The CV31 is a directly heated full wave rectifier and essentially the U20 from M-OV.
This exhibit is new and unused.
The maximum reservoir capacitor is 4 µF and the minimum series resistance specified is 150 Ω.
The cathode is an oxide coating on a thin ribbon filament that has a single hairpin fold at the top and is held in place in a slot in the top mica. The anode is blackened to form a better radiator.
The KB/T identifies this valve as being made to specification K1001 or K1006, the B denotes qualification by a UK authority and the T identifies the maker as British Tungsram, Tottenham.
The twin anodes with coated ribbon filament within.
The filaments are wired in series and form an inverted V. The anodes are wider than essential to give greater area for heat dissipation.
The filaments are looped over the top mica and thus fitted into the anodes and finally welded to the supports at the base
The classic envelope is 45 mm in diameter and, excluding the B4 base pins, is 112 mm tall.
