The VI103 'magic eye' tuning indicator is housed in a tubular envelope with the electrodes held in a glass pinch. The leads from the pinch are connected to pins in the International Octal base.
The triode requires a grid voltage change of 22 Volts for maximum visual change. The display is green.
This is a second generation indicator with a 6.3 Volt heater. This type of indicator was used in many radios including the R1155.
The CV1103 was the Common Valve name after 1941 for the existing NR69 and VI103.
The Crown and AM on the glass indicates the UK Air Ministry.
The anode of the amplifier is connected to the flat control electrode that passes into the display bowl.
The end window envelope is 28 mm in diameter and, excluding the IO base pins, is 87 mm tall.
References: Data-sheet, 3002, 1043 & 1040. Type VI103 was first introduced in 1937. See also1937 adverts.
