511 series AF transformers - Printable Version

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+--- Thread: 511 series AF transformers (/showthread.php?tid=1477)

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511 series AF transformers - Guest - 11-08-2008

After replacing a burned out 71A tube I was getting one strong channel but no volume control. I figured I'd recap it and see what I got. While waiting for the new caps to arrive I went through the chassis more thoroughly and found that the output choke was taken out of the circuit with the speaker connected directly to the 71A and worse, the 2 AF transformers (#3077) appear to be open... I doubt I'll be able to find replacements and I don't want to put a lot of money into it. Is it possible to rewind these myself or use some modern replacements?

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Re: 511 series AF transformers - Ron Ramirez - 11-08-2008

Hi

While these can be rewound, modern replacements are available for the audio interstage transformers from a few sources. You will want transformers with a 1:3 ratio.

Or, you could change the audio interstage transformers to resistance coupling. Details here:
http://www.philcoradio.com/tech/audio.htm
Scroll down to "Modification C."

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Re: 511 series AF transformers - Guest - 11-09-2008

Thanks Ron, I will try the resistance coupling if I can't find an appropriate match. This may be a silly question but, could I use a 110v to 36v power transformer (1:3 ratio) as a substitute? Also what kind of current rating should be used?

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