Behold, Pete KE9OA signalled from keyed 4-1000A filament:

That's a definite...........LED backlighting is the way to go. It
sounds like you are in the industry.

Pete

My work is repairing, my hobby is designing. I currently have an all-tube
SW receiver on the go ;-)

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