[TMC] XFK - AC leakage to chassis

[Nick England]

I started to resurrect an XFK and before applying power checked for
possible leaky AC line bypass caps - Uh oh - measure about 50K ohms from AC
line to chassis. Disconnect the bypass caps and no change. Disconnect the
power transformer and no change. Eventually I found that the heating
elements in the 200kc oscillator oven were the culprit.
Well, in a device with an ungrounded two wire AC cord, that sure sounds
nasty to me.

I pulled out the heating elements which look like a ceramic tube within a
metal jacket that fits into the oven. Yep, 50K from line to that metal
jacket .

The other oven for crystals measures OK. Of course....because I'm never
going to use a crystal that one is fine!

Surely this isn't normal? Has anyone come across this in a TMC oven before?
Am I missing some layer of insulation between the heater jacket and the
metal of the oven?

Cheers,
Nick England K4NYW
www.navy-radio.com