Abstract: A combination tuner and harmonic suppressor apparatus is provided for a klystron having a gap defined across a resonant cavity. The apparatus comprises a back cavity coupled to the resonant cavity by a coupling iris. Harmonic resonances within the resonant cavity are conducted to the back cavity through the coupling iris. An absorber disposed within the back cavity absorbs and attenuates the energy of the harmonic resonances. The coupling iris can be capacitively tuned to optimally conduct the harmonic frequencies into the back cavity. The apparatus further comprises an open-ended diaphragm providing a wall of the resonant cavity, disposed between the back cavity and the resonant cavity. A bellows provides a barrier between a vacuum environment within the klystron and a non-vacuum environment external to the klystron, and enables a broad range of movement of the diaphragm.

Abstract: A leaky wall filter for use in an EIK comprises a plurality of guidelets intersecting perpendicularly with a wall of an output waveguide of the EIK. The guidelets would propagate 2.pi. mode oscillation frequencies from the EIK out of the output waveguide. A load matched to the 2.pi. mode disposed at the end of the guidelets provides termination for the 2.pi. mode oscillation frequencies and prevents the initiation of oscillation. The load comprises a plenum disposed at an end of the guidelets opposite to the output waveguide, a window having a first surface within the plenum, and a water load provided at a second surface of the window. The 2.pi. mode oscillation frequencies propagating through the guidelets are impedance matched by the window and coupled into the water load for termination. Since a portion of the operating frequency power also leaks through the guidelets into the plenum due to insertion loss, this combined RF power also couples into the water load and is converted into thermal energy.

Abstract: A capacitive stub for adjusting an impedance level of an output gap of a klystron is provided. The klystron includes an iris coupling RF power from the klystron to an output waveguide. The capacitive stub extends from an inner surface of the output waveguide into a position generally adjacent at least a portion of the iris. The stub is capable of adjustment from external to the output waveguide to vary the position of the stub relative to the iris, and in so doing, change the capacitance of the iris. By changing the iris capacitance, the impedance of the output gap can be altered.

Abstract: A coupled-cavity circuit for a microwave electron tube is shown having one or more cavities whose cross-sections are polygonally shaped, such as rectangles. Located in one or more corners of the polygonally shaped cavities are irises which have a higher resonant frequency. These irises are generally triangularly shaped with rounded corners and one leg of the triangle rounded about the drift tube of the microwave electron tube.