I agree that biasing the control grid off is better.
Because of negative screen current, an active (rather than VR tubes or zeners)
shunt regulator is best, and not difficult to do, although the heavy bleed
current approach worked.
Question: Why do these modern ceramic tubes show negative screen grid current
under some conditions? What is the mechanism that causes it? Straight
thermionic emission from the screen seems unlikely, especially as a gold
sputter would effectively prevent it.
73 es HNY
Peter G3RZP
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