50s Triad 2485 OT

[MHProd]

Anyone knows the primary Z for this OT? I know the secondary is 4 Ohms...

This is the OT used in the wide panel Twins 5C8 and 5D8.

Thanks!

[sluckey]

Easy to check. I like to put 1VAC on the secondary and measure the voltage between the primary plate leads. Now square the measured voltage to determine the impedance ratio. Finally multiply the impedance ratio by 4Ω to get the primary impedance.

[MHProd]

I wish I had one! I’ve only seen pictures. It’s a huge OT for a 25w amp. I wonder if it’s rated at 30w or more...

I guess it’s probably 4K... just wondering if people know more about it as I’d like to build a 5D8 and would like to find an approximative period correct replacement (not a clone/newer OT).

[martin manning]

Looks like 8k primary: https://www.mercurymagnetics.com/product/fttwin-o/

[MHProd]

Wow, thanks Martin. I didn't think of checking MM.