Radio Broadcast - 1927, October - 81 Pages, 8.1 ... - VacuumTubeEra

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OCTOBER, 1927 NOW YOU CAN RECEIVE RADIO PICTURES! 343RADIO BROADCAST PhotographsTHE COMPLETE RECEIVING APPARATUSHere is the entire receiving apparatus. The receiver in this case was a well known set operating from aloop, picking up signals on 208 meters which originated in another part of the Laboratory. They aretuned-in and sent through the picture apparatus which is described in greater detail in the otherphotographstotal cost of the apparatus, exclusive of batteries,tubes, and broadcast receiver will be less than$100. All of the electric apparatus can be madefrom material easily available to the experimenter.Complete descriptions by Mr. Cooley ofthis equipment and how to operate it will follow.A word about the availability of pictures.Inasmuch as the original equipment for a broadcastingstation need involve no more than theexpense of a phonograph, there is a certain sourceof these radio pictures in every broadcast station.Broadcast stations will find in the transmissionof the Cooley "Rayfotos" a sensational extensionof their activities and by the time thisarticle is in the hands of experimenters, and bythe time the receiving equipmentis ready, pictureswill be on the air. The Cooley systemisbeing exhibited at the New York Radio Showthis month.And there you are: Pictures by radio and inyour own home.SPECIAL MODULATIONTRANSFORMERintensity varies with the shading of the transmittedpicture.The counterpart of the rotating drum of thetransmitter will be found at the receiver. Here,instead of an electrical motor we use for sake ofsimplicity a phonograph turn-table which isgeared to a small aluminum drum around whichthe sensitive photographic paper is wrapped.The corona discharge sprays the paper from afine needle and in some way not well understoodaffects the emulsion of the photographic paper.Whether this is an electrical or chemical effect orwhether there is enough light from the corona toexpose the paper is not fully known.But for Cooley's purpose it does not matter.When developed, the paper shows black spotswhere the discharge was heavy; light spots wherethe corona was weak.Now in all picture systems, some means mustbe provided to keep the receiver in exact synchronismwith the sender; when the latter startsthe receiver must start, and not in the middle ofthe picture which as anyone can see would havecertain disadvantages! A simple scheme for holdingthe receiver and transmittertogether has beenemployed.It is known asthe "start-stop" system,and isvery simple and flexible.In operation the receivingdrum revolves slightlyfaster than the transmittingdrum and it therefore completesa revolution in aslightly shorter time. Atthe end of each revolutionthe receiver drum is held bya trigger until the transmittingdrum completesitsrevolution. A signal is transmittedthen that releases thereceiving drum so the twostart off together. The radioThe modulation transformer, which was -hidden in the view on page342 by the corona coil is shown here. All of the parts for this appara-signals are not strong tus have been especially designed, and will be available soon. A goodenough in most cases to idea of the gearing mechanism and of the width of the drum on whichoperate the trip magnet that the picture is received may be had from this photograph. The picturereleases the receiving drum may be as wide as the metal drum. The needle point actually ridesat the beginning of eachon the paper as is shown hererevolution so this magnetisoperated through a more sensitive relay.Both the trip magnet and relay can be seenin the picture of the apparatus shown on thispage. The single pole double throw switch Sis really part of the trip magnet. When the armatureof the trip magnet is against the stop on thedrum, terminals 2 and 3 on the switch are pushedtogether and therefore all of the energy from theaudio amplifier passes into the relay. When thesynchronizing impulseis received it activates therelay and the trip magnet thus releases the drumand also causes the switch S to make contactbetween terminal I and 2 and then all of theenergy passes into the oscillator.The present apparatus transmits 4x5 photographsat a rate of one and one-half inch perminute or a little over 3 minutes for a picture.The Cooley receiving apparatus consists offirst of all one's broadcast receiver, then certainmechanical parts which will be on the marketsoon, and then certain electrical apparatus whichany experimenter can build and operate. TheCORONA DISCHARGEOCCURS AT THIS POINTACLOSE-UPWHAT THE PICTURES LOOK LIKEThese photographs have been transmitted by theCooley Rayfoto system. Pictures may be fiveinches wide and about six inches long and a littleover three minutes for each picture is required.These pictures have not been retouched
THEModern Radio Receivers Are a Good InvestmentRadio World's Fair opens theradio season for the broadcastlistener. Fitting its significance, theFair is held in mid-September atthe huge Madison Square Garden in NewYork.No radio season has ever started moreauspiciously. Technical progress, representedby simple, easily operated andmaintained radio sets, many powered directlyfrom the electric light mains, withbroadened tonal range, bring the manufacturedreceiver to a standard so high thatrevolutionary change can no longer beexpected. Greater broadcasting programsand improved receiving conditions makethe possession of these modern receivers allthe more desirable.Every industry goes through the samecycle of growth; first, it has a discouragingstruggle for recognition, then a boomperiod with almost day to day improvement,and finally, stabilization, with slow,continued and healthy progress, keen competitionamong leaders and the gradualelimination of the less capable who thrivedonly during the boom period.In stating that radio has reached a slowerlevel of development and that the purchasermay now select his receiver with theconfidence that it will not be hopelesslyobsolete within a year or two,or even four or five years, we drawour conclusion from fairly simple andindisputable premises. Improvementof any device is a matter of renderingit so simple that no technical knowledgeis required for its operation, sorugged and self-sustaining that butlittle attention is needed to maintainit in good condition, and so pleasingin appearance that it harmonizes withthe most luxurious surroundings.High standards of simplicity havebeen attained in radio when we havemany receivers in which five circuitsare simultaneously controlled by onedial and calibrated so that stationsmay be promptly logged. The onlyperishableelements in some receivingsets now are the filaments ofthe vacuum tubes themselves whichneed be replaced perhaps onlyonce a year. In tone quality, radiohas reached a standard of reproductionfar above that which satisfied the phonographindustry after twenty years ofprosperity. This standard can be raised atwill with our present knowledge and facilities,although the cost of doing so is prohibitiveand the effect hardly noticeable to theaverage listener. As to appearance, there isstill room for some improvement by theattainment of greater compactness in themore powerful receivers, but models areavailable for which no apologies need bemade even in the most exacting surroundings.Radio has certainly not reached its limitof development. Improvementswill continuealways and this year's sets will alwaysbe better than last. Two or three yearsago, a radio receiver was but a one-yearinvestment for those who would possessthe best available in the market. This year'sstandards are making the latest and bestmodels perhaps a five-year investment inapproximately the best radio receptionattainable.It is a strange paradox that the substantialdevelopments in manufacturedreceiving sets are not more widely appreciatedby the technically minded radioenthusiast. From extensive contact withCOLONEL LINDBERGH INSCHENECTADY" Aviation and radio are twin sisters engaged in the joint enterpriseof overcoming time. Distances are no longer measured inmiles, but in hours, minutes, and seconds. Colonel Lindberghreduced the distance from New York to Paris from days tohours. Radio has brought all parts of the world into talkingdistance of the United States," said Martin P. Rice of theGeneral Electric' Company. Above: Martin P. Rice, and atthe extreme right Colonel Lindberghthe better informed element of radiolisteners, we have analyzed this lack offamiliarity as attributable in part to theexperimenter's preoccupation with theintricacies of set building and the failure ofthe radio set manufacturer to lay beforethis group, so invaluable to the building ofreputations, the real facts about the designand construction of his receiving set. Glitteringgeneralities about performance donot intrigue the radio experimenter who,in past years, has successfully excelled inthese proclaimed qualities with his homemadecontraptions.But a new day has dawned. The experimentercannot deny the superiority ofthe better manufactured sets. Already he isturning his attention to new fields. Whilebuilding radio receivers was still an experiment,the successful outcome of which dependedupon skill, ingenuity and patience,this hobby had no rival in the hearts ofthose who considered the soldering iron aninstrument of conquest. The element ofmystery is disappearing. Set building hasbecome the following of a well establishedformula. The thrill of accomplishmentstill exists but the procedureis so wellcharted that the joy of exploration anddiscovery is practically gone. These missingelements, which satisfy the experimenter'sinsatiable desire to overcomeobstacles and to conquer the unknownare being rapidly supplied by new linesof endeavor. Telephotography and,some day, television, internationalshort-wave broadcast reception, moderninstallations with remote controlof the radio receiver, laboratory experiments,home motion pictures,aviation, mechanical models and athousand one avenues of expressionbeckon the experimentally inclined.The pages which follow attempt toreflect accurately the trends in theinterests of our readers. The manufacturedreceiver deserves an increasingamount of attention, as do newfields of development like telephotographyand short-wave reception.We do not propose, in the least, toneglect the set builder, but ratherto keep him in touch with thelatest developments of the art. We
Page 1 and 2: RADIO BROADCASTOCTOBER, 1927WILLIS
Page 3 and 4: THE SMOST 'POWERFUL ^BROADCASTING S
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THE COUNTRY LIFE PRESS, GARDEN CITY
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Radio Broadcast - 1927, October - 81 Pages, 8.1 ... - VacuumTubeEra

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