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2K25 Klystron and Mount

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This exhibit is an example of a low power (20 mW) commercial X-band Klystron and mounting arrangements. The style of the screw valve retainer is in keeping with the EF50 retainers employed in WW2 for air-borne equipment to prevent valves from being shaken loose in flight. The 2K25 is an equivalent of the KS9-20D.

Seen on the left near the top of the valve is part of the external mechanical frequency adjustment mechanism. This would normally be connected to a linkage to the equipment front panel. By deflecting the adjustment arm the internal cavity size would be changed and thus the resonance point of the cavity.

The assembly is based on waveguide 16. The closed end of the waveguide is fixed, in amateur designs a sliding short is often to be found to achieve optimum match. The adjustments that are available operate on the waveguide opposite the probe entry. The actual details are obscured by the shielding plates.

The Klystron adjustment arm can be seen on the right of the picture. As the screw is turned the thin plates are forced apart and the effective length is changed. This length change is then passed as a smaller movement in the top lever, and the latter is directly coupled to the corrugated top plate of the cavity. Even with these reduction devices the setting of the mechanical frequency control would be a critical operation.

The CV2792 is the actual valve fitted. The CV or Common Valve designation was introduced by the UK Government in 1941 to rationalise the purchase of valves for all armed services and other government departments. The CV reference was accompanied by a detailed specification and was usually based on a commercial design but normally with slight variations to meed a particular need.

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