The CV430 is a directly heated diode with an inverted 'W' single strand filament.
The KB/F identifies this valve as being made to specification K1001 or K1006, the B denotes qualification by a UK authority and the F identifies the maker as STC, Paignton.
The bright anode with the twin V filament loops held in the hooks of the tension springs.
Edge view.
Face view. The filaments are wired in parallel.
John Rehwinkel has supplied data on this exhibit. It is a temperature saturated diode and it was used to measure and regulate voltages. The method was to place the voltage to be measured across the filament and monitoring the anode current. Tektronix used a 2AS15 for the regulation of filament current in some oscilloscopes.
The wide glass tube envelope is 29 mm in diameter, and excluding the IO base pins, is 60 mm tall.
References: Data-sheet & John Rehwinkel. Type CV430 was first introduced in 1961. See also1961 adverts.
