abstract:The inductive output tube (IOT) or klystrode is a variety of high frequency transmitting linear-beam vacuum tube, similar to a klystron, which evolved in the 1980s to meet increasing efficiency requirements for high-power RF amplifiers. The primary commercial use of IOTs is in UHF television transmitters, where they have mostly replaced klystrons because of their higher efficiencies (35% to 40%) and smaller size.