>
>I'm curious.
>How do I figure out how much current I can squeeze through a tube.
>Lets use the 4cx250FG for example.
>
Look at the constant current curves for the highest screen potential
allowed. Find the zero grid volts line. When the emissive limit is
reached the curves begin to turn upward. My guess for the 4cx250FG is
around 1100 peak mA of cathode emission in SSB service with a screen
potential of 400v. . .
>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?
>
>I'm asking because this is generally available as a $10 to $20 tube for NOX
>at
>local hamfests. If I cut some channels in the fins at the bottom of the
>tube
>and solder a cap on it making a U shaped channel for water to flow through
>and fax some fittings on the top and blow a lot of air on the base, can I
>squeeze
>1.5KW out of a pair of these?
No. 500W per tube is about it.
>Rated plate current is 250ma. I'll have to
>cram 1.25amp through the pair to get 1.5KW out in AB1, less in C (about an
>amp).
>
>Also, Is there any room in the 2KV plate rating?
>Like maybe run them at 2.3KV?
>
I have heard that 2500v is semi-ok if one does not go hammer down on
tuneup. In my opinion, the safe limit for AØ is 2000v.
later, Bob.
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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