[AMPS] 3-500Z amplifiers and grid current

[km1h @ juno.com]

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.
BTW, what was the date code on that tube and did it come from the NY/NJ
area?

Tnx  Carl  KM1H


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