The Mullard 85A2 is a small, special quality voltage stabiliser. The striking voltage is 115 Volts and the maintaining voltage is 85 Volts. For a tube current variation of 1 mA to 10 mA the voltage regulation is 4 Volts.

This valve would have been used to directly stabilise the voltage for an oscillator or be employed as a voltage reference for a stabilised supply. In the latter case the tube would be operated at constant current.

The interesting thing about this exhibit is the identification label. This places this valve within the BBC in 1954. This valve was also used in UK government equipment under the reference CV449.

The thin glass tube envelope is 17 mm in diameter and excluding the B7G base pins, is 46 mm long.

 
Pin Connections

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

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This exhibit was last updated on 02 December 2007