High power coaxial cavity resonator tunable over a broad band of frequencies

An output coaxial cavity for high power electron tubes is described in which the output coupler is directly connected to an intermediate coaxial conductor of the coaxial cavity at a distance from the tube that is greater than one-quarter wavelength and less than one-half wavelength over the tuning range of the cavity. The intermediate coaxial conductor is spaced between and concentric with an inner conductor and an outer conductor of the coaxial cavity. A first shorting stub is positioned between the inner conductor and the intermediate conductor and a second shorting stub is coupled between the intermediate conductor and the outer conductor. The positions of the shorting stubs are arranged to resonate the cavity at the desired tuning frequency.