The ECH42 is a triode hexode mixer in an all glass envelope fitted with a B8A base and designed for radio receivers. This exhibit was made outside the UK and has yellow lettering and so was possibly made in 1969, the year of the Mullard 50th year celebrations.
See alsoUCH42 with a 100 mA heater for series heater chains.
The outer expanded metal screen hides most of the inner detail. The base seal between the hard glass foot and the soft glass envelope looks typical Philips. The locating pip can be seen on the right and this all glass style was the final version of the B8A based valves.
The triode oscillator is located at the top of the envelope and the control grid is wound on copper supports.
The thin glass tube envelope is 20 mm in diameter, and excluding the B8A base pins is 53 mm tall.
References: Datasheet & 1040. Type ECH42 was first introduced in 1949.