The AN/FPS-26 Radar was a height finder radar used by the United States Air Force Air Defense Command. It was an early application of a concept called "Frequency Diversity", which took advantage of a tunable output power device (a 3-cavity power klystron) to allow the radar operator to easily and quickly change the frequency of the radar to avoid enemy jamming. (Earlier generation radar transmitters typically used a magnetron as a high power output generating device; the output frequency of a magnetron cannot be controlled at will.) The output power of the transmitter pulse was approximately 5 megawatts.