The Z63 amplifier pentode was designed as a low noise audio pre-amplifier and was first seen at the Radio Show in 1937. This M-OV experimental valve is considered to be a prototype of the Z63.
looking up from the base reveals the three wire grids of this pentode. The anode is a bright cylinder just inside the outer grey screen.
The control grid is wound on copper supports and connects to the top cap.
The wide glass tube envelope is 29 mm in diameter and, excluding the IO base pins, is 88 mm tall.
References: Data-sheet & 1040. Type E2192 was first introduced in 1937. See also1937 adverts.