The CV397 (commercially the DET24) is a disc seal triode based on the VX3058. In use the valve would be fixed into a pair of cavities. The grid is a fine mesh and the anode is in close proximity to the grid. The central base connection is one side of the heater and the surrounding tube connection is the other end of the heater and the oxide coated cathode.
The CV397 design date from the latter part of WWII. It could produce up to 10 Watts of output at frequencies up to 2 GHz.
The KB/Z identifies this valve as being made to specification K1001 or K1006, the B denotes qualification by a UK authority and the Z identifies the maker as MO Valve Company, Hammersmith.
This envelope is a pointed tube, whereas CV397 and DET24 have re-entrant top tubes that allows for a shorter length by up to seven millimetres.
The flanged ring connects to the anode and the cylindrical ring connects to the grid. The latter is almost impossible to see but is a disc with fine wires stretched across it - an early frame grid in effect. The spacing between anode, grid and flat topped cathode is very small.
An attempt to see the grid. The cathode connects to one side of the heater.
The planar envelope is 21 mm in diameter, and is 72 mm tall.
