Tiny GE 7077 UHF planar triode, measuring 12x12mm (the penny is 20mm across). 6.3V/240mA heater. This little valve is designed for use in grounded-grid amplifiers. It was used as a Class B final amplifier in the Pioneer III space probe.
Markings are 67-39 and 68-04.
Heater connections are the buttons at the bottom, the grid connection is the ring, and the anode is the plate on top.
Thanks to John Kaesehagen for this info, and Dave for the extra additions to the collection.
This file was last modified
14:56:18, Tuesday September 02, 2014