Glass instead of ceramic and only a 150C seal limit means lots of air when
trying for 1500W.
That really is an ancient technology tube and is only good to 6M.
Carl
KM1H
----- Original Message -----
From: "Bill, W6WRT" <dezrat1242@yahoo.com>
To: "AMPS" <amps@contesting.com>
Sent: Monday, July 30, 2012 1:18 PM
Subject: [Amps] Another interesting tube
> An interesting tube you might want to play with is the GU43b. About half
> the
> price of a GS35b ($65 USD) and 1000 watts plate dissipation. It's a
> tetrode so I
> used the swamped grid configuration. UR4LL seems to have the best price.
> Sockets
> are expensive, but since it uses concentric ring terminals, a clever
> machinist
> could avoid a socket entirely by using homemade spring clamps.
>
> Pix at
>
> http://www.zeitmann-tubes.com/MilitarySurplus/NosRussianMilitaryTubes/GU43B.htm
>
> which is a beautiful picture by the way. I downloaded the picture and used
> it
> for a desktop background. Gorgeous. :-)
>
> Some schematics at
>
> http://pa0fri.home.xs4all.nl/Lineairs/Frinear1500/FRI1500eng.htm
>
> I built an amp with one of these and it worked but with a couple of
> caveats:
>
> 1. Although they are rated to 3.3 kVDC anode, they tend to arc with that
> much
> voltage. Several European hams have confirmed the same thing. Hold the DC
> down
> below 2.5 kVDC or less. The only PS I had was 3 kVDC so I gave it up.
>
> 2. There are two different base styles, differing in the center pin. Be
> sure to
> get a matching socket when you buy the tube. I got a mismatched socket and
> was
> able to fabricate a new center pin but it was a hassle. Get the right one
> to
> begin with, or make your own connectors.
>
> You should be able to push a single tube to 1500 watts out but that leaves
> basically no headroom. If I were to do it again I would use two in
> parallel and
> hold the HV down to 2.0 kVDC or so. Lots of headroom.
>
> I'd be interested to hear from anyone who has built an amp with one or two
> of
> these.
>
> 73, Bill W6WRT
>
>
>
>
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