English: The Eimac 2-50A, a high power diode vacuum tube, used in radio equipment to convert alternating current to direct current. The terminal at the top of the tube is attached to the cylindrical plate electrode, at center. The two wires at bottom support a filament, not visible inside the plate. When the tube is operating, electrons emitted from the hot filament travel to the plate, allowing current to flow in one direction, but not in the opposite Idirection, rectifying. The datasheet says the tube has a maximum DC plate current rating of 75 milliamps, maximum peak plate current rating of 1 ampere, maximum power dissipation of 30 watts, and a maximum peak inverse voltage (PIV) rating of 30,000 volts. In a half-wave rectifier circuit with a capacitor input filter, a single 2-50A can deliver 12,500 V DC at 60 ma from a 10,600 V rms supply. The filament voltage is 5 v. Datasheet can be found here.