George A. Philbrick
en.wikipedia.org
en.wikipedia.org
http://www.philbrickarchive.org/k2-w_refurbished.pdf
+-300V supply + 6.3V heater. Amazing little thing. And technically this is an integrated circuit.
The plot thickens:
https://web.archive.org/web/20040417203904/http://www.eetime...
Fascinating stuff this.