The DET23 was used in airborne radio. The UK services purchased to a specification from both M-OV and Mullard. The M-OV valves had a black label and the Mullard a white label. This is the same as DET23 but with a re-entrant envelope.

Both Mullard and M-OV versions should have given the same performance, but in practice the MOV valves had a slight edge. Over time the specification from the RAF altered to favour the MOV DET23, which then took the greater part of the business.

Technically the difference in the two makes was a slightly thicker wire gauge used in the MOV for the flying leads. These were made of red platinum at 0.6 mm diameter. The thicker wire increased the problems of achieving a good durable vacuum seal, but avoided the operational dip in performance over a narrow band of frequency. The latter effect being known as 'suck-out'. The DET23 was in production from the post war period up until the mid 1950s.

Taking the TD03-5 as a model, we can infer a five Watt anode dissipation, and a 6.3 Volt heater.

This physically small disc seal valve has, of course, co-axial connections. The heater and cathode are opposite the main envelope. The grid has a circular connection to the flat internal metal mesh. The anode appears to be copper and has a flat surface facing the grid. For an example of the construction technique see CV90

A grounded grid configuration would allow for a two cavity mechanical design.

The disc seal (glass) envelope is 58 mm tip to tip and the glass is 15 mm in diameter.

 
Absolute Maximum Operating Conditions

Triode	Vh	Ah	Va	Vg	gm	μ
	6.3	0.4	350	0	7.0	70

Thanks to Frank Philipse for supplying the above datasheet

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This exhibit was last updated on 02 February 2008 {find valves by name}