Tom Schlangen wrote:

Hi Patrick,

I think Yves talked about transmitting tubes
in satellites. No air stream or water flow to
cool them in space ... only radiation cooling
is available out there.

I wasn't sure what TWT stood for.

I live down hera on terra firma,
and my mind and amps don't have to survive space.

Water cooling would still work up there if there was someplace cool
to radiate the heat out from a large heat exchanging panel,
say from the shady side of a space craft
They say you get a suntan easy when you work
outside repainting the weather boards of the space station.





Surly there are internal cooling systems like
heat pipes leading the heat power from the point
the heat origins from (e.g power tube plates,
or the nuclear reactor "batteries" often found
in military satellites) to the radiation cooling
fins at the outside of the satellite, but in the
end it is all pure radiation cooling to get the
heat power away from the satellite structure/body.

Exactly....



And with water cooling, the tubes could be small,
and no trouble for 500 watts of dissipation.

As far as I know, HAMs sometimes put generic RF output
stage tubes "upside down" into oil baths and run them
_way_ beyond their nominal "air cooled" dissipation.
Together with intermittend CW morse/pulse operation
they draw power ratings from a 6L6 (or what else they
use) which would make us AF types simply _faint_.

Indeed, ony could simply lower the whole amp into an oil bath,
and the insulation is improved as well.
But the plate inside a glass vacuum tube would still get very hot.
The ability to produce say 300 watts of power from a pair of
EL36/6CM5 is assisted by the use of class C.



Probably HAMs lurking here due to the AM radio thread
can elaborate a bit ...

Tom "hurrying to order a 1cbm tank full of SF6 at
-20C to drown my ECL82PSET in which surely will
be good for 1,5 KW sustained AF power then ;-)"

P.S.: Don't try liquid nitrogen, the temperature gradient
in operation would be too steep for the glas envelope ...

But at least the wires would have low resistance, and imagine the sound
quality,
with super cooling.
Liquid helium might be better.

Patrick Turner.



--
A gleekzorp without a tornpee is like
a quap without a fertsneet (sort of).