The Radivac valve was made in Holland and is a bright emitter triode. The data-sheet packed with the valve states that with 160 Volts on the anode, the emission allows for loud speaker working.
The bulb is coated with silver gettering but here the pinch can be seen. The B4 base pins have the lower part of the pins of reduced diameter and split to grip the valve-holder.
By looking up from the base the horizontal electrode structure can be seen. The anode is a sheet coiled into an open cylinder, the control grid is a helix and the filament is a single strand passing centrally through the grid.
The data-sheet that was packed with the valve.
The balloon envelope is 40 mm in diameter and, excluding the B4 base pins, is 73 mm tall.
Reference: Data-Sheet. Type Radivac was first introduced in 1924. See also1924 adverts.
