>SNIP
>
>
>>On Mon, 16 Mar 98 07:29:35 -0800 Rich Measures <measures@vc.net> writes:
>>from melted grid wires, however, I have seen many that failed from
>>sudden grid to filament shorts due to a bent filament helix which manifested
>>itself immediately after an arc and "big bang". Last week, I tested an
>>Eimac 3-500Z that was virtually brand new. It had recently been
>>installed in an out of the box, new TL-922. Within several minutes,
>>there was a "big bang", and reverse grid current plus anode current
>>was indicated on standby. . . When I tested the tube I discovered a
>>grid-filament short. . . It is my opinion that the tube shorted due to
>>an intermittent oscillation at c. 120MHz.
>
>I am glad you stress that it is only an opinion Rich.
What is your opinion as to why a virtually new Eimac 3-500Z would
generate a big bang and sustain a grid-fil. short?
>BTW, what was the date code on that tube and did it come from the NY/NJ
>area?
>
date code 8939, NY was where it was shipped from, Carl, although I do not
from which dealer the "new" TL-922 came from. At the time of the fault,
the 1A-rated grid choke opened.
cheers
Rich...
R. L. Measures, 805-386-3734, AG6K
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