[Amps] James Millen Variable Capacitor

[David C. Hallam]

I have a James Millen air variable capacitor and the only marking I can find
on it is 125Y5.  None of my reference catalogs have any listing for Millen
capacitors.  Can anyone tell me what the capacitance and voltage rating are
from that number?  Plate spacing is approximately 0.060-0.070" so I am
assuming the voltage rating is about 2500 volts.

I have tried to measure the capacitance on my Solar capacitance bridge, but
some reason (probably because I am not using it correctly) I can't seem to
get readings on air variables.

David C. Hallam
KC2JD