Broad band frequency tuning of the split cavity oscillator

Summary form only given. Two methods of frequency tuning of the split cavity oscillator have been investigated. The first makes use of the fact that the cavity resonance depends on the total beam current present. As the beam current increases, the cavity is more heavily loaded and the resonant frequency is pulled higher. Frequency tuning is achieved by adjusting the diode gap to increase or decrease the injected current. While this technique works, it has the disadvantage that the beam power must be changed in order to set the frequency. A more suitable method is to modify the cavity itself by inserting a series of inductive posts radially between the outer wall and the central grid. In this way, the operating frequency can be adjusted over a 200-MHz range while maintaining constant tube power. These two techniques have been compared, and the effects of frequency tuning on tube performance and extractor efficiency have been investigated.