File:Bell telephone magazine (1922) (14752704504).jpg

Identifier: belltelephonemag00vol2930amerrich (find matches)
Title: Bell telephone magazine
Year: 1922 (1920s)
Authors: American Telephone and Telegraph Company American Telephone and Telegraph Company. Information Dept
Subjects: Telephone
Publisher: (New York, American Telephone and Telegraph Co., etc.)
Contributing Library: Prelinger Library
Digitizing Sponsor: Internet Archive

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fects the amount ofcurrent that will flow in a circuit. Bell Telephone Magazine SPRING tive field. As research has added to width of frequencies it can amplify is understanding, and as invention has limited by resonance effects. The produced new devices for getting traveling-wave tube provides an es- around obstacles, the frequency range cape from this limitation, and the available for communication has been highest frequency at which currents pushed to the region of billions of have been amplified to date has been cycles where formerly it was limited reached with a traveling-wave tube to millions. working at 48,000 megacycles—with Figuring prominently in this ad- waves only a quarter of an inch long, vance have been three essentially dif- We can expect it to go even higher. ferent types of amplifying devices—the klystron, the traveling-wave tube,and the ordinary triode modified inform. The klystron has found con-siderable use in communication atvery high frequencies, but the band
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A close-spaced triode tube is shown against an enlargedcross-section drawing of it Many radical new schemes for am-plifying at high frequencies havegrown out of the traveling-wave con-cept. Among them are tubes inwhich two electron streams are used,one working on the other, and tubeswhich combine the fea-tures of the traveling-wave tube with thoseof the magnetron usedfor generating radarpulses. Indeed, this isan area of researchthat is probably unsur-passed in activity, andinventions are appear-ing from many parts ofthe world. It is, however, aboutthe simplest type ofelectron tube, the tri-ode, that I want prin-cipally to talk, both be-cause of its simplicityand because it illus-trates the contributionof persistent researchand clever inventive-ness to improving thecapabilities of an ex-isting device by goingto extremes without in-troducing new funda-mental principles ofoperation. 1950 Some Observations o)i Industrial Research 19 This little tube, about the size ofan English walnut, is

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