The 6H8 is a metal envelope double diode triode and is another implementation of the final valve in the magic three series. The double diode triode acting in a superhet receiver as signal detection, AGC detection and first audio amplifier.
The reverse is plain.
The top cap insulator sealed into the metal can.
The IO base with the lugs of the can bend to hold the plastic base cap in place. The metal can we see is non-ferrous and there is no magnetic attraction - thus no steel inner can.
The wide metal envelope is 31 mm in diameter, and excluding the IO base pins is 90 mm tall.
References: Data-sheet & 3002. Type 6H8 was first introduced in 1939. See also1939 adverts.
