[Amps] Maximum RF output in practical application: 4-250A

[Bill L. Fuqua]

Reading the emails I have not seen one that states the obvious. The 4-250A is electrically identical to the 4-400A except for plate dissipation.  They just added fins to the 4-250A to make the 4-400A.  So, what ever you can do with a 4-400A you can do with a 4-250A just as long as you don't exceed the plate dissipation.

73
Bill wa4lav


-----Original Message-----
From: "W.F van Wyk" <zs6arf at telkomsa.net>
To: <amps at contesting.com>
Date: Sat, 1 Jul 2006 15:15:34 +0200
Subject: [Amps] Maximum RF output in practical application: 4-250A

I have been hearing claims at the local flea markets here in South Africa
that a single 4-250A valve is capable of between 800 - 900 watts in ham band
amplifier application.

 

Now I have used these myself in a number of homebrew amplifiers, and never
have I even come close to that type of output from a single 4-250A.

 

Have I missed something in my amplifier education or is this High Grade
Fertilizer which I currently believe it is.

 

The local experts claiming this indicate voltages on the plate in the region
of 5,000 Volts and get a blank look when I enquire about IMD and splatter.

 

Now I am aware on the specification sheets for this valve RF power above 800
watts are indicated under certain conditions but I still have to see that
put into practice in a Ham amplifier say for normal HF band usage.

 

Please steer me in the right direction here.

 

Thank You

 

Wynand van Wyk (ZS6ARF)    

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