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Old 19th June 2006, 10:08 PM   #1
bst is offline bst  United States
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Default Questions on 1:1:1 driver transformer

I recently uncovered a large quantity of Stancor TA-61 driver transformers in a local industrial surplus warehouse. I'm trying to figure out if I can use these as input transformers and/or phase splitters for tube audio projects.

The specs are a little unusual. I found a 1966 Stancor catalog online, and page 11 of this catalog has most of the TA- series transformers listed. The TA-61, however, is the only one that does not have values listed for impedance, maximum power in mA, or audio watts.

Instead, it has a footnote which states: "Trifilar-wound - Ratio 1:1:1".
The three sets of windings measure identically, with primary and secondary DCR's of only 1.8 ohms, and an inductance of 18.8 mH.

Is there any chance these could be useful for tube audio projects, or should I leave them at the warehouse for another experimenter?

Thanks in advance for your help.
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Old 19th June 2006, 10:22 PM   #2
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and an inductance of 18.8 mH
I see that most interstage trafo's used in audio have inductance in the order of H, which is fundamental for good bass reproduction. A value in the range of mH is therefore (probably) way too low... but maybe there are other options and opinions for using them. I leave it for the experienced!

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Old 20th June 2006, 10:38 PM   #3
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Could this have been intended to feed a transistor class-B power stage?
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Old 25th June 2006, 04:34 AM   #4
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This is certainly intended as higher frequency use or low impedance AF use. What´s the size of those.

If they are big, it might work as speaker splitting, one amplifier feeding two speakers, but probably the DC resistances are too high for this purpose.

Strange one. Would be nice to know the original intended application.
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Old 25th June 2006, 08:36 AM   #5
cerrem is offline cerrem  United States
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The inductance is a property of the intended impedance vs. frequency.....
So for 18.8mH ..... You would need a 2 ohm load to have -3dB at 20Hz..... Since 2 ohms in unusual... then it is not for low freqquency...
The intended application sounds like a IF inter-stage coupler in tube radio reciever... Or possibly for the phase discriminator for FM mutliplexer..

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