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49-906 FM hum
Eric Adams
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#1

08-11-2013, 12:21 PM
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

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Mondial
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#2

08-11-2013, 12:54 PM
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.
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Eric Adams
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Posts: 825
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Joined: Aug 2012
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#3

08-11-2013, 01:48 PM
Thanks, I'll try a swap and let you know.
Eric
The Villages, FL
Member: Philco Phorum, ARF, ARCI & Radiomuseum.org

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Eric Adams
Phorum Expert
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Posts: 825
Threads: 113
Joined: Aug 2012
City: The Villages State, Province, Country: Florida
#4

08-11-2013, 03:16 PM
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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