-----Original Message-----
From: Bob Duckworth <wb4mnf@atl.org>
To: amps@contesting.com <amps@contesting.com>
To: <amps@contesting.com>
Date: 19 September 2000 15:25
Subject: [AMPS] Some tube questions...conversion to H2O cooling
>
>I'm curious.
>How do I figure out how much current I can squeeze through a tube.
>Lets use the 4cx250FG for example.
>
>4cx250FG
>It's heater draws 14 watts.
>The max plate voltage is 2KV and it's rated
>as a 500W input tube.
>Plate dissapation is 250W.
>
>If I can keep it cool, how much plate current can I expect to run
>before there are not enough electrons coming off the heater?
The most I've ever known of is running them in real cut off class C with
about 400mA of anode current key down. The user had a source of really good
ones that took 3kV in cutoff and 2.7kV key down. Output from a pair was in
the 1.5kw region, and they lasted around a year of regular skeds. For EME or
MS cw use, transmit duty is about 60%, and there's 50% rx time so the anode
dissipation isn't compromised.
At $10 each, I'd stick to 2kV, 250mA and just put more in parallel.
Steve
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