This compact pulse magnetron, produced by the English Electric Valve Company, was designed for use in marine radar systems. Derived from the 2J42, the M558 operates in the X band and has a power output of 8 kilowatts. The M558 is designed to be mounted in an external cavity, which would include the large curved magnets necessary for the tube's operation. Interestingly, the tube's 6.3 volt filament is brought out to a standard bayonet lamp connection, similar to the type used on an ordinary flashlight bulb. In operation, this filament connection would poke out through a hole between the two curved magnets on the external cavity. The example shown here was still packed in its original carton, which includes a thermoformed Styrofoam clamshell to protect the tube during transit.
Special thanks to Antony Evans for providing this unusual part.
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