10-23-2017, 07:48 AM
I need to replace the output transformer in a 37-660 I am repairing. I measured the voice coil resistance as 1.2 ohms, so I assume the impedance is about 2 ohms. The tube manual says I need a load impedance of 10K ohms. Maximum plate current 80ma (from tube manual) and output power 10 watts (from Riders).
I have a NOS Utah 5999 universal output transformer in stock. It is about the same physical size as the original. Searches online say it is rated at 12 watts (PTOP says 8 watts). But I have not found any sources for the maximum DC plate current or impedance ratios available (but those can be measured at 400Hz). I suppose that a Hammond 125E would be a better choice since it is rated at 15 watts and 80ma maximum plate current. But it is HUGE and also pricey. Any advice? Other alternatives? Thanks.
I have a NOS Utah 5999 universal output transformer in stock. It is about the same physical size as the original. Searches online say it is rated at 12 watts (PTOP says 8 watts). But I have not found any sources for the maximum DC plate current or impedance ratios available (but those can be measured at 400Hz). I suppose that a Hammond 125E would be a better choice since it is rated at 15 watts and 80ma maximum plate current. But it is HUGE and also pricey. Any advice? Other alternatives? Thanks.
