[R-390] bfo problems

[Steve Hobensack]

My r-390a has a slight hum when the bfo is on. Cw and ssb signals have a 
slight "vibrato" sound. Cw notes are not clean and crisp with any setting of 
the mgc level. I suspected one of the filter caps, but they are ok. The 
decoupling cap on the bfo 150v b+ is ok , there is no cathode to filiment 
short. I turned off the bfo switch, and injected a 455 khz carrier from my 
urm-26d signal generator to pin 5 (plate)of the tube socket. I still had the 
hum with the signal generator acting as the bfo. The radio sounds fine 
listening to a m broadcast. Any ideas ???  Thanks
.......Steve.....KJ8L





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