The VT45 is a battery RF triode with a 3.5 Watt anode dissipation and a working frequency up to 20 MHz. The prototype was the M-OV X56. The later CV code was CV1045.
The base shell is ceramic and this has a lower loss at RF at high humidity. VT is the RAF code and this was very likely used in an aircraft transmitter.
The gettering is on one side only and the other reveals the construction.
The circular anode and top mica gripping the glass.
The filament passes through the grid four times and the hairpins at the top are held by two helical tensioning springs with hooks to hold the oxide coated filament.
An enhanced image reveals the M shaped filament and two sets of grid wires. The inner is the control grid and the outer set is strapped to the anode.
The classic envelope is 45 mm in diameter, and excluding the B4 base pins is 92 mm tall.
