[PhilcoPhan1936]

Hi Jeff,
You might want to measure the AC voltage from each of the small pins (plate) to the chassis w/o the 5Z3 in the socket. Voltage should be half of what you see from plate to plate + the 400 ohm tapped bias resistor. The important part is that the two voltage (from each plate to chassis) are pretty equal by a few volts. If you have a large difference then I would be think about a PT.

By measuring the resistance of the winding from the center to each end doesn't tell you much as one side is always longer than the other.

GL

Thanks, I'll try that out. It might be a a bit of time before I have time to pull the chassis and run that test. I'll post back here when I do.