[R-390] AGC Cap Revisited

[Barry]

A few months ago, I discovered that the 2mfd AGC capacitor was leaking and
affecting the proper AGC action in one of my R390As.  I removed it and
attempted to open it up with the intent to restuff it; however, when I tried
to unsolder the can with a torch, I decided that the fumes from the hot oil
were something that I really didn't want to expose myself to (no one was
really sure they didn't contain PCBs) so I decided to take a different
route.

After thinking of a few designs and staring at the open hole as shown below,

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

it occurred to me that this looks very much like a hole that an octal socket
would fit nicely into.  Sure enough I found a socke that would fit right in
the opening with no modifications to the deck required.

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

The next picture shows the underside with the connections to the socket
complete.

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

Using a tube base, I easily soldered the new capacitor in place and plugged
it in.

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

Whaddya think?  It might not be as "pretty" as the original, but it's sure
to work.  Also, it makes it convenient, if one should so desire, to be able
to plug in different value AGC capacitors to suit however you like it.

Of course I wouldn't have done this if the original capacitor had been okay,
but since it needed to be replaced, this seemed like a non-invasive and
completely reversable approach.

I need to replace the carrier-level adjustment resistor and it got late so I
haven't put the IF deck back in and tried it yet, but I don't see why it
won't work.  I plan to machine a small cover to epoxy over the tube base so
the capacitor isn't sitting there bare, but it should be fine for now.

Regards,

Barry - N4BUQ