[Top] [All Lists]

[AMPS] 3-500Z amplifiers and grid current

To: <>
Subject: [AMPS] 3-500Z amplifiers and grid current
From: (Rich Measures)
Date: Mon, 16 Mar 98 16:14:43 -0800
>>On Mon, 16 Mar 98 07:29:35 -0800 Rich Measures <> 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
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.  


R. L. Measures, 805-386-3734, AG6K   

FAQ on WWW:     
Administrative requests:

<Prev in Thread] Current Thread [Next in Thread>