The IW4-500 is an indirectly heated full wave rectifier that was designed to work with a maximum reservoir capacitor of 16 µF and to have an effective series resistance of 150 Ohms. At 500 Volts and 125 mA this rectifier would supply the needs of equipment of between 50 and 60 Watt consumption. The cathode is connected to one side of the heater.
The the anode is mounted high in the envelope.
The twin anodes.
Top view showing the mica disc tightly gripping the shoulder of the envelope. The cathodes are rectangular.
The classic envelope is of classic shape and 45 mm in diameter. The length excluding the B4 base pins, is 102 mm.
References: Data-sheet, 1040 & 1043. Type IW4-500 was first introduced in 1939. See also1939 adverts.
