The Mullard 90C1 is a voltage regulator discharge tube. The tube will strike at 115 Volts and will regulate to 90 Volts for currents of between 1 and 40 mA. The specifications show a regulation of 14 Volts for this range of currents. This would be a wide tolerance by any standard. It is probable that this was intended to supply something like an oscillator that required sensibly constant current.

A special quality version was made and given the type designation M8206.

The thin glass tube envelope is 17 mm in diameter, and excluding the B7G base pins is 45 mm tall.

 
Pin Connections

B7G	1	2	3	4	5	6	7
	a	k	ic	k	a	ic	k

 
Absolute Maximum Operating Conditions

Stabiliser	Vh	Ah	Va	mAa
	-	-	90-115	1-40

Thanks to Frank Philipse for supplying the above datasheet

This exhibit was last updated on 05 July 2007 {find valves by name}