I would appreciate some help understanding some basic transformer stuff. Awhile ago, Tom Mcnally and Mesherm helped me a lot with the following idea:
The cheap and easy way that a lot of guys use is a reversed
filament transformer, feed 6.3 into the 12.6 winding and get
about 60 volts out ... the tiniest of transformers will work.
I have to do this because my power toroid doesn't have a 70v tap.
So, I have several small power transformers that I've tried on the bench, but the results don't make sense to me. I must be doing something wrong. The primary is rated at 117vac and the secondaries are 12.6-0-12.6. When I apply 6.3 volts (the toroid is rated at 10 amps) across the 12.6 volts taps, the 117 output reads 27vac (no load). When I apply 6.3 volts across the 12v CT and just one leg of the 12.6 tap, I measure 52.5 vac across the primaries.
I don't understand. A simple calculation (assuming no losses) tells me I should expect about 79vac across the primaries. Obviously, there's something I don't get here and could surely use some help. I don't understand this as well as I thought I did...
As always, thanks in advance. Once I get this straightened out, I'm ready to heat up the Mark III X2 Integrated Stereo Amp. Maybe even by tonight, with pictures to follow as soon as tomorrow.
Cheers,
Chris