The 100TH is an RF power triode with a thoriated tungsten filament and an anode dissipation of 100 Watts. It is designed for use at HF up to 40 MHz and with 3 kV on the anode a Class C RF amplifier can deliver 400 Watts.
Details are given for a pair to be used for audio modulator or amplifier service. With 2.5 kV on the anodes the push-pull pair would produce 425 Watts when used in Class AB2.
The Eimac brand, Made in USA and the VT-218 equivalent designation.
The side contact for the control grid and the pinch and stem are made from uranium glass to match the coefficient of expansion of the glass to the metal - possibly tungsten.
The anode cylinder has four small side flanges. The base is ceramic for good RF stability at altitude or in humid conditions.
The green/yellow of the uranium glass as the intermediate material between the metal and the envelope glass. The control grid is a cage of vertical wires held in place at both ends and with a helical wire around the outside. The filament is also a helix.
The balloon envelope is 80 mm in diameter, and excluding the UX4 base pins is 175 mm tall.
References: Data-sheet. Type 100TH was first introduced in 1949. See also1949 adverts.
