Author Topic: can a 6BG6C handle 700volts on grid2?  (Read 437 times)

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Offline ELS122Topic starter

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can a 6BG6C handle 700volts on grid2?
« on: January 28, 2020, 01:42:40 pm »
the datasheet says that it can hold 700 volts on the anode and I want to use all of it but I am gonna put a "triode" switch which connects grid 2 to the anode. but it says that it can only hold 350 volts max on grid 2.
so does this mean I can only power it with ~350v if I want to have my "triode" switch?
 

Online Gyro

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Re: can a 6BG6C handle 700volts on grid2?
« Reply #1 on: January 28, 2020, 02:05:44 pm »
You can normally safely put much more voltage (often anode voltage) on G2 when a tube is wired in triode configuration, in general anyway. The close anode voltage minimises the dissipation of G2 - the anode collects most of the electrons and takes most of the dissipation.

The problem comes in pentode or UL mode (your intention I think). This can cause the voltage on G2 to be significantly above the anode voltage during parts of the cycle - that can increase G2 power dissipation a lot (electrons are attracted by G2 preferentially), hence the much lower voltage limit.

EDIT: That's the problem with your UL / Triode switch anyway. If you want to know what voltage you can safely put on G2 in Triode mode, connect it to the anode via a milliameter, measure the G2 current and calculate it's dissipation. As long as it's below the limit (3.2W?) you should be fine at that anode voltage. NOTE, also check the pinout - you may risk insulation breakdown if G2 is higher than normal (the Anode is on the top cap, G2 pin is next to a heater pin!)

EDIT1: To cut the story short, you ought to be able to use more than 350V in triode mode, but not as high as 700V.
« Last Edit: January 28, 2020, 02:22:24 pm by Gyro »
Best Regards, Chris
 
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