[R-390] SSB mod

[Bill Wilson]

Greetings to the list,

  Currently I'm restoring a Collins R-390A that a friend of mine salvaged from 
the landfill.  The AGC circuit has the SSB mod that works great for SSB with no 
distortion or complaints.  The issue I am having is that on regular AM listening 
the volume is very low and sometimes the audio on some stations is only heard by 
turning up the local gain fully clockwise.  This particular mod was done by 
removing R545 (100K) and removing R546 (180K).  Instead of R546 a diode was 
installed going to pins 1 & 2 of V509A (AGC rectifier).  R547 (220K) was reduced 
to 10K.  Spot checking some resistances indicated a 1 meg+ resistance on pin 2 
of V504 which should be about 280K with the AGC in the "on" position.  


  Any hints on getting the AM audio (AGC on) back up a few notches short of 
scrapping the entire SSB mod would be welcome.

Thanks in advance,

Bill