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Re: [Amps] 3CX800A7 Spares - cook them periodically?

To: <K1SG@aol.com>, <amps@contesting.com>
Subject: Re: [Amps] 3CX800A7 Spares - cook them periodically?
From: "Carl" <km1h@jeremy.mv.com>
Date: Thu, 17 Jul 2014 14:17:25 -0400
List-post: <amps@contesting.com">mailto:amps@contesting.com>
The resistor is the other half of the suppressor. The 3CX800 is a very stable tube and is gentle on a basic 2W carbon resistor.

Carl
KM1H


----- Original Message ----- From: "Steve via Amps" <amps@contesting.com>
To: <amps@contesting.com>
Sent: Thursday, July 17, 2014 1:14 PM
Subject: Re: [Amps] 3CX800A7 Spares - cook them periodically?


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?

Thanks,

Steve

Steve  Gilbert
K1SG
K1SG@AOL.com


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

-----Original Message-----
From: Amps  [mailto:amps-bounces@contesting.com] On Behalf Of John Lyles
Sent: Tuesday,  July 15, 2014 1:14 AM
To: amps@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.

73
John
K5PRO


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