The 6F8G is a medium-μ double triode. Primary use is as a Class A voltage amplifier with resistance/capacitance coupling.
Each triode has the characteristics of the 6J5 triode. From the 1950s the ECC82 was providing almost identical characteristics in a miniature envelope.
Side view of the two triode towers.
The triode on the right has a curved anode and a cooling fin on the copper supports of the control grid.
The classic envelope is 38 mm in diameter, and excluding the IO base pins is 95 mm tall.
References: Data-sheet. Type 6F8G was first introduced in 1943. See also1943 adverts.
