The UM4 tuning indicator from Mullard has dual sensitivity. The grid voltage change can be 4.2 V or 12.5 V.

The control element is clearly visible in the centre of the picture.

The wide glass tube envelope is 26 mm in diameter and, excluding the IO base pins, is 73 mm tall.

See also EM4.

 
Pin Connections

IO	1	2	3	4	5	6	7	8
	h	ic	a(2)	t	g1	a(1)	k	h

 
Absolute Maximum Operating Conditions

CRT	Vh	Ah	Va	mAa
	12.6	0.1	300	1.4

Thanks to Frank Philipse for supplying the above datasheet

This exhibit was last updated on 12 June 2007 {find valves by name}