"Phil Hobbs" wrote in message
m...
SNIP

Aren't the filaments welded to the elements at the ends? It would seem
that
this would cause a narrowing. ISTR most filaments broken near the
supports,
which would be counter to the hotter-in-the-middle theory.

The feedthroughs are made of Dumet, which is basically 42Ni stainless with
a borated copper coating to bind to the glass. It's much lower-melting
than the tungsten, so spot-welding them together shouldn't affect the
tungsten much.

Just crimped over AFAIK. Should work fine - the softer metal will cold form
around the tungsten see

http://upload.wikimedia.org/wikipedi...8/Filament.jpg


I've never seen one burn out that wasn't energized.

They can, but no very often.

But you're the big-iron transmitter guy. Gotta run, I have a bunch of
guys coming to the lab in a few minutes, and I have to start the coffee
pot!

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics