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understanding transformer codes
understanding transformer codes
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Old 6th March 2006, 04:19 AM   #1
Nanook is offline Nanook  Canada
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Default understanding transformer codes

I'm finally gonna cut up an old Sparton Radio of Canada model 12M6, volt amp 165. The tag indicates some RCA copyrights or licencing.

Trying to modify it into something like a Super Triode Connection type..

4 6bm8 tubes (push pull) stereo, 1 5AR4 rectifier tube (I'll use a 5AS4A instead because I have it). Trying to find information on the three transformers. only markings are as follows:

2 (output transformers) 21AR89-1, EEH2

rectifier: 21BR102, EE12

I assumed Hammond numbers but not. Any ideas? I am assuming 7-10 watts per channel in PP, is 1/2 of that going to occur in STC connection?

as always, any and all help appreciated. I did do a search and didn't find much regarding the 6BM8 or ECC82 as power tubes.

stew -"A sane man in an insane world appears insane."
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Old 6th March 2006, 11:47 AM   #2
SY is offline SY  United States
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understanding transformer codes
Everything you'd want to know about ECL82:


You'll probably need to actually measure the transfomers to get the connections and impedances.
"You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."
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Old 7th March 2006, 05:00 AM   #3
lndm is offline lndm  Australia
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You'll probably have to work it out for yourself.

Try this - Pull your OPT, apply a sinusoidal signal across the primary winding. Measure the amplitude at the secondary. Divide the Applied signal level by the measured secondary level. Square it. Multiply that by the impedance of your speakers.

This gives you the load seen by the output stage. Find a secondary winding that matches your design load.
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