[R-390] R390A Update

[n4buq at knology.net]

Many weeks ago, I posted some pictures of the replacement AGC capacitor:

http://www.knology.net/~thelanding/R390A/AGC/AGCReplacement1.jpg
http://www.knology.net/~thelanding/R390A/AGC/AGCReplacement2.jpg
http://www.knology.net/~thelanding/R390A/AGC/AGCReplacement3.jpg
http://www.knology.net/~thelanding/R390A/AGC/AGCReplacement4.jpg

I finally got around to reinstalling the IF deck into the radio and tested 
it.  It works great.  Almost no differences in Carrier Level readings when 
switching between the AGC settings.

Also, a few weeks ago, I asked about a good replacement for the 100-ohm 
carrier-level pot.  I had a 100-ohm ten turn pot, but the connection pins 
were rather small and it was going to be a pain to mount the 22-ohm 
resistor along with the other wiring.

I started searching for another replacement and found a 20-ohm single-turn 
wire-wound pot made by Clarostat.

http://www.surplussales.com/Potentiometers/PBM-SlotAdj/PBM-SlotAdj-1.html

Reference P/N (RWV) CM20255-2.

This pot works fine and eliminates the need for the 22-ohm parallel 
resistance.  The drawback (it always seems there's one) is it has 1/4" 
threads instead of 3/8" so you have to shim it with some appropriate 
washers.  It has a locking tab that doesn't match with the original so you 
either have to shim it underneath, clip the tab off, or drill another 
locking hole.  I opted to shim it for now with some 1/4" stainless steel 
washers.  I plan to make an adapting collar for it that will accomodate the 
existing locking-tab's hole and center the 1/4" shaft in the 3/8" hole, but 
for now it works fine.

Just thought I'd pass this along as another possible solution for the 
carrier-level adjustment issue.

Regards,

Barry - N4BUQ