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

WD2XEQ, AMBIENT CORPORATION, 0118-EX-PL-2003
New experimental to operate in 1.7-88 MHz for testing power line
carrier systems. Fixed: States of NY and MA

--Thanks to Bob Gonsett

Heh, your neighbors with digital appliances will love you ;-)

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