The CV1503 is an audio output pentode/beam tetrode based on the M-OV KT33C. The old RAF service code is VR503.
The M-OV etched lozenge carries the commercial designation of KT33C.
The heater wire is made into a coil to fit the required length into the available space. The two sections are in series.
The dome is left clear and the heat radiating fins attached to the copper supports of the control grid can be seen. The S shaped wire connects the two beam plates to the central cathode.
The classic envelope is 44 mm in diameter and, excluding the IO base pins, is 103 mm tall.
Reference: Data-sheet. Type CV1503 was first introduced in 1938. See also1938 adverts.
