The 6AK5 is an amplifier pentode that is physically small and the electrode assembly is no more than a 10 mm cube. The use of this device lay in low noise RF amplification at VHF.
The ugly term foreign used as British was suggested to be the best at the time. Later non domestic production was labelled imported as the public grew used to the fact that Japanese and German products were much admired - and purchased.
The open ends of the anode give a clear view of the inner grids and show the relative spacing of the turns and their distance from the cathode.
The thin glass tube envelope is 18 mm in diameter and excluding the B7G base pins, is 37 mm tall.
References: Data-sheet & 1040. Type 6AK5 was first introduced in 1942. See also1942 adverts.
