The CV90 disc seal triode was used in a post WW2 type 505 British Naval transmitter.

The small closed cylinder at the bottom is the heater/cathode assembly. The top circular surface is flat and faces the grid wires that can be seen running vertically. The anode is the disc seen behind the grid mesh. The latter disc is the tip of the anode that extends into the large circle of copper.

Small disc seal triodes like this were also used in signal generators.

The re-entrant envelope provides access to a coaxial heater connection. The grid connects to the smaller ring and the anode connects to the wide copper disc.

The thin glass tube envelope is 19 mm in diameter and, excluding the base pins, is 75 mm tall.

This exhibit was last updated on 13 February 2004