Behold, harry signalled from keyed 4-1000A filament:

Wow! Thanks! Cool pics! I'd like to find something like that on eBay!
It sure would make a neat lamp, or tesla coil! Harry

There's a bigger one too, but I can't remember the URL. It was used by
an American propaganda station beaming programming to Cuba, IIRC. It's
all glass, about 6' high and was a self-contained oscillator and 500KW
power amplifier. Only three were ever made.

--
Gregg
*It's probably useful, even if it can't be SPICE'd*
http://geek.scorpiorising.ca