The PV4200 is a full wave rectifier from Tungsram. The valve is directly heated.
The filament tension springs are held in a glass rod placed between the anodes and fixed to the anode supports.
The Filament is oxide coated ribbon.
The identification is printed on the dome together with the operating details. The filament is open circuit and in the foreground can be seen the broken ribbon.
Here the lettering has been mildly enhanced.
Top view.
The balloon envelope is 53 mm in diameter and, excluding the B4 base pins, is 111 mm tall.
Reference: Data. Type PV4200 was first introduced in 1931. See also1931 adverts.
