[R-390] Mod discrepancy

[Gary Weddle]

Greetings to the list;
   I am working on an Amelco R390A receiver that has had the Capt. Lee Product 
Detector Mod installed. When I got it, it worked for a while and then just quit. 
I checked the as-built against the circuit published in the 2009 Y2K 21 Century 
Reference Manual (so many names) and found the circuit to be identical in all 
but one area: The capacitive network outboard of the Z502 BFO Pitch unit is 
different. The original circuit diagram calls for a series 100 pf cap, C526,  
between pin 1 of the Z502 and pin 1 of the 6BA6W shunted to ground with a 5 pF 
cap, C527. (Pin 1 of the tube also has a 150k resistor to ground.) The Y2K mod 
schematic calls for the same configuration but the cap size(s) are 0.033 uF. 
(Only one cap is labeled so the intention is not clear.)
   Does anyone know about this change? Has anyone had difficulty with this 
circuit? I have no voltage chart for the 6BE6W replacement tube (after socket 
re-wiring) and the 455 kHz peak voltage is around 20 mV when the BFO is engaged. 
It this correct?
   Thanks.  <G>