Re: VTTC Tubes

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "David Speck by way of Terry Fritz <twftesla-at-qwest-dot-net>" <dspeck-at-relex-dot-com>

Winston,
The problem is that your lithium would not get rid of the nitrogen in the
tube, which makes up about
80% of the atmosphere.  Even if the oxygen were entirely consumed, your
tube would contain Nitrogen
and Argon gas at a pressure of about 608 mmHg , making it a very gassy tube
(more or less a poor
quality neon sign) with very lousy to nonexistent amplification
characteristics.  The tube would arc
continuously when the ionization voltage of the nitrogen was exceeded, but
you wouldn't  any
amplification.   Electrons from your filament will be bumping into gas
molecules rather than flying
straight to the anode.

The article previously cited showed that commercial vacuum tubes were taken
down to vacuums of about
1 micron  (0.001 mmHg), a whole lot less pressure than the arrangement you
would propose.

Sorry,
Dave

>      Evacuating the tube would be crude, but possible (no vacuum pump).  The
> getter, which in this case would be lithium (extracted from lithium
> batteries), is cut into strips, and dropped through the hole in the top
> of the tube into a pan mounted to the top of the filament/grid module.
> Now the fun part!  Oxygen is jetted in through the hole, displacing the
> air in the tube.  The plug is then screwed down tight, sealed (brazed),
> and the whole tube is placed in a hot oven for a few hours.  During this
> time, the lithium ignites, and consumes the O2 in the tube.  This system
> gets rid of the leftover noble gas problem.
>
>         Some of the evacuation procedure is questionable, but I will test it.
> I have some experience with lithium, and believe that this MIGHT work.
>
>         The design is hard to follow, but it is a bit clearer in my mind.  It
> sure would be nice if we could find an alternative to expensive tubes.
>
> Thanks for putting up with my stupid ideas. :-/
> Winston
>
> PS- I'll try a diode first, to test the idea.