>>>So why don't we see more extensive damage in 3-500Z's with bent filaments
>>>if arcing is the real cause?
>>>
>>>I've asked this question at least twice and no one has responded to it
>>>yet. So I am asking it again.
>>>
>>How much damage should you expect? I don't know.
>>
>>Nobody has come up with a real explanation of how the forces necessary
>>to bend a filament are generated, applying the same principles as an
>>electric motor.
>>
>>The other question that's still unanswered is what was the state of the
>>filament just before the event? Was it properly centered in the grid
>>cage... or was it already bent, so that even a small movement would
>>cause it to touch?
>
>It still doesn't answer the fundamental question:
>
agreed
>* According to literature (as posted by John Lyles), it is stated that
>gas arcs usually cause SEVERE damage to a tube, as in melted grids, fused
>grids, etc. "Bent" grids are not mentioned although, I assume they are
>possible.
I have never seen a bent grid in an autopsied 3-500Z. The grid wires are
rather brittle.
>
>So the question still stands (I'll ask it again):
>
>Is there anyone who has done a post mortem on a 3-500Z who has seen
>*EXTENSIVE* damage? And I don't mean in a case where we know there was
>an arc. And if this extensive damage has not occured due to arcing, then
>why?
>>
>>The same question can be asked about burned-out resistors etc: what
>>state were they in, just *before* the event?
>
>Correct. We have no way of knowing.
>>
Several times I replaced the damaged vhf parasitic suppressor resistors
in my SB-220, whereupon the new resistors would apparently be damaged by
whatever was causing the Tune-C to arc and spark. How could 7.25MHz RF
damage such resistors if they are paralleled by <100nH of L?
Rich...
R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
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