Okay, so I came back to this. Took a 25V AC source, attached it on the supposed B+ and UL and Plate taps each at a time, and measured output voltages across the secondaries.
It turns out the amp indeed was mistakenly wired.
The way the OTs were wired gave turns ratios of 100@8ohm and 250@4ohm which is total nonsense. That is 800 and 1000 Ohms of Ra load :O How the hell did this even work!!??
The good ratios are 500@8ohm and 1400@4ohm when wired as it was supposed to be.
However I don't get the UL operation now! In your personal XPs, is the UL always this shouty ??? Could it just be poor quality OTs ??
Thank you all again!
Best.
It turns out the amp indeed was mistakenly wired.
The way the OTs were wired gave turns ratios of 100@8ohm and 250@4ohm which is total nonsense. That is 800 and 1000 Ohms of Ra load :O How the hell did this even work!!??
The good ratios are 500@8ohm and 1400@4ohm when wired as it was supposed to be.
However I don't get the UL operation now! In your personal XPs, is the UL always this shouty ??? Could it just be poor quality OTs ??
Thank you all again!
Best.
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Do you actually mean turns ratios of 100 and 250? Impedance ratios are the square of these, so it seems pretty extreme.
All good fortune,
Chris
Sorry, mistake in wording. Those are impedance ratios, turns being the square roots of them yes.
Best wishes.
op
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