Earth station klystron amplifier, c 1980.

A klystron is an electron tube that generates or amplifies microwaves by velocity modulation. This type of amplifier is designed to be used on the uplink transmitter of a satellite ground station. It operates at 5.925-6.425 GHz with a minimum power output of 3 kW. High power klystrons such as this are the only devices able to deliver enough power for satellite communications.