[Amps] 3CX800A7 Spares - cook them periodically?

Steve via Amps amps at contesting.com
Thu Jul 17 13:14:43 EDT 2014

I understand the concept (although not the black magic) of parasitic  
surpressors and chokes; but you raise the issue of damping resistances.  What do 
you mean by that?  Where in a triode circuit would they go?
Steve  Gilbert
K1SG at AOL.com

In a message dated 7/17/2014 12:03:12 P.M. Eastern Daylight Time,  
amps-request at contesting.com writes:

-----Original Message-----
From: Amps  [mailto:amps-bounces at contesting.com] On Behalf Of John Lyles
Sent: Tuesday,  July 15, 2014 1:14 AM
To: amps at contesting.com
Subject: [Amps] 3CX800A7  Spares - cook them periodically?

> Anyone have a schematic for a  burn in fixture?
If it were to be made, it would be a simple socket with  blower/fan, 
airflow interlock, filament power at a slightly low voltage with  the proper 
current limiting during turn on. More elaborate would be a tester  that applies 
plate voltage, and of course bias on the grid or cathode to  prevent 
excessively high beam current. As this is done, though, the chances of  the tube 
becoming an oscillator goes up, so 'stoppers' like parasitic chokes  and 
damping resistances would be considered. Its just not worth the effort if  you 
have the amplifier that can test them  occasionally.


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