35z5 tube pins 2 and 3 soldered together

[fanman1980]

I took the tube put of an old radio and found pins 2 and 3 shorted together with a thin piece of wire but without it they have no connevtion so i tried with a good 35z5 and pins showed a short between them. Is it ok to use this tube?

[RollyShed]

Some information here -
https://www.radiomuseum.org/tubes/tube_35z5.html

and the information sheet here -
https://docs.google.com/viewer?url=https%3A%2F%2Ffrank.pocnet.net%2Fsheets%2F093%2F3%2F35Z5GT.pdf&pdf=true

Pin 2 and pin 3 are connected internally and part of the heater wiring.

Heater voltage is 35 volts pin 2 to pin 7
Heater tap voltage 7.5 volts pin 2 to pin 3

 

What is the radio? It doesn't appear to be one I've worked on as they were all 6.3 volts for the heaters unless the valve (tube) heaters were in series, common on some Philips models..

[H713]

35 V filament is going to be for a series string. Watch out, this thing probably doesn't have a power transformer and directly rectifies the AC mains. Rather dangerous to work on without an isolation transformer.

 

 

As a note, the 35Z5 is a rather bizarre tube, with the filament tapped to allow for a panel lamp in parallel with half of it. I would love to know what the engineers at GE were smoking when they came up with this idea. In any case, the GE datasheet that I've attatched tells you everything you need to know.

35Z5GT.pdf

[fanman1980]

The radio is a motorola 51a. And the tube had a thin a thin wire soldered between pibs 2 and 3.