Replacement output transformer for speaker conversion - Printable Version

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+--- Thread: Replacement output transformer for speaker conversion (/showthread.php?tid=12466)

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Replacement output transformer for speaker conversion - Philcokid - 06-07-2015

Hello all,

I recently acquired a model 20 speaker that I am planning on using for my model 70.  I have read the article on converting the 20 model speakers to use in both the 70 and 90 models.  I am searching for a new output transformer and wanted to ask if anyone that has made this conversion has a preferred brand or source for them?  I am wanting the new transformer to fit in the old transformer frame.  I was thinking of the 125ASE from radio daze. Any thoughts or concerns? 

Thanks

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RE: Replacement output transformer for speaker conversion - Radioroslyn - 06-07-2015

Hiya Kid,
Well after consulting my 1947 RCA toob manual I find that plate load resistance for the push-pull 71A's is close the resistance the singe ended 47. Meaning that you could just rewire the xformer you've got. I won't hurt anything as the current is less with the 47 than the two 71A's. So what you would do is connect the plate of the 47 to one end of the primary and the HV to the other end. The center tap is left unused.

Terry
ps You didn't state if your xformer is good on the model 20 spkr ,I assumed that it is...

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RE: Replacement output transformer for speaker conversion - Philcokid - 06-07-2015

Terry,

Thanks for the information! The transformer I have is good.

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