RS McCown wrote:
This doesn't answer any questions, but Mullard made filiments like so.
http://www.r-type.org/static/add045.htm
http://www.r-type.org/static/add044.htm
Tungsten wire making goes on today in a big way because of the many
different applications of the use of tungsten.
Its a tough metal with a melting point over 3,400 degrees centigrade
making it ideal for a tube cathode or a tube cathode heating element
where if it runs at about 900C it is under little stress and very
unlikely to easily fail, especially in a vacuum of a tube.
So no need to feel anxious about the tube cathodes stressing out. They
are very reliable.
Unless some idiot connects too much voltage and current.
http://www.tungsten.com/mtstung.html
Also of interest about tungsten,
http://www.tungsten.com/tunghist.html
Its easy to take this stuff for granted but without tungsten we might
not be able to have tubes.
Patrick Turner.