Behold, Michael Dunn signalled from keyed 4-1000A filament:

Thanks to all so far for the various comments. I guess i should have
explained my design philosophy for this a bit.

I don't want to do anything fancy, like DSP or even synthesized tuning.
But, I don't want to go for a minimalist six-transistor design either!
;-) And I certainly don't want to use a radio-on-a-chip! I do want
something of good quality in the end.

Hmmmm, some 12AT7's, a 6U8 mixer..... ;-)

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