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Re: [Amps] 4CX800 & GS35B

To: Amps Reflector <amps@contesting.com>
Subject: Re: [Amps] 4CX800 & GS35B
From: Mark Hill <g4fph@mjha.co.uk>
Date: Mon, 28 Nov 2005 12:17:46 +0000
List-post: <mailto:amps@contesting.com>
Mike,

GS35B are regularly run with up to 4 kV on the anode, seemingly 
without problems, sometimes even more.  Some useful info. on this 
site:  http://www.nd2x.net/tube-1.html  As most of this Russian stock 
appears to be NOS (New Old Stock) it usually pays to burn the tubes 
in before applying lots of HV.

Of course, swapping from tetrode to triode could make a fair amount 
of work for you.  I would guess a 4CX1500B might make a 'low-hassle' 
substitute if you happen across any, or even the Russian GU78 / GU84 
tetrodes as used in some of the Emtron amplifiers.  Bases for the 
latter are available from Tom's Tubes and elsewhere, I think.

Regards.

Mark.

------------------------------------------
At 11:11 28/11/2005, you wrote:
>Will the 4CX800 take 3100 V DC continuous?
>
>The specifications for the 4CX800 has a 2000 V continuous (anode)
>limit.  Some schematics for 4CX800 amps. show more than 2000 V on the
>anode.  The Alpha 99 runs ~2700V on the anodes before being keyed, so
>I've been told.
>
>Reason for the inquiry is the 4CX1600B tube in my homemade amp looks
>to be bad and would like to replace it with a tetrode.  Also, looking
>for something a bit less expensive than the "new" 4CX1600B.   A pair
>of 4CX800s seem to be a natural replacement with just minor
>adjustments to the amp circuit.  However, my power supply furnishes
>3100 V and then goes to around 2900 V when keyed.
>
>If the 4CX800 will not take the 3100 V will the triode, GS35B, handle
>the 3100 V?   Trying to keep the tube/socket cost within "reason" as
>another amp will need to be built soon for the second station in a
>SO2R set-up and want both amps. to have the same tube.
>
>          73,
>          Mike, K4GMH
>_______________________________________________
>Amps mailing list
>Amps@contesting.com
>http://lists.contesting.com/mailman/listinfo/amps

*******************************************
Mark Hill - G4FPH
E-mail: g4fph@mjha.co.uk
Current web pages at: www.g4fph.net
Old web pages at: www.qsl.net/g4fph
----------------------------------------------------------------------
Dipoles resonant on 1942 / 3720 / 7085 kHz
Three element wire beam coming soon on 14180 kHz!
----------------------------------------------------------------------
Remember - SIDE for HV safety:
S witch off
I solate
D ump
E arth
*******************************************


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