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RE: NYAL OTL3

A bit more information.

I checked the grid 1 resistor to ensure the tube was properly biased and it tested fine, but replaced it anyway: No change, V3/5 still turn red.

Wanted to take other measurements to see if that would help me track down the issue. Lowered the plate current to ~220mA and found the B+/2 a bit off. Lower grid V, upper grid V, B+, and now B+/2 all per target and stable. Adjusting the plate current and/or balance fixed the red 6LU8, but the V3 6LF6 still turns red after a couple minutes. Tried a couple other tubes and same result. (Have an unused 6LF6 matched dozen from RAM Labs I bought a long time ago, but don't want to use until I'm certain they'll be okay.)

The 6LF6 V3 was hot enough to melt the top off the jumper top, so this doesn't look normal to me.

Any inputs?

Regards,


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