[R-390] R-390A balanced input question

[JAMES GREEN]

I have way too many projects to work on and just want to have a good receiver to listen to when I'm not in the shop. I have an EAC R-390A that I used to listen to quite regularly about a year ago. I put it aside for a few months and started listening more to 2 channel Hi-Fi. I had the yen to catch the BBC out of ascension Island again so I pulled it out and ran into a small problem.

Knew exactly where the radio was stored. I can't for the life of me find the "C" to so-239 adapter I used before to hook it to my antenna. I did find a balanced to SO-239 adapter, but I found I could not get a signal from the balanced input. Upon close inspection and some dis-assembly I found the plastic insert in the balanced connector was twisted. This twisted the relay contacts so there was no connection. I replaced the antenna relay with one from my parts radio & have verified it is now passing a signal. 

Here is the problem:

I still am unable to pick up anything through the balanced input. Upon looking in the R-390A Y2K manual schematics it looks like the unbalanced connector bypasses several tuned transformers that the unbalanced input does not bypass. I suspect these tuned transformers are in need of alignment. However, the alignment procedure in the Y2K manual instructs one to connect the sig gen to the unbalanced connector. & aligning from there.

Am I missing something? Is there a separate alignment procedure that I did not find that shows how to align from the balanced input?

Cash flow at the moment prevents buying another "C" to SO-239 adapter, & I have heard some extra sensitivity can be gained by using the balanced input.


Jim