TV IOT: Achievements and Prospects

An opportunity of IOT gain increase more than 12 dB is considered using two-gap input cavity with unequal rf voltages across gaps. A new approach to IOT efficiency increasing is proposed using interaction of the beam with two harmonics in output section (class F). Such a mode allows achieving maximal efficiency up to 74%. Device linearity can be improved provided low-frequency video signal at the tube input (dynamical bias)