[Amps] GU 74 operating parameters

[Karl-Arne Markström]

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 at frizon.org>
To: <Amps at 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
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