Sensibly equivalent¶ to:
This valve has a service marking. The actual type of valve is an L2. Many similar types existed.
Our specimen is new and came on a small wooden mounting block.
The directly heated filament is designed to be run from a 2 volt accumulator, and takes the form of a fine wire supported as an inverted "W'. The grid is supported on notched round supports and is of flat zig-zag construction enclosing the filament. The anode box is made of two shaped metal plates that are flat across the width and height but open top and bottom.
From its appearance, the valve was probably used for low frequency radio reception.
The balloon envelope is 41 mm in diameter and, excluding the B4 base pins, is 97 mm tall.
References: Data-sheet, 1043 & 1040. Type VR21 was first introduced in 1929.
Absolute Maximum Operating Conditions¶
Updated April 03, 2015. shape:balloon construction:pinch type:triode age:1920.1930 base:b4 heater:2.0v pins:4 pin:1.a pin:2.g1 pin:3.f pin:4.f