The CV90 is a disc seal triode developed during WWII to operate at frequencies up to 3 GHz. The DET22 was an improved higher performance replacement for the CV90 that was developed during the war.
The CV90 disc seal triode was used in a post WWII 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 and has about a 10 W dissipation limit. 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 grid ring in the centre and the wide anode connection disc that would be clamped into the cavity the valve worked within.
The heater connection pin, heater and cathode connection within the re-entrant base tube. The cathode is coated on the top surface of the small bright cylinder. The grid is clamped to the grid ring and the anode is set closely behind the mesh.
The fine grid wires are wound onto a metal plate and it is thus of frame grid construction. The grid wires are on one side of the plate only and so after winding and sealing to the plate the wire not required is removed.
The valve is new old stock and came in this substantial card box.
The tray at the base has a hole for the anode end of the envelope.
The top tray mates with the lower tray providing a flat surface to hold the thin anode disc.
The valve located within the top tray.
The small valve alongside the large two part box. Overall two of the sides are three thickness or 3 mm thick as the outer box has card stuck within as extra protection.
The thin glass tube envelope is 20 mm in diameter and, excluding the base pin, is 75 mm tall.