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Varian VA-842 klystron
Varian Associates (Palo Alto, Calif.)
Date Created and/or Issued
1959/ /
Contributing Institution
History San Jose Research Library
History San Jose Online Catalog
Rights Information
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This 1959 Varian Klystron (VA-842), a liquid-cooled, multicavity radar transmitting tube, was the largest documented production klystron. It was used in the Ballistic Missile Early Warning System, a Cold-War radar system designed to detect Russian missiles and aircraft. The original exhibit label from the Perham Collection reads: "This giant liquid-cooled, multicavity radar klystron was, in 1959, the largest (physically) production kystron in the free world. Hundreds of these klystrons were manufactured for the Ballistic Missile Early Warning System (BMEWS) by Varian Associates and Litton Industries. The BMEWS radar system was designed to pinpoint a Russian missile shortly after it was launched. The range of this radar was about 1,000 miles, and actually extended beyond the horizon. There were three BMEWS radar sites located in Clear, Alaska, Thule, Greenland, and Scotland. The original contract between Varian and the U.S. Government called for a 90 day delivery, with all development work to be done exclusively by manufacturing personnel. The first tube was completed in 100 days (with lots of help from Engineering). Some of these tubes worked continuously for twelve years. The VA-842 klystron produced a peak power output of 1.25 million watts and was modulated with 2 millisecond pulses. Its duty factor was 6 percent, which resulted in an average power output of 75 kilowatts. The output frequency of these tubes was tunable from 400 to 450 MHz, and power was conveyed to the antennas through 21-inch rectangular waveguide. One transmitter could have two or four of these klystrons in parallel, and each of them had to be housed in its own "lead shed" because its accelerating potential, 20,000 Volts, caused the emission of huge amounts of X-rays. All technicians who worked on the BMEWS transmitters wore dosimeter badges. The BMEWS radars became obsolete upon the introduction of surveillance satellites capable of detecting the launch of Russian missiles. Later, similar klystrons were developed for use in UHF-T transmitters in the commercial broadcast service. The brothers Russell and Sigurd Varian, along with fellow scientist William Hansen, with a $100 grant from Stanford University, invented the klystron in 1937. Credit: Stan Allen Manager, Klystron Engineering Varian Associates Palo Alto, California December 12, 1991"
Klystrons (LCSH)
Military intelligence
Cold War
Communications, Military (LCSH)
Varian Associates
Ballistic missile early warning system (LCSH)

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