• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

G2 overvoltage ??

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puginfo

Member
Joined 2007
i just got this cct using 6550 PP fired up with B1+ of 465Vdc wrt common gnd with rectifier but without the 12AU and AX plugged in.

did a quick check on the G2 and found its at 465Vdc as well wrt to gnd. i shut if off quickly as the 6550 specs says G2 max is 400V. isnt the 6K// resistors (3k total) insufficent to drop the voltage or is it the way i measured it which was wrong?

the OPT is hammond 1650R, 40% UL. is something really out here?

can someone pls help? thks
 

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SY

SY

Ex-Moderator
Joined 2002
SYclotron.com
No, it's not a pentode. In triode, the screen and the plate swing the same AC voltage with respect to the cathode. In pentode, the screen stays fixed with respect to the cathode while the plate swings. In ultralinear, the screen swings lees than the plate but more than zero; it's somewhere between triode and pentode.

Think AC, not DC.
 
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