[R-390] R-390 IF Mod Identification

[Don Heywood]

HI guys, I have an R-390/URR here which has an unknown mod in the IF deck.

Here is what I can see:
The BFO on/off switch has been replaced by a three position switch with 
three leads (in addition to the BFO B+ contacts).
These three leads enter the back edge of the IF deck through a three pin 
inline cinch connector so the deck can still be removed.
There is an R/C network tucked in around the base of IF transformer T505.
One of the three extra leads goes to what I think is the BFO coupling cap 
area. This cap has been clipped and these leads attached to the above 
circuitry..
The second extra lead also connects to the extra circuitry around T505
The third extra lead has been placed in series with the original lead to pin 
1 of V510.
Has anyone seen or have information on this mod. My plans are to uninstall 
it and return the deck to original.

The benefit of your experience will be appreciated.

Don WC4G
Charleston, SC