18 Nov
2002
18 Nov
'02
4:40 p.m.
Not too long ago I read where someone wrote that
it's impossible to
manufacture thermonic valves without a large amount of very expensive
equipment, which is no longer manufactured. Now, I've seen where some
people are experimenting with, and having some success with, making
valves/tubes at home.
The "trick" with making tubes is not so much having proper equipment
(getting a _good_ vacuum pump is not that hard these days), but how the
equipment is used. The critical point of manufacture is the very end of
the assembly process - outgassing the elements, pumping the tube, sealing,
and flashing the getter. These steps are very dependent on each other, and
timing is critical. There is quite a bit of magic at this point, and it
only comes up with years of tube building experience and lots of duds.
With practice, I suppose one could make tubes about as well as the
industry did back in the 1920s.
William Donzelli
aw288(a)osfn.org