Identifier: belltelephonemag12amerrich (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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d in these various types of apparatusare of all sizes ranging from the miniature peanut tube witha power output rating of about one-hundredth of a watt to thelarge water-cooled tubes with power output ratings of manythousands of watts. About 90 per cent, however, of all ofthe vacuum tubes in the telephone plant are of the two typesfamiliarly known to telephone engineers as L and V tubes.These two types account for nearly all of the tubes used in thetelephone repeaters, carrier systems and ringers. Althoughmany improvements have been made from time to time whichhave decreased their power consumption, and increased theiruniformity and average life these general types have beencontinued from the earliest days of the commercial applicationof vacuum tubes to telephony. The 1933 models of these tubesare illustrated in the accompanying pictures. Long after their introduction into telephony, vacuum tubeshave in recent years been popularized by their widespread use 243 BELL TELEPHONE QUARTERLY
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F«u^ 2. P- TUB. L T„.. ^. ,0 Ki.ow.„ Wa™-coox.„Tube Shown to Same Scale. 244 THE VACUUM TUBE IN TELEPHONE COMMUNICATION in radio broadcast receiving sets. Nearly everyone is nowfamiliar at least with the appearance of a vacuum tube. Verymany have some degree of technical appreciation of the mannerin which a vacuum tube may be used as a rectifier to transformalternating to direct currents, as an oscillator to transformdirect to alternating currents, as an amplifier to amplify eitherdirect or alternating current, or as a modulator, demodulator ordetector to modify the frequency of an electrical current. Itis, therefore, not important to discuss in a technical manner theway in which a vacuum tube works. We are interested, however, in noting the special problemswhich distinguish the application of vacuum tubes to telephonyfrom other applications such as radio. In serving these differ-ent applications, the vacuum tube finds telephony the hardertaskmaster. To give satisfactory serv

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