Philco 46-1209 strange behavior - Printable Version

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+--- Thread: Philco 46-1209 strange behavior (/showthread.php?tid=25814)

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RE: Philco 46-1209 strange behavior - MrFixr55 - 07-01-2025

The pin 1-pin2 short will quite likely cause hum. Pin 1 is the filament, pin 2 is the cathode. Since this tube is the phase invertor and is fed by a center tapped winding, 3V of 60 HZ hum is placed on one of the output tubes. It is likely also amplified and placed on the other output tube. This is not a very common tube but if you do a search, you will see several available on eBay and one vendor, Antique Electronic Supply has "NOS" (New, old stock) available. Do check other suppliers to get the best price for a good tube.

Disclaimer- My mention of eBay or AES does not constitute a recommendation by either me or the Philco Phorum regarding the desirability of these vendors.

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RE: Philco 46-1209 strange behavior - RodB - 07-01-2025

Bob Dobush at findatube.com has them. Several of us on the Phorum use his service.

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RE: Philco 46-1209 strange behavior - sq65 - 07-19-2025

Sorry guys, I forgot to update you. A couple weeks ago I rigged in a single section tube in place of the 7AF7 and it worked fine. I bought a 7AF7 on ebay and it works great!

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RE: Philco 46-1209 strange behavior - MrFixr55 - 07-25-2025

Congrats SQ65, enjoy the radio and bask in the glow of solving a rather pernicious problem.

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