The VT61A transmitting double triode was designed for use up to 150 MHz. It was made by Rogers of Canada and carries the Air Ministry markings. The VT prefix is an Air Force designation.

The operating parameters given are from the 4074A and this was a UX7 based valve. The 4074B is a B5 based valve of pinch construction in a classic glass envelope. The anodes are brought out to separate top caps.

Triodes were favoured for transmitter work over tetrodes because of lower capacitances and an ability to be driven harder. This valve was designed to pass a grid current of 17 mA.

The classic envelope is 46 mm in diameter and, excluding the B5 base pins, is 110 mm tall.

 
Absolute Maximum Operating Conditions

Triode	Va	Vg	mAa	Pdriv	Pout
	300	-50	90	1W	15W

This exhibit was last updated on 08 August 2006