The CV121 is a directly heated high voltage high vacuum half wave rectifier. The 19H1 is the commercial equivalent but the V1920 was the prototype.
The pressed metal anode is carbonised to radiate more heat and so allow the valve to run cooler. The construction is rugged.
As Zaerix were a reseller the original identification has been removed.
The side flange is placed at the centre of heat generation by electron bombardment.
The other side.
The tension springs secured in the ceramic top support. The filament can clearly be seen to be oxide coated.
The base end showing the lower ends of the filament. These ends are held in folds of the supports and this suggests that the base wire for the filament is tungsten - too high a melting point to spot weld.
The wide glass tube envelope is 51 mm in diameter and, excluding the B4 base pins, is 174 mm tall.
