The 6GH8 is a triode pentode designed for television receivers. The heater is rated at 6.3 Volts at 450 mA and thus can be used either parallel connected or as part of a heater chain.
The original design purpose for the pentode was as a line oscillator.
The 5GH8 is electrically identical but with a 600 mA heater.
The open end of the pentode showing that it is in fact a beam tetrode.
The beam tetrode on the left with the independent triode on the right.
The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins is 48 mm tall.
Reference: Data-sheet. Type 6GH8 was first introduced in 1959. See also1959 adverts.
