The CVX397 looks like the M-OV DET24 and the style of the paper label also looks M-OV. However, we can find no operating details to confirm the visual similarities. The DET24 can produce up to 10 Watts at 2 GHz.
The valve is designed to be fitted into cavity with the re-entrant top acting as the knob to insert and withdraw the valve. The heater connects to the pin and the heater and cathode connects to the first ring. The grid disc is brought out to the middle ring and the anode connects to the flanged ring.
The re-entrant top of the valve.
The cathode end. The grid wires are secured to a retaining plate much like a frame grid would be. The small separations between the active elements require that the grid wires be held tightly in place and do not move when hot.
The anode has an open cylinder of thin metal fixed above the connecting ring and to this cylinder is connected the getter holder.
The planar envelope is 21 mm in diameter, and including the base pins is 70 mm tall.