SSE pentode/triode/UL

[neomat]

Hi guys!!

I may misunderstand something but I'll ask. George website mentionned that SSE can be run on triode, UltraLinear and Pentode. But UL/triode has only 2 positions. So my question, certainly a silly one : how switching to pentode ?
By using a On Off On switch?

Thanks to enlighten me.

[rknize]

Triode: screen is strapped to the plate with a resistor
UL: screen is attached to the UL taps on the OPT
Pentode: screen is attached to a fixed supply (would be B+ in this case)

You would need a DP3T switch to do it with just one switch. Not many people bother with pentode operation. If their OPT has UL taps, they use those. If not, then pentode is the closest option.

[neomat]

Thanks!
SSE pcb seems not to allow pentode mode. As far as I understand, B+ should be connected to R18/R28 lead going to tube, is that right?

Have a nice day.

[rknize]

I think you can leave R18/28 where it is and just connect the board terminal to B+. Be sure to observe the specs of the tube. Make sure that your raw B+ does not exceed the tube's maximum rated screen voltage. Ideally, the screen should have it's own supply. This is because it really should not operate at a higher voltage than the plate. Because of the loss across the OPT primary, your plate voltage is lower than your B+. However if the tube you are using is designed for UL operation, it should be fine.