The Triotron G4120 is a directly heated full wave rectifier. The maximum input voltage is 500 Volts and the rectified current is up to 120 mA. The G4120N rectifier has the same HT rating but is indirectly heated and the anodes are different.
The T shaped anode with a single inverted ribbon filament within.
Here the filament ribbon can be seen. Above the top mica are the tension springs holding the top of the coated filament.
The centre supports have the tension springs welded to them. The side mica rectangles hold the electrodes firmly against the walls of the envelope.
The classic envelope is 44 mm in diameter and, excluding the B4 base pins, is 100 mm tall.
Reference: Data. Type G4120 was first introduced in 1934. See also1934 adverts.
