The construction follows the usual pattern with the triode like amplifier above the pinch and the display viewed through an end window. The screen is circular and the central electrode is a small black button. The full display range is given for a 22 Volt alteration in grid voltage.
The Marconi paper label.
Side view of the voltage amplifier triode with the display above.
The triode anode connects to the display control electrode. The display bowl is fixed to a thin plate under the top mica and this connects to the side rods and thus connects to the target.
The display: the coated cathode has a grid around it and the bowl has a green phosphor coating.
The wide glass envelope is 28 mm in diameter and, excluding the IO base pins, is 85 mm tall.
Reference: 1040. Type Y61 was first introduced in 1939.