866 A ULTRON

http://en.wikipedia.org/wiki/866A

866 A Mercury Vapor Diode with a peak inverse voltage of 5Kv and peak anode current of 1 ampere. Average anode current, 250mA, forward drop, 15 volts. Heater voltage and current, 2.5 at 5A. American 4-Pin(UX) base.

"so amazing ...."