In article ,
miki wrote:
My catalogue is probably 25 years old and has listings for audio
output transformers up to No. 1668. Do you have a center-tapped
primary and the various output impedances showing continuity amongst
themselves ? (but insulated from the
promary) miki.

If you are sure this is a broadband audio transformer, get your scope
and a 1KC square wave generator (the calibration generator on the Tek
scope is probably good enough. Pick one winding, and apply the square
wave, then pick another winding and look at it on the scope. Apply shunt
resistance across the scope probe until you see a nice square wave with
only a tiny overshoot. Now you know the impedance of one winding. Do
this repeatedly and figure the winding impedance of all of them.

From this you should be able to figure out what is intended as the primary
and what is intended as the secondary, if you have a vague idea of the
intended application.

Now, you can put 6.3V AC across the primary through a capacitor, then
look at the secondary on a scope. Use a bench supply to add some DC
offset to the primary, and keep craking the DC voltage up until you
see the level of the sine wave on the output start to drop off. NOW
you know the level of acceptable DC offset current before the core saturates
at near-zero power, from which you can fudge a full-power value.

These are the two important things you want to know about an audio
transformer. Power level is a little harder but you can just apply 60 Hz
into a big load resistor until the transformer saturates. Full power
fresponse tests will require an amp, though.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."