File:Bell telephone magazine (1922) (14569598187).jpg

Identifier: bellvol25telephonemag00amerrich (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

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
t go into, but onewhich is outstanding. As you allknow, the arts of television and longdistance telephony have developedaround electronic tubes, and their ad-vance has been coupled with the ad-vance of electronics. As means havebeen devised to make vacuum tubesoperate at higher and higher frequen-cies, the way has opened for broad-band telephone transmission and for 1946 The Bell Systems Progress in Television Networks 157 the transmission of television. Onelimit after another has been over-come. I can illustrate by the transmittingtube presently in use in the WestStreet-Murray Hill beam radio cir-cuit. It is one of the Klystron typewhich was designed by Dr. Samuelof Bell Telephone Laboratories justprior to the war, and made use ofprinciples discovered by the Varianbrothers of Stanford University. TheKlystron provided a way to overcomethe limit set by the time it takes elec-trons to travel the small distances be-tween the electrodes in the amplifyingtube. It does this by making use of
Text Appearing After Image:
Dr. John Pierce with the traveling-wave tube hedeveloped at Bell Laboratories variation of velocity of electrons.This is sometimes referred to asbunching, for the distribution of elec-trons is varied along the electronstream in contrast to the oldermethod of varying the number ofelectrons which could pass a grid. The availability of this type of tubehas let us go to 6,000 megacycles ormore, which means waves less than5 cm in length. These short wavescan be focused into sharp beams, andthis permits using low power to trans-mit from one station to the next.But this tube, too, has its limits. Onecannot amplify very much with asingle tube of this type. Also, theband width, and so theamount of intelligenceor detail of picture,is limited, especiallywhen you come to longdistance transmissionwith many repeaterpoints. Recently this limithas again been broken,with a new tube work-ing on quite new prin-ciples which I want totell you about. It isa tube which was de-veloped by Dr. JohnPierce of Be

Note About Images