File:Reflex klystrons and microwave cavities.jpg

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Summary

Description	English: Two reflex klystrons attached by waveguide to microwave cavities, from an ad by Varian, Inc. in an electronics magazine. At top is the Varian VA-1281 cavity with the VA-201 klystron, at bottom is the VA-1282 cavity and X-26 klystron. The reflex klystron is an obsolete vacuum tube used around World War 2 to produce microwaves. The microwave cavities, consisting of closed cylindrical metal containers, serve as tuned circuits, determining the resonant frequency.of the oscillators. Cavity resonators are used instead of tuned circuits at microwave frequencies because the size of discrete inductors and capacitors required would be very small. They can have much higher Q_factor than LC circuits, approaching the frequency stability of quartz crystals.
Date	October 1955
Source	Retrieved December 29, 2014 from Tele-Tech magazine, Caldwell-Clements Inc., New York, Vol. 14, No. 10, October 1955, p. 18 on http://www.americanradiohistory.com
Author	Unknown authorUnknown author
Permission (Reusing this file)	This image is from an advertisement by Varian, Inc. without a copyright notice published in a 1955 magazine. In the United States, advertisements published in collective works (magazines and newspapers) are not covered by the copyright notice for the entire collective work. (See U.S. Copyright Office Circular 3, "Copyright Notice", page 3, "Contributions to Collective Works".) Since the advertisement was published before 1978 without a copyright notice, it falls into the public domain.

Licensing

This work is in the public domain in the United States because it was published in the United States between 1929 and 1977, inclusive, without a copyright notice. For further explanation, see Commons:Hirtle chart as well as a detailed definition of "publication" for public art. Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (50 p.m.a.), Mainland China (50 p.m.a., not Hong Kong or Macao), Germany (70 p.m.a.), Mexico (100 p.m.a.), Switzerland (70 p.m.a.), and other countries with individual treaties.

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