Behold, Kirk Mohror signalled from keyed 4-1000A filament:

I am now looking for schematics, articles, web sites ect., for those
tubes that I have.

Check the links on my site. I have a few articles there too.

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