The ML-6442 or 6442 is a planar UHF triode for use up to 5 GHz and it has an 8.0 Watt anode dissipation. The valve is designed to be mounted in a co-axial cavity. The design use is for both CW and pulsed operation.
The heater and cathode connections. The central disc connects to the grid that sits across the width of the valve as a disc.
The makers name and country of origin as seen from the anode end.
The ceramic rings separate the grid from the other electrodes.
The disc seal ceramic envelope is 10 mm in diameter, and including the connections is 61 mm tall.
Reference: Datasheet. Type ML6442 was first introduced in 1964.