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 3KV 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 2.5kV on the anodes the push-pull pair would produce 425 Watts when used in Class AB2.
The anode is supported from the top cap and has six extended flanges in an hexagon around the cylindrical anode inner space. The glass to metal seal for both the top and side caps contains uranium glass as can be seen by the green/yellow colour of the glass at these points.
The anode with supporting bell. The underside shows the grid cage with helical retaining wire.
The grid cage seen from below with helical filament within.
The support rod from the top cap is joined to the bell with tape welded in place the bell then connects to the anode. It can be seen that the grid cage extends beyond the anode and into the bell above.
The balloon envelope is 78 mm in diameter, and excluding the UX4 base pins is 176 mm tall.
References: Data-sheet. Type 100TH was first introduced in 1949. See also1949 adverts.