6F8G GE black parallel ribbed plates NOS 1940”s (6.2ma/7.2ma)

6F8G GE black parallel ribbed plates NOS 1940”s

6.2ma Gm=2500

7.2ma Gm=2800

Good Ma range 7-9ma

Good Gm range 2400-2600

NOTES:

GE, Sylvania and Raytheon have mirror image parallel black plates

RCA and Ken Rad have staggered black ribbed plates

6F8G dual triode = (2) 6J5G”s triodes in 1 tube