[Amps] 4-400A ratings

[Radio WC6W]

Hi Vic,
  A 4-400A is just a 4-250A with a larger plate structure.

  It is an emission limit.

73 & Good morning,
  Marv WC6W

http://qsl.net/wc6w/

******************************  

--- On Sun, 5/8/11, Vic K2VCO <vic at rakefet.com> wrote:

> From: Vic K2VCO <vic at rakefet.com>
> Subject: [Amps] 4-400A ratings
> To: "Amps reflector" <amps at contesting.com>
> Date: Sunday, May 8, 2011, 11:01 PM
> I've come into a pair of 4-400A's.
> I'm thinking about building an amplifier with one tube 
> and using the other for a spare. Looking at the data sheet
> for class-C CW, the maximum 
> rated plate current is 350 ma. This means that at 3 kV on
> the plate I can expect to get 
> only about 750-800 watts output. This does not come close
> to utilizing the 400-watt plate 
> dissipation of the tube.
> 
> At 4 kV, I could get 1400 watts input and about 1050-1100
> out. That's a lot better. But it 
> means a lot of extra expense -- the power supply, tuning
> capacitor, etc. need to be bigger.
> 
> Is this correct? Why is the plate current limited to 350
> maA? Is it a limitation on 
> filament emission?
> 
> Of course I can use both tubes and get full legal power.
> But then I need another socket, 
> chimney, etc. Or maybe I can use the "SB220 cooling method"
> and cheaper sockets.
> -- 
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco/
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