[AMPS] Some tube questions...conversion to H2O cooling

[Bob Duckworth]

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?

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? 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 wrote Anton to see if he had any deals on water cooled tubes but he
doesn't
sell them.

As an aside,
Heath claimed 1200W into a pair of T-160L/572B.
160W plate rating.
At 60% this is like 80W extra per tube.
For class C it's almost within ratings.

-bob



--
FAQ on WWW:               http://www.contesting.com/FAQ/amps
Submissions:              amps@contesting.com
Administrative requests:  amps-REQUEST@contesting.com
Problems:                 owner-amps@contesting.com