[Milsurplus] Query

[mikea]

> > Hi Pete, Jim and all,
> >
> > Yes, interesting thought, operating a vacuum tube in the vacuum of space.
> > But consider the temperature in space and what it would do to the
> > elements.
> > Could you even light the filament?
> > Now that's a cold 807!

On Wed, Mar 12, 2008 at 07:51:40AM -0700, jfor at quik.com wrote:
> Of course you could. The heat loss from a filament is by conduction
> through the leads, which would be unchanged, convection, which is
> essentially zero, and radiation. The only material influence would be the
> loss of heat to the filament from radiation back to the filament from the
> envelope, and that's essentially trivial.

You'd probably want to put a dust cover around it, to keep out any 
particulates generated during close-by EVA or from people and rocks
kicking stuff up on the surface of the Moon or other object. 

Various Golden-Age science fiction authors wrote about _BIG_ tubes    
out on the Lunar surface. I think it's a wonderful idea. I have this
image of a 4CX-ninety-zillion sitting out in the Lunar vacuum, under a
big bell jar, everything glowing at least cherry-red, hooked to a BIG
tank coil and thence to a BIG rhombic, but that's just me. 

Milsurplus connection: at least one of the stories had the surface-
                       mounted[1] "tube" as part of a military comms 
                       outfit. 

-- 
Mike Andrews, W5EGO
mikea at mikea.ath.cx
Tired old sysadmin