The effects of variable load on the abrupt change of power output and discontinuity of oscillation of a. reflex klystron are investigated. The reflex klystron under study is of metal construction with integral resonant cavity operating in the "X" band.Analysis is made of the effects of overload

long line

multiple transits of electrons

parasitic resonance and imperfections in the design of the integral resonator.Among the factors which affect the load characteristics the most important one is shown to be the design of the resonator

especially that of the distribution of side and gap capacitances as well as the curvature of the grids in the gap.The theory of parasitic resonance is briefly treated

and the experiments which have been performed to locate the parasitic resonance are described. Finally

a method of eliminating the parasitic resonance is illustrated.