Fender 125A10B vintage transformer specs vs modern ??

[spunko]

I have this '69 output transformer that reads:

Green - Black = 0.9 ohm
Blue - Brown = 305 ohm
Blue - Red = 152.7 ohm
Brown - Red = 152.7 ohm

Searching on the web I haven't found info about those spec values. I've found an old Reverb.com link that sold the same transformer and have pictures with a meter that shows almost the same values, they are pretty close. I have also found a pic on google images for a vintage deluxe from the '50s with the same spec values.

Now, every single link I follow shows new transformers from mojotone, hammond, etc, and they all say Primary 8k, Secondary 8 ohm.

I'm confused, why so much difference in readings from vintage to new production?

https://reverb.com/item/33721492-fender-princeton-reverb-output-transformer-125a10b-1965

[SEL49]

I'm confused, why so much difference in readings from vintage to new production?

You're comparing apples and oranges. The resistance numbers you measured are DC RESISTANCE. The numbers you see on the net are AC IMPEDANCES. They are not the same.

[glass54]

Sounds about right.  With Multimeter on Ohms ie DC resistance
But if you checked the Impedance (with say a B+K 879B LRC meter) @ 1kHz, you may be surprised.
By the way an Output transformer has a ratio which is applied to Primary voltage vs Secondary voltage, as Tube are high voltage, low current devices.
(I'm am not trying to be smart) After this you will need to do some AC circuit analysis (see https://www.valvewizard.co.uk/se.html) Good info from Merlin.
Regards
Mirek

[AlNewman]

Or you could do the Uncle Doug method...

eature=shared