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About The Omaha morning bee. (Omaha [Neb.]) 1922-1927 | View Entire Issue (Feb. 21, 1925)
Efficient Three-Tube Reflex Receiver Based on Development of Two Coils By I,. K. BARBIJCY. FOK a great many months engi neers of the Ambassador com pany have been striving to per fect an efficient three tube reflex cir cuit. which would use a tube for a detector Instead of a crystal, anti which would hnvo great selectivity and volume enough to bring in the real |1X stations on the loud speaker. As far as the writer knows there is no receiver on the market today or in any great use outside of experimental laboratories similar In any great de and (Vac, (’anada: WOC, Daven port, etc., on the loud speaker suffi ciently loud to he heard all over a seven-room apartment—and through tlie walls into the next apartment, too, if the neighbors' kicks count for anything. For the locals and the not too dis tant stations an indoor aerial from 20 to 30 feet long is ample to give satisfactory reception, hut this re ceiver i« so selective that the fan can use an outdoor aerial without any real Interfere** ^ "v* n from the locals. ,ly as possible, take the baseboard off and fasten the parts In place. The antenna coll should be fastened to the baseboard just behind the con denser of the radio frequency unit. You may also attach the coil to the condenser. After drilling the*back panel and mounting the neutralising or by pass condenser, proceed with the wiring. Follow ilie diagram ns closely as pos sible ns to spacing of the wires and your results will be better. The re ceiver was designed with a view t«» conned ions between bus wire and parts. If you prefer a different panel ar rangemeiit you may put the tuning roll In the center of the panel and the two 23-plate variable condenser* at either end. The accompanying photograph shows tills arrangement as opposed to the diagram, which is the more efficient receiver of ihe two. The set which the writer hnllt proved to hr more efficient when tile negative side of ihe A battery was grounded between the negative side teur has had experience enough in the matter of wiring to proceed as in dicated by the diagram, but the writ er will explain the method of stablli /ation after the set Is completed and indicate a few little things to do to bring It to its highest state of efli eiency. If yon wish, you can provide fur a third rheostat on the panel to con trol the last audio frequency tube, which the writer took care of by us ing an automatic filament control. This proved thoroughly satisfactory : 1 ' The above drawing shows the location of the parts of the newr Ambassador three-tube reflex receiver as well as the circuit. It can be used as a mounting imIIiui if tin ul.iii\ in "g followed. , grce to the circuit described herein. ■\V*lille the idea of reflexing one or Wore tubes in a receiver is not new and the theory of regeneration has had full away, reflex receivers of one »ort of another are going to become more and more popular both with the manufacturers of radio sets and -* “home builders.” - The objert of the engineers was to ; ninke the three tubes of tills new reflex hookup do double duty or, in *»*.. other words, come as nearly as pus 2*‘ '-$WMe to making the three tubes do the work of five. No three tit lie re «v reiver will ever achieve this aim at S% Ho per cent, probably, but the set ' •' dc-crtbcd by the writer rnrnrs as near to it as appears possible now ’ for the amateur radio receiver build er. This new circuit employs first a , stage of radio frequency, a detector ve .'tahe and then one stage of audio fre •.% fluency. The tube detector is era *■- ployed rather than a crystal because •v for additional sensitiveness it was necessary to provide for a feedback . in the detector circuit. The princi ples of both regeneration and reflex are comparatively old, lint Utile has ■J, been done either by amateur ex peri *■ menters or in the laboratories of con eerns marketing radio products to Va rd the development of a receiver * combining bolh of these principles. There have been, however, several ''kits” put on the market for reflex receivers, but the more successful ones used a crystal for delect Ion. * The receiver described hero is reflex In principle, pure and simple, al though regeneration Is developed to a slight extent, and the two principles of radio signal reception are thm •>> combined. The receiver described herein is not an easy one to build nor K to properly stabilize after it Is built, i’. None but advanced "home builders” i had better try it, although a fan who has built a three-tube set should be able to put this reflex together and . synchronize It properly. When the re t reiver hna been completed however, *" the fan will be amply rewarded for his pains and will he highly amazed l at the remarkable results obtained * ns to selectivity and its ability to v ySnk'in truly distant stations. jet ^Selectivity is this reflex receiver’s Strong point. One half a point on the * dials Is sufficient to tune nut one sta tion and bring in another one, shnrp , end clear. A half turn of the knoll ST of the vernier condenser mounted on *. the panel will itself frequently serve ‘ to tune out a station and bring In another without disturbing the con denser dials at all. The ri^eiver does not possess enormous volume. It. will Y-, not produce a signal that will tear f< th’f signal off Ihe walls, but it will bting In medium distant stations such ' as KYW an<l \Vi,S, Chicago; CNRO Kven with an outdoor antenna the locals may he tuned out by moving the dials one degree In either direc tion. The outdoor aerial gives great er volume on distance, and the writ er has both and can change from one to the other by merely throwing a switch. % New foils Set's Heart. The basis of this reflex receiver are the new low loss Ambassador and the antenna coils, which actually is the stator of the low-loss coll. The wir ing of these two colls, especially marie "lltx." represents months of ex pcrlmentation and research work. The- parts needed for this newly de veloped reflex receiver are—r One Ambassador tuning coll, low loss type. One Ambassador ant»nna roll. Two 23-plate variable condensers, 1 low-lpss type. Two baby variable t.mdensers. Two 4 to 1 audio transformers. Three sockets. Two rheostats; one 6 ohm; one 30 ohm. one automatic filament adjuster. One open circuit jack. Two .00023 fixed condensers. Two .001 fixed condengeis. One tWo meg. grid leak. One variable gird leak. .Six binding posts. One panel 7x21 Inches. One black panel. 2 1 4x20 1 4 Inches. One cabinet, 7x21 Inches. Hus wire, screws, soldi ring lugs, etc. In this reflex the radio frequency tube Is used also ns an amplifier, as Is the detector to some extent. In order to achieve the reflex amplifi cation the secondary of the first audio frequency transformer is Intro duced into the grid circuit of the ra dio frequency tube, between the con denser and the filament of the tube. The secondary of the first audio fre quency transformer then becomes a part of the radio frequency unit. As the capacity of this winding Is usual ly not large enough to provide »p effluent by-pass for the indio fre quency currents, a small hy-pass con denser, one of the two baby variable condensers mentioned, Is plai ed across the terminals of the secondary wind ings. In starting your set, drill-the panel first. The accompanying diagram showa only one hole for all parts to he attached to the panel. Follow the measurements on the front and rear panel diagrams and you will avoid mu< h trouble. Mount the condensera, two rheostats, cull, switih, baby vari able condenser and Jacks on the panel and lightly screw the baseboard to the panel After marking the poai tlons of the other puts on the base I mat'd, following the diagram as neat the greatest err; •iency possible and the spacing of wires is of paramount consideration. 1'nder no circum stances use any spaghetti; none Is needed. I se soldering lugs for all of the switch and the No. 5 connec tion on the primary of the radio fre quency or antenna coll. Thin !>* shown on the diagram. The writer avainura that the arna Issuing a Few Gold Notes Via Radio — John McCormack, owner of the world's most famous tenor »olce, hss finally yielded to the radiobroadcast urge. He Is seen hurling gold-plated notea Into the ether from • New York station. I.urresla Horl, famed prlma donna, lias also Joined the radio ranks, as yon sec._ finite I LOW LOSS Interference Eliminator Whet Radio Liters Hars Been Looking For For thnae who have had interferes** Troubles this ntw eualllary tuning de'ic# will lr«p not the un dtilred station*. Sslect Your Station* o» Will Tk* air ie »n ernwrled with mini* end ' oii-ee that the star*** set fs I' 'o bring In the desired sta tions properly. The Ktelnlte Intrrferenre Kllintnatnr • hut* eut local and other Interfere nr*. You set one • i at Inn at s time. »h*tt*»r on* you want, and tan tun* H la loud aad clear. Improved reaull* with tuh* or crystal. Try for youraelf entirely at my risk ihe wonderful Improvement thi* in expensive little devire will melt* In Ih* reception of your set. Bold on absolute guaranty* of aatlafaetton m money lierk *nd Ih* (raeteat dol lar'* worth *v*y offered th* radio public. Improve* reeulta on both rryatol and tub* aeta that ue* an indoor aerial, outdoor aerial or light socket ; but will not help a «*t using loop antenna. Clear* up reeeptlon wonderfully and partially abaarha , ■'•'•t'_ . — - me Amasing Soliafoction or *£ ZXrilfZE- mataaao * 1 Mon.y Back Crratal Sal*. SSi Da Lu*a Cryetal put thla tnterferenr# ellmloei.ir on Sat complete with heedphonaa. >0ur art anil nnle *m»,liig Impiove. aerial end ground. $tf)l 1-Tub* Set. m«t. No Ionia needed sml hut * ■» SIS; 1-Tube Amplifier, Stl. hltf-K ment's tlm* required to Install, l ull descriptive literature on request. directions with eerh InSItilment Sim ... , a y.iicw tnst it iton». Kniliiru no RfMMUmal nr ply conniet with ••t •n^ { 1 . I,tr«l «»r you money l'*rk promptly on your .ay.o.M l»*'»aM anywhere m rrll.h.llly I- rrlnnre N* I these two big Ateh'.ee bank. Will testily ( > <,o|Ul. .. STEIN1TE LABORATORIES A CHLtON1. KANSAS | 1 1 " " ^ If sn automatic filament control is used It should he provided with grid leak dips. When stabilizing your re ceiver you must rely on experience to decide whether tu use a grid-leak the* or not. It will he noticed that there are two fixed condensers on the first audio frequency transformer. The first one la .OOOJ.'il is shunted across the pri ■nary and the second (a .001) Is put between the plate terminal of t hr secondary winding of ihe transformer and the filament terminal of the pit maty. This may seem an unusual ar rangement of fixed condensers, but ihe writer found that It was the prop er combination to produce results The placing of fixed condensers fre quently must he different In receivei • that look exactly alike, because o 1 different values of the transformers and other parts used. A second .001 fixed condenser should he placed across the secondary winding of the second audio frequency transformer j A fourth fixed condenser and a variable grid leak are placed between the grid terminal of the detector tube and one of the terminals of the sec ondary winding of the tuning coll. In: the event of difficulty In balancing the set try reversing ihe leads from Ihe secondary winding of the tuning coil, putting the condenser on , the other terminal and the lend to fila ment of the audio and detector tuhj-s on the other. The hook-up as shown In the diagram proved the more suc cessful way fer the writer, however. If you follow these directions your receiver should bring in broadcasting stations at alsiut Ihe same points on I You Can Have the Brunswick Radiola Super-Hetrodyne ...for... « ’400 It’s the superlative a c h i e v ement in Radio, the world's outstanding Phon ograph in scientif ically developed condensation — an instrument years ahead of its field. Don’t Let 4 Walls Imprison You Bring all the wonderful world to you with the Radiola. Come today. See it Hear it. Trade in your old Phonograph. Payment terms are exceedingly liberal. ^ A. HOSPE CO. I 1513-15 Douglas Street S both dials and should cover a range from something less than -00 meters to nearly 600 meters. In balancing the receiver there are several methods of arriving at the proper setting of the balancing or neutralizing condenser mounted on the back panel. The best way of all Is trial and experimentation, (let it where it gi'ey Ihe best results arid lei il alone. Once it Is properly set there is no peed of touching it again no piatter what wave length you are working on. If you are bothered by howls, which sometimes occur because of peculiar characteristics nf the audio frequency transformer which cause oscillations In the amplifier circuit, try swapping the leads to the primary tremlnals of the transformer. This will clear up per cent of any trouble you may have in this part of the circuit, with a good ground to a water pipe or It is recommended that yon use r>lther an outdoor or ir.door aerial steam radiator for the receiver, al though a (Ounterpoise ground works very well. To tune ihe receiver start with the rotor at an angle of about 4r» degrees and rotate the dials, al ways in step or approximately so. IYEAK should come In at approxi mately 65—65. You may find that, loe to some peculiarity of your own receiver, the sellings may vary a little, but you will pick up the same stations at the same setting on the dial every night. .fust a word of caution about trans formers. Due to the extraordinary duty required of ihe first transformer which becomes a part of the radio fre fluency circuit, it is absolutely nec sesary to use the very best ones ob tainable. for if there is a defect in \nur transformer this hook-up will show it up and, by the same token, if you have trouble swap your trans formers one for the other and see what happens WO AW Program I v__J Saturday, February SI. F i a V M —Public r>#wa period, con ducted by Eugene M. Koneckjr. <5 P. M.—Dram * tic hour. Davia Studlc of Expression Selected rending* from we||-known author* *nd poet* Rending* < a > My Shadow.’ tb) "Naught? « M 11) Sweat naan" Hauer* «'ii»a b ft I jeaf-'bl reader, puptl of Elia* Davie. f. :ia P if Plano nob.■ toy flat a Ye< h out. pup I of Aufuat Borglmii f. 45 P. M —Dinner program transmitted from l)t'a if Me i a afore reitaurant* 9 p ■< •—Program tinder ■ !»pl< •' Omaha Printing rtintpani. "The Off*1 e Supply Ifoitne. • arranged by Eugenie Whitmore Minkina Pia no d net. *ele« t e-t Eugenie Whitmora DfnVina. Mvr» Hre< ken ridge Oortltth. < *onf ral t «» nofon tk) "I Km Th>- 11 • r n ‘ Woodnirtn (li) **A Good Night Pong’ . . . . Roe* lie A Whitmore Hrrrlet ritirk Meigren. Inalrumentnl tri*.: (at 'Serenade from tb* Ballet”. . Mflenkft tan Block (b| Meditation' H«ch*GoUnod Mr* t'on rad Young Belie von Manufelde. Eugeo'o Whitmore lunkini, piano Baritone ■ofoa; <at "When Two That I*n>e Ac# Parted.. Seech i tb > "Song of the Open"... .l.a Forge (crWly" . Harry Plabrow. Violin aolo "Romanae". Lehmann Mr*. Ct.nrad Young Sopcano aolo*: (*1 "\utumn". Roger* tb) "W'altx Song Roaalie A Whitmore Mable Allen Smail* Vocal duet "Starry Night" ... John Den ant ore Mable 'lien Small* Harriet <M«rk llelgren f'ello aolo 'mlantlr- ' T.entar H»Me vt»n >lanafel*L*. Pont rail * aolo* ; lal Son* of Al'il” Salter tb) "«*©ntentiner*t" Salte1 Ilar»iet t’latU llelgren. Violin aolo. Ber.*u»* ..Dunning Mm Conrad Young Plano #n|oe Walls.Cbopia (h| • c.rrllllon S>in( S«.n» ** Knatnii* Whitmore Pinktna. it aid tone aolo* tat "The Houa# of Mentone* Flo: #ni e A vl ward <!,i "The Lftftt Song K>gere < * • v< , j.Mtlft Woman ® Mine Bartlett Harry pluhrow. Cello ado "Ballade . ....Friml Belle von Manafelde.___ Vocal duet. "Carmens Walt*”.\\ llson Harriet Clark Jlelgien. Inal rumental trio: „ , __ (a l "Love's Harden” . Schumann (l>) "Londonderry Air . Frit* Krelaler Mr*. Conrad Young Hello von Mt»»af»*1de Kugenio Whitmore Dinkins. Soprano solo#: ,, . . (a I "Black Bird" .Meyer ilehnund <h) "A Brow n Bird Singing ’ " UIM| M a hie Allen Small*. Plano Solo Selected Myra Hreckenrldge (Jordon. Plano Duel Sol**, t e«l Eugeni* Whitmore Dinkins Mvm Hreckenridge Gordon 1 I iid p M Frank W. Ifodek, ir . and hla Omaha Nightingales at ft* aeland ga rdenr*. 11:30 I\ M.—Organ music. [__— _—J PRO*.RAM FOR FF.BRI VRY St. (Courtesy of Radio Digest.) Bv Associated Press. WKKl. Boston (silent). * W(j R. Buffalo (119): 6. Itjuaic. WLS. Chicago (34 4.6): 7. entertainers; 7:20. barn dance. Harmony Ace*. Ianani .lone* harmony girl*: 11 15. revue WEBH Chicago (370) 7. religious, concert. Riviera theater: 9. dance, read ing*. vocal; 11. dance, solos. KYVV. Chit ako (546.4): 7. corn erf: *. mualcale. 9 36-11:36. < Isash al program; 12-1. oonular: 1-2. frolic. W MAW Chicago New* < 447 5 )' 6 an noun* ed; *1 orchestra; 8'30. photologue. ». < h < is<» theater. WLW. Cincinnati ( 422 3): 6. concert. )af« ohon**. WFAA. Dallas News ( 475 9 ): 8:30. ban quet • ii. enter talner* WOC Davenport <4M> 7. Sandman; 7:3d religious: 9. orchestra KOA, Denver (323): 9 dame. WHO. 1m* Moines (ai!*nt). WW.I. Detroit News (352.7): 6. or chesr ra. WHAI*. Fort Wot r h (silerP). KNX. Hollywood (227): 8.15. mu* 9 ■ ::0 organ 10, feature*: 12, orche*'* 1. nopuia.' song*. WI ».\ F. Kansas Cltv Star (.65 6 ): School of the Air: ll’t- frolic KHI Dos Angele* Times ( 404» concet t : 8 ;0. children: 9.45. (alk : !■ fea turns; 12 orchestra; .1. Dost Ante • \ V HAS. Louisville Time* (3998): cot " \v m< * Memphis Commercial App* (499*78 30. concert, xvccu Allnnea t»oii*-St Paul (416.4)' * Philo-.Ithit- s :*«». aurpt lae. 9 30. dm CK AC Mont ten I (417). 6:30. con< » 7 x.i tie.I 9:30. orchestra \N (•• X r. Wxx York (491 a): 6 tfio 6 «io, m h :::i» blind cnlertninei . 9. ten*< 9 ;•.*(» pianist: 10. orchnstfa XVII N New York (3612) . « 30. he* talk 6:35. dance: 7 orchestra » music ■ 10:15, entertainers; 10:30. dan XX.fZ New Yo-k (454 if 6. dance to 1 . 1'. soprano *. talk; player*. 8 1 aongx. trm. orchestra. WN TC New York (52«>: 6 35. f hate:. . five 7:30. police quartet; g. songs: 8 Instrumental: 9 in. talk WUR. Newark (405 2): <‘30. pian 8:45. nlanti. . _ . Kao. Oakland (299 8): 6. concert; 1 "Fill ia h " soloist*, address. 12. dsn soloist*. , . WOAW. Omaha (526) 6. dramat 6:3o announced: 6:45. program: 9 pm* grant IV Nightingales 11:30. organ. WFI. Philadelphia (296): 6. talk; recital. . . ,, XX* IP Philadelphia (509 9): « *»’ 715. fop- nrt: 8:15. com ert: 9. orefaettr.t ; 10. recital. _ . KDKA Pittsburgh (309 1): € 45-. special. _ Wr.\n, Pittsburgh (461 2): 6:45. mo' • chats 7. roads. 7 :0. lamboree KH'xV. Portland (493) 12. Melody men PXVX San Juan (400): 7:30. concet". pupjlr \V(JY. S■•hnpectady (379 5): 8 30. dsn- - , songs. ,, kF'vjX Seal tie (238): 10. ore heat, a: 1 concert 1. dance XVHZ. Springfield (321 1): 6:15, history; 6:3«. trio. . , r . K SI > St Ixiuls Post Dispatch (^4-.lt: 9. •vmohony. XVfH* Washington (Hi): € music; Billie tall 7:15 ttopera no: 7.30. talk; 9:<0. dance; 10:15. organ. ^^ * w—vm [ erformance proip* tnat rM f T' T 1 r I ^ I 1 the Zenith has been cor M B I I I rectly named. This Super M -J I il x| JL -Jl. JL -A. Zenith model, in a deluxe rabinet. gives all that radio offers. Easily tunes in on distant stations, despite inter ference. You pick up most any desired station with great clar ity and volume. Six tubes, two for tuned radio frequency am plification, one for detector, three for audio frequency ampli fication. ZENITHS are priced from $95 to $550 m ~ a: MASTER beautifully designed speaker has made „ —in ;elf a foremost place in the rad:o world, distinguished by its amplifying bell of 'd Mexican mahogany. This helps to ts enjoyable violin-like quality of tone. 11. rich tones are delightful to hear. Its y is a decoration for the finest home, it at the first opportunity. $30 to $100 THOMPSON gtg priced much higher. '* represent* th•• wide-; expc’ience in ’ ! For 15 years, the makers have been building wireless and radio ap paratus exclu sively. This model has five •be* and em bodies all ad anced principles $125 to $180 Wonderful clear and powerful repro duction i* ' given by the Thompson Speaker. It delivers pure tones in any desired volume. A cone-shaped bake lite diaphragm replace* the common felt diaphragm. This gives a larger area for e.pial diameter, producing greater volume and a natural tone. $28 j————T--~ »■" - _m_ You’ll have a radio some day. Why not start NOW to investigate. Come into our headquarters or any of the dealers listed below and inspect our stock. We carry complete assortments of parts and equipment. Experienced men are in charge to help you. Come m. NEBRASKA BUICK AUTO COMPANY LINCOLN OMAHA ^ ! Schmoller & Mueller P. A. Clark Motor Co., Piano Co. Benson Wilbur Brandt, Inc. W. Peperkom, Florence