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49-906 FM hum
#1

I just finished my 49-906. Replaced all caps, out of range resistors and a few tubes. Alignment was done also.
AM is good and strong-no hum. FM picks up a few stations but has a hum all across the dial. It does almost go away when tuned to a station.
What did I miss?

http://www.nostalgiaair.org/PagesByModel...013675.pdf

Thanks,

Eric
The Villages, FL
Member: Philco Phorum, ARF, ARCI & Radiomuseum.org

#2

You might try changing the 14F8 converter tube. If it has heater to cathode leakage, then the AC voltage for the filament will FM modulate the oscillator, causing a hum. It could also be the 19T8 tube, since different diode sections are used for FM.
#3

Thanks, I'll try a swap and let you know.

Eric
The Villages, FL
Member: Philco Phorum, ARF, ARCI & Radiomuseum.org

#4

That did it! The 19T8 made a difference.

Thanks, Mondail,

Eric
The Villages, FL
Member: Philco Phorum, ARF, ARCI & Radiomuseum.org





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