The "Auto Pilot," a Broadcast Receiver for Your Car; How to Get the Most out of the Short Laves; Television in The

'Price 15 cents

OFFICIAL ORGAN OF THE RADIO INTERNATIONAL GUILD

The "Auto Pilot," A Broadcast Receiver for Your Car; How to Get the Most Out of the Short laves; Television in the

rticles by Da rid ,rimes. Alfred . Çhir,'rdi, Robert Kruse, John 4elosc, /_'r /r Rote. k and Albert R udick

Summer, \ Issue a

LikeS You've Xe e r Had Since..You First Heard Radio "Radio?" you say. "Same old stations-same old programs." L'A LOT NOT-with a PILOT Super -Wasp! sscper_ Imagine every time you listen, the pleasure of hearing - announcements in German, Spanish, Dutch, French, or GASP any other language under the sun, directly from some The PILOT Super -Wasp foreign country, and without dependence on Kit for full A.C. opra- other tion-everything necessary except power pack rebroadcasting. (Pilot R-111 is recommended) uses one Pilot- identify a station ron P-224 (A.C. screen - The call letters you hear will as likely grid tube) and three bring- Pilotron P-22 7's. Cata- 6,000 miles away as one 600 miles away. That's logue No. K-115-$34.50. Power pack and tubes ing back the old DX thrills with a "kick" you never extra. got out of your first radio, even though you did log PILOT Super -Wasp Model for Batteries has big station in the U. S. A. all the features of the every A.C. set except that it uses one standard type a real dramatic thrill in listening in on the 222 screen -grid and There's three Pilotron P -201A PILOT Super-Wasp! tubes with a six -volt whole wide world with your storage "A" battery and at least three 45 -volt on "B" batteries. Cata- And-you can also hear programs from local stations, logue No. K-110-$29.50. Batteries and tubes their regular wavelength, as well as when these sta- extra. tions rebroadcast on short waves. Don't forget that the PILOT Super-Wasp is a broadcast and short wave receiver combined; wave length range 14 to 500 meters. Radio.Tub Corp. Pilot Mass. Brooklyn, N. Y.-Lawrence, 323 Berry Street, ('al. 234 South Wells Street. Chicano, I11.-1275 Mission Street, San Francisco. BLUEPRINTS ONLY 1 (tØ 1 EACH

These drawings average 24 by 30 inches, and show the sets full size. They are clear and understandable, and you will be proud to tack them to your wall.

Use the coupon below, merely checking off the blueprints you want. Postal money order or U. S. stamps accepted. Do not send coins through the mail.

The "Auto Pilot" Screen-(irid BP -140 BP -122 (P.E.6) Complete set of prints shows as- Full-size assembly and wiring of sembly, wiring and installation the K-122, K-123 and K-124 kits. of the new receiver for your car. Only a limited number available; Described in this Issue. order now.

Pilot "Pre -Selector" Battery Operated Super -Wasp BP -126 BP -110 The last word in broadcast re- Several thousand of these sets, ceivers. Fully described in the in daily use, testify to the sound Spring issue. Blueprint is full design of the original Super - size and shows all details of the Wasp. Every short-wave fan construction. should have a copy of this blueprint.

A. C. Super -Wasp 245 Push -Pull Amplifier BP -115 BP -113 Full-size assembly and wiring A high -quality power amplifier blueprint of the first A. C. short- using two 227's and two 245's. wave receiver, described in the Suitable for radio, phonograph Fall issue. and public address work.

Check Here RADIO DESIGN PUBLISHING CO., INC., 103 BROADWAY, BROOKLYN, N. Y. BP -140

BP -126 Enclosed find , for which BP -115 send me blueprints checked at left. BP -122 Name BP -110 BP -113 Address

Vol. 3, 2, Design No. Radio 1 EAFI4D IDIESIC-N OFFICIAL ORGAN OF THE RADIO INTERNATIONAL GUILD ROBERT HERTZBERG, Editor ALFRED A. GHIRARDI, Associate Editor JOHN GELOSO, Technical Consultant ROBERT S. KRUSE Contributing Editors DAVID GRIMES

Vol. 3 Summer CONTENTS OF THIS ISSUE No. 2 11:30

THE "AUTO PILOT," A .BROAD-ADJUSTING THE PRE -SELECTOR. CAST RECEIVER FOR YOUR CAR. By Alfred A. Ghirardi 36 4 By John Geloso A FEW WRONGS TO BE RIGHTED. TELEVISION IN THE THEATRE. By Robert S. Kruse 38 By Robert Hertzberg 15 How THE "PILOT RADIO' MADE THE GETTING THE MOST OUT OF THE FIRST BERMUDA FLIGHT. SHORT WAVES. By Zeh Bouck 42 By Robert Hertzberg.... 21 WHO INVENTED BROADCASTING? SHORT-WAVE STATION SCHEDULES 29 By David Grimes 48 MORE NEW PILOT PARTS 54 SUMMER RADIO, How TO PRE- PARE FOR IT AND ENJOY IT. THE RADIO INTERNATIONAL GUILD By A. A. Dolid 33 By Albert L. Rudick 58

NOTICE The next number of Radio Design will appear during the third week of September. It will contain more than 100 pages, and will be the biggest and best issue published so far. If your subscription rune out with the present number (the Summer one), by all means renew it immediately so you won't miss the Fall number. It will be worth reading and saving.

RADIO DESIGN MAGAZINE Is Published By RADIO DESIGN PUBLISHING CO., INC., 103 Broadway, Brooklyn, N. Y.

RADIO DESIGN Magazine is published quarterly, or four times during the year. The subscription price for the four issues is 50 cents for the United States and all other countries of the world. Checks and money orders should be drawn to the order of Radio Design Publishing Company, Inc.; U. S. coin as well as U. S. stamps accepted. Remittances for foreign subscriptions should be made by international postal money order. Subscriptions are always started with the current issue unless otherwise ordered. Single copies of current and back numbers, 15 cents each. The contents of this magazine may be reprinted by other publications if full credit is given. The editors will be glad to cooperate by supplying illustrations. SUBSCRIBERS: PLEASE NOTIFY US PROMPTLY IF YOU CHANGE YOUR, ADDRESS, WRITE OR PRINT YOUR NAME AND NEW ADDRESS CLEARLY.

2 Vol. 3, No. 2, Radio Design 2 BOOKS radth -been. w for "Radio Physics Course" "Theory of Radio Communication" by ALFRED A. GHIRARDI B. S. in Electrical Engineering; Instructor in Radio and Elec. by LIEUT. JOHN T. FILGATE trical Engineering, Hebrew Technical Institute; Consulting Engineer, Pilot Radio & Tube Corp.; Associate Formerly Instructor at U. S. Army Signal School Editor, "Radio Design" A complete course, simple enough for the nov- Published with approval of U. S. War Depart - ice, yet technically correct, covering the entire ment, this is first public printing of the officers' range from radio fundamentals to short -waves, radio manual used by the U. S. Army Signal television and the "talkies." A valu- Corps. A splendid technical text- able reference work of 362 pages $250 book for advanced Radio Ama- with 300 illustrations. Postpaid teurs. 250 pages, 200 illustrations. anywhere. . . . . Postpaid anywhere. . These Books Published Exclusively by RADIO DESIGN PUBLISHING CO., INc. 103 BROADWAY, BROOKLYN, N. Y.

Vol. 3, No. 2, Radio Design 8 The "Auto Pilot" -a Broadcast Receiver for Your Car A Sturdy, Full-Grown Screen -Grid Set, Remotely Controlled, That Will Increase Your Motoring Pleasure; Easily Assembled and Installed

by JOHN GELOSO Chief Engineer, Pilot Radio & Tube Corporation the ADIO in the automobile is just people flock around your car to admire and enjoyable as radio music that issues from the loud speaker, as useful being in the home and greatly in- you will find great satisfaction in creases the pleasure you can able to say, "I made the outfit myself." week-end jaunts in the obtain from your BOARD MOUNTING country with your friends or family. RUNNING When you stop by the roadside or drive The receiver unit proper is contained in into a clearing off the road to rest or to a black japanned steel case intended for eat lunch, you can turn on the set and mounting on the running board. It is enjoy the programs amidst the beauties controlled from the inside of the car by of nature. means of a thick flexible cable which ter- Until now this added pleasure to minates at a small, neat control box, on motoring has been something of a luxury, which are placed a tuning dial, a filament to be enjoyed only 1 y the more wealthy. switch, a volume control and a pilot light. The available sets have cost more than a In this cable, which is six feet long, are hundred dollars, and in most cases their five flexible wires for the connections of installation involves considerable car- the latter three devices, and a pair of penter and upholstery work on the car flexible metal tubes. These tubes carry itself. To make radio available to the lengths of flexible brass chain which great mass of people who own small cars transmit the motion of the dial on the and do most of their driving on Satur- control box to the shaft of the variable days and Sundays, the Pilot company has condenser in the receiver. The ends of developed a simple, inexpensive automo- the chain are merely secured to molded bile receiver that will fit all makes and bakelite pulleys, one on the dial and the models of cars and that will produce re- other on the condenser. Special fixtures sults equal to those obtained from outfits to guide the chain and make it run smooth - costing two and three times as much. Like auto receiver is fur- The photo at the top of the page shows an all Pilot sets, the "Autq Pilot" installed on the right running - nished in kit form, and may be assembled board of a Hudson roadster. Note that the door and installed easily and quickly. When swings free and that the set is out of its way. Vol. 3, No. $, Radio Design 4 ly are provided. The ceiver proper, the wires and tubes are steel case, the con- enclosed in a strong Important Notice trol cable and panel waterproof fabric For your own safety and the and wires for sheath. safety of other drivers, we strongly an under -car aerial. The steel case is recommend that you use your auto- A special small cone 22 inches long, 8 mobile radio receiver only when the car is stationary. speaker, only 8% inches wide and 6% With road condi- inches in diameter will tions the way they usually are, you inches high, and should concentrate on driving, and and 354, inches thick, not interfere with you should not have your attention catalog number 8,- the opening of the distracted by musical programs or 000, is available as doors of practically talks while the car is in motion. For a separate acces- a 11 makes of cars. this reason, no provisions have been sory, and is highly It may also be made in the Pilot "Auto Radio" for recommended for its mounted in the the suppression of interference from sensitivity and tone rumble seats of the ignition system. To prevent a quality. No "B" bat- wave of accidents, it is likely that roadsters and State legislatures will make radio- tery container coupés. The control ing -while -you -drive illegal. is supplied, as each box is molded in one car has been found piece of natural to present an indi- color bakelite, and is vidual problem i n 6'li inches long, 5% inches wide and 134 this regard. The three 45 -volt blocks re- inches deep. The front panel, on which quired for the set may be slung under the the controls are mounted, is of walnut - rear floorboard of closed cars, in a wooden finished bakelite, and is held in place by box that the constructor can make him- screws in the corners. The box is fitted self at little trouble and expense; or they with a removable aluminum back plate, may be put under the rear seat, or in the by means of which the whole unit may luggage carrier. In roadsters and coupés readily be screwed to the dashboard or the rumble seat or baggage compartment other place in the car. is convenient for the purpose. The cable leaves the receiver case For an aerial, a length of wire is mere- through a hole in the side bearing the ly strung from insulators beneath the hinged cover. It then is passed through a front and rear axles, under the car. This hole cut in the step -plate of the car, and is easily and quickly installed and works appears again inside the car through an- perfectly. other hole made in the floorboard. In some The radio receiver proper is built on cars it is not necessary to drill the floor- a formed and drilled aluminum chassis. board, as there are already openings in It comprises three stages of tuned radio - it through which the cable can be frequency amplification, using screen-grid "snaked." Additional wires passing tubes, a screen -grid detector, one resist- through the same hole in the side of the ance -coupled audio stage and one trans- car lead to the storage battery, the "B" former coupled output stage. Tubes of batteries, and the loud speaker. the A. C. type are used, their filaments WHAT THE HIT INCLUDES The Pilot auto kit, which has been given t h e number K-140, includes all the parts for the re-

888888888888888888888888111111111111111111111116,888881111111111111 The receiver installed in the carrying case. Note how the cable fits between the tubes, and how the chassis and "C" battery are pro- tected by the sponge rubber pads. An- other pad is on the variable condenser. Vol. 3, No. 2, Radio Design 5 PLACING THE CONTROL PANEL The position for the control panel \ uiquu(Itirpi e\.\\° a should be chosen with a view toward ease ° ° of installation of the cable and conve- .° nience of operation. The instrument board usually presents itself as the first choice, because it is easily reached and worked on. Keep the panel to the extreme left, if the set is mounted on the left running board, or to the extreme right, if the right running board is employed. In the Ford sedan used as an experimental car, the control box was first mounted on the left end of the instrument board, and then tried on the left side of the car just in front of the rear seat. In this position a passenger sitting in the back could operate the set quite comfortably. This arrangement presented no real inconve- nience to the driver, as the set is used only when the car is stationary anyway. In the Oakland coupé, the panel was put on the instrument board. In the Hudson Front view of the control panel and box. The knob in the lower right cor- roadster, it was placed under the right ner is the volume adjustment. end of the dashboard, as shown in an accompanying photograph, with the set on the right running board. The control being wired in series -parallel to work off cable was cut very short and the smooth- the regular six -volt storage battery in the ness of operation increased somewhat. In car. These tubes are much stronger than the La Salle coach, the control box was battery type tubes and are less suscep- screwed to the back of the driver's seat, tible to microphonic disturbances. Four just above a little sample compartment. P-224, one P-227 and one P-245 are used. The "B" batteries were dropped into the The P-245, used as the audio output tube, latter, out of sight. normally requires 250 volts on the plate Placing the loud speaker is also a mat- and about 50 on the grid, and some sort ter to be settled by the individual car of a protective output device; however, it is operated in this set with 135 volts on the plate and 221 on the grid, without an output filter, and produces highly satisfactory results. It is much more convenient than a 171A in this particular receiver because its filament takes 21 volts and therefore can be ganged with the 224's and the 227 very nicely. The total filament drain is four amperes; the plate current about 20 milliamperes. The sensitivity, selectivity and tone quality of this receiver leave nothing to be desired. Mechanically both it and the control apparatus are very sturdy, and will last indefinitely. The outfit has been tested very thoroughly, sample sets having been driven many thousands of miles in a number of cars representing different price classes and body types: a Ford sedan, an Oakland coupé, a Hudson roadster and a LaSalle coach. The weak points that showed up during the preliminary trials have all been eliminated, and the Back view of the control panel, show- auto set is now presented as a finished, ing the pilot light, Volumgrad, switch, reliable product. pulley, chain guide and start of cable. 6 Vol. 3, No. °l, Radio Design owner. In a closed car, a good place is just above the rear vision mirror on the windshield. The special Pilot speaker, being very flat, lends itself to this position. Another good place is near the dome light, or on the back of the front seat. In coupés and roadsters a good place is under the cowling, behind the dashboard. It is a good idea to arrange the mounting so that the speaker can be removed easily, as many times it is desirable to have it out on the running -board so that a large group of people near the car may be entertained. The Pilot No. A very good location for the control panel: on the 1106 extension cord is use- side of the car just under the dashboard. Note how ful for this sort of thing. the cable drops straight down. This is the same car Following is a list of the shown on page 4. parts supplied in the Pilot auto receiver kit, and also detailed in- 14 ft. Cotton Covered Black 2 Chains (about 14 ft.). structions for assembling, wiring, install- 2 Pulleys. ing and operating the outfit: 1 Guide with base. Flexible casing. LIST OF PARTS Quan- Cat. tity. No. IMPORTANT 1 598 Special Metal Chassis. In assembling a portable receiver 1 3084 Quadruple "Vaultype" Condenser. like the Pilot "Auto" set is 5 217 Sockets. it im- 1 216 Socket. portant that a lock washer be placed 2 806 Condensers. under every single nut used in the 2 807 Condensers. outfit. Being curried on an auto- 1 500 Resistoblock. mobile, the receiver 2 758 Grid Leaks, 2 megohms. will be bounced 1 750 Grid Leaks, 100,000 ohms. around a great deal and the move- 1 240 Set of coils, consisting of 3 R. F. ment will quickly cause the fastening and 1 Ant. nuts to loosen 1 413 Transformer. and perhaps fall off 1 963 Fixed Resistance, 1,500 ohms. if lock washers are not used. In 4 222-8 Tube Shields. places where a screw goes into a 8 Bakelite Binding Posts. threaded hole, place the lock washer 1 596 Bakelite Binding Post Strip, 1% in. under the X 5 in. X % in. head of the screw. 1 594 1% Volt Dry Cell. 1 2503 Metal Cabinet. THE ASSEMBLY 1 592 Rubber Pad. 18 in. X 8 in. X % in. THE 3 590 Rubber Strips, 2% in. X 0 in. assembling and wiring of the 1 48 Switch. set is very simple. Of course, the 1 941 Volumgrad. first 1 1274 Dial. thing to do is to unpack the 1 586 Bakelite Panel. parts from their boxes and to 1 584 Bakelite Box. open all the 1 582 Flexible Cable, 6 ft. long. hardware packages. 1 40 Pilot Light. Start the actual work by mounting the 1 588 Hardware package consisting of: six tube sockets 2 1 in. N. P. R. H. Screws. in the large holes on the 2 1% in. N. P R. H. Screws. bottom step of the chassis, using the 25 % in. N. P. R. H. Screws. round -head machine screws 12 % in. N. P. R. H. Screws. packed with 11 B. P. Bushings. the sockets. Before tightening the screws 4 Screen -Grid Caps. on the first four 2 Grid Leak Fuse Clips. sockets (for the P-224 40 Lugs. tubes) catch the edges of the tube -shield 45 Hex Nuts. bases under their heads. 55 Lock Washers. Notice that 2 Cond. Brackets for No. 806. soldering lugs are held by some of the 2 Cond. Brackets for No. 807. socket-mounting screws. To avoid short 18 ft. Bus Bar Wire. 18 ft. Spaghetti Tubing. circuits against the aluminum chassis, 7 ft. Rubber Covered White Wire. carefully bend up all the . socket 22 ft. Rubber Covered Black. ter- 7 ft. Rubber Covered Red. minals. 7 ft. Rubber Covered Blue. (Continued on page 10) Vol. 3, No. 2, Radio Design 7 00

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This view the "Auto Pilot", chassis shows the The top of positions wires in the upper right hand corner marked C-22.5 of the tube sockets, the quadruple Vaultype variable condenser, and C + are each about ten inches long, and run to the single the binding posts and the bakelite pulley and chain guide (on 221/2 -volt "C" battery block held next to the chassis in the the right end of the condenser). Before tightening the screws carrying case by means of two pieces of sponge rubber. The holding the sockets in place, catch the bottom sections of the wires from the stator posts of the condenser connect to the caps tube shields under their heads; the shields will then be ground- on the four screen -grid tubes. ed properly to the chassis. BOTTOM VIEW TH/S LID GRO'A'DLD

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The wiring of the "Auto Pilot" is exceedingly simple, and resent aluminum shield cans, which are screwed in place after should not take more than about two hours. Notice that one all the wiring has been finished. terminal each of the tube sockets, the 806 and 807 by-pass con- Use the tinned copper wire supplied with the kit, and be sure densers, the 1500 -ohm resistor, the Resistoblock, the .1 megohm to slip lengths of spaghetti tubing over all connections that are leak, the `SC" battery and the tuning coils is grounded to the not grounded. In pulling the spaghetti through holes in the chas- chassis. The dotted rectangles surrounding the tuning coil rep - sis be careful not to tear it, as short circuits may easily occur. (Continued from page 7) condenser on the top of the chassis and Mount the two grid leak clips between the fasten it securely in place by running third and fourth sockets. Note that one of screws through from the bottom. these clips is completely insulated from In doing the wiring of the set use tinned the aluminum by a pair of molded bakelite copper wire throughout, insulating it with washers. The other clip is grounded, but lengths of spaghetti. Start with the fila- it uses one bakelite washer on the bottom ment posts and proceed to the by-pass side of the chassis merely to place it on condensers, the R. F. coils and the audio the same level with the other clip. In circuit, and finish with the variable con- mounting these clips, put the screws denser. On the top side of the set, con- through from the top of the chassis and nect three-inch lengths of wire to the spread the lips to accommodate the small stator posts of the condenser and to their 6-32 nuts. After doing this, mount the other ends solder the little snap caps that loud speaker binding posts on the extreme go on the tops of the screen -grid tubes. end of the set, using bakelite insulating With all the wiring finished you can now washers for both. screw on the coil shields. Now take the paper case by-pass condensers and fasten them against the bot- THE CONTROL PANEL tom inside of the chassis just under the Proceed with the control panel. Mount tube sockets, using the special straps that the pilot light in the upper right-hand you will find in one of the hardware pack- corner, the filament switch in the lower left ages. Also put the 1,500 -ohm resistor in corner, and the Volumgrad in the lower position and then mount the single -cell right-hand corner. Turn the Volumgrad so flashlight battery as shown. The little "C" that its binding posts face upward. The battery has a screw soldered to its bottom. molded bakelite guide for the control cables Merely push the screw through the hole is already fastened in place, so that you in the chassis directly over the grid -leak need not bother with this. Take the ends clips, and fasten with a nut on the top. of the double flexible tubing (bound up With these parts in place, screw the in the thick cable) and push them into four coils to the chassis, using short flat- the bottom holes of the bakelite guide. head screws. The antenna coil is marked Tighten them into position by merely "ANT" and must be placed to the extreme screwing in the two set screws. Make left. The other three coils are inter- the various connections to the pilot light, changeable. Place the coils with the pri- the filament switch and the Volumgrad as maries (the green windings) facing away indicated in the accompanying drawings from the tube sockets. and the blueprint furnished with the kits. Complete the assembly on the under- It is a good idea to test the receiver side of the chassis by mounting the Re- now, before attempting to place it in the sistoblock, the No. 413 transformer and car. If you have no separate battery at the battery terminal strip. To complete home, take the set, control panel, tubes, the whole receiver, place the Vaultype loud speaker and "B" batteries down to

Back view of the carrying case, showing the control cable and the battery wires coming out of the protective pipe clamped to the case. The wire at the extreme left is the aerial connection.

10 Vol. 3, No. 2, Radio Design Under view of a completely assembled and wired chassis. The second shield can from the left has been removed to show how the coils are mounted. the garage and make a temporary connec- pulley, and pull the ends of the chain tion to the storage battery in the car. around the groove until they catch in the String a length of aerial wire 20 or 30 little notches just under the head of the feet long to the nearest pole, connect up screw. Then merely tighten the screw so the "B" batteries and the loud speaker, that the chain does not slip off the pulley. and see how the set works. Of course, you Before mounting the receiver on the will have to make temporary connections car, make a thorough examination of the to the filament switch and the Volumgrad running board, the step plate, the dash on the control panel, through the cable. board, and floorboard, and all the inci- You can turn the variable condenser by dental machinery underneath the latter. fastening the bakelite pulley to the shaft. In nine cars out of ten the best place for The circuit used in the Pilot Auto re- the set is on the left running board, al- ceiver is of the sure-fire type, and will though in some coupés or roadsters it may work without trouble. Of course, if it does be practicable to put it in the rumble seat not produce results, you will have to start or on the right running board. The run- looking for the cause of the silence in the ning board is by far the best place for set itself or in the tubes or batteries. an automobile radio set, as here the out- THE CONTROL CHAINS fit is very easy to get at for adjustments In one of the hardware packages you or repairs. will find two lengths of brass chain. These You will have to cut two holes in the connect the dial on the control panel to step plate, just above the running board. the tuning condenser on the chassis, and One hole must be IA inches in diameter, constitute the remote -control feature of for the main control cable, and the other the set. Straighten out the thick cable so about U, inch in diameter, for the aerial that the double flexible tubing hangs wire. You can easily judge the distance straight. Then drop each of the chains between those holes and their height above through the tubing, feeding it in through the running board by placing the metal the smooth mouth of the bakelite block containing case of the set on the running on the control panel. Knot the ends of the board and spotting through the holes in chain so that they the back. The easi- will not slip out. est way to make the Now put the shaft large hole is to cut of the molded bake - Get Into the Swim! a circle of small lite pulley through ones. it Don't be envious of the man who Of course, the hole in the cen- has a radio receiver in his automo- will also be neces- ter of the control bile. Build a set yourself and put it sary to cut another panel, from the in your own car! The Pilot "Auto 1% inch hole in the back, and fasten the Radio" is as easy to install as it is floorboard of t h e dial on the front inexpensive, and it will give you c a r, directly under side. Loosen the set many hours of enjoyment when you the spot you intend screw a n d washer are out in the country. to mount the control on the edge of the panel. The best posi - Vol. 3, No. 2, Radio Design 11 LEFT: Complete schematic diagram of the "Auto Pilot. The filament connections a r e shown separately f o r the sake of clarity. The series -parallel arrangement of the filaments is very simple; don't let it confuse you.

tion for this panel is either at the extreme left or the extreme right end of the instrument board, as then the control cable will drop straight down without interfering with the movement of the driver's or passengers' legs. Another good position is on the back of the front seat in sedans or coaches. Fastening the control box itself is a simple matter. Leave the ti front panel unscrewed and then simply pass screws through the aluminum back plate into the dashboard. Then screw the panel -; llllllllllllller, in place and snake the cable through the hole lllllllllll in the floorboard. With this much work done a you are ready to place the receiver itself. With the kit you will find a short length of flexible pipe, about 1 11j, 111111,. inch in diameter, and ä also a clamp by means lÌlllllllllllll1..riz of which it may be large 11111111111 fastened in the hole in the back of the receiver case. The pur-

ti pose of this pipe merely is to protect the a 'Hoot - cable where it passes Q through the side of the Hi Qo car into the case. Tighten the end of the pipe in the clamp and llllllllll111W ; then tighten the clamp I> Sr L tlllllllllllv-r{III itself in the hole in the back side of the black

Vol. 3, No. 2, Radio Design 1:'. NrION/207 L/Girl 6Y0L7 A/AZ LAMP LOUD SPEARfa N' 94/ BLuf YOL VA GRAS IJ VOLT ,Y, 577772-2/1"S .TEMO TE CON TRÖL 7L/N/NG. 6 VOLT STORAGE RED 6077E27 BL ACA' COTTON COYCREO W/RC W/6/7T N7I6 srv/rCA BLACA COTrON COYfRID MYRE Z.7-fÂRE METAL CAB/NE7 A /67 Y CNO_B- qNCNOR roi/ 1JJ V ANT

2212 YOL /J JAL/CC BO7N 'C"BATTtRY »Air/1f W/RES Complete diagram of connections of the "Auto Pilot," showing the receiver proper, the control panel, the loud speaker, and the "A" and "B" batteries.

case. Slide the pipe through the hole you your car keep it propped up as high as have already cut in the side of the car possible with the cable already running and adjust the case on the running-board through it. With this board out of the so that there is about 1 inch or 11/2 inches way you can lean over and push the free of clearance between its back and the step end of the cable through the pipe in the plate. This clearance is necessary to al- step plate and into the receiver case. At low the top of the case to swing open. this time, do not fasten the cable any Now simply bolt the case down. place under the car, as you must first In the kit you will find four pieces of tighten it in the receiver itself. Go back thick sponge rubber, one large and three small. Place the large piece on the inside bottom of the case, leaving the edges turned up a little on the sides so that when the chassis is placed on it they will prevent the set from rocking from side to side. Place the chassis with the tube sockets facing the back of the case and adjust it so that the left end of the condenser shaft appears in front of the opening for the cable. Before pulling the cable through the protective pipe you will have to tape seven wires to it. Three of these run to the "B" battery, one to the "A" battery, one to the chassis, and two to the loud speaker. These wires are not included in the cable itself because they are arranged differently in different cars and they do not run the full length of the fabric covering. Tape them flat against the free end of the cable for a distance of about one foot, and leave them long enough to reach the rod //A/GRAD ..,s., CARL C places where the batteries and speaker will be located. The connections of the control devices If you can remove the floorboard of in picture form. Vol. 3, No. 2, Radio Design 13 to the receiver and untangle the wires of steel and make certain that the wire the cable. Unknot the ends of the chain makes good contact with it. Another one and slip them carefully through the holes of the wires runs directly to the un- in .the special little molded bakelite piece grounded terminal of the storage battery. that has an aluminum base screwed to it. Another pair goes to the loud speaker. At the same time, push the ends of the If you are going to place the speaker in double flexible tubing into the bakelite the back of the car you will have to use piece and tighten them in place by means your ingenuity in concealing the wires in of the two set screws. Be very careful the upholstery. If you are going to place not to lose the ends of the chain, as they it up front you can run the wiring along- will tend to slip back into the cable. side the pipe to the windshield wiper. You Slide the set back and forth a little simply have to examine your own car and until the little aluminum plate fits ac- determine for yourself the best arrange- curately over the two threaded holes in ment. the top of the chassis near the variable The construction of your car will also condenser. Screw this plate down with determine the exact disposition of the "B" two small 6-32 round-head screws. In do- batteries. If there is room under the front ing this, still be careful not to lose the or rear seats, place them there. If you ends of the chain. Before tying the chain feel ambitious you can cut out an open- to the variable con- ing in the rear floor- denser, set the dial board and hang a on the control panel wooden or metal box to 100. Also turn from it. If your car the plates of the is of the coupé or condenser all the roadster type the way in by twisting rumble seat is prob- the shaft as far as ably the most con- it will go in the di- venient p 1 a c e. In rection of the tube any event the three sockets. Then place batteries should be the bakelite pulley tied securely toon the left end of gether so that they the condenser shaft The "Auto l'ilot" installed on the running - will not shake and fasten it with board of a Ford sedan. It is neat against each other. the screw on its edge und unobtrusive. You now need only pointing it directly an aerial to com- upward. It is essential that you place the plete the installation. We have found that pulley directly in line with the opening a simple loop of wire stretched between in the little block guiding the chains; the front and rear axles provides adequate otherwise the chain will not run smoothly. pick-up and is installed much more easily Still keeping the control dial at 100, pull than wire screening. The under -car aerial the chain tightly and fasten it in the has the additional advantage that it is groove of the condenser pulley with the out of sight and does not involve any aid of the screw and washer. You will mutilation of the car's upholstery. Simply have to experiment a little in order to de- regard the front and rear axles as you termine the best tension on the chain. would the spreaders of a regular aerial, With this work done, you can complete and stretch the wire between them. You the wiring to the binding posts on the ter- must be very careful not to have the wires minal strip, at the right end of the set. interfere with the action of the steering The 221 -volt "C" battery for the last au- gear or any of the brake rods. In some dio amplifier tube fits in the box at the left cars it is advisable to fasten the aerial to end of the chassis. Simply jam it in place the spring shackles, to make them clear with two of the pieces of sponge rubber, the steering rod that connects the, two front and connect, it as shown in the drawings. wheels. You can install the whole aerial Before replacing the floorboard in the system in about five minutes the next time car, tie up the cable so that it will not you have the crankcase oil changed. Pull shake excessively while the car is in mo- one end of the aerial wire through the tion. Try to avoid sharp bends, as these small hole you had previously cut in the tend to make the action of the control step plate and connect it to the aerial bind- cable rather sticky. ing post on the terminal strip on the set. One of the extra wires that you taped The adjustment of the receiver is very to the control cable must be connected to simple and involves nothing more than the chassis of the car. Clean away the (Continued on page 57) 14 Vol. 3, No. 2, Radio Design NI

The television projector, screen, and loud speakers set up on the stage of Proctor's Theatre, Schenectady, N. Y. Television in the Theatre Remarkably Clear Images of Distant Vaudeville Performers Flashed on - Foot Six Screen Set on Stage, With Voices Reproduced Through Loud Speakers; Radio Transmission Used Throughout, Without Any Wire Line Connections.

By ROBERT HERTZBERG

AS A MAGAZINE for the experimenter excellent foundation on which to start and constructor, RADIO DESIGN has their experiments with visual broad- deliberately ignored television during the casting. past year and a half. We have refrained While RADIO DESIGN still has nothing from publishing articles on the subject be- tangible to offer in the way of . cause of the scarcity of television television broad- receiver "dope," it is publishing this ac- casting stations, the uncertainty of the count of the recent results obtainable from achievements of the the few active General Electric Company because of the stations, and the difficulty and cost of pur- spectacular nature of the chasing even crude demonstrations apparatus for recep- and of the impending opening of the tele- tion purposes. Instead, we have swung vision field to the individual our readers' interest to experimenter. the short waves, The Pilot Radio & Tube Corporation, which have proved to be the most inter- which did some pioneer esting phase of radio television broad- ever opened to the casting in 1928 but was prevented from amateur. continuing its We development program by believe this policy has been a wise lack of space in its Brooklyn factory, has one. Television has definitely been placed recently acquired a gigantic in the short-wave plant at Law- channels, so the expe- rence, Mass., where it will resume its in- rience that radio fans have acquired from terrupted work on a large their short-wave work scale. It will will give them an help the amateur by operating a television Vol. 3, No. 2, Radio Design 15 station of its own and eventually supply- Alexanderson, was seen and heard as he ing necessary receiver parts. explained the method by which the images For the present, our answer to televi- reached the theatre. Other performers sion inquiries is the same as it was a year were Matilda Biglow Russ, soprano; ago: When we find an outfit that works, Frank Camadine, harmonica player; and that costs somewhat less than the and one of the vaudeville performers, million -dollar affairs used by the G. E. who, after his appearance on the and the A. T. & T., we'll run a full de- stage, was seen in the same act via tele- scription of it. vision. * * * The performers appeared before the television camera in an improvised studio N MAY 22, 1930, for the first in the laboratory of Dr. Alexanderson at time in history, television images the General Electric plant. Light im- transmitted by radio were pub- pulses, converted into electrical impulses licly exhibited as part of the or radio signals, were sent out by a trans- regular0 performance at a theatre. Through mitter in the laboratory on a wavelength a loud speaker system similar to that of 140 meters. A microphone close to the used for "talking movies," the voices of artist picked up his speech and song, and the televised performers, also transmitted converted the sound into electrical im- by radio, were heard by the audience. pulses which were carried by wire to a The theatre was the R.K.O. Proctor, in short-wave transmitter at South Schenec- Schenectady, N. Y. The active images of tady, from which point they went on the the performers were reproduced on a air on a wavelength of 92 meters. screen six -feet square and were clearly visible even in the back rows of the bal- THE THEATRE APPARATTB -- cony of the big playhouse. While they At the theatre R. D. Kell, assistant to flickered a little, in the fashion of the Dr. Alexanderson in television research, early movies, and rocked sideways a trifle as the disc - driving motor s "hunted," they were astonishingly 1 i f e - like and real, and evoked prolonged applause. The system used was developed by Dr. E. F. W. Alex- anderson, consulting engineer of the Gen- eral Electric Com- pany, a pioneer in the development of television and its kindred art-radio. Audiences at the afternoon and evening shows saw the musical director, John Gamble, lead the orchestra. The musicians were in their customary position in the pit, but the director, miles away, hearing his men over a tele- a s phone line, w Dr. Alexanderson in front of the television projector used in present only in the theatre demonstration. The scanning disc is enclosed for image. Merrill the protection of the men working around it. In the background Trainer, laboratory cure the powerful amplifiers needed for the operation of the assistant of Dr. system. 16 Vol. 3, No. 2, Radio Design Photo -electric tuba frema I'lrcrophona 900 watt arc Light. Antenna

Oscillator(talevtslon) Modulator Recttfimr

Microphone ampLrfier

To voice. transmitter - Pictorial representation of the television transmitter. The light thrown on the subject by the arc light is reflected into the photo -electric cells, the output of which operates the modulator section of the television radio transmitter. The modulated signals are then radiated by the antenna. The voice of the performer is transmitted over a separate transmitter on another wavelength.

in the rôle of control operator, received THE TRANSMITTING LAYOUT the picture or light impulses, reproduced In the television studio, the method was them on a small monitor telopticon and similar to that used by Dr. Alexanderson then transferred these impulses to the in previous demonstrations. The subject light valve, at which point the light was to be televised stands before an incandes- broken up to produce an image corre- cent lamp. Between the subject and the sponding in every detail to the subject at light is a metal disc about the size of a the studio. Head and shoulders only were bicycle wheel and drilled with forty-eight shown. A second receiver picked up the holes. The revolving disc covers the com- sound signal and fed it into loud speakers plete subject twenty times per second; which converted the electro-magnetic that is, there are twenty complete pictures waves into sound. The size of the image made up of light and shade. A large was a distinct advance over any previ- square frame contains four photo -electric ously shown. Dr. Alexanderson's first tubes, sensitive to light. The tubes re- demonstration, three years ago, was a pic- spond 40,000 times per second to impulses ture in a three inch aperture. Last fall, reflected back from the subject. at the Radio Show at the Madison Square At the theatre the electrical impulses Garden, New York, an image fourteen were received and passed on to a light inches square was exhibited. valve, based on an invention by Dr. Au- The image shown was not simply black gust Karolus, of Leipzig, Germany. The and white, on the order of a silhouette. light valve is in the middle of an intri- All the gray shades between black and cate lens system, in front of a high in- white were reproduced, registering every tensity arc lamp of a type similar to those shadow and shade of the features and used for the projection of motion pictures. giving both depth and detail to the The light valve operates delicately and image. accurately to permit the passage of light In radio broadcasting the frequencies in correspondence to the impulses received of speech and music modulate the current from the television transmitter. These sent out from the antenna. In television light emissions are passed on through the antenna radiation is modulated by a lenses to a dies corresponding in size, succession of light impulses. number of holes and rate of rotation to Vol. 3, No. 2, Radio Design 17 the disc at the camera or originating "The engineer and inventor who fore- point. Additional lenses pass the light for- casts the future confines himself to the ward to the screen, where these light im- next five to twenty years. His forecast is pulses, at the rate of 40,000 per second, determined by his knowledge of the prob- become the living, active image of the sub- lems and difficulties presented and he ject. must have a belief that events are in a The arc lamp, with the lens system and broad way predestined by natural social the light valve, the whole making up the forces. television projector, is placed seventeen "Looking back over the development of feet back of the screen. Heavy black cloth the electrical industry we can clearly from the projector to the screen makes an trace those forces; how the science of elec- effective light tunnel which eliminates the tricity gave birth to the electrical indus- possibility of stray light hitting the screen. try; how later the electrical industry took All the elements in the system, including hold of another branch of science and cre- projector, amplifier and loud speaker, are ated the radio industry. We are able to mounted on wheels to permit assembly some extent to project into the future the and disassembly when used as part of a working of the forces that give birth to vaudeville program. The accompanying new epochs, but as to the destiny and sig- photographs and drawings show the con- nificance of these new movements after struction of the transmitting and receiv- they have been launched, the engineer is ing apparatus in detail. peculiarly blind. Mr. Owen D. Young has repeatedly said that he has the great DEVELOPMENT AND FUTURE OF advantage of not being handicapped by TELEVISION scientific knowledge. His predictions of Naturally, this demonstration of tele- the future have also been much more far vision in the theater brought up many spec- flung and correct than those of the en- ulations as to the development and future gineers associated with him. of the art. Dr. Alexanderson made this "For fifteen years radio was simply an the subject of a talk, which we are priv- auxiliary to navigation. In 1915 and 1916 ileged to publish. We have italicized cer- we held daily communication by radio tel- tain portions of it because of their partic- ephone from Schenectady to New York. ular significance to readers of RADIO DE- We found that many amateurs adopted SIGN. the habit of listening in, and our noon Antenna receiving Antenna receiving /television signal voice signal

projectorArc tight Monitor Voua receiver Light volve Screen Telavistonrace iver Amplifier

Disc Ra.ct ifitar Amplifier

The arrangement of the receiving apparatus in the theatre. The television signals are picked up on a small receiver, detected, strengthened by an audio amplifier using the enormous power of one-half kilowatt, and then lead to the light valve. The latter modulates the light from the arc and the scanning disc reconstructs the picture on the screen. The voice is picked up, amplified and reproduced in the usual fashion. 18 Vol. 3. Na. 2. Radio Design Projector Lens System

Polar' 3ing prisms -- Condensing tans --- Diaphragm Lams .-Condensar tans Diaphragm Condensing Screen fans Projection lens Lighc valva

DLSC

The layout of the television projector in detail. The heart of the system is the light valve, which is the only known means of modulating the great amount of light required for the projection of life-size images on a large screen. Its inner construction is a. secret its makers will not yet divulge. It is evident from this drawing that the design of the apparatus is more of an optical problem than an electrical one. hour of radio became part of the first tests with different wavelengths which regular broadcasting. But we had no proved to be failures because one ray idea what it would lead to. Our idea was followed the surface of the earth, where- to telephone across the ocean, and so we as the other was reflected from a did at the close of the war, but we failed layer of electrons 100 miles above the to see the great social significance of earth. We are now working with a wave- broadcasting. Television is today in the length of 140 meters in which the ground same state as radio telephony was ih 1915. wave is predominant. For long distances, We may derive some comfort from this on the other hand, we have found it ad- experience of the past, but on the other vantageous to use the shortest possible hand, we are not sure that the analogy is wavelength so that the bulk of the radia- justifiable and that television will repeat tion leaves the earth and only the lower the history of radio telephony. We must fringe of it will arrive at the receiving then fall back upon our conviction that station. It is expected that the tests that the development of television is inevitable are now in progress are going to throw on account of the forces working in the much more light on the subject of wave scientific world today, and that it is a propagation. satisfaction to make one's contribution to this evolution even if, in this case, the TELEVISION FOR THE AMATEUR results should prove to be only a stepping "Television apparatus is for this pur- stone to something else. pose an ideal working tool, and I venture "If you ask who invented television, the to predict that we will soon see a wave of nearest to a simple answer would be that activity in amateur television. There are a German, Nipkow, invented television more than 100,000 experimenters in Amer- about fifty years ago. However, he did ica, young and old, who go in for radio, not have the radio amplifier or the neon not to be entertained, but who like to build lamp, and therefore his invention could their own sets and get a thrill from ex- not be completed at that time. He did, ploring the unknown. These amateurs however, clearly explain the idea of scan- have been rather starved of real interest ning the picture, line after line, by a spot in the last years due to the commercializa- of light. tion of broadcasting. They will be the "Before we could produce the results ones who will popularize long distance you have seen, we had to make several television just as they were the ones who Vol. 3, No. 2, Radio Design 19 the created the interest in broadcasting. In to see whatever is of interest and and the profes- whole theatre audience will be with him this interest the amateurs audience sional experimenters are on common seeing what he sees, and yet the ground. will be perfectly safe and comfortable. "We got a real thrill out of sending a MILITARY ASPECTS and have it television wave to Australia in the wars its tale even though it "Or what will this mean come back and tell when a staff officer can see was a simple one. We observed that after of the future had the enemy through the television eyes of traveling 20,000 miles a rectangle still they can send which was more than we his scouting planes or when four corners, plane without a man on board had expected. As a matter of fact, it was a bombing time. which can see the target and be steered broken up into pieces most of the when it hits? of encourage- by radio up to the moment But there were glimpses will it mean for peaceful avia- ment and a fertile field for the imagina- Or what of the ex- tion when the ships of the air approach tion. These are the incentives on a local pilot, not he is an amateur or a a harbor in fog, take plorer, whether from a little craft that comes to meet the professional. television, whereby the "Whether the general public will be ship, but by satisfac- trained eyes of the pilot, functioning by enough Interested or get enough guide the ship to the air- television to make it possible television, will tion out cf port in safety." to commer. ;alize home sets for television is still to b seen. A new technique of entertainment will be required. As a sup- plement to broadcasting it can make a reality of the radio drama. Political and educational speakers may use it as a medium, and entertaining personalities like Will Rogers will tell the latest wise- cracks and comment on the news of the day. You have seen our test at Proctor's Theatre in this city. It is likely that every moving picture theatre in the large cities will have to be equipped to give a short television act. "What you have seen today is just one of the many steps that must be taken in our efforts to conquer distance by television. THE LIGHT VALVE "The improvement of light control which makes it possible for us to show a picture of theatre size is due to an invention by Dr. Karolus, whom I visited in Leipzig, Germany, some years ago and whose inventions we have been endeavoring to perfect. In our past exhibits the improvements of light control have been Merrill Trainer, assistant to Dr. Alexan- due to Dr. D. McFarland Moore and his derson, in front of the television trans- neon lamps, and I should not be surprised mitting frame containing the photo-elec- would go one bet- tric cells. The hanging device at the left, if next time Dr. Moore is a ter than Dr. Karolus. Invention is a de- which looks like a burglar's lantern, and if we did condenser type microphone. It is just out lightful and friendly sport, the scanning rays. not have competition we would not have of range of as you could not have a The scanning rays of light, which sweep inventions, just the subject are generated race unless you have somebody to race across the face of by an arc light and a revolving scanning with. disc, located behind the photo -electric-cell "The possibilities for new inventions in frame. The light comes through the hole this art of television are inspiring. Just in the center of the latter. The cell frame think of it, when you can put an electric and the subject are enclosed in a light- eye wherever you wish and you can see proof booth made of black cloth. This through this eye just as if you were there. prevents stray light from hitting the cells An airplane with a news reporter will Sy and registering as undesired lines. 20 Vol. 3, No. 2, Radio Design

1 LTHOUGH the reception of for- screen -grid R. F. and also the usual re- eign short-wave broadcasting generative detector. The nature of the stations is no longer an unusual power supply and of the audio amplifier experience for thousands of system is of little consideration. The suc- radio fans, there are still many owners of cess of the receiver depends mostly upon short-wave receivers who have never the apparatus that precedes the audio am- heard anything outside of the United plifier. States or Canada. Their disappointing failures can be explained usually by either REGENERATION CONTROL IMPORTANT or both of two reasons. They do not ex- Without question, the most important ercise enough patience in adjusting and feature of any of the foregoing types of tuning their sets or they do not know short-wave receivers is the regeneration when and where to listen. control. Unless the regenerative action is The writer has been carefully studying smooth and quiet and can be controlled ac- many letters written by readers of RADIO curately, the receiver will never produce DESIGN, and has prepared this article as satisfactory results. Obtaining this neces- a general answer to the many questions sary smoothness of control is really an they have asked. The information given easy matter. The factors that control the herein applies not only to the well-known action are the plate voltage, the size of Super-Wasp receivers, but also to short- the tickler windifig, the detector filament wave receivers of practically all other temperatuïe in battery -operated sets, and- makes and designs. Short-wave receivers the resistance of the grid leak. The first differ greatly in general appearance and two factors are the most important. construction, but fundamentally they are If you are using a set of factory-woun all very much alike. coils or have wound your own coils accord- Short-wave receivers can be divided into ing to reliable information, the tickler three general classes: the first and oldest windings are probably of the correct size is the straight regenerator; the second is and you will not have to bother with them. a combination of untuned screen -grid If the regenerative action is cranky and R. F. amplification and a straight regen- the detector tube falls violently into oscil- erative detector; and the third is the lat- lation, regardless of how carefully you est and most advanced design using tuned turn the regeneration condenser, the thing Vol. 3, No. 2, Radio Design 21 for you to do is to provide the detector put tube in the last stage of audio ampli- plate circuit with a potentiometer, by fiers, but it also happens to be an extreme- means of which you win be able to adjust ly sensitive detector. Its filament takes the actual detector plate voltage to the 5 ampere at 5 volts, like the 201A, so you best working value. In most sets it is not can plug it right into the detector socket possible to leave the detector voltage fixed without making any changes in the wir- over a wide range of wavelengths, as the ing. circuits tend to oscillate more easily on If you have obtained the best potentio- some wavelengths than on others. meter adjustment for one wavelength The potentiometer should have a resist- range, plug in the next coil or coils and ance of at least 100,000 ohms, the Pilot try again. In a few sets one adjustment No. 941 Volumgrad being especially suit- may hold for a rather wide range of wave- able for the purpose. The instrument is lengths, but in most outfits some re- connected as shown in Fig. 1. One end adjustment is very necessary. of the potentiometer resistance goes to Fig. 2 shows the actual connections of B- . The other end goes to B + 90 volts, a No. 941 Volumgrad to a battery model on either the "B" batteries or the "B" Super -Wasp. Do not fail to make the power pack, and the center connection or usual connection between the B- post on arm runs to the binding post on the re- the receiver and the B- post on the bat- ceiver marked B + detector. This hookup teries. applies to any short-wave receiver using In battery -operated sets the detector a variable condenser as the means of regeneration control. There are a few sets TO e. ot r using a variable resistance or potentio- ON St meter for the actual regeneration control of course, the additional po- and in these, to e. tentiometer is of no value. If the regen- 6 - 90 roils eration is not smooth the trouble is in 149 94/ 904 UM094D some other part of the set. /00,000 ONMJ

ADJUSTING THE POTENTIOMETER To adjust the potentiometer with any one plug-in coil, as in the case of the Wasp and other straight regenerative receivers, or pair of plug-in coils, as in the sir Super -Wasp, set the tuning condenser or condensers to 100 and start turning the 8 - potentiometer knob until the set slides quietly into oscillation just as the regen- B 90 Y. 100 on the eration condenser approaches Fig. 1: How a No. 941 Volumgrad scale or maximum capacity. You will now (100,000 ohm potentiometer) is con- find that the regeneration all the way nected for control of the detector plate down the tuning scale is quite smooth and voltage. easily controlled. If a marked reduction in plate voltage filament temperature also has an import- still leaves the regeneration very short ant effect upon the regeneration. In fact, and abrupt, there are too many turns on in some of the older types of receivers the tickler winding for the particular de- vernier rheostats were used for the regen- tector tube you are using. Note this last eration control instead of variable con- qualification very carefully. Tubes that densers in the plate circuit. The 201A appear to be alike when tried in a broad- tube is not at all critical, but if the set cast receiver may work very differently oscillates rather strongly it can be calmed when used as regenerative detectors in down by a reduction in the filament cur- short-wave sets. This is particularly true rent. In other words, merely turn the of A. C. tubes. You should always try all rheostat down a little. the tubes you have in the detector socket, The grid leak used in the detector cir- as you will undoubtedly find one that cuit is not at all as critical as most writ- works better than the others. ers would have you think. Three megohms, If you are using a battery receiver by with a .0001 mf. condenser, is just about all means try a 112A tube as the detector. right for most tubes of the 201A, 200A, This tube is usually used as a power out - and 227 types. 22 Vol. 3, No. 2, Radio Design - BATTERY MODEL SUPER -WASP - B. C- B. Lì* C- B+ B. DE T 4.SV. A#B- A-ct /35V 90V 9v IIET /33K L. S. LS- GN."

Fig. 2: How the Volumgrad is con- TO B+ No 94/ VOL!/MGRAD /oo, 000 OHM nected to a battery -model Super - 90 VOLTS Wasp for detector control. Do not fail to make the usual connection to D-.

THE TUNING PROCESS CHECK THE POWER SUPPLY The actual tuning process, once you It seems almost superfluous to say that have tamed down the regeneration, is very the "A" and "B" batteries, as well as the simple. Keep the detector in a continual A. C. power pack, should be in first-class state of oscillation by rocking the regen- condition if good results are to be expect- eration dial back and forth as you turn ed. However, it is surprising to learn how the tuning dial a fraction of a degree at a many people try to get along with run- time. When you encounter a carrier wave down storage batteries, dried -out "B" bat- you will hear a tell -tale whistle. If the teries and gassy rectifier tubes. The folks signal is fairly strong, you can back down who know the most about such things are the regeneration until the whistle disap- usually the ones who neglect the power pears; if the signal is rather weak, it is supply most shamefully. best to "zero -beat" it. This is the process Unscrew the vent caps from the storage of keeping the circuit in oscillation, but battery and pour in some distilled water tuning it so that the frequency of the if the edges of the plates show above the local oscillations is exactly the same as acid solution. Test the acid with a hydro- that of the incoming carrier wave. Under meter and, if it reads below 1200, have this condition no whistle is generated the battery charged. A test with a volt- (there being no heterodyne action), and meter is really of no value, as even a dis- the voice or music can be distinguished. charged battery will read pretty close to The signals will sound rather "mushy" if 6 volts on open circuit. Likewise, test the they are zero-beated, but at least they will "B" batteries with a voltmeter. If you do be recognizable. Sometimes, after a sta- not own a meter of your own you can tion is brought in by the zero -beating usually borrow one from your local radio method, its strength may increase so much dealer. Forty-five volt blocks should be that the detector can be thrown out of discarded after they drop to 37 or 38 volts. oscillation; the signals will then clear up If the set is of the A. C. type the D. C. considerably. voltmeter used to measure the plate volt -

.9 C SUPER - iN 9S.o

,wnri+ 9 AC. R+/JSV B- r, ND 4ß

B+/3S V P/L or H° 94/ VOL (MGR/7D3 ON K-/// F0 WER /00, 000 OHMS PRCK

B+¢J V.

Fig. 3: The best arrangement for voltage control in the A. C. Super - Wasp: two volumgrads connected as potentiometers. Again remember the B- connection. Vol. 3, No. 2, Radio Design 23 age must be of the high -resistance type. coils are placed between the set and the The small watch-case voltmeters sold for pack, and the whole assembly can be battery -measuring purposes are not at all moved around comfortably without dis- suitable for measurement of "B" elimi- turbing any of the connecting wires. No- nator voltages. They usually draw as much tice that the various filament and plate current as the whole receiver itself and leads are tied up in a cable, telephone give altogether false readings. style. As mentioned in previous issues of CONNECTIONS RADIO DESIGN, an incidental little trouble SIIPER-WASP BATTERY the sometimes turns up in the A. C. Super - There has been much confusion over Wasp due to the use of too much voltage proper method of making the battery con- on the screen of the P-224 tube. The usual nections to the K-110 model of the Super- result of this excess current is uncontrol- Wasp, when output tubes of either the lable oscillation in the radio -frequency 112A or 171A type are used. Fig. 5 shows portion of the set. The simplest way to in picture form the connections when a cure this is to connect a potentiometer in 112A tube is used as the second audio am- the B + 45 volt lead. Once the potentio- plifier. Note that only three 45 -volt "B" meter is set it may be left alone. Fig. 3 battery blocks are needed for the plate shows the connections of this potentiome- supply and a single 9-volt "C" battery for ter and also an additional potentiometer the grid bias. Of course, two 4% -volt "C" for the adjustment of the detector plate batteries connected in series may be used voltage. The screen potentiometer is the instead of a single 9 -volt unit. Fig. 6 one on the right, the detector potentio- shows the same receiver with enough bat- meter the one on the left. As these instru- teries for a 171A output tube. This time ments require only occasional manipula- four 45 -volt "B" battery blocks are need- tion they need not be mounted on the front ed, along with two 22% volt "C" batteries. panel of the receiver. Instead, they can The binding post on the receiver marked be placed conveniently on a small bakelite B + 135 volts actually gets 180 volts, for shelf fastened between the two shield cans. the plate of the 171A. This strip may be held in place by means There is little to choose between the of two simple L-shaped brackets, held by 112A and 171A tubes as last audio ampli- the screws in the facing sides of the cans. fiers. The two tubes give just about as The illustration marked Fig. 4 shows these much amplification, although the 171A is two potentiometers mounted in a standard capable of handling more volume. Please Super-Wasp. Incidentally, this photo- distinguish carefully between amplifica- graph also shows a good way of mounting tion and volume. The 171A tube will not the whole outfit. Both set and pack are make any given signal louder than the screwed down to a board 25 inches long 112A will. It is simply capable of han- and 12 inches wide. The two boxes of dling, without distortion, very loud signals

in an Fig. 4: How the two Volumgrads shown in Fig. 3 are actually mounted A. C. Suver-Wasv between the two shield cans. 2, Radio Design 24 Vol. 3, No. B+ G H- B+ B+ C- 5" B+ 2)E7 4SV B- C+ /3SV. 90V 9V. DET. /JSV. L.S+ L.S.- GNd. ® O O O O O O O O O

T'i. _q;Y -9V 6 VOLT pt}. 8.977:

Fig. 5: Battery connections for the K-110 model of the Super-Wasp when a P -112A is used that would overload the 112A. For all comfortable. Fig. 7 shows how an ear- ordinary purposes, the 112A is to be pre- phone jack may be connected in the bat- ferred because it has plenty of power -han- tery model Super -Wasp, and Fig. 8 shows dling capacity and requires a cheaper bat- how this jack is used in the A. C. model. tery layout. It is absolutely essential that the jack in the K-110 be completely insulated from USING EARPHONES the panel or chassis. If it is not it will Many Super -Wasp owners have inquired shortcircuit the "B" batteries. In the as to the best method of reducing the K-115 the frame of the jack should make audio amplification when earphones are good contact with the panel, insulating used, as some stations are so strong that washers being unnecessary. they actually hurt the ears. It is possible In Fig. 7, the jack completely cuts out to reduce the amplification of the audio the audio transformer when the earphone system by connecting a potentiometer plug is inserted in it. In Fig. 8, the phones across the secondary of the first audio are merely connected across the trans- transformer. However, it is much better former primary. The 1-mf. condenser con- to eliminate one stage altogether, by connected between the spring of the jack and necting the earphones in the plate circuit the upper or P post of the transformer of the third tube. With only one audio prevents the high voltage from flowing stage, the incidental little noises are re- through the phones and from possibly duced considerably and reception is more causing the wearer a severe shock. While

B. C- A + A- B B+ C- B+ B+ DCT 1.5V Q- C. /11V 90V. 91'. DCT ¶000/71V [.S. [.J: GAO.

4. s1'ii.t + + erz Q61 6yoLT VOi.z...... _,...... ,- - a5ß 45'B Y 45'8 Y BÂTI. é, - B./ Wit 6/ aAc rr / Fig. 6: Battery connections when a P -171A tube is used. Vol. 3, No. 2, Radio Design 25 this condenser effectively blocks the direct separate aerial for the short-wave receiver current supplied by the "B" power pack, it if you are already using a medium sized offers very little resistance to the fluc- aerial for your regular broadcast set. tuating signal currents. In neither of these Merely run a wire from the aerial bind- two arrangements is any provision ing post of the short-wave outfit to the made for shutting off the fourth tubes, as additional aerial lead-in, and see if both sets operate switches are undesirable. In at the same time. Whether they will or the battery set the simplest thing to do is not to pull out depends on the particular arrange- the last tube. In the A. C. set ment of the primary circuit in the broad- it is advisable to leave the tube running. If it is cast receiver. In many cases this stunt removed the "B" voltages to the works very well. other tubes will rise and unbalance the receiver. If the broadcast aerial is a rather large one, merely wrap the wire In connection from the short- with the use of earphones, wave set around the lead-in for a distance it should be stated that because of the irregularity of about a foot or a foot and a half, with- of short-wave transmission it out actually making connection to it. This is extremely difficult to tune in distant stations gives a capacitive coupling that is usually directly on the loud speaker. It is sufficient to produce excellent very much to results. If easier plug in a pair of ear- you find that neither of these two connec- phones first, locate the stations, and then tions connect the proves satisfactory, you can then loud speaker, if the signals are erect a separate little aerial for the short- strong enough for loud speaker reproduc- wave receiver. tion. People who have grown accustomed In connection with aerials, it is to tuning in broadcast stations by the loud appropriate to remark that dead spots on the tuning scales of many straight regenera- he//es JACK tive receivers is usually due to the absorp- /N9U24TED FROM PANEL. tion defects of the antenna system. The JeiTuee *Cruet natural wavelength of the aerial and ground may just happen to fall within the tuning range of the set, and the antenna then absorbs the energy from the plate circuit just as quickly as the tickler feeds it back to the grid circuit. The result is P that the set refuses to show any of the usual symptoms of regeneration or oscilla- SECOND AN- J9/ TRANSEORAFER tion on certain points on the dial. The remedy for this trouble is merely to Fig. 7: Connections of an earphone change the electrical jack in the battery constants of the an- -model Super -Wasp tenna system by inserting in the aerial lead a very small fixed condenser. The speaker method may find earphones a bit Pilot VM -81 Micrograd is especially rec- inconvenient at first, but after a few eve- ommended for this purpose, as it is very nings of use they will find them very much more comfortable and effective than the speaker. Telephone receivers are extremely sensitive and will make audible to the human ear minute signals that will not register at all on a loud speaker.

SHORT-WAVE AERIALS For short-wave work, the N //e5 JAC.r receiving HO4.Vr(D aerial need not be more than 50 feet or ON PANEL so in length. Of course, it should be strung Fig. 8: Connections of an earphone as high and as clear as possible, and jack in the A. C. Super -Wasp. should be carefully insulated. The usual ground connection may be made to a small and steam or water pipe, or can be adjusted in a few sec- to one of the spe- onds. Sometimes a cial grounds described in the article slight increase in the en- detector plate voltage will overcome dead titled "Summer Radio," which appears on Page 17 of spots, and in this connection the plate cir- this issue. cuit It is potentiometer mentioned in the early sometimes unnecessary to erect a part of this article is particularly valuable. 26 Vol. 3, No. 2, Radio Design HAND CAPACITY EFFECTS with the matter of increasing the wave- In many older types of short-wave re- length ranges of both the Wasp and Su- ceivers considerable trouble is experienced per -Wasp receivers. Many owners of these from hand capacity effects, the causes of sets want to make them tune up to 600, which are not clearly understood by most 700, 900, and even 1200 meters. This can- radio fans. If the parts of a short-wave not be done efficiently without re -building receiver are left out in the open, without practically the entire receiver. The Wasp the protection of metal shields, they will and Super -Wasp are essentially short- act as one plate of a large variable con- wave receivers and use the very small tun- denser of which the operator's body forms ing condensers necessary for short-wave the other plate. The dielectric is the air work. With the aid of the special bank - between the set and the body. This effect wound blue ring coils supplied with the is illustrated in Fig. 9. As the operator kits, they just about manage to reach 500 moves his hands toward and away from meters, but their range cannot be extended the set he changes the overall capacity of beyond this point without the substitution the system, and as the capacity of the tun- of larger condensers. ing coils and condensers in the set are af- Merely winding larger coils and using fected, the signals will fall in and out of mf. condensers is no tune. the present .00016 solution of the problem, as the capacity - inductance ratio of the combination be- cl comes very bad and selectivity practically disappears. If you are interested in long - wave reception, the best thing for you to / ,/,' \ do is to make yourself a separate tuner using honeycomb coils for inductances and 11 :maul!' tuning condensers of at least .0005 mf. capacity.

ABOUT S. W. ADAPTERS RADIO DESIGN receives many letters in- quiring as to the effectiveness of short- wave adapters as distinguished from com- WNSH/E[JJED SET plete short-wave receivers. In general, our Fig 9: Cl and C2 represent the ca- experience with adapters has not been sat- pacity effect of the operator's body in isfactory. The reason for this is not so relation to the receiver. much a technical one as it is a psychological one. The people who are most easily If a receiver is shielded by means of a sold on adapters are those who do not un- metal cabinet, or at least by a metal front derstand short-wave radio and who expect panel, one plate of the condenser is formed to hear foreign stations merely by plug- by the metal frame work and not by the ging the magical instrument into their parts of the receiver itself. Therefore, present broadcast receivers and twisting a changes in the distance between the oper- little knob. Foreign reception is not at all ator and the set do not change the con- as easy as all that, and only the man stants of the receiver and do not cause de - who will go to the trouble of making his tuning effects. Fig. 10 illustrates the ca- own short-wave receiver and studying the pacity action of an installation of this incidental literature on the subject is able kind. to appreciate the situation. Many people want to know how they As a matter of fact, the construction can eliminate hand capacity troubles in and operation of a separate short-wave their own receivers. The answer must be receiver like the Super -Wasp is cheaper obvious from the foregoing discussion. Re- and involves fewer difficulties than the use build the outfit to use at least a metal of an adapter. With an adapter, you have front panel, or better, a completely en- to pry into the bowels of the receiver, re- closed metal cabinet. The metal may be move tubes and in general disturb the out- copper, brass, or aluminum, the latter fit. Of course, you also temporarily put the usually being used because it is cheap, set out of commission as an instrument of light and easily worked. entertainment. With a separate short- wave set you can explore the ether waves SUPER -WASP WAVELENGTH RANGES without depriving the rest of the family A frequently recurring question deals of their usual radio programs. Vol. 3, No. 2, Radio Design 27 WHEN AND WHERE TO LISTEN operate powerful transmitters, and if you Having a good receiver in operating tune way down low on your smallest coil, condition is only half the battle. You you can get them loudly enough to wake must know when to listen and at what up the family next door. If you have al- points on the dial. The accompanying ways confined your listening hours to the chart of dial readings for the Super -Wasp early evening, you won't know your set should be of great assistance to owners in the early morning. The air is nice and of this popular receiver. (See page 32.) quiet, and the very low -wave stations skip One thing many people cannot seem to in without much coaxing. get into their heads is that time is differ- During the afternoon the German sta- ent in different places. Many short-wave tions get busy, and come through just a set owners finish their suppers at about little under WGY, G5SW starts at 2:00 7:00 or 7:30 in the evening and then sit P. M., E. S. T., and is an old.stand-by. down to their receivers with the innocent As you know, skip distance effects vary expectation that there will be short-wave with wavelength and the condition of the atmosphere. Therefore, divide your listening schedule something like this: 14 to about 20 meters, best from daybreak to about 2:00 P. M. and then fades out as darkness approaches; 20 to 35 meters, Eu- Vf ropeans from 1:00 P. M. to about 10 in the evening (if they happen to be putting on late programs); 35 to 75 meters, best between twilight and daybreak.

SPOTTING THE STATIONS You can locate many of the foreigners JN/ez'DED .SET by spotting some of the American stations. For instance, you can get W2XAF (WGY) Fig. 10: Here the capacities Cl and pretty easily on 31.48 meters; crawl just C2 exist in relation to the shielding, under him and look for PCJ, NRH, and and therefore have no influence on the receiver itself. the German station at Koenigswurster- hausen. You can spot these groups of stations because they are about 10 degrees stations to hear all evening. Seven o'clock below a very powerful code station on New York time is midnight in London, and about 33 meters. This is XDA, in Mexico G5SW, the famous B. B. C. short -waver, City, which also occasionally uses voice. is just signing off for the night. The There is a whole mess of stations around writer has seen hundreds of letters from 48 and 49 meters. Generally the Ameri- people complaining of their inability to can stations fill up the ether pretty well bring in London for their bridge guests- in this range, but if your set is selective at nine o'clock. This is an age of scien- you can cut between them and pick out tific achievement, but a dozen short-wave some interesting stations in Central and sets won't bring in a station that isn't South America. First locate W3XAU transmitting. (Philadelphia), and tune just above him Probably the best time to hear foreign for station HRB, in Honduras. Log stations is early in the morning and about KDKA on its new 49 meter wave, and just the middle of the afternoon. Between below him find HKT, in Bogota, Colum- four and about eight A. M., the stations bia. After tuning in the powerful Amer- in Australia, Siam, Siberia, the Dutch ican telephone transmitter WND, on 44.4 East Indies and Holland are quite active, meters, hang on closely and listen care- and they deliver astoundingly strong sig- fully for VRY, in Georgetown, British nals. VK2ME, in Sydney, Australia is Guiana. It is quite easy to identify the testing pretty regularly with Schenectady Central and South American stations, as and with the British Post Office stations they obligingly announce in English as in England, and comes through with fair well as in Spanish. reliability. They are not on every morn- Short-wave reception conditions have ing, but if you don't get him one day you the habit of changing quickly and with- probably will the next. out apparent provocation. If you don't Those Dutch stations are by far the hear a single foreign station for a week best ones. PLE and PLF, in Java, work- don't feel discouraged; the next week you ing with PHI, PCO, and PCK in Holland, may hear a dozen at a time. 28 Vol. 3, No. 2, Radio Design Short -Wave Station Schedules The Latest Information on the American and Foreign Transmitters, and Where to Find Them on the Super -Wasp

HE short-wave broadcasting sta- KZRM, MANILA tions of the world have not been The short-wave station of KZRM, at changing their wavelengths and Manila, Philippine Islands, apparently hours of operation recently as has been shifting its wavelength. We are frequently as they did during .the past in receipt of a letter from Miss Margue- Winter and Spring. However, we have a rite Cromwell, station manager, in which number of new items to report that will be two wavelengths are indicated. One is of interest to all short-wave fans who are 26.2 meters, and the other 48.94 meters. trying to keep up with the short-wave The operating hours, in Eastern Stand- situation. ard Time, are as follows: 5 to 6 p. m., First of all, we wish to acknowledge 2 a. m. to 4 a. m., 5 a. m. to 10 a. m. This some letters received from the Westing- short-wave transmitter is rated at one house Radio Stations and the Crosley kilowatt and is heard quite regularly in Radio Corporation. In the Spring issue of the United States, particularly along the RADIO DESIGN we stated that neither of West Coast. Station KZRM is owned and these two organizations would answer our operated by the Radio Corporation of the requests for information about their Philippines, to whom reports of reception short-wave activities. Now, however, they may be addressed. have made up for their silence by telling all there is to be told. XSXN, OAKLAND, CAL. WSXK, PITTSBURGH, PA. Mr. Joseph A. Copeland, 85 Main Street, South Cortlandt, Maine, who is the From Mr. P. A. Boyd, manager of press owner of a battery model Super -Wasp, relations for the Westinghouse stations, has forwarded to us the operating sched- we learn that W8XK, the short-wave ule of W6XN, which is operated in con- transmitter associated with KDKA, is on junction with KGO, the General Electric the air only on Sunday, Tuesday, Thurs- Company station day, and on a slid- at Oakland, California. Saturday. It operates A power of 10 kilowatts is on a wave- of fol- used ing schedule three wavelengths, as length of 23.35 meters, or a frequency of lows: 8 a. m. to 12 noon, on 19.72 meters 12,850 kilocycles. The station is on the or 15,210 kilocycles; noon to 5 p. m., on air on Monday, from 8 p. m. to 2:45 a. m.; 25.25 meters or 11,880 kilocycles; 5 p. m. on Tuesday, from 8 p. m. to 3 a. m., to 12 midnight, on 48.86 meters or 6,140 and kilocycles. on Saturday, from 8 p. m. to 4 a. m. As The silence of the station on KGO is Monday, Wednesday, and accounts part of the National Broadcasting Friday Company network, many of the NBC for the many complaints we have had chain programs from short-wave set owners that they are are heard through it. unable to hear Pittsburgh at certain times. CHICAGO AND SPOKANE STATIONS Station W8XK relays the regular pro- Mr. Stannard Smith, 1823 Grinshaw grams of KDKA, which include many of Boulevard, Los Angeles, California, re- the features of the National Broadcasting ports Station WLS of Chicago, Illinois, Company. transmitting on about the same wavelength as station WENR, which is on THE CROSLEY STATION 49.83 meters or 6,020 kilocycles. He also The mystery regarding the Crosley sta- reports Station KGA of Spokane, Wash- tion is cleared up by Mr. Z. A. Chambers, ington, which has also been heard by a its technical supervisor. It seems there number of other listeners. Judging from has been some misunderstanding regard- the Super -Wasp dial readings that he ing the license for W8XAL, and the trans- gives, this station is on about 65 meters. mitter is off the air until the difficulties Mr. Smith also reports hearing a Cuban are straightened out. Mr. Chambers station on 49.1 meters and would like to promises to advise us of the return of the correspond with any other listeners who station and to keep us informed on its can help him in identifying it. Mr. Smith activities. also gives his right dial reading for sta - Vol. 3, No. 2, Radio Design 29 tion RA97, Moscow, traffic between the as 51 with the yel- The past two issues of Radio De- Atlantic liners and low coils. sign contained what are probably both America a n d the most accurate and complete lists Europe w i 11 prob- UOR2, VIENNA of the active short-wave broadcast- ably be very heavy. From several of ing stations of the world ever pub- The steamers Levia- the foreign radio lished. These lists not only give than, Olympic, Ma- magazines we learn the wavelengths, but also the operat- jestic, Bremen, Eu- that Station ing hours of the various stations re- ropa a n d Homeric UOR2, duced to Eastern Standard Time. t h e official short- Every owner of a short-wave re- are known to have wave transmitter of ceiver should have them on hand for stations o n board, Vienna, Austria, has reference purposes, as they are of and their transmis- definitely acquired great value in locating and identify- sions have been the wavelengths of ing both American and foreign sta- heard with excellent 25.42 a n d 49.40 tions. Copies may be obtained from strength and clarity meters. The longer Radio Design, 103 Broadway, Brook- by many listeners. wave is unlikely to lyn, New York, at the price of 15c Each one seems to be heard in the each. Merely ask for Vol. 2, No. 4 use a number o f United States be- and Vol. 3, No. 1. Stamps accepted. wavelengths. In cause of time dif- general, the short- ferences and interest waves are used ference from local stations. during daylight hours, and the longer waves during darkness. The American, ITALIAN STATION ACTIVE British and French shore stations that An Italian short-wave transmitter, lo- engage with these ships are also heard cated in Rome, has passed its initial trials quite regularly. Most of the American very successfully. Reports as to the wave- transmitters seem to be located along the length are rather conflicting, but we be- coast of New Jersey. lieve that 25.4 meters is correct. A number of American listeners have reported H82PJ, SIAM hearing this station, which uses the con- A good target for short-wave fans to siderable power of 12 kilowatts. shoot at is station HS2PJ, which is located at Bangkok, Siam. According to a letter PARIS CHANGES WAVES received from Ghara Aram, radio engineer The French short-wave station which for the Royal Siamese Post and Telegraph announces itself as "Paris Radio Experi- Department, a wavelength of 29.5 meters mental" has recently changed its wave- is used. This station operates on Tuesday, length from 31.65 meters to 29 meters, in Friday and Sunday, from 1,300 to 1,600 order to avoid the jam that exists on the Greenwich Mean Time. Get out your time former channel. The daily broadcasts conversion charts and translate this into begin at 5 p. m., the power used being your own local time. (See page 43, Vol.2, 1,200 watts. No. 4, RADIO DESIGN.) Speaking of time reminds one that day- SHIP ACTIVITY light saving must be taken into considera- With the advent of the summer tourist tion in all calculations involving interna- season the ship -to -shore radio telephone tional time. The time conversion chart

Reproduction of the two sides of VK2MEs verification card-the prize of the short- wave fan. Mr. White picked up the Sydney station on a Super -Wasp. 30 Vol. 3, No. 2, Radio Design Amateur operators will be interested in this picture of W8XK, the shoat -wave transmitter of KDKA, at East Pittsburgh, Pa. This is one of the oldest and best known of all short-wave stations.

published by the government deals only Standard Time. During this hour the with standard time. names of 15 or more members will be THANKS FOR THE LETTERS called, and each member reporting the re- RADIO DESIGN wishes to acknowledge in- time and date of his own name will teresting and informative letters from T. ceive a souvenir from the station. J. Perry, 620 Moody Street, Waltham, We take pleasure in reproducing here- Massachusetts; C. M. Stevenson, 820 Park with a photograph of some of the staff Avenue, Weehawken, New Jersey; Thom- artists at HRB. These people are quite as N. Cranstoun-Day, Capetown, South up-to-date and are known to broadcast ex- Africa; and E. L. Cavitt, 272 Park Ave- cellent programs. nue, Carrollton, Ohio. Many other people SUPER -WASP DIAL SETTINGS who sent in reports on short-wave stations received acknowledgments direct. Following is a list of right-hand dial We again take the liberty of drawing settings of the Super-Wasp for the most on the bulletin published by the Interna- important and frequently heard American tional Short-Wave Club of Klondyke, and foreign short-wave stations. These Ohio, of which Mr. Arthur J. Green is figures represent the average taken from the enterprising president. We also wish the reports of several dozen set owners, to again recommend this organization very and give at least an approximate idea of highly to all short-wave fans. where to tune. The readings on your own Full parti- may culars regarding membership can be ob- set be higher or lower, depending tained from Mr. Green. Address him at on the detector tube you are using. If, for Box 713, Klondyke, Ohio. instance, you find that W6XN (Oakland, California), comes in on 81 on the right SPECIAL PROGRAMS dial instead of 78, as shown, you will Station HRB, the Tropical Radio Tele- know that your readings in general will graph Company, Honduras, Central Amer- be slightly higher than those on the list. ica, is putting on a special Saturday- If you can pick up a few of the stations night program for the benefit of members indicated, you will know whether to tune of the short-wave club. This station above or below them for other stations broadcasts on 49 meters and stages the that you are now missing. Use the list in programs from 11 to 12 p. m., Eastern this way and you will find it very. valuable. Vol. 3, No. 2. Radio Design 31 As most short-wave stations are of ex- G5SW, Chemlsford, England 86 perimental nature, they make frequent CJRX, Winnipeg, Can 87 changes in their operating wavelengths KIO, Hawaii 88 and schedules. Drop RAnIO DESIGN a card IBDK, Italy 88 and give us all the "dope" when you pick KZRM, Manila 90 up new stations, or old ones giving their DHC, Germany 91 frequency, hours of operation, or other pertinent information. The readings of the left-hand dial will ORANGE COILS depend greatly on your antenna, and can- VK2ME, Sydney 20 not be predicted in advance. After locat- HS2PJ, Siam 22 ing a few of the near-by American sta- GBU, England 24 tions you will be able to judge the exact NRH, Costa Rica 26 relation between the two dials, and then PCJ, Holland 27 you can make a "log" or station record Zeesen, Germany 271/4 of your own. W2XAF, Schenectady, N. Y. _ 28 RED COILS 7LO Nairobi, British East Africa 28 WSBN, "SS Leviathan" 33 PLE, Island of Java 15 W2XV, Long Island City 36 GBU, England 15 6AG, Perth, Australia 78 PLF, Island of Java 16 VRY, Georgetown, British Guiana 81 PLG, Island of Java 16 WND, New Jersey, U. S. A 82 PHI, Holland 21 HKC, Bogota, Columbia... 88 G2AA, England 40 HKT, Colombia 89 GBX, England 42 W8XK, Pittsburgh, Pa 91 G2IV, "SS Majestic" 47 HRB, Honduras 911/4 W2XAD, Schenectady, N. Y 52 W2XE, New York 92 W6XN, Oakland, Cal 78 W3XAL, Bound Brook, N. J 93 G2GN, "SS Olympic" 79 W3XAU, Philadelphia 93 W8XK, Pittsburgh, Pa 85 W9XF, Chicago 94

This trio entertains short-wave listeners regularly from HRB, the Tropical Radio Broadcasting 'Company's station in Honduras, Central America. LEFT TO RIGHT: Senorita Davilla. Fernando Ferrari, and Senorita Cordova. 32 Vol. 3, No. 2, Radio Design How to Prepare: for . It and Enjoy It by A.A. Dalid.,{

Getting an aerial swung from a tree is an attempt to easy job if you know how. Don't climb the tree; instead, throw the wire up cowboy -fashion.

RADIO receivers that have been in ply turn them slowly until they slip use during the past spring and the sockets. into winter should be examined, cleaned and overhauled in prep- aration THE AERIAL AND GROUND for further service during the hot Tighten summer weather. They up the aerial and ground wires deserve a little at- at the set, and trace tention, and if you give it to them you will these wires to the be window lead-in and steam or water pipe, rewarded with trouble -free results. respectively. If you have a factory-built A. Unhook the wires at these C. broad- points, scrape them clean with cast receiver, first disconnect the 110 -volt a the edge of plug, and then turn knife, and tighten them back in place. the cabinet around or By all means go open the top, so that you can get at the up on the roof and examine the aerial. You probably chassis and the tubes. With a soft brush looked haven't or a dry rag clean at it for months, and the winter out the accumulation storms may have of dust, being careful not to disturb any done lots of damage. wires. Make certain that it clears other wires Remove one tube at a time and wipe or near -by it clean with a damp objects, and if it appears to cloth and then a dry hang a bit loosely, one. Tubes of the A. C. tighten it as much as type get pretty you can. A length hot during normal operation, but if the of aerial wire, hang- glass is kept ing exposed all day to the sun, will sag clean the heat radiates off considerably, and into the surrounding air without injurious should be pulled up results. occasionally to prevent it from swinging too much during windy In removing four -prong tubes, weather. Also look like the over the lead in, and tape over frayed or 171A, 226, 245, 250, 280 and 281 types, worn note carefully the sections. direction in which the If your receiver is of little brass pins in the bases face, and the battery type, and you charge the "A" battery yourself, replace the tubes with the pins in the it is a same direction. Five good idea to go over all the connec- -prong tubes like the tions and to clean 224 and 227 have no guiding pins, away any evidences of so sim- corrosion. Wash the case of the battery Vol. 3, No. 2, Radio Design 33 with a soaking wet rag and also tidy up wire up without the aid of a dirigible. the tray or rubber mat on which it Instead of attempting to shinny up the stands. In warm weather the water in the trunk (which you can't do unless you have battery solution evaporates faster than a pair of heavy leg spurs called pole usual, so keep a small bottle of distilled climbers), tie one end of a length of water on hand and squirt some in before flexible wire or stout twine to a stone the tops of the plates break through the about the size of your fist and curl up the acid. wire loosely in your left hand. Leave a The "B" batteries require little atten- piece about five feet long, and start tion. Try to keep them in a cool, or at swinging it in a circle in the direction of least, a shaded spot, as they wear out the tree you have selected. When you're more rapidly in hot weather than in cool. twirling pretty rapidly let go with a heave so that the rock goes flying up into the VACATION TIME RADIO branches. The first two or three attempts The matter of providing radio reception usually are failures, but after a while at the summer vacation place requires you'll be able to get the wire way up in careful consideration. If you and your the air. family are moving into a beach bungalow If your receiver has the loud speaker or country cottage for the whole summer built right into the cabinet, move the out- season, or at least for a month, and elec- fit as near a porch window or door as tric power is available, by all means take possible, as you and your family will prob- out the radio receiver from your home. ably do most of your summer listening of Make sure, however, that the power is out -doors. If the loud speaker is separate, the same kind you have in the city. You or you feel affluent enough to buy another can easily determine this by calling up speaker even if the set already has one, the electric light companies at both places. run a length of double wire out to the Of course you must now erect an aerial. porch and connect either a phone jack or You should have at least thirty or fifty a pair of snap clips to the ends. You can feet of wire exposed, and more if the loca- then connect the speaker quickly by means tion allows a good spread. Use seven of a phone plug fastened to the tips, or by strand No. 22 flexible wire and small glass merely catching the tips in the jaws of insulators, and string the wire as high as the clips. from the edge of the possible. Run it Take the speaker indoors as building to any convenient pole or tree; or at night, of the man on the most diaphragms tend to absorb moisture. make the acquaintance A drenching in the morning dew won't other side óf the street or yard and run If your receiver is do the instrument any good at all and is the wire to his house. likely to give it an attack of sore throat. a recent model of high sensitivity, you twenty feet or so may not need more than THE "PORTABLE" SET wound around the edge of the porch. Study the local conditions and erect an If you are going away for just a few aerial to suit them. weeks to a country camp or beach colony For a ground, simply run a wire to the where no electric light power is available, nearest water pipe. Use any wire that my earnest advice to you is not to bother you happen to have: flexible lamp cord, with radio at all. Most of the so-called annunciator wire, etc. "portable" receivers pictured in enchant- Although the danger from lightning is ing summer surroundings in advertise- very slight, it is advisable to install a ments are about as portable as a baby lightning arrestor on the outside of the grand piano with a handle on it. The building, with a wire running directly to real thing is an automobile radio set like the ground. If an outside faucet for a the Pilot "Auto Radio," described in this garden hose is near -by, wrap the wire issue. The car itself carries the weight around that. If nothing like this is avail- of the instrument, and the storage battery able, drive a two- or three-foot length of problem is automatically disposed of. iron pipe into the earth or bury a couple It is hardly worth dragging a separate of old pots or pans, and run the ground storage battery to a camp unless you have wire to them. a car and there is a charging station in some near -by village. And don't attempt THE TREE AERIAL to get around this problem by replacing Trees are good natural aerial posts, but the storage battery by a bank of dry cells. they often present problems. It is easy Dry cells are all right if they are used on enough to say "String the aerial to any a light load for short periods and are convenient tree"; the trick is to get the given time to recuperate. They pass out 34 Vol. 3, No. 2, Radio Design very quickly when subjected to current tralia or South America, point the lead-in drains that normally require a storage at battery. those countries. Most people have the idea that an aerial In addition to the broadcast receives by all receiver, beet from the direction in which means take your short-wave set if the free end the power points. This isn't so at all; is available. Listening during it is strongly directional daylight on the very the other way. short waves is very If you still feel energetic after stringing interesting sport, and you will hear sta- aerials, it will tions that are be worth while for you to altogether inaudible at pay some attention to the ground. Where night. Receiving conditions in general are no buried water usually better at pipe system is available, the seashore or mountain a good ground can be obtained by burying place than in the city, because of the ab- all the sence of large loose bodies of metal you find bodies of metal and other around. Old wash boilers, frying pans, disturbing influences, and even small an- pails, large tenna systems gasoline tins, etc., are fine produce very good results. for the purpose. Connect them altogether by means of NOVEL AERIALS heavy wire and bury them AND OROÜNDS just below the surface of the earth. If you have enough space and wire, By can you far the best thing is an old auto- perform some interesting experi- mobile radiator, the mental reception leakier the better. with very long aerials. Leave the neck sticking out just above the Piece together all the loose wire you can lay ground, so that you can pour it full of hands on, and string it along the coun- water every now and try -side in as them. The water straight a line as possible. leaks out of the honeycomb and seeps If you have never had much luck in pick- ing through the earth, making the latter high- up the European stations, try to lo- ly conductive. If you cate the antenna bury the radiator in so that the lead-in end, the midst of a lot of other miscellaneous not the free end, points in the general junk and keep the direction of system well watered, Europe. If you're after Aus- you will have a really good ground system.

Bring the loud-speaker outdoors and enjoy your radio pro grams in comfort. Run extension cords to the porch or merely place the speaker on the window, as shown above. Vol. 3, No. 2, Radio Design 85 Adjusting the "Pre - Selector" A Few Simple Suggestions for Obtaining the Best Possible Results From This Popular Broadcast Receiver, Which Is Sold in Kit Form. by ALFRED A. GHIRARDI

HE Pre -Selector broadcast re- in. The Vaultype condensers are com- ceiver, described in the Spring pletely enclosed, but you can tell where issue of RADIO DESIGN, has al- the rotor plates are by noting the posi- ready achieved wide-spread pop- tions of the little nicks in the rotor shaft ularity, because of the excellence of its close to the bearing. The nicks point di- electrical design and the completeness of rectly toward the outer end of the rotor the kits furnished for the sets. Construct- plate assembly. In the Pre -Selector, the ors have experienced very little trouble, condensers are at zero when the nicks but a few little difficulties have turned up, point straight up. The dial set screws that are not serious and can easily be should be tightened with the condensers cured. at zero, because, with the dial set to this figure, the screws can be reached very SHORT AERIAL ESSENTIAL conveniently with a screw driver. In the first place, we wish to emphasize This alignment of the variable con- the necessity for using a short aerial. The densers is very important. The set will Pre -Selector is a high -gain screen -grid tune very broadly and will appear to be receiver, and as such need not and should very weak if the two condensers are off not be used with an indoor or outdoor only a few degrees. aerial more than about 30 feet in length. Longer aerials simply ruin the selectivity ADJUSTING THE COMPENSATORS with ,ut adding anything that is partic- Once the kit has been completely as- uls . ly advantageous to reception. Only in sembled the only adjustments that can be case of dead spots or under unusually ad- made in the receiver itself are on the verse conditions are long aerials needed. compensating condensers, which are con- The entire purpose and value of screen - trolled by the screws protruding from the grid tubes and the high -gain amplifiers tops of the cases. To set these properly, designed for them is the elimination of pick out a weak station somewhere in the the clumsy roof aerial, which has elec- middle of the dial and turn the screws in trical as well as mechanical disadvantages. and out, one at a time, while rocking the Short aerials are usually less susceptible dial back and forth a degree or so. When to atmospheric interference and, since the signals sound loudest, lock the screws they produce perfectly satisfactory results in place by tightening the nuts with a with screen -grid sets like the Pre -Selector, pair of pliers. they should always be used wherever pos- Only the first two compensators to the sible. The shorter the aerial that can be left are at all critical. These are on the employed in any location, the better will condensers that tune the band-pass stage, be the tuning. on which the selectivity of the receiver Another thing that evidently has es- depends. The other compensators, on the caped attention is the little single -pole right-hand condenser, are not at all crit- double-throw knife switch located on the ical, but should be adjusted anyway for chassis just behind the left tuning con- best results. denser. The set should be tried with the switch in both positions. One setting will THE POWER PACK give decidedly better selectivity than the Do not fail to put the cover on the K-112 other. power pack. It not only saves you from serious shocks from the high voltage ter- SETTING THE CONDENSERS minals, but also dampens the whole can In setting the shafts of the Vaultype and reduces mechanical hum. condensers in the studs of the No. 1285 It is advisable to check all the filament dial, make sure that the condenser plates voltages with an A. C. voltmeter, and all are in the same position. When the dial the plate voltages with a high -resistance reads zero both condensers should have D. C. voltmeter. The output from the 90 - the rotor plates all out of the stators; and 180 -volt posts can be adjusted by when it reads 100 the plates should be all means of the Resistograd on the bakelite 36 Vol. 3, No. 2, Radio Design terminal step. Use a screw driver with a wooden handle in turning the slotted shaft of this instrument, and keep your other hand off the chassis. This resistor does not affect the 300 - volt tap.

BLUEPRINTS AVAILABLE Copies of the Spring, 1930, issue of RADIO DESIGN, containing the detailed description of the "Pre -Selector," may be obtained at the cost of fifteen cents apiece, coin or stamps. Full-size working blueprints of What you should adjust carefully in the Pre - the set are also available, at ten Selector: A, the condenser compensators; B, the antenna switch C, the voltage control on the cents apiece. Merely order blue- power print BP -126. pack. Tkia photo shows a completed set with the top of the cabinet removed.

8000 -Mile Signals on Super -Wasp Wake Up Listener's Family RADIO DESIGN has received well sometimes, but they haven't the pep many interesting letters from somehow. Super-Wasp owners, and has PCJ printed some of them (Holland) is pie. Longwave stuff in past from Nairobi (in Central issues. Recently we received what we con- Africa) and sider a particularly Rome, Italy, occasionally. The set has unusual one, and we surely got fans talking. are printing it in full. The experience of our South African friend indicates While at Cornell, having served from quite 1915 clearly the possibilities of the short waves to 1918 in the last war, I had the and the peculiar manner in which they opportunity of studying tubes, etc., the reach out. knowledge of which stood me in good stead when I finally had to leave there RAND CARBIDE, LIMITED and go on to the General Electric works WITBANK, TRANSVAAL at Schenectady, about the time that the old SOUTH AFRICA 2XQ began to reach out to the California April 9, 1930. coast. We used a couple of ordinary elec- RADIO DESIGN MAGAZINE, tric fans to hold down a transmitting Brooklyn, New York. tube with a white hot plate; Great days! Dear Sirs: Can you account for our frequently Enclosed please find five shillings. En- hearing the transatlantic telephone con- roll me in the Radio International Guild versations here? We are supposed to be as per slip enclosed. right out of the line, but I have heard I purchased an A. C. Super-Wasp London saying "Hello New York," have about a month ago. These are some of gotten the call through, and have heard the results I got. I heard a service at the the conversation between two engineers, Union College Chapel, Schenectady (where on transformers, etc. Some man rang his I studied, class of 1922) loud speaker wife or sweetheart, and the conversa- strength, heard by the folks next door, tion was sure edifying-all this 7,000 through the open window. G5SW (Eng- miles out of the beam line. Guess the land), on loud speaker, was heard out of Marconi Company would be interested to the room. KDKA, WGY, etc., are heard know of all this. Have heard sugar deals at 3 to 6 a. m. here, but I have to cut between Havana and New York, and sev- down because it wakes up the better half eral two-way tests between G5SW and and the youngsters. The organ recitals one of the Westinghouse stations. from Albany are particularly appreciated. Yours faithfully, The Australian stations come through LOWNE H. SIM. Vol. 3, No. 2, Radio Design 37 A Few Wrongs to Be Righted Robert S. Kruse A Discussion of Short-Wave Receiver Design and Why Certain Circuit Features, Considered Old -Fashioned in Broad- cast Practice, Are Still Desirable for High -Frequency Work By ROBERT S. KRUSE

AM not a reformer; I do not belong I worked for one once. We were so busy to a single association for the sup- being impressed with a lot of ardent needs pression of anything, nor do I attend that we were not able to go ahead with meetings for the purpose of fur- any work on the cures that were in sight. thering some flaming cause. Of course, I can enjoy the arrival of WHY WE KEEP RIGHT ON BEING WRONG a badly belated reform. I have chuckled Maybe a reformer is necessary; once in over the removal of the utterly useless a couple of years he does present a good traffic lights at West Hartford Center, idea, but I am afraid that most of the where I live, and I expect to enjoy gloat- time he is talking without much informa- ing over some other things, such as the tion. eventual silencing of the National Broad- The radio manufacturer gets his full Íi casting Company's wearysome gongs, share of this sort of thing. Every one is and the appearance of a decently marked able to tell him what is the matter with road in New Jersey. his product and methods-and none of Furthermore, I grinned with the rest them is as familiar with these things as of you when David Grimes publicly chal- he is. If he is any sort of a manufacturer he will, of course, listen to critics, just because they do occasionally offer a good idea, but he doesn't depend on them. He is digging out ideas and testing them whether anyone demands it or not. His product, if he remains in the game, shows the effects of these searchings. If this is sometimes not too evident it is perhaps because we do not appreciate the why of some things that ar built into the product. THE SHORT-WAVE TUNER FOR EXAMPLE Take the short-wave tuner as an example. Pretty consistently our short-wave of "I ant not a rejor»aer." tuners are made to cover a variety ranges and quite as consistently they use two tuning controls or one control and a lenged KDKA's right to the resounding regularly title of "Pioneer Broadcasting Station of vernier. In addition they quite the World" and suggested that East Pitts- use a regeneration control. burgh, Pennsylvania, is not the whole Is someone asleep at the switch? Isn't it time to get the things cooked down to world. regenera- these things do not make me a re- one control and to throw out the But been done in the former; I have no wish to rush out and tion control just as has afternoon. A broadcast -range tuner? Is this not a case correct a lot of things this been reformer may be a necessity, but he is where the manufacturer has clearly uncomfortable to have around the shop. dozing? No. 2, Radio Design 38 Vol. 3, I think not. On the contrary, I think G-The remaining irregularities are taken that the better short-wave tuners like the out by means of "trimmer" condenser Super -Wasp show an amazing amount of adjustments. performance with very limited equipment, which is sound engineering. Their per- All that for just four coils and four formance can be improved-it will be im- condensers in ONE tuning range! proved-but not until the market pays for Now, suppose that we started to make those improvements. Furthermore, the im- such a tuner cover the range that is provements will be sur- handled by a dual-pur- prisingly costly to make. pose tuner of the Super - This is not idle talk. Wasp type. Since it is The facts are before us not especially practical to choose from. Advanced to tune four circuits sep- designs exist at this arately we will need to moment; we would build gang all the controls; t h e 1932 short-wave the demand was for a tuner today if the mar- single -control tuner, any- ket would pay us about / ) way. $600 each for such f Now we know at the tuners. (r -,l ü start that one coil can- Does the price sound not possibly tune from insane? Let us analyze a 16 meters to 550 meters, bit and see if it really is. which is the range we What are we to de- have to cover. We know mand of the 1932 tuner? "Is someone asleep at the that our tuning scales The answer is ready switch?" will be very crowded at enough: single control, the short waves if we no regeneration control and enough we attempt to tune more than about a tuned R. F. to make up for the ab- 2 -to -1 range with one coil. Thus we can sence of the regeneration control,-and cover more. Simple, isn't it? Suppose we try to do 16- 32 meters it and see. 32- 64 meters 64-128 meters GANGING TROUBLES 128-256 meters The modern broadcast receiver of the 256-512 meters Pre -Selector type uses about four tuned circuits at the least, sometimes as many as Actually we cannot do exactly this. In six. Let us take the simplest case because the first place we MUST allow a little good design will admit of high-grade per- overlap between coils to make certain that formance with four tuned circuits. This there will be no gaps. In the second place means that for the ONE tuning range of the coils just listed break at very clumsy 550-1,500 kilocycles we have four tuning places. The ordinary broadcast band is condensers and four coils, all carefully cut in two and several other groups of matched. stations are split. The process of matching is, with minor A practical arrangement is to use five variations, as follows: coils to cover the range from 15 meters to A-Condenser sections are made as nearly alike as is economical. B-The sections are measured and sorted into groups that are still more nearly alike. C-Gangs are built from sections of the same group. D-Coils are built as nearly alike as possible. E-The coils are measured and sorted. F-Coils from the same group The four coils used in the Pre -Selector. Getting are put into the same set. these matched is a comparatively simple job. Vol. 3, No. 2, Radio Design 39 r serve when the coils are exchanged be- 550 meters. This can be done and is being done. cause each set has different irregularities. Thus one would need to re -align the set "TRY AND DO IT" each time the coils were changed. This Now then, we will go back and try to means that we do not have ONE tuning fit such a set of five coils into EACH of control but FIVE tuning controls-worse the FOUR tuned circuits in our nice mod- than the old three -handed neutrodynes ern Pre-Selector. First of all we realize ever were. that this means THE POSSIBLE WAYS OUT 5 coils X 4 tuned circuits = 20 coils.! There are several ways out. One can, of course, make the coils and condensers Think of trying to keep them straight. so carefully that they will actually ex- If we let them lie around loose the whole change without re -trimming. This means table is full of them, and if we build them a good deal more care than is taken in the all into the set it will be enormous. usual broadcast -tuner construction; there- Besides, a set with four tuned circuits fore it means more cost, especially as the has a great deal of R. F. amplification, process is applied to twenty coils instead and the shielding must be good. We will of one set of four. It can be done-it has need to take off a lot of shielding before been done-but the tuner was found to we can even start to pull out four tuning necessitate a retail price of $400 without coils and put in four other tuning coils, counting a final audio stage, loud speaker, after which the shielding is all to be re- or cabinet. placed before we can proceed with our We are still in the habit of regarding nice simple one -control set. dual-purpose receivers as auxiliaries and Even then, this is simple compared to insist on proportionate prices. We are not the job the manufacturer has in trying to paying $400-$600. for them. Of course, make the four tuned circuits run together later on we will quite probably have dual with five different sets of coils. He can- purpose receivers that will be made at not even use the same method that was costs much below $600, just as Ford last used before: touching up the final irreg- year made 1,340,000 cars at a cost vastly ularities with trimmers. This will not below what the first few of the series A cost him. Even then it is a perfectly safe prophecy that these improved short wave - plus-broadcast receivers will not be sold at $35 or any price near that. We will be lucky if we get it for the price we now pay for a broadcast receiver, which does only part of the job. Meanwhile, therefore, we must concede something to cost and convenience, and in the end it will develop that we are not conceding as much as one might think. We will drop out one of the tuned circuits and see if three instead of four will offer any relief. A very little thought will show that it offers almost no improvement at all. Very much on the contrary, we must now match MORE carefully to make up for the loss of one tuned stage. Clearly, we do not obtain any financial relief until we go to two tuned circuits, either with separate controls or with a unified control and a vernier. Instantly our trimmer condensers go overboard. We no longer need them because every tuned circuit is now controlled completely from the panel. WHAT HAS HAPPENED TO THE GAIN? If the regenerative detector is elimi- But, say you, what about R. F. gain? nated, you will need all these coils out with four tuned circuits in a T. R. F. set to get equivalent We started results! and now we have but two-our R. F. am - 40 Vol. 3, No. 2, Radio Design plifier must have gone to pieces in the process. Fortunately it is not as bad as one would think. We started with four tuned circuit: 12- IZZA.1532EMI 2 tuned circuits ahead of the first rBr"' R. .O_E F. tube. 'vs' mm NI 1 ahead of the 2nd R. F. tube. 1Ef/23%N M MO.' A- 1 ahead of the detector (Cost about Kam $400.) No regeneration. Total of one main control and at l/II à least 3 verniers. /,y M 1111y0112715MME Thus we had two stages of R. F. and r. ö RUMiecuw a non -regenerative detector. swan / The new setup just suggested is: rtzu WWII 1 tuned circuit ahead of the first R. F. tube. mei 1 tuned circuit ahead of the S. detector. B- Two main tuning controls (Cost w,, w monoo about $35). I..memer, Regeneration-to be decided on in a Y.II!(lN6lM /N N!/!Re moment. The advantages of regeneration on the short waves are made quite plain Obviously our selectivity is a bit less by a comparison of the two curves than before, and in the broadcast band we above. will miss that quite severely, though not . enough to make us sorry for the saving So then, we have the curious result that of $365. Obviously, also, our gain is less at the SHORT short-waves we are actu- than before and we must make sure that ally better off with our $35 tuner than it has not gone down too badly. In the with the $400 one. Let us twist the dials broadcast band it is not uncommon to get of it, and the regeneration control as well, voltage gains of 40 per stage, or even 60, and be content with the saving of 365 dol- which drifts down gradually as we go to lars! shorter and shorter waves until we can Have I seemed to sell you any partic- expect about 10 per stage at 20 meters ular make or type of tuner? I suppose and as little as 6 per stage at 15 meters. that I have; but that has been altogether Dropping out our one stage of R. F. has unintentional and only the natural result not been so terrible at that; we have lost of taking you over the route that many only about 50 at one end of the scale and designers have traveled before, always about 6 at the other end. Regeneration with the same conclusion except as to de- will easily make this up for us. We can, tails of design and of the audio amplifier, in fact, secure gains as high as 500 by the and of the ease of construction and opera- use of regeneration if we have patience tion, which are things that are a separate enough and there is no static to trigger story, told elsewhere for each tuner. At off the delicately adjusted detector. It is least we have wound up with a tuner quite easy, without any critical adjust- using TUNED R. F., not one of the "fixed ment, to gain 100 by means of the "regen- input" type. We have therefore a gain erative contribution," and there is your ahead of the detector that amounts to 50 back again with 100% interest, while something, for recollect that our detector at the low end, 15 meters, we are as well is a "square-law" detector and that an off as if we were using five or six stages R. F. gain of even six means much to such of R. F. because regeneration has the very a detector-as much as a gain of thirty-six pleasant habit of working very neatly at would mean ahead of a "power" detector wavelengths all the way down to 5 meters such as used in most broadcast receivers. while tuned R. F. gets flatter and flatter This is easy to prove: just remove the and finally quits us altogether at about 10 R. F. tube and couple the antenna to the meters. (Special tubes can be made to detector, and then attempt to hear G5SW, work further down as R. F. amplifiers, but PCV or NRH. The resulting silence is the present ones are not suitable.) (Continued on page 47). Vol. 8, No. 2, Radio Design 41 How The "Pilot Radio" Made The First Bermuda Flight The Full Story of the History -Making "Hop" in Which Radio Played an Important Part, Told by the Radio Operator Himself. By ZEH BOUCK NE of the primary objects in the land Lightship the day before. As for promotion of the recent flight WHD's signals, it was impossible to tune to Bermuda was to determine in this station to full strength, as the the extent to which reliable com- signals were painfully loud. munication0 with land might be maintained on an over -ocean flight. And when I TRANSMITTER AND RECEIVER DESIGN write "reliable communciation," I refer to The transmitter and receiver were built a continuous interchange of messages be- in the laboratories of the Pilot Radio and tween the plane and land, comparable to Tube Corporation, sponsors of the flight, the traffic handled by an ocean liner. and the plane used in the flight was their That this object was achieved is demon- flying laboratory. The problems confront- strated in the fact that while over fifty ing us were those of electrical efficiency, messages were handled, back and forth, weight and space. Electrical efficiency between WHD, the radio station of the involves several angles, including the New York Times, and W2XBQ, the air- ability to transmit and receive over long plane "Pilot Radio," not a repeat of a distances, and the necessity, from the single word was requested. The signals point of view of safety, of being able to received on plane and land suffered from operate for a reasonable period of time practically no diminution throughout the from the surface of the sea. eight -hundred mile flight. The problem of weight is omnipresent One of the last messages transmitted in designing aircraft radio equipment. from New York, just before the plane Space was a matter of convenience and alighted in Murray's anchorage, Bermuda, comfort, and was both psychological and was to the effect that the signals were physical. A comfortable radio shack is al- every bit as consistent and powerful as most essential to efficient operating. when we took our departure from Scot- Two transmitters, combined in one unit,

The "Pilot Radio" as it appeared after landing in Hamilton Harbor, Ber- muda. Yancey and Alexander are standing on the port pontoon, and Houck is sitting on the wing strut. 42 Vol. 3, No. 2, Radio Design A Splendid Feat of Aerial Navigation! ON THE morning of April 1st, 1930, the airplane "Pilot Radio," fitted with pontoons instead of its usual landing gear, and carrying William H. Alexander, Zeh Bouck and Captain Lewis A. Yancey as its crew, took off from Flushing Bay, Long Island, with the tiny island of Bermuda as its goal. This feat, never before attempted, has been considered by many fliers as a more difficult and dangerous undertaking than flying to Europe, as the island is only nineteen miles long and is a mere speck In the ocean. Faced by darkness when only sixty miles from Bermuda, the three intrepid aviators made history by alighting on the ocean, spending the night on the tossing waves, and then taking off in the morning without assistance. On the morning of April 2nd, the plane made a triumphant entry into Hamilton Harbor, to the wild acclaim of the excited populace. This flight was a splendid tribute to the navigating of Captain Yancey and the piloting of "Bill" Alexander, but in the minds of the public Its most interesting feature was the remarkably steady radio contact maintained between the plane and New York. Zeh Bouck, well-known to the readers of RADIO DESIGN, sent a constant stream of messages back to the New York "Times," allaying the fears usually felt for adventurous fliers who skip off into the sky and remain unheard from until the time they land safely-if they do land safely. The flight demonstrated more forcibly than ever the value of a properly designed aircraft radio installation properly handled by a capable operator. Because of the lack of facilities in Bermuda for repairing the damaged pontoons, the "Pilot Radio" and its crew returned to New York by steamer. By the time this number of RADIO DESIGN reaches you the plane will already have started on the South American Good Will Flight described in the Spring issue. were carried, covered below the trans- ing both long and mitter in order to short waves, t h e provide the greatest long -wave transmit- possible isolation of ter being effective the short-wave between 600 a n d transmitter, a n d 1,100 meters, a n d slides in and out on the short-wave its shelf to facilitate transmitter cover- changing coils. The ing a band from 35 receiver is a modi- meters to 50 meters. fication of the Pilot Changing from long A. C. Super -Wasp, to short waves which is well known w a s accomplished to all readers of by switching over RADIO DESIGN. A. C. inductors, the same tubes, operated in tube and meter com- series through a binations being em- suitable resistor, ployed on all wave- were employed in lengths. In addition, preference to t h e an exterior loading D. C. type in view coil was used for of the lowered mi- transmitting crophonic response. on wavelengths above 700 meters. THE A Hartley oscillator POWER SUPPLY was employed in Power for all fila- both transmitters. ments is supplied The receiver was Welcome home! from a non -spillable mounted on a slid- Left to right: Yancey, Alexander and twelve -volt storage ing shelf below the Bouck, sitting on one of the pontoons of the "Pilot Radio" on the upper battery, which also transmitter, both turned over t h e receiver and trans- deck of the Royal Mail steamer "Ara- guaya," photographed on their return dynamotor feeding mitter being com- to New York on April 10th, 1930. t h e transmitting bined in a single The wings and tail surfaces of the tube with 100 mil- suspended unit. The plane were removed in order to make liamperes at 1,000 receiver was mount- the body fit on the steamer. volts. The storage Vol. 3, No. 2, Radio Design 43 functioning of the oscillator (somewhat unreliable on the fundamental with close coupling) and provided a highly satisfactory pick up when receiving. The arrangement of the radio cabin is shown in the accompanying photographs and considers the convenience and comfort of the operator. There is plenty of leg- room under the folding desk, the key is located for comfortable operating, and all controls are at the fingertips of the operator. The cabin is well lighted by a window at the operator's left. There is no loose equipment. All spare parts are carried in closed shelves, and the entire layout is one that lends itself to electrical and mental efficiency. THE FLIGHT On the morning of April the first, 1930, with W. H. (Bill) Alexander at the controls, and Captain Lewis A. Yancey, our The power box inside the cabin of the navigator, alongside of him, we taxied "Pilot Radio." The 12 -volt storage across Flushing Bay, New York, to Clason battery, charged continuously by the Point for our first attempt at a take-off. wind -driven generator on the body of Our first four efforts were failures. There the plane, operates the dynamotor, was practically no wind, and Long Island which supplies filament and plate cur- Sound was almost without a ripple. Un- rent for the transmitting tube. The der these circumstances it is next to im- object in the lower right corner is a possible to break the suction under the single 135 -volt "B" battery block. pontoons and take-off a heavily loaded When closed, the box forms a comfortable seat. plane. Between attempts we lightened the ship by draining gas and discarding our anchor and kit of spare pontoon plates. battery was charged continuously during Just before our fifth attempt a slight wind flight (except during reception) by a wind arose. We waited until two ferry boats driven generator driven by a one blade crossed in front of us, to take advantage constant speed propeller. With this power of the waves created in the wake, and Bill combination and an emergency antenna, Alexander gave her the gun. As she about ten hours of average communication gained speed, George Post, in his Travel - is possible when the plane is down on air, taxied across our path, wide open, water or land. throwing up a choppy sea that helped con- A convenient switch made it possible to siderably. In another second the "Pilot disconnect the generator, eliminating com- Radio" was on the step, the bumps becom- mutator interference during reception. A ing sharper and sharper as the air speed send -receive switch on the radio panel con- indicator rose from fifty to fifty-five, sixty, trolled the filament and dynamotor, trans- sixty-five, seventy, seventy-five miles an ferred the antenna from the transmitter hour. One more sharp rap on the pontoons to receiver and disconnected the plate volt- and we were off. We gained altitude rap- age from the receiver during transmission. idly and cleared the bridges in good style, A separate filament switch made it pos- Post tagging along with us as an escort. sible to burn the receiving filaments while Half way down the East River, I transmitting, eliminating the heating lag. crawled aft into the radio room, let down The plate voltage to the receiver was sup- ninety feet of antenna and called WHD, plied by a special aircraft unit "B" and the New York Times radio station, and "C" battery. sent my first message at 9:54 A. M. to Po- A trailing wire antenna was employed, lice Commissioner Grover Whalen, thank- measured lengths being indicated on the ing him for the cooperation of the New wire for different frequencies. The trans- York City police in getting us underway mitter was operated, during the Bermuda from North Beach. At 9:55 A. M. we an- flight, on 41 meters, the antenna being nounced that we had swung into our about ninety feet long and working on the course just off Staten Island, heading third harmonic. This resulted in stable along a line of buoys that run 138" true. 44 Vol. 3, No. 2, Radio Design At 9:58 we took our departure from Scot- land Lightship. About this time, WHD wanted a list of the provisions on board. We carried rations for five days, and radioed the following: "Rations on board consist of two broiled chickens, four boxes wholewheat crackers, five pounds chocolate, twelve oranges, five gallons water, one quart of Scotch." This message was published and transmitted, and the last item for some unknown reason created a bit of excitement. This was, I must assure you, a perfectly legitimate part of our medical stores. About this time Yancey wanted to take a sight, which was a most efficacious way of shutting down the radio. In taking sights, Yancey opened the top of the plane, admitting a hundred -mile -per-hour blast of cold wind that worked havoc with the papers in the radio cabin, to say nothing of the good right hand. Sights are taken from an airplane in pretty much the same way they are from a ship, only in bumpy weather, such as we were experiencing, it is considerably more Looking backward from the pilot's difficult. A bubble sextant is generally seat into the radio cabin, where Zeh employed, which provides an artificial ho- ,Bouck is shown with the earphones rizon. Captain Yancey used Longines on. The inside of the plane 'is well chronographs, which are pocket chronom- lighted because of the transparent eter to check time. Three chronographs pyralin top. are carried so that, if any one of them changes its daily rate of variation, it is immediately identified by reference to the let anyone worry about us. The sea is like other two. Our first position report was a lake." radioed in at 11:35 A. M., New York At 5:50 we signed off with: "Setting time, as follows: her down right now. Position sixty miles "At 16:07, Lat. 39:31. Long. 72:50, north of Bermuda. Tell everyone not to Course 138, true speed 76 knots." worry. Please notify my wife and Gold- berg. Sea calm, very. Will continue to LANDING ON THE OCEAN Bermuda in the morning. Did you get And so went the day. We were in con- all? See you five A. M. tomorrow." stant contact with WHD, signals at both And Bill set her down. From above, ends showing absolutely no diminution as the sea may lve looked "calm, very." the "Pilot Radio" pushed the miles away But close to the surface it was another with the back wash of her prop. As even- proposition. It look the finest sort of piloting approached, it appeared doubtful if ing, and Alexander had it, to put her we could make the Island before dark due down on that heavy ground swell without to the fact that our speed had been cut a crack-up. The pontoons stood the gaff considerably by unfavorable winds. A perfectly. As we came to a stop, broached landing in'Bermuda at night was a hazard- to on a rolling sea, Bill acknowledged our ous possibility, and we went into a quick congratulations with: huddle. I told Iverson, radio operator of "Gentleman, I'm going to be sick." He the Times, that if we did set her down, was. I'd sign off for the night, rather than rig A half hour later it was pitch dark, an emergency antenna to the wing tips, with only the stars and the stingy sector and "see" him again shortly after of a pale moon. This set around nine five the next morning. At 5:20 we sent o'clock. We maintained three watches the following: when we weren't sleeping. Yancey slept "If we don't see the Islands pretty soon well. I dreamed of railroad trains and will set her down for the night. If we Bill of stomach pumps. We sighted the have to set her down for the night, don't lights of a steamer at three different Vol. 3, No. 2, Radio Design 45 times, and finally, considering the possibil- antenna, gave WHD a short call, threw ity of its being a ship out from Bermuda the switch over the receiving side, an91 he to look for us, signaled her with a Very was back at me in an instant, as loud and pistol. Two hours later she hove to. At clear as when we were over the East first we talked with blinker and then River! This was at 5:50 A. M., New York hailed her. She was the Lady Sommers, time, on April 2nd. A half dozen mes- requested by Bermuda to keep a weather sages flashed back and forth between the eye cocked for us, and too much credit "Pilot Radio" and the New York station. cannot be given her master for his fine Iverson told us that the more flagrant of seamanship and sportsmanship. We re- the New York papers had given us up as quested that she report that everything lost, which news amused the lads up for- was okay with us and that we would pro- ward. At 6:17 we sent through the fol- ceed to Bermuda at dawn. lowing message: "Bermuda sighted dead ahead at 6:15 A HISTORY -MAKING TAKE-OFF At daybreak we cleaned up the cabin a bit, up a stay wire on the pon- tightened 70 65 toon struts that had been loosened in the 75 stress of landing, and took -off. Here again his of a LEFT Bill showed mastership ticklish 40 NEW YORK job, and for the first time in the history 9:37 A.M. of flying a plane forced down in the middle of the ocean took -off again. Five minutes later I came in for the greatest thrill in my life. I reeled out the

Right: The course followed by the 35 35 "Pilot Radio" on its epochal flight to Bermuda. Below: The editor of RADIO Hatteras DESIGN examines the little w in d - PLANE DOWN driven generator that charges the 5:500 storage battery inside the cabin. ARRIVE BERMUDA 6:25 A.M.

o o

75 o 65

46 Vol. 3, No. 2, Radio Design New York time, about thirty miles off," a simple, but eloquent tribute to the finest aerial navigator in the world, Captain Lewis A. Yancey.

CONCLUSION From the radio point of view one of the most interesting observations was the absence of skip -distance effect. In a pre- flight conference with Fred Meinholtz, engineer in charge of the New York Times station, we roughly guessed that the signals from the plane would be lost at about five hundred miles out. It seems apparent, and reasonable, that the distance with which the skip -distance effect becomes no- ticeable is a function of the altitude of the radio station. There seems little necessity for carrying long-wave transmitting equipment on trips of this nature. An airplane flying over water should be in constant contact with a land station-a contact which it A close-up of the radio panel and seems is best maintained via short waves. operating table inside the "Pilot In case of emergency the SOS can be most Radio." Notice the shock -cord sus- expeditiously handled by the shore station, pension of the panel, the antenna reel without the loss of time and general con- under the table, and the transmitting fusion that often accompanies a distress key in the far left corner. call transmitted directly from sea. The elimination of the added weight makes it mitter along these lines, the now possible to increase the power and effi- famous "Pilot Radio" will take off on the first ciency of the short-wave transmitter. A commercial good will master oscillator design is tour of South Amer- recommended ica about the time this magazine reaches by tha author, and with a modified trans- your hands.

Last Minute News of the A Few Wrongs to Be South American Flight Righted The "Pilot Radio," carrying Capt. Lewis A. Yancey as navigator, Zeh Bouck as (Continued from page 41) radio operator and Emil Burgin as pilot, very instructive, to say the least. left New York on May 14, 1930, on the Even the two-stage audio amplifier in first leg of its South American trip. An our short-wave receivers has a good rea- extra passenger who went only as far son for existence; namely it permits us as Washington, D. C., was Mr. I. Gold- to work the detector at a low level where berg, president of the Pilot Radio & Tube we get the benefit of the square -law just Corporation. The four men met President mentioned and in addition are able to Hoover, who wished the fliers good luck. make regeneration work smoothly and con- Yancey, Bouck and Burgin then hopped trollably. off for Miami, Florida, and continued from These things are there perhaps all transient, to Havana, Cuba, Yucatan, Mexico but I judge that it may have been inter- City, Managua (in Nicaragua), and esting to you to run over them thence with me to the Canal Zone. Here Bouck and to see how the regenerative detector established something of a record when -abandoned at broadcast he got in wavelengths- direct touch with the New York is a highly useful tool at short waves. If Times radio station in New York, a dis- in the process we have also tance of 2,500 discovered miles. that the manufacturer is in this case not a At the time this issue of RADIO DESIGN stick-in-the-mud went but an astute judge of to press (second week of June) the value-well and good. I fliers were told you that I preparing for the next jump was not a reformer and got no delight to Peru. from throwing bricks. Vol. 3, No. 2, Radio Design 47 r Who Invented Broadcasting? Further Light on the Activities of Some of the Early Experimenters Whose Work Forms the Foundation of Present -Day Radio: deForest, Dubilier, Stearns, Logwood, Gowan, Cockaday,,Conrad, and the U. S. A..Signal Corps (Second and Concluding Part) By DAVID GRIMES

UNEARTHING information con - our readers presented some interesting cerning the scientific achieve- data on early radio broadcasting by Reg, ments of early broadcasters is inald Fessenden around 1907, but close both interesting and exhausting. study of this seems to confine the efforts There hasn't been an important discovery entirely to radio in telephony as distinct the past fifty years without its fringe from radio broadcasting. For, all, of co after -inventors and even wider circle of early radio telephonic tests were carried claimants. Periodicals and books in gen- on even before 1907. eral circulation have more to do with this Among all the letters received from than any other cause. A single article in various sections of the world, none has a "fan" publication will start dozens of revealed an earlier date than January, readers off to perform all sorts of circuit 1910, for a real broadcasting station. But gymnastics. So important has this phase this does not detract from the interest of of development become that the large cor- the tales told by many of those who know- porations hesitate to disclose recent engin- ingly or otherwise were emulating the eering work until there is some feeling great de Forest. Many important improve- that the work has been fairly well covered. ments in the art were fostered by these Otherwise, the casual experimenter will pioneers. After all, if the younger en- pick up the loose ends and perhaps carry thusiasts hadn't kept trying to make a the work through to completion before the success of radio broadcasting, it would more slowly moving laboratories who have never have arrived. started the program are able to finish it. In that way, life is And peculiar. The very so it has been with early broad- first venturers soon weary of the public's casting efforts. In proportion to the phlegmatic reactions, and try their abili- amount of information that leaked out on ties in other fields. The other fellows less Dr. de Forest's broadcasting efforts, the familiar with the details of past failures number of local geniuses all over the to arouse the necessary country interest proceed increased. Many of these acquired and often succeed. Some of you will recall nation-wide fame, while others only re- the first talking movies which went out ceived credit in their local newspapers. over the vaudeville circuits before the war. Apparently the famous date of January, Edison invented and developed them to a 1910, established by the Doctor, the details point where they were at least present- of which were related in the late issue of able. The public reaction was somewhat RADIO DESIGN, stands alone and unchal- adverse, so Edison did not attempt them lenged. again. Shortly after the war, Dr. de For- est, who had become somewhat WHAT IS A discour- BROADCASTING STATION? aged with broadcasting, took up the talking It is desirable to clarify at this point movie cause, adding vacuum tube ampli- just what is meant by the first broadcast- fiers on both recording and reproducing. ing station. The mere transmission of the Pictures under this process were shown human voice, or even phonograph music, on Broadway about 1923 under the name by radio does not constitute in our mind of de Forest Phonofilm. De Forest's system a justifiable claim to pioneer broadcasting. differed in another way. He employed the After all, de Forest transmitted speech film for recording the sound instead of the and "canned" music over the air long be- phonograph record. But whether or not fore his famous January, 1910, date. The these additions had anything to do with very idea of broadcasting, in view of its the subsequent success is beside the point; present development, conveys the thought the public at this time was on the verge of of well-known artists performing over the being interested. station for the benefit of the listener and There is something very dramatic about on more or less regular schedules. One of this whole story. Here is the radio pioneer 48 Vol. 3, No. 2, Radio Design who was a mere "voice crying in the wil- identified with derness," who was not able to condenser manufactur- popularize ing and fixed condensers of his broadcasting inventions, coming all sizes along and descriptions that his name and con- and succeeding in the talking picture field densers where the are practically synonymous. First electric light genius had become he became famous discouraged. Such as the guiding light of experiences serve to the old Dubilier Condenser better illustrate the fickleness of Company, and fame. later was associated with the Dubilier It is becoming well nigh impossible to Condenser and give a comprehensive report Radio Corporation. Yet on all the few except the old timers ever connect his early broadcasting efforts. The number is name apparently with early broadcast efforts, al- legion. Many other writers in though he was one of the past have attempted the first. Dubilier's to do likewise, experiments were carried on up in and have met with similar experiences. the Every mail Northwest country. Seattle, Wash., papers brings in new anecdotes and of the time carried pre-war broadcasting stories. much news of the One thing young inventor, and mention was made is certain: there were about as many even in the broadcasting stations editorial columns. "Bill" was erected before the initiated into the radio business war and which passed out of the through picture these first efforts back in October, 1910. as there were after the so-called 'broad- The casting station way no second-rate affair era started in 1921. So we have either even though it didn't decided to choose only operate on any those installations regular schedule. Reports were recorded which were connected with well-known in the names, or daily press of good reception as far which had some interesting away as 75 miles. The story associated therewith. electrician in the government navy yard reported excellent volume DUBILIER'S and quality at his location, a dis- BROADCASTING tance of 45 EXPERIMENT miles from Dubilier's antenna. And please don't overlook the fact that There is no radio experimenter in exist- this reception was ence to -day who has not accomplished entirely heard of the name on crystal sets with no amplification what- William Dubilier. So long has he been ever. Some station!

2%K, a famous station during 1921-1923. E. J. Quinby is shown playing the organ and singing, while L. M. Cockaday/ operates the Regular vocal modulation control. and instrumental concerts were broadcast every Sunday evening. Vol. 3, No. 2, Radio Design 49 wavelengths were reports of the time state that neapolis, Minn., when Technical guessed at by turns on the helix rather Dubilier used a special type of "oscillat- It was a than by instruments. ing" spark of his own design. starting with the 1912 con- very ingenious affair, according to all ac- Of course, the imprint ference, the radio transmitting industry counts, and served to stamp out of the chaos. ability on its inventor at worked its way gradually of outstanding wavelengths were divided into early date. All known that telephone three general groups for government use, Then there was the radio or experi- owned and operated commercial use, and amateur broadcasting station purposes. The classification be- the John Wanamaker store in New mental by operation tween 600 and 1,600 meters was reserved York. This station commenced the group of waves using a rather unusual type for government work; in May, 1914, the between 200 and 600 meters was set aside of hydrogen arc light for generating chan- wave. The old for commercial messages; while the high frequency carrier nels below 200 me- Wanamaker organi- ters were left to became fa- ex- zation by Wireless. the amateur and mous, in the scien- Heard a Cdncert, It was was busy on the evening of perimenter. tific world, through Ether was at this time that the June 16, when an enjoyable concert sponsoring scientific Super, United States was several given under the auspices of the .New, infants in 2XK, divided into nine of endeavor. Badio Corporation, Station fields novel was the radio districts for This is probably the York City. Especially p u r - entertainers, all Yonkers - supervisory first case of record fact that the poses. Government Res, assembl ;'at the sending ,,station, where a department orlâ .City,, licenses had to be radio ,4,414 Bayley vetivai . Ne store employed ant ti; :vas secured specifying to increase its public arid rendere power and wave- and pres- transmitted wide .bv. tirelessireless goodwill fore- length for ever y many of telegraphy. Ía B.;llasbn, tige. Now :the a York station. the best stations are man in the mp', '' of, . after the has a,? ne .re- Shortly nurtured by mercan- Telephone C ínpany. who Ex- at his 'home, 456 I ellevue Panama -Pacific tile organizations, ceiving set position at S a n avenue, says he heard the concert at and the Wanamaker instrumen- Francisco in 1915, store in Philadelphia his residence, the vocal and being transmitted very Morton W. Stearns still maintains its tal music the opened up a radio clearly. Exceptionally clear was radio interest. who intro- telephone station Up to about this voice of the station operator entertainers to their audience, on Washington time little or no duced the New York in all parts of the State. Heights, thought had been gathered City, under the call wave- The entertainers were the Rivoli Or- placed on Quartet, letters 2AB. Suc- lengths. Amateurs chestra, the Rivoli Saxophone L violin, and his accompan- cessful tests were a n d experimenters Mr.,Dennison, con- The concert, ell carried on for a chose what e the r ist, Mrs. Mocolist, organ. such popular selections siderable period of channels they de- which included entry Old Sweet Song," "Mighty C time until our sired and plugged as "Love's into the war closed signal Lak a Rose," "I Used to Love You," ti away with etc., all independent strengths governed "Sleepy Hollow Waltz," "Pekin," I( at 0:30 an" lasted unt:l 11:20. a radio operation. only by the size of began Speech and phono - their pockets. Com- t of a clipping from a Yonk 'rs graph music were mercial communica- Reproduction f r o m ships (N. Y.) paper of 1919. Certainly of his- transmitted tions between torical interest! time to time, and were being inter- the music, on at fered with to such was picked up at Mor- an extent that something had to be done. least one occasion, in ristown, N. J., for a dance. Stearns' sta- An international conference was called interest- the entire situation, and tion is mentioned because of an 1912 to discuss because of the music and out of this grew certain regulations which ing fact and not broad- speech transmitted, which was no different governed affairs very well until the stations in 1921. This nebulous from dozens of other experimental cast era started which limited space prevents condition of affairs at the start explains of the time the lack of wavelength and power data on us from mentioning. early transmitting stations. The author PROGRAM his first radio trans- THE FIRST SPONSORED can well remember runs something like this: A mitting experience back in 1912 at Min - The story Vol. 3, No. 2, Radio Design 50 Another view of 2XK. Phc graph music was ning, and was featured every Thursday eve- highly popul with amateur listeners. Compare this pioneer station with : huge plants in operation today.

certain phonograph inventor dis yed his Doctor, who is once more product at the World's endeavoring to Fair al e men- arouse public interest. The station on this tioned. He and his company w ere rela- occasion tively was located at New Rochelle, unknown but, in spite of this, their N. Y., and, of course, at instrument received this period had First Prize at the ex- definite call letters. The call was 2ZK, position. It was called the Crippen Inter- and the wavelength was pretone. Well, in the 420 meters. course of time, the Sometimes the call letters 2SK were em- Crippen Company heard of Morton ployed. Stearns' radiophone station. Conferences The most followed astounding feature of this par- during which one of the new ticular station was the use of phonographs was promised a vacuum as a gift if tube as an oscillator in place of the old Stearns would only mention its name when cumbersome electric arcs he played it over used in previous the air. The machine attempts. The "oscillions," as they were arrived in due time and was played ac- called, were blown in de cording to Forest's own lab- arrangements, accompanied by oratory at Highbridge, in the Bronx. The appropriate announcements. Thus, what tubes were operated in a red hot was probably the condition, first "sponsored" pro- attempts being made to cool them by gram was born-the beginning of modern blowers. "Charlie" radio Logwood made his advertising. first reputation on this job when he worked The next step finds us back H `11 Lee de out the system of grid Forest, modulation for im- aided by Charles Log ' and pressing the program on the carrier wave. Robert Gowan. Our last article how de Forest became rather discourag. DANCE MUSIC BY RADIO! on radio broadcasting as an entertainment Every evening during the winter wit- .,usiness after his Metropolitan Opera ness..d a regular radio program transmit- House experiment. We also stated that ted for a range of 150 miles. It went out this served to discourage others who had from nine to ten P. M., and varied from financial aspirations along this line. But Edison Disc records, because of their vol- here we are almost seven years later in ume and quality, to banjo selections by a the late Fall of 1916, back with the well-known vaudeville performer of the Vol. 3, No. 2, Radio Design ii day, Harry Hicks. On one evening, special editor of the New York Herald-Tribune, arrangements were made to send out the started a broadcasting station wLh the music for a dance in Morristown, N. J., call letters 2XK. Twenty-five watts of -apparently a similar stunt to that just power were used, employing a push-pull described in connection with Stearns' sta- oscillator and push-pull modulator. Not tion. Morristown must have been an up- only has that station gone down in his- and-coming community in those days! De tory because of Cockaday's connection Forest, himself, rigged up the "loud speak- with it, but also because it was probably ers" at the dance. The installation con- the first to employ a 100% modulation cir- sisted of six earphones connected to horns. cuit. Programs consisted mainly of pho- Great credit is due the designers and nograph music, although once in a while builders of 2ZK because, from the first a real treat was given the listener. On night on the air to the forced closing on one occasion in the first year the station account of the war, there was not one was operated, the Rivoli Theatre Orches- breakdown in the operation. Quite a rec- tra crowded into the small studio to enter- ord considering some of the fiascos hung tain the amateur listeners over a 700,000 up by the so-called pioneering stations in square mile area. Newspaper accounts of 1921-22. this particular event also listed the Rivoli Until the close of the war, all radio Saxophone Quartet. We hope "Larry" entertainment was at a standstill, in fact, wasn't the first to put saxophones on the it just didn't exist. War necessity reg- air. Just think of the ignominy of it. ulated all private transmitting and re- The year 1920 found Charles Logwood ceiving equipment out of existence. But back in the limelight-literally as well as immediately following the close of hostil- figuratively, for "Charlie" was busy in- ities, Lawrence M. Cockaday, creator of stalling and operating a radio broadcast- many famous circuits, technical editor of ing station for the California Theater in Popular Radio, and lately technical radio San Francisco. Apparatus was ordered

A rare photograph showing Richard Barthelmess, movie star, on the occasion of his radio debut over the Army broadcasting station on Bedloes Island, New York Harbor, during the winter of 1921. The apparatus shown is still in active use, but only for radio -telegraphic work. 52 Vol. S, No. 2, Radio Design from Lee de Forest, Inc., and Logwood had preceded it, a large local popularity was the company's representative on the was enjoyed. The Westinghouse Company scene. Much of the equipment was hand- had had lots of business on army radio made, a large portion of it being fabri- apparatus during the war, and saw the cated right on the job by Logwood himself. commercial possibilities if the general The California Theater station was lo- public could be aroused. They set about cated over and behind the stage, and was that very task by erecting a series of sta- reached via a rather long, vertical ladder. tions on their various plants in different No studio was provided, but regular pro- sections of the country. In September 1921, grams were sent out according to a pub- WBZ was set in operation at the Westing- lished schedule. Even this installation was house plant in Springfield, Mass.-the fol- in operation before the advent of KDKA, lowing month WJZ was started at the which was officially opened for election plant in Newark, N. J., and in November returns by Frank Conrad on the night of of that year, the Chicago station KYW November 2, 1920. started on the Westinghouse works in that Radio broadcasting developed rapidly city. from then on. As many reasons for its The sudden surge of popularity can only sudden growth have been offered as there be seen by viewing cold statistics. KWY have been individuals to offer them. All of Chicago had just been completed in are probably right, for the sudden popu- November, 1921. Two months later (Jan- larization was undoubtedly due to all com- uary, 1922) there were 36 stations on the bined. There is, however, one great credit air, and by the end of the year there were due to the Westinghouse Electric and 575. What chaos with all operating on Manufacturing Company, as we believe or about 360 meters! they were the greatest of all forces, which, It was at this point that Herbert Hoover, combined, gave the necessary impetus to as Secretary of Commerce, stepped in and put broadcasting over. For the real broad- added new laurels to his already long list cast boom didn't arrive for nearly a year of achievements. A series of voluntary after KDKA started,-not until Westing- conferences were arranged between all house had built a whole series of stations. broadcasters whereby certain gentlemen's agreements were made for the broadcast THE ARMY ENTERS THE PICTURE industry, which had found itself in a But we are getting a little ahead of our legislation. You story. In January, 1921, only a few weeks see, the radio law of 1912 placed no curb after KDKA started on its regular sched- on the number of stations; in fact, that ule, the U. S. Army Signal Corps opened law took no cognizance of broadcasting as up a powerful station, much better than such. For several years Mr. Hoover skill- many in operation to -day. The transmit- fully maneuvered these anomalous radio ting equipment, located on Bedloes Island, conferences until Congress became suffi- in New York harbor, in the very shadow ciently aroused to enact proper laws. Mr. of the Statue of Liberty, was operated Hoover has always been much interested with an input power of three kilowatts on in the progress of radio. He was probably a wavelength of 1,450 meters. Call letters the first great public man to speak over WYCB were employed. It is interesting to the air when he first broadcast from note that most of these early stations went KDKA in Pittsburgh on January 15, 1921. on the air for only one hour each night. That sèemed to be standard practice in CONCLUSION those days. Many notables were introduced This, we hope, will give you a bird's- to the radio listeners during those all too eye view of broadcasting development. brief hourly programs from the Army Many of the early stations have not been station, among them being Richard Bar- mentioned merely because there was noth- thelmess, the famous moving picture star, ing particularly interesting connected with and Jack Binns, famous radio pioneer. them. Others that deserve mention there The amplifying equipment was designed are undoubtedly, but we have not heard by Lieutenant Howard S. Parrock. The of them. This type of omission we know station was operated by Edwin A. Red- you will pardon. The present trend of ding, Jr., staff sergeant of the Signal broadcasting no one knows. We only know Corps. In continual use to -day is that where we have been and not where we are same transmitter, but only for the dot going. If the picture presented herewith and dash code messages of the army. gives someone the necessary perspective to After KDKA opened in November, 1920, predict where we are going, these articles it remained on a regular schedule one hour will have accomplished great good as well nightly. Similar to other stations which as offering some slight entertainment. Vol. 3, No. 2, Radio Design 53 More New Parts for the Builder Improved "Vaultype" Condensers; Power Units and Amplifying Trans- formers for the 250 -type Tube; Microphone Transformer and "Pre -Selector" Coils.

a condenser which, NvE ARE pleased to announce vided wiith balancing the appearance of a number of because it is grounded to the frame, may new Pilot products for the ra- be adjusted with the fingers while the set dio constructor and experi- is in actual operation. The insulation be- menter. These will be generally available tween the rotor and the stator is of in radio stores throughout the country by molded bakelite. who the time this issue of RADIO DESIGN For the benefit of those readers reaches you. are not familiar with the Vaultype condensers, we are again publishing the di- NEW VAULTYPE CONDENSERS mensions. The condensers are all 4 inches The condensers, which have wide and 3% inches high, and vary in Vaultype con- already been on the market for several length as follows: No. 3021 single months, have been improved by the use of denser 2'/8 inches; No. 3042 double con- die-cast aluminum frames, which replace denser, 4% inches; No. 3063 triple con- the pressed steel cases formerly used. denser 6'/s inches; No. 3084 quadruple The new cases are exceedingly strong and condenser, 8'/sinches. The 14 inch shaft rigid, and may be fastened securely in extends 7/s of an inch from each end. Any any position without causing the con- combination of these condensers may be denser plates themselves to lose their ganged by means of the Pilot No. 12-A alignment. The covers of the condensers, condenser couplings. which were formerly also made of steel, Single Vaultype condenser-No. 3021 are now being stamped of aluminum and Code: YETEM. are strengthed by a neat bead running Double Vaultype condenser-No. 3042 around the top. Code: ZENEG. 3063 The electrical constants and overall Triple Vaultype condenser-No. of the condensers re- Code: ZEHUD. physical dimensions 3084, main the same as before. The condensers Quadruple Vaultype condenser-No. are made in single, double, triple and Code: ZARDA. section has a max- quadruple units. Each UNITS imum capacity of .000365 mf. The cali- 250 POWER type, Because of the interest expressed by bration curve is of the centraline vari- which strikes the best balance between many readers of RADIO DESIGN, the and straight line ous power units designed for the Pilot straight line frequency in wavelength. Each .000365 section is pro - Public Address Amplifier (described rt-i $ a i, It

Inside view of the No. 3042 con- Outside view of the No. 3042 denser, showing the one-piece double Vaultype condenser. The die-cast frame, the tension ad- single, triple and quadruple units justing screw at the right, and are similiar in appearance, differ- the compensating condensers at ing only in length. the bottom. 54 Vol. 3, No. 2, Radio Design The No. 970 resistor. The No. 969 is similar, but has no tap.

Appearance of the The No. 443 choke is No. 441 transformer + like the No. 441 and transformer, but has the No. 444 con- only two binding denser block. posts. the Spring, 1930, issue) are being made transformer serves the purpose. It up as separate units, for assembly into gives 7% volts at 3% amperes for one 250 power packs and power amplifiers of or two 210's or 250's, and 2% volts the constructor's own design. The power at 8 amperes for four or five 227's. The transformer has been given the catalogue can is 51.E inches high, 5 inches long, and number 441, the choke coil 443, and the 3 inches wide, is fitted with a bake- condenser block 444. These instruments lite terminal plate with screw connec- are extremely heavy and well-built, and tions, and is finished in black Japanese are generously under -rated to enable them lacquer. to operate over long periods without over- To complete a power pack When using the heating or overloading. used with new 250 units, it is necessary to have a pair of 281 rectifier tubes, they make up special heavy-duty output ideal resistors. The power packs for heavy-duty audio main dividing resistor used in the Public amplifiers and low -powered amateur Address Amplifier has a total resistance short-wave transmitters. of 39,000 ohms, with a tap which divides The same size steel case is used for all the units into two sections of 12,000 and three units. This is 5 inches by 4% inches 27,000 ohms. The second resistor, which by 51/ inches high, and is finished in feeds the last 227 amplifier tube shown in black Japanese lacquer. The connection the accompanying diagram, has a resist- plates are of molded bakelite, with screw ance of 47,000 ohms and no taps. terminals. The No. 441 transformer has Both resistors are wound on insulating two secondaries, 7% volts at 31, am- tubing 4% inches long and % inch in di- peres, to light the filaments of the 281's, ameter. Connections to the wire are made and 1,200 volts (center -tapped) at 140 by means of straps encircling the tubes. milliamperes, for the plate voltage of one The first resistance has the catalogue or two 210 or 250 tubes. The filament number 970, Code ZUTYH, and the second winding is not center tapped. has the number 969, Code zYnuC. The No. 443 choke has an inductance of Power transformer for 250 tubes (for 32 henries, at 145 milliamperes. 115 volts, 50-60 cycles A. C. The No. 444 condenser has No. 441, Code: YIPUV. three sections: 2 mf, and 3 mf. Same transformer for 220 at 800 volts working, 5,000 volts, 50-60 cycles A. C., No. volts flash test, and 3 mf. at 441A, Code YUTIJ. 650 volts 3,600 volts working, 32 -Henry Choke Coil for 250 flash test. tubes, No. 443, Code YIUGM. FILAMENT LIGHTING TRANS- Filter condenser block for FORMER 250 tubes, No. 444, Code: The No. 441 power trans- YOBLO. former is not provided with Filament lighting trans- filament windings for the 250 former for 250 tubes, for 115 or 227 tubes, the use of a sepa- volts, 50-60 cycles A. C., No. rate heating transformer be- The No. 480 446, Code: YUJOY. output trans - ing highly advisable because of f ormer is a Same transformer for 220 leakage in a common trans- husky instru- volts, 50-60 cycles A. C., No. former. The new No. 446 ment. 446A, Cede: YUZME. Vol. 3, No. 2, Radio Design 55 S/N6Lf CKCu/T./IC.f DOOOLC C/RCL//T FOR PNAYOGPAPN Afx:POP,i0N2 M/CROPNONC vPJ OP Rl TRANSFORMER ;AV";L/F/fRJ /*PUT JACK N'I?A Rs//65'

AM/-CARiC/TT A*TT CAP. 4497. CAPACITY ANT/CAPAC/TY I Sw/1CN SW/TCI? SM/TCH 'Mr ch, j

N, 925 o 500,000 ONA7 M/IL/AM(TER 50MA. YOLu/ACFAD Orr orr oY or,. o, N°945 50A0,"000 ONM .500.000 OYALr 500.000 0M4, re ('416R45 VOL vMG.MD VOL UMGRAD J.N6 DRY COILS

2# .05MF 6MF. AT 607 .02.0l. 59 P-227 P-227 NrI.d9 250 WPM

..0/STOA /NDA:ATOR

.Mâv AJIY%7CN 'R'9502

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WICIf l5 VOLT N/46 YOLTAGC, flASNL/6//T 7 JM?CN LAMP F.A.

The lower part of this diagram shows how the new 250 power units are connected to form a power pack for a four-stage amplifier (center section) which will operate six auditorium model dynamic speakers for public-address work. The top section shows a control arrangement. This hook-up is practically identical with that used in the Pilot W-145 Public Address Amplifier. The values of all parts are indicated.

AMPLIFYING TRANSFORMERS 2% inches wide, and 2% inches high, is The high plate voltage and heavy plate sealed air -and-moisture -proof and is fin- current of the 250 tubes make the use of ished in black Japanese lacquer. This in- an ordinary push-pull output transformer put transformer has a ratio of 1:1%. impossible, as the windings quickly burn The output transformer is contained in out under the load. To over- a special large case which is come the situation and to take 3% inches high, 2% inches advantage of the full possibili- wide, and 3% inches thick. The ties of the 250 power tubes in secondary winding has a total push-pull, Pilot engineers have impedance of 2,000 ohms and designed a pair of new push- is centertapped. The impe- pull transformers especially dance between the center -tap designed for this class of ser- and either of the outside vice. The input transformer, connections is 500 ohms. This -tapped sec- arrangement permits the most which has a center Appeartln ce of the ondary, is contained in the advantageous connection of No. 428 microphone to six dynamic speak- same one-piece steel case used trans f orm er and the from one for the 422 series transform- No. 429 amplifying ers. The input transformer has ers. This can is 4 inches long, transf ormer. been assigned the catalogue 56 Vol. 8, No. 2, Radio Design number 429, the output transformer 430. THE PUBLIC ADDRESS AMPLIFIER An additional accessory that will prove Since the appearance of the Spring is- very useful to radio constructors is the sue of RADIO DESIGN, the Pilot company new Pilot No. 428 microphone coupling has decided to market the Public Address transformer, which is designed Amplifier only in completely assembled to couple any standard two- and wired form, at the standard retail button microphone to the in- price (in the United States) of $350, put grid circuit of the audio minus accessories and F. O. B. Lawrence, amplifier system. The primary Mass. No kits will be sold, as the assem- is accurately center -tapped, bly of the outfit involves the use of special to insure good quality of trans- tools and equipment not generally accessi- mission. The No. 428 trans- ble to the individual constructor. How- former uses the same case as ever, the more important of the component the No. 422 series, the dimen- parts, like the power transformer, filter sions of which are given in units, etc., have been made available for the foregoing paragraph. No. 286 sale separately for the convenience of builders who care to make amplifiers PRE -SELECTOR COILS of similar design; these are described on the The special coils used in the Pre -Selector foregoing pages. receiver are now available separately as the No. 236. The set of four coils includes The amplifier accessories are also ready for the market. one antenna, one band-pass, and two inter - They are listed as fol- stage units wound on formalite tubes 21 lows: (Prices shown are list prices.) inches long and 1 inch in diameter. The four special aluminum shields used in the Pilot Public Address Amplifier, completely assembled and wired, for 115 volts, receiver are supplied with the coils. The 5U-600 Cycles A. C. without tubes or shields are pressed of one piece other accessories. No. W-145. of alu- Code: WYOWB minum, are 4 inches long and 2 inches $675.00 square on end and are open on long `Jame amplifier for 220 volts. 50-60 cycles the A. C. No. W -145A. Code: YESSO side. The No. 236 coils must be tuned by 675.00 variable , ondensera of .000365 Amplifier accessories: mf. capac- Double button microphone, table type. ity, being designed especially for the Vaul- No. 1101. Code: YIHMO 75.00 type condensers.. Floor stand for above microphone, max- Push-pull input transformer for 250 imum height 5% feet. No. 1102. tubes-No. 429, Code: Yuol~r. Code: YOUVG 45.00 Push-pull output transformer for 250 Phonograph turntable, electric motor drive (Motor for 115 volts, 50-60 cycle tubes-No. 430, Code: ZADPA. A. C.) No. 1103. Code: YUGRA 45.00 Microphone coupling transformer-No. Same turntable for 220 volts, 50-60 cycle 428, Code ZEEWP. A. C. No. 1104. Code: ZAWPY 45.00 Pre -Selector coils, with shields-No. 236, 2% volt flashlight bulbs, used as high voltage fuses in power pack. No. F-43. Code, YUKVA. Code: ZOOCH .25

The "Auto Pilot"-a Broadcast Receiver for Your Car (Continued from page 14) twisting the little compensating con- After the set has been in service a few densers on the side of the Vaultype con- days, it may be necessary to take up on denser. the driving chains a notch or two, to keep Before closing the cover of the case, the control accurate. You can do this place the fourth piece of sponge rubber in a few seconds by opening the receiver on the top of the Vaultype condenser. The case and loosening the set screw on the cover will press down on the set and will condenser pulley. hold it firmly in place. In some cars an aerial strung between the axles may not be very effective, be- ADDITIONAL OPERATING NOTES cause of the shielding effect of the chassis. To compensate for the increased drain If you find this to be the case, tack a on the storage battery, it is a good idea piece of copper screening to the inside to increase the charging rate a few am- top of the car, or string a piece of thin peres. This is a very simple operation, and wire around the outer edge. Sometimes merely involves the adjustment of the third two aerials, one under the car and an- brush on the generator. Refer to the book other in the top, give very much better of instructions that came with your car. results than one alone, Vol. 8, No. 2, Radio Design 57 News and Notes of Doings of Individual Members and Chapters. by ALBERT L. RUDICK, Executive Secretary, Radio International Guild

THE various chapters of the Guild are member on October 15th, 1929. At that beginning to be heard from. The time she was Miss Anna Waddell, of organizers of these chapters are members Santa Maria. Mrs. Hartley and her hus- who have shown their willingness to un- band are now busy with their amateur dertake this task, and a desire to take an station 6DIU, located at Orcutt, Calif. active part in the work of the Guild. We are proud to have both Mr. and * * * Mrs. Hartley as members. The picture of ALBERT WILLIAMS, organizer of their station and their own pictures give Chapter 48, at Marion, Indiana, re- a new angle on matrimonial bliss. When cently sent in the names of eleven new this charming couple adopted radio as members whom he had recruited. Mr. their hobby they opened up a new avenue Williams expects to have a total member- for couples of the future to follow. ship of thirty-four by the time this issue * * * of RADIO DESIGN goes to press. The Hartleys hope to install a Super- This Chapter wants it known that they Wasp in their amateur station very soon. will welcome any visiting member of the We will all want to hear more about their Guild to their club rooms. If you should progress, no doubt. ever visit that town do not fail to drop in. Ask for Al Williams. * * * By the way, the Marion Chapter also BRUCE GREEN, of Clinton, Iowa, expects to install a laboratory or work- would like to correspond with the other shop in connection with their club rooms, members of the Guild. His address is 1355 which will be open to members at any Caroline Avenue. He says that he would time. They make no welcome letters from secret of the fact that foreign members and they are just as anx- will answer all corre- ious to get girl mem- spondence. bers as they are to get * * * young men. JUAN LUGO, of 44 * * * St. Augustine Street, THE mention of "girl Pta. de Tierra, San members" brings us Juan, Porto Rico, to the subject touched wants to correspond on in the last number with Spanish-speaking of RADIO DESIGN. There members. If you can now seems to be some write Spanish you question as to who real- might drop Juan a ly was the first lady line. member of the Guild, * * * not that it makes any MESSRS. R. V. But- difference, but we must ler, of Deepdene, please the ladies at all Melbourne, Australia, events. and P. A. Ball, of Mel- * * * bourne, recently wrote MRS. M. L. HART - us, expressing their re- LEY, of Orcutt, solve to foster the in- California, became a Mr. and Mrs. M. L. Hartley terests of the Guild to 58 Vol. 3, No. 2, Radio Design their utmost ability and to the mutual in- in your own town, let us hear from you. terest of the radio fraternity in Australia There is nothing like it for those having and America. a mutual interest in radio. You would be * * * surprised to know how much you could LESTER B. FLETCHER of Fletcher & do for each other. Company, Limited, Montego Bay, Ja- * * * maica, British West Indies, agents for the ANTHONY M. PLANITZER, of Pitts- Pilot Super -Wasp, has recently become a burgh, Pennsylvania, has some very member of the Guild. Mr. Fletcher is a optimistic plans for his Chapter No. 27. radio engineer and he is deeply interested Anthony makes the bold assertion that he in RADIO DESIGN, finding it invaluable. will make the Pittsburgh Chapter the * * * largest in the world. We are waiting to MISS MURIEL MULLER, of Blue hear more from him. Point, Long Island, is another lady * * * member of the Guild who should come in WILLIAM J. LYNCH, of Coshocton, for some measure of recognition. Miss Ohio, is organizing a chapter of the Muller enrolled in the Patchogue Chapter Guild in his city. Mr. Lynch brought up early in November. We salute Miss the question among the fellows who Muller. visit his radio repair shop, and he says By the way, the Patchogue Chapter has that it was carried with a unanimous its headquarters with the Nassau Broad- vote. casting Corporation. Nearly everyone connected with this broadcasting station, WPOE, is a member, all through the effort of Leslie Satterly. * * * MISS NELL YEATES, of Asheville, North Caro- lina (Box 365, if you must know), makes a very good suggestion that the official Guild pin be made in brooch form, for the lady members. We will have to look into this. Miss Yeates pays that she is only a radio student just now, but finds RADIO DESIGN of great interest. She would like to get in Station W6DIU, owned by Mr. and Mrs. M. L. touch with Guild members of Hartley, members of the Guild other countries. * * * JOHN N. MACAULAY, Jr., of Phillips- PORTLAND, Oregon, Chapter No. 55, burg, New Jersey, is the organizer of through George W. Ballard, its or- Chapter 60 of the Guild. His chapter is ganizer, just sent in the names of seven called the "Pilot Super-Wasp Short-Wave new members. Mr. Ballard says he is Club." Mr. Macaulay reports that his going to build up Chapter No. 55 and members are spending money to make this suits the action to the word. We will club successful. They are very wisely hear more from him and the Portland working with a local radio dealer who is Chapter. technically qualified to give them many * * * pointers. At the last writing, Mr. Macau- lay expected to have between ten and fif- 28, of San Francisco, Cali- teen members. CHAPTER.fornia, organized by John R. Ban- * * * croft, Jr., reports that 28 is coming in LEON LITVINE, of Brussels, believes very strongly now. San Francisco evidently is right he can be useful to the cause of the on the job. Radio International Guild by securing * * * members in Belgium. We have been get- THERE are over sixty chapters of the ting members from this country regularly, Guild in existence at the present time. and the interest in radio there seems to be If you would like to form a local chapter unlimited. Vol. 3, No. 2, Radio Design 59 w i11F BARGAIN11E, 11E,7 CRADIO ATA LO G cArÂió ALSO -FREE RADIO GIFT Send now for this new free radio catalog which saves you many dollars on radio outfits, kits, parts, tubes and accessories! Also TIME CONVERSION CHART FREE. Tells you instantly what time it is in any part of the world! Given free if your request for catalog reaches us this month.

234 - 236 SOUTH WELLS STREET, CHICAGO, ILL. Genuine PILOT (Products' 20th Century has the new "Auto Pilot" kits in stock.

FAIDIm IDIESICN "Radio Amateur's Hand book" By Francis E. Handy Communications Manager, American A whole year's subscription to "Radio Radio Relay League: and ROSS Design" costs only fifty cents and in- A. HULL, Associate Tech- cludes membership in the Radio Interna- nical Editor, QST. tional Guild. You receive four copies of the magazine, a membership certificate, This is the sixth and latest edition of a identification card and lapel pin. Fill book that has become so popular that it out is generally referred to as the amateur's this convenient coupon TODAY. "bible." More than 75,000 copies have been sold to radio fans all over the world, and U. S. stamps and money orders accepted. orders for It continue to arrive In every Foreign subscriptions must be paid by mail. international money order. The handbook contains 211 pages and over 200 illustrations. It is written in clear, understandable English. end is free of all Radio Design Publishing Co., Inc., the confusing mathematics that no one ever reads. It was written for YOU, the 103 Broadway, Brooklyn, N. Y. practical experimenter and constructor who know Enclosed find wants to the how's and why's. Con- fifty cents to cover one year's tains all the most advanced "dope" on subscription to "Radio Design" and member- short-wave reception and trans- ship dues in the Radio International Guild. mission. Postpaid $1.00

Naine We carry this book in stock. and can ship immediately. Street and Number Radio Design Publishing Co. City and State 103 Broadway, Brooklyn, N. Y.

60 Vol. 3, No. 2, Radio Design Iwill train you at home to fill a OBIG P

will giveYoumy new 8 OUTFITS Radio of RADIO PARTS If you are earning a Job for a home penny less than $5n a (.tiPiiLe.. week, send for my book of information on the Experimental Laboratory opportunities in Radio. coupon It is free. Clip the 1721fevi- NOW. Why be satisfied with $25, $80 You can build over 100 circuits Jr $40 a week for longer than the short time it with these outfits. You build takes to get ready for and experiment with the cir- Radio. cults used In Crosley, Atwater - Radio's Rent, Eveready, Majestic, Zen- growth opening hundreds of ith. and other popular sets. $50, $75, $100 a week jobs every year You learn how these sets In about ten years Radio has grown from work, why they work, how to a $2,000,000 to a $1,000.000,000 industry. make them work. This makes 600,000 jobs have Over learning at home easy, fasci- been created. Hundreds more nating, practical. are being opened every year by its continued growth. Men and young men izoe a with the right Back view of 5 tube week training-the kind of training I give you-are Screen Orti A. C. set- "My earnir.gs 1n Radio needed continually. oaly one of many cir- are many times greater cuits you can build. than I ever expected You have many lobs they would to choose from be when I Broadcasting stations use engineers, enrolled. They seldom ators, station managers oper- fall under $100 a week." a and pay $1,800 to $5,000 E. E. HINBORNE, year. Manufacturers continually need testers, 1414 W. 48th St.. inspectors, foremen, engineers, service men, buy- Norfolk, Va. ers, for jobs paying up to $15,000 a year. Ship- ping companies use hundreds of Radio operators, give them world wide travel at practically no expense and a salary of $85 to $200 a month. Dealers and jobbers employ men, service men, sales- buyers, managers, and pay $80 to $100 a week. There are many other 8o opportunities too. many opportunities many N. R. 1. men make $5 to $25 a week extra while learning Jumped The day you from $35 how enroll with me I'll show you to $100 a week to do 10 jobs, common in most every neigh- "Before I entered borhood, for spare time money. Throughout Radio I was your course I send making $35 ing you information on servic- a week. Last week I popular makes of sets; I give you the plans doubling and tripling the earned $ 1 1 0 servicing and ideas that are making $200 to and selling Radios. I hundreds of N. R. I. $1,000 for Iamsalaries of many owe my success to N. while students in their spare time R. 1." studying. in one year and J. A. VAUGHN Talking Movies, less 8715 S. Ringshighway, Television, Wired Radio Find out about St. Louis, Mo. are also Included this quick way to Radio principles as used in Talking Movies, Television and home Television BIGGER experiments, Wired Radio, Radio's use in Aviation, are all given. Radio I I am so sure that Needs can train you satisfactorily that I will agree in writing to refund every penny Trained of your tuition if you are not satisfied Men with my Lessons and Instruction ti upon Service $500 extra in 4 completing. 64 months -page book of information FREE J. E. SMITH, President. "I find I made $500 from tells you where National Radio Institute, Dept. 0ll-47 January to May in Radio's good jobs Washington. D. C. my spare time. My best tday.Itthey pay, tells you week about my course, what others who Pear Mr. Smith: Send me your book. brought me $107. I it are have taken This request does not obligate m:. should have taken it long doing and making. Find out what Radio ago." offers you, without the slightest obligation. ACT HOYT MOORE NOW. R. R. 3, Box 919, Name Indianapolis, Ind. J. E. SMITH, President National Radio Institute Dept. ODD Washington. D. C. Address City Efate tfettmeEmploymentleruicetoallQradaates

Vol. J, No. 2, Radio Design 61 PI LOT PUBLIC ADDRESS AMPLIFI ER

C-0)

FOR commercially flawless sound re- 'rf production, activated either by motion AB, picture sound apparatus, direct speech, t) A radio received programs or phonograph PP- music. Easily operates six auditorium joie t, A model dynamics at full volume. Control ï system permits announcements simulta- .i.y,y,?X neous with musical ou+put... Engineered on basically sound principles; substanti- y oily constructed. Utilizes 3 -227 -type, CT. j 2-250-type,and 2-281's...Availablecom- pletely assembled, including 2 sets of tubes, 40. phonograph pick-up and table -model microphone . 46.°.- Prices and Detailed Information Upon Request PILOT RADIO &TUBE CORP. 323 Berry Street, Brooklyn, N. Y. 234 So, Wells St., Chicago 1278 Mission St., San Francisco

62 Vol. 3, No. 2, Radio Design

-ä - FR EE thehN EW RADIO NEWS

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