The VT-200 is the American procurement code for the 0C3 cold cathode voltage stabiliser. The design has several names, the RAF VR105/30 included.
The basic operation conditions are contained in the 105/30 of the alternate type code. This tube will stabilise the voltage across it to 105 Volts for output currents between 5 mA and 40 mA. To strike the tube the voltage must exceed 135 V.
As with all such stabilisers the voltage will vary slightly with the current drawn. For this stabiliser the figure is 4 Volts across the current range. For making a stabilised power supply the reference tube would be run at as close as possible to a constant current. For general use the circuit designer would try to minimise the variation on load on the stabiliser.
The silver gettering hides most of the internal structure.
The United States Navy logo on the base cap. The construction is a cylindrical outer cathode with a central rod anode.
The classic envelope is 38 mm in diameter and, excluding the IO base pins, is 87 mm tall.
References: Data-sheet & 1040. Type VT-200 was first introduced in 1939. See also1939 adverts.
