OT primary wiring help !

[showbander]

hi all...I have a mid 60's OT that i would like to identify the primary leads if poss.
I have the seconary side sussed as the ohms /colurs weres penciled in ontop the tranny.
I have 3 leads off the primary side...they are RED/RED/ORANGE.

many thanks

[martin manning]

Measure DC resistance across red-red and then red-orange. If you come up with about half of the red-red on the red-orange(s), then you probably have a push-pull transformer. Since the orange is different from the other two, I'm guessing it's the center tap.

To find out what the primary impedance might be put a low-voltage AC signal on the outer legs of the primary, from a 6.3VAC filament transformer or AC wall wart power supply. Then measure AC voltage across the primary and the secondary (pick one tap, say the 8-ohm, and measure to the common lead). Then calculate primary impedance as (Vpri/Vsec)^2 x 8.

[showbander]

thanks martin. yep you were right about the orange being the CT and being push pull...all sorted now and amp up & running.
cheers mate.