Abstract: An adjustable feedback in a pencil tube oscillator is provided by a pick-up element closely spaced from the center conductor of the output cavity of the oscillator with the pick-up element connected via a short length of rigid conductive wire to the cathode electrode in the input cavity. This pick-up element is a thin sheet of deformable conductive material fixed to the end of the rigid wire in a manner that permits the sheet to be easily bent toward or away from the center conductor to accommodate adjustment of the feedback coupling capacitance.

Abstract: An output coupler for a radio frequency oscillator includes a coaxial transmission line connector having a center conductor terminating in a coulping loop in the oscillator, the terminated end of the loop being secured to the cavity wall of the oscillator. Both the magnitude and depth of penetration of the loop are concurrently adjustable without altering the orientation of the loop by sliding the transmission line and center conductor with respect to the cavity wall. When optimum coupling is achieved, the transmission line connector is clamped in place.

Abstract: 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.