[R-390] R-390 rf gain

[Ziegenbein, Randy]

I'm new to the R-390A world and have a couple of questions.

My 390A is a Collins first production run and has a mod so it 
supposedly receives SSB better by a couple of 4148 diodes 
in the agc ckt (one in parallel with R-547, grid of the AGC 
time constant, one in parallel with R546, grid and plate of the 
AGC rectifier ckt, and finally a 47 pf in parallel with C535, 
which is the coupling cap between the BFO and the Detector.  
Is this a good mod? 
 
Next, the RF gain control seems to only be effective the last 
1/4 turn clockwise (man or agc modes).  Is this normal or do you think
the pot is bad or some other problem in the rf gain control circuit?  
Or is it a result of the AGC mods above?

73,
Randy, K6RCZ