Sensibly equivalent¶ to:
This valve is marked VR123 and carries the Air Ministry logo. The commercial equivalent is the variable μ pentode EF8. The literature shows four grids for this valve, and EF8 explains the use of the fourth grid.
The side contact base was reported to cause contact difficulties and was not popular with UK servicing technicians.
The variable μ amplifier pentode would be used in AGC controlled stages of superhet receivers.
The classic envelope is 29 mm in diameter and, excluding the Ct8 base pins, is 82 mm tall.
References: Datasheet & 1043. Type VR123 was first introduced in 1938.
Absolute Maximum Operating Conditions¶
Updated December31, 2012. shape:classic construction:pinch type:pentode age:1930.1940 base:ct8 heater:6.3v pins:8 pin:1.m pin:2.h pin:3.h pin:4.k pin:5.g4 pin:6.g2 pin:7.g3 pin:8.a pin:tc.g1