100pf silver mica and C537 is a 180pf silver mica. It wouldn't hurt to 
replace them both as long as you are in there. They are in a very 
hard-to-reach area beneath other wiring so it is a tedious job to replace them but well 
worth it to bring the audio back to life. It might not hurt to replace C531 .1uF 
with something newer also while you are in there although C531 rarely seems 
to give trouble.
73 Todd