>
>measures wrote:
>>
>> With a grid/filament short, there would not be any output.
>
>I'm not sure of the mechanism. There is certainly part of the grid which
>is not
>touching the filament,
The grid is a welded cage. There is only one part.
>and the whole structure has a certain amount of
>inductance, allowing for some voltage to appear on it.
>
Very little. The grid cage is grounded in three places.
>However, I can say for absolute certain that I observed the plate glowing much
>hotter than normal (with no drive),
With a shorted grid, one has zero volts bias. This typically doubles
ZSAC.
>and low output in the range described by
>Hans (with drive). When I removed the tube, I was able to measure a short
>with an ohmmeter.
This is the worst short possible. The filament helices have welded
themselves to the grid cage. We have never been able to remove such a
short with our centrifuge.
>When the tube was replaced with a good one the amplifier
>returned
>100% to normal.
>
cheers, Vic
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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