[R-390] Mechanical filter alignment

[k2cby]

You may be barking up the wrong tree so far as AGC problems are concerned.

 

The most likely failure mode for the AGC bus is a leaky bypass capacitor,
not the AGC delay capacitor C551, which is a very solid unit.

 

Open the jumper between terminals 3 and 4 of TB-102.  Measure the resistance
from Terminal 4 to ground. It should be infinity. If it isn't your problem
is one of the .005 uF bypass capacitors on the AGC bus.

 

If the resistance from Terminal 4 to ground shows open, check C543, C547 and
C548, all of which are "black beauties" and should be replaced in any case.

 

Miles B. Anderson, K2CBY
16 Round Pond Lane
Sag Harbor, NY 11963
Tel.: (631) 725-4400

Fax.: (631) 725-2223
e-mail: k2cby at optonline.net