>
>
>-----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.
>
good idea, Steve. Paralleling tubes is a lot easier than most builders
think. As RL decreases, more Tune-C is naturally needed to maintain a Q
of c. 10.
cheers
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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