First, the quoted limits apply to the 4CX800, for the Russian GU74B they are
2000V and 0,5 A respectively.
Assuming you will "get away" with the 4CX800 ratings,
the plate voltage swing will be limited downwards by the screen voltage. It
is reasonable to expect a peak plate voltage swing of around 2100 V with a
300 V screen voltage and a 2500V no-load voltage. This translates roughly
into a plate load impedance of 2800 ohms at the 1 kW output power level.
A PI-L network using a plate load impedance of 2800 ohms and an
intermediate impedance of 200 ohms would be a good starting point.
73/
Karl-Arne
SM0AOM
----- Original Message -----
From: "Ulf Tjerneld" <star@frizon.org>
To: <Amps@contesting.com>
Sent: Wednesday, January 06, 2010 7:26 PM
Subject: [Amps] GU 74 operating parameters
>
> Hi all,
>
> I'm building my first amplifier - or my first serious amplifier that is.
> The chosen tube is a GU74B and I'm wondering about the operating
> parameters when I'm designing the Pi-L filter. I have of course read the
> specs sheets where a maximum plate current of 800mA at a plate voltage of
> 2500 volts is stated. But what I really would like to know are the "best"
> conditions to operate this tube under. I guess I will get different
> answers from all of you, but it would help me anyway to decide on
> something to use as as a basis for tank calculations.
>
> My PSU will deliver 2500 volts under no-load conditions.
>
> Thanks!
>
> 73's
>
> Ulf /SM0NOR
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
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