The B7G voltage stabilisers were the last to be developed before semiconductor zener diodes took over as voltage references. The commercial 0B2 was also used by UK government departments including the BBC and to encourage several manufacturers to make the product a CV (common valve) specification was issued from 1941 onwards.

The regulation of this tube was 3.5 Volts for currents of between 5 and 30 mA. So the voltage across this tube in service would have been held at between 106 and 110 volts. The striking voltage was 133 volts.

The thin glass tube envelope is 18 mm in diameter and, excluding the B7G base pins, is 45 mm tall.

References: Datasheet & ¹⁰⁴⁰. Type CV1833 was first introduced^¶ in 1957.

 
Pin Connections

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

 
Absolute Maximum Operating Conditions^¶

Stabiliser	Va	mAa
	108	30

Thanks to Frank Philipse for supplying the above PDF datasheet