40s Philco 40-145 BUMMER!

[Kamakiri]

Originally Posted by DavGoodlin

A 7Y4 is like a 6X5 or an 84/6Z4, there is 300+ VDC on the indirectly-heated cathode, which is wrapped around the 6.3 V heater, one side of which is grounded. One arc across and these tubes will fry your transformer.

Disconnect and cover or remove the tube socket and add two 1N4005 silicon rectifiers and an appropriate wirewound resistor before the electrolytic caps and field coil.

I have two 1941 Zenith console radios, both had original thier power transformers smoked due to these lousy full-wave rectifier tubes.

Just a thought on minimizing the risk of a bad failure, nothing more.

Yep, I have a Zenith 8S359 that uses the 6X5. Recapped but almost no volume. Gonna take another crack at it in the fall......