English: A 5 kW klystron vacuum tube, from an advertisement by Eitel-McCulloch Co. (Eimac) in a 1952 radio magazine. The klystron is a specialized linear beam transmitting tube used at high frequencies. This one was designed for use as the final amplifier in UHF television transmitters. The right end of the tube contains an electron gun, which emits a high energy beam of electrons which is absorbed by a collector electrode in the left end. A series of cavity resonators are installed along the tube. The UHF television signal to be amplified is applied by a coaxial cable to one resonator, called the "buncher". This causes the electrons to form bunches. The bunches excite a more powerful radio signal in a second cavity, called the "catcher", from which the output signal is taken. The source did not give any details about the tube.

All the contacts on the tube are in the form of metal rings rather than pins as in ordinary vacuum tubes, to reduce the parasitic inductance, which can cause instability and parasitic oscillation at the high frequencies used.

Alterations to image: Cropped out surrounding ad copy.