The ME4 dates from between 1936 and 1940. The target would have a maximum voltage of 250 at up to 2.0 mA. The grid voltage would need to change from 0 to - 5 V for a full 90 degree change in the shadow angle.
The envelope is labelled a 'Tunascope' on the side of the envelope.
The heater is twisted together in a double helix. The triode grid extends above and below the bright anode. The triode anode is connected to the helical control of the display.
The side view and the etched identification.
The display section.
The wide glass tube envelope is 26 mm in diameter and, excluding the Ct8 base pins, is 72 mm tall.
References: 1043. Type ME4 was first introduced in 1937. See also1937 adverts.