Re: Mystery OPT


"BFoelsch"
>
> flipper
>
>> Problem is, when I put 120.7 AC on the primary I get 1.9VAC out for a
>> ratio of 63.5/1,
>
> Well, if these are really rotten output transformers, which are down 3 dB
> at 60 Hz, your calculations would be way off, no?


** No.

Voltage drive to a transformer will overcome the usual low frequency 3dB
down point experienced with drive via a tube or other high source impedance.

120 volts at 60 Hz should be within core saturation limits of the tranny the
OP has described - a 6BQ5 would likely supply it with more AC volts.



> Measure them again at 400 or 1000 Hz.


** No need and no point at all.

The OP has the right numbers now.


> Connect them backwards to the output of a small amp fed with1 kHz and
> report back. I'll bet the calculated ratio is different at 1 kHz than it
> is a 60 Hz.


** You will lose your dough.


> Also advise your test equipment. Many old VTVMs and VOMs are horribly
> inaccurate on the low VAC ranges. They may also be bad at frequencies
> other than 60 Hz.


** How asinine.

1.9 volts AC is NOT a low voltage .

The OP has a digital meter.

He used 60 Hz for his test.



............. Phil







.