The EM80 miniature tuning indicator produces a fan shaped display in green and this exhibit was made by Tungsram.
The original design was from Mullard who describe the EM80 as a tuning indicator for use in FM or AM receivers. The grid voltage range is 13 Volts. Electrically it is similar to other tuning indicators, the valve consists of a triode amplifier that is linked to the indicator device. The control of the image is effected by the triode cathode being connected to the display grid.
Side view: the heater enters horizontally from the right of this image. Above the wire grid are two rods that form the triode anode. The target is the large metal section in the centre.
The target is at the top with a shielding plate below hiding the triode section.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 57 mm tall.
References: Data-sheet & 1040. Type EM80 was first introduced in 1954. See also1954 adverts.