[R-390] 1960 S-W 390A update

[Jordan Arndt]

Hi again group...

It looks like I can safely say that I've dealt with the numerous problems 
and concerns I found and had with this receiver, and I can't find or provoke 
any more intermittent noise or loss of gain scenarios.

I did get a little sidetracked when I found that the optical encoder in my 
Ailtech 460 signal generator had died and the +/- 1/10dBm RF output selector 
switch had also become intermittent, but that's a whole other story...!

If no-one objects, I'll post messages detailing as briefly as possible what 
I found with each module so far...

RSVP....73...Jordan VE6ZT