Broadband frequency stabilization of a reflex klystron by means of an external high Q cavity

The cavity frequency stabilization system operating over narrow frequency bands described previously has been extended for 40% bandwidth operation in rectangular waveguide. The development of a variable coupling type high "Q" cylindrical stabilization cavity and a compact phase shifter-mode suppressor required for the system is discussed. These components operate over the entire 8,200 to 12,400 Mcs./sec. bandwidth of 1" 1/2" rectangular waveguide. The system has been applied to two klystrons differing electrically. An improvement in the frequency stability of these klystrons by factors between 4 and 40 has been attained, with a power loss from 10 to 20 DB., depending on system adjustments. The frequency stabilization system can be applied to most klystrons operating into 1" 1/2" waveguide.