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The KH-27 RECEIVER by Kenneth Harkness

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The KH-27 RECEIVER by Kenneth Harkness TELEVISION ON LIGHT RAY! 15 Cents Tubeless Amplifier Announced D10 Grid Biasing Through Resistors Reg. U. S. Pat Off. A Simple 4 -Valve Circuit America's First and Only National Radio Weekly Hookup for Overseas 'Phone Set ol. 10 No. 19 Illustrated The KH-27 RECEIVER By Kenneth Harkness FIG. 1-The wiring diagram of Kenneth Harkness' latest receiver, the KH-27. See article on page 3. J.; FIG. 2-Top view of the receiver after the wiring has been completed. 110W TO RID RECEIVERS OF PARASITIC NOISES 1,ANGMUIR'S GREAT LABORATORY ADVENTURE RADIO WORLD WITH so much interference these days, why not improve your detector tube action and gain selectivity? Simply install a Bretwood Variable Grid Leak.Price $1.50. .,.moo al The Bretwood Variable Grid Leak NORTH AMERICAN BRETWOOD CO., 143 West 45th Street, N. Y. City. Enclosed find $1.50, for which send me one Bretwood THE Bretwood Variable Grid Leakmay Variable Grid Leak (or $2.00 for leak with grid condenser attached) on five-day money -back guarantee. be installed in any receiver ina few minutes.Single hole panel mount makes NAME this possible. Use a Bretwod andmarvel at STREET ADDRESS the difference! CITY and STATE (Inquiries Invited from the Trade) By ARTHUR H. LYNCH How to Build A Series of Five Important Articles on THE DIAMOND 5 -Tube Model HOW TO USE THE DE LUXE SYSTEM Herman Bernard, designer of this wondercir- mai, has written at, illustrated bookleton "How This seriestells how tobuildthe 2 -tube to Build RADIO WOILD'S Improved Diamond the Air." of De Luxe Receiver (without audio) and how to Send 50c and getthis booklet,in- cluding afull -sited wiring blueprint and free adopt this or any other set so as to obtain the name piece. necessary power from the AC electric lamp Outstanding Features of Set: (1) Fans, charmed socket. by tone quality, sensitivity and selectivity, port speaker reception of far -distant stationsre- Mr. Lynch is one of America's leading radio authors and designers.He has done with great volume. the best job of his life (2) A 2 -tube earphone set, in this comprehensively illustrated series, adigest of which a5 -tube speaker set, and aseparate 3 -stage follows: audio -amplifierforimmediate use Dec. 25 issue-Theoretical and historical discussion of the De Luxe Receiver and tuner, are combined in one. with any the audio channel and B eliminator. (3) No rheostats Jan. 1-The 2 -tube set fully described and illus- are used.(4) The setisinexpensive to con- trated,including wiring and choiceoftubes.Jan.8 --The National Lynch Power struct and maintain.(5) The set works from Amplifier and B Supply(3 -stage AF and B and C eliminator, adaptable to any outdoor aerial or loop; henceno aerial problems receiver).Many illustrations include picture diagram of wired connections to photo- present themselves, in city or oonistry. graphed parts.Jan. 15 and 22-Be Luxe reception from lamp socket with latest de- Send $6 for year's subscription and vices, including trickle chargers and A battery, relay, trickle charger and Alox filter, blueprint. get booklet, with picture diagrams of wiring, from antenna to the Acme speaker. [Newsdealer, or radio dealers, orderthe book- Send 15c for any one copy, or 60c for all five. lets with blueprints included, in quantity,direct Send $6 for one year's subscription (52 num- from American News Co.or braneheel bers) and get the five copies FREE! RADIO WORLD RADIO WORLD 145 WEST 45th ST. NEW YORK 145 West 45th St., NewYork City Ira X A Weekly Paper Published by Hen- No. 19 nessy Radio Publications Corporatiorw from Publication Office,145 W. 45th JANUARY 29, 1927 RAW:RM. PAT.'CiFF 0 Street, New York, N. Y. Whole No. 253 Phones BRYant $558 and 5559 15e Per Copy- $9.90 Per Year WORLD [Entered as senond.nlasamatter, March, 1923, at the poet office at New York, N. Y., under Actof March 3,18971 The Harkness KI-1027 Receiver A orc s Sensitivity, Simplicityand Pure Tone. By Kenneth Harkness Consulting Radio Engineer Designer of the famous Harkness Reflex and the Harkness Counterflex Circuits. IT isreally astonishing that after six years of broadcasting,afterthein- stallation of elaborate and costly radio receivers in thousands of homes, the vast majority of those who listenin nightly have actually no conception of how radio tttNNETWOINF,N should really sound. This statement may seem to be rather FIG. 3 a wholesale indictment of present day The front panel view of the receiver. The antenna circuit is tuned by the dial at radio receivers.Itisnot.Fortunately, left. The righthand dial controls two gauged condensers with one motion. The volume many sets are capable of faithfully re- control is the rheostat at center. producing voice and music. Nevertheless, thevast majority of set owners have never really heard the almost perfect re- in a natural, unstrained manner. This ef-and relative strength of the various par- production which modern methods of ra- fect of realism can be achieved with the tialtones which combine to form the dio transmission and reception have made proper equipment. sound. possible. They have no conception of the Similarly, most music can be reproduced amazing realism with which voice andwith the same realism. When the strains Accurate Reproduction music can be reproduced. of a violin issue from the loudsn-,ker, To achieverealisticreproductionof The set, particularly the audio amplifier,the sound should bring to your mind'smusical sounds, therefore, itis necessary is usually to blame. But even if the re-eye the figure of the musician and youaccurately to reproduce not only the fund- ceiverisgood, the loudspeaker oftenshould feel his very presence there inamental tone but all the overtones, with- causes distortion. And if the set and theyour home. A radio receiver should andout distorting any of the tones.If any speaker are both nearly perfect, the tubes, can be the medium through which actualof the tones are lost or distorted, the ef- the battery voltages or the battery elim-voice and music come to you throughfect of realism is destroyed. The repro- inators may be unsuitable. Few and far theether,carryingwith themeveryduction may be a fair imitation but it is between are the installations which har-shade of tone color which makes themnot an exact duplication of the original moniously combine to give true repro- distinctive, recognizable. sound mid the essential tone quality is duction. If the voices produced by your radio lost. It Is Up to the Listeners receiver are not the actual voices of the When John McCormack sings into the performers in the broadcasting studio, ifmicrophone his voice is distinguished by It seems a pity that such a small per- every note of music does not come to you itsquality, the warmth and color with centage of radio listeners enjoy the realwith all its tone shadings, as it would inwhich itis endowed. All the tones and benefits of radio. Most broadcasting sta-the concert hall, your receiver is failingovertones which combine to form this tions have modernized their equipmentyou as a medium of reception. There isquality are faithfully transmitted by the and have eliminated practically alldis- something wrong with your radio installa- broadcasting station. But if your receiver tortion from their transmissions. Famous tion.It may be the receiving set, it maydoes not embrace all of this, if it fails ac- artists are appearing before their micro- be the speaker, the tubes or the batteries.curatelytoreproduce each and every phones. The stations are supervising their The audio amplifier of your receiving settone, from the highest overtone to the programs carefully and are weeding out may alone be responsible. Whichever itlowest fundamental, you might justas the performers lacking real merit. They is, you are missing the true gift of radio,well be listening to an amateur singer arereplacingthem withthebest the thing which makes a radio receiverwhose performance is technically correct symphony orchestras,operaticstarsof more desirable than any phonograph- but without that quality which makes for the first magnitude, famous violinists and reality. greatness. pianists. The finest talent of the musical world is being offered freely. Reality Defined It is the purpose of this series of articles Unfortu- to describe a radio installation whichpre- nately, most radio listeners are not equip- Whatisreality?What makes oneserves and accurately reproduces all the ped fullyto avail themselves of these radio receiver sound better than another?tones and overtones of musical sounds, gifts of the air.Their receiving equip-How is the effect of reality obtained? To as mentdistortsthepure broadcast, and thereby creates the illu- transmissions answer these questions we must under- sionofreality.The receivingset,of of the broadcasting stations and theout- stand thenature ofsound. We mustcourse, is the most important part of this put of the average loudspeaker is justa realize that one musical sound isdis-installation and itsconstruction will be poor imitation of the original. tinguished from another not only by its described in detail. The best loudspeaker, Radio is no longer a mere "imitation"pitch and volume but by its tone qualitytubes and battery voltages touse with of voice and music. The days of howling,or tone color. It is this tone quality which this receiver will also be enumerated. squealing, distorting receptionare past.makes a note struck on a piano sound Itis now possible to possess receivingunlike the same note played on any other Set's Qualities Discussed equipment whichcan instrument. reproducevoice The pitch, or fundamental The receivingsetisknown asthe and music with almost perfectaccuracy frequency, is the same inall cases butKH-27 and was designed byme after and whichcancreate theillusionof thedifferenceintonequalitymakesmonths of experimentation, to reality. When the stationannouncer talks reproduce into the microphone, his voice, reproducedthem distinguishable from one another.
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