Abstract: A borided dispenser cathode of the type including a metallic base material is made by cleaning the cathode by annealing it in a hydrogen-containing atmosphere, depositing boron on the cathode by heating the cathode in an atmosphere containing a gaseous boron compound, and forming a boride of the metallic base material by heating the cathode to its operating temperature in a non-reactive atmosphere and maintaining the temperature for a time period sufficient to enable deposited boron to combine with the metallic base material.

Abstract: A simple but effective filter attenuating one or more frequencies other than the fundamental frequency of a magnetron is provided in the magnetron. The filter comprises one or more stubs each of which extends along one side of an output probe connected to an anode vane of the magnetron. Each stub forms a slot which has an effective electrical length of a quarter wavelength at the frequency to be attenuated by the filter. The probe may be a metal strip and the stub, may be a lug formed by cutting in the strip a mainly longitudinal slot which opens into a side edge of the strip.