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..1 1 MAR -CO .1 I

Ì RA DIO PRODUCTS 1

1 The Best in Design, Finish and Workmanship

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l l Good Wiring Means Heavy Wire i 1 You can easily connect heavy wire l .1 to the special loop terminals on .1 l

I MAR -CO SURE -GRIP JACKS 1 1 Nine styles-all with sterling silver 1 contacts .1 Micarta insulation and heavy springs. $ .60 to $1.25 .I Balancing Condenser (left) $1.25 Variable Grid Leak Î (right) $1.50

A new Grid Leak, ranging in smooth A new neutralizing condenser. Bake- easy adjustment from 1/5 5 lite insulation. Nickel -plated working to megohms. Bakelite insulation. Entirely parts. Easy to mount. Easy to adjust. enclosed weather-proof construction. Send for Circulars Showing Over Thirty Radio Accessories

MARTIN-COPELAND COMPANY Department RP PROVIDENCE, RHODE ISLAND Î If your dealer buys his Radio merchandise from us

What he sells you is O. K. We are Rhode Island distributors for All leading manufacturers of sets and parts

UNION ELECTRIC SUPPLY CO. 60 PINE ST., PROVIDENCE, R. I.

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HORACE V. S. TAYLOR, EDITOR

Volume 1 Number 2

Contents for APRIL 1, 1924

PAGE HOW TO MAKE YOUR GROUND BETTER 5 MOST IMPORTANT PART IN BUILDING SET 8 NON -SQUEALING REGENERATIVE RADIO 9 RADIO AND PHONOGRAPH GET TOGETHER 14 WHAT HAPPENS WHEN YOU OSCILLATE 15 A LIFETIME IN A SECOND 16 WHAT WILL BROADCASTING BE IN 1925? 18

UP IN THE AIR ABOUT RADÌO , i EDITOR'S LOUD SPEAKER: HAM AND FAN 21 THE AIR DOES NOT BREAK 21 LINES FOR LADY LISTENERS 22 WILL CITIES OF THE FUTURE BE LIGHTED VIA RADIO? 23 BEHIND THE SCENES AT STATION WGY ... 24 RADIO REPORTED IN BEST OF HEALTH 26 THE FIGHT IS STILL ON 27 DR. RADIO PRESCRIBES 28 UNITED STATES BROADCASTING STATIONS 30

RADIO PROGRESS is issued on the 1st and 15th of each month by the Oxford Press at 8 Temple Street, Providence, Rhode Island. John F. O'Hara, Publisher. Gordon B. Ewing, Advertising Manager. Yearly subscription in U. S. A., $3.00. Outside U. S. A., $3.50. Single copies, 16 cents. Application pending for entry as second-class matter at the Post Office, Providence, R. I. Copyright, 1924, Oxford Press. Ad- dress all communications to RADIO PROGRESS, S Temple Street (Post Office Box 728), Providence, R. I.

The publishers of this magazine disclaim all responsibility for opinions or statements of contributors which may at any time become subjects of controversy. RAD APPARATZU The Giblin Broadcast Receiver

-rEIE (.il,liu Radio Frequency Broadcast

1 Receiver makes it possible to obtain T1IE fL STAM04RP FADIO LEIECTPIC CO. radio entertainment without the necessity PAwtuCMCTg.I. of erecting outside antenna wires or using © © a troublesome ground wire. A small, loop \% STABILIZER O placed near the set will pick up sig DETECTOR aerial A"SWITCH AMPLIFIER nais, which, though they have come long distances, and are weakened by hills, val and Cr leys, trees and buildings, will be clear ISYSTEP of great volume. Many families, living in SED STEP apartments where it is undesirable or im possible to erect antenna wires, can now hear enjoyable, ever-changing programs through the day and evening by "listening in" with a Giblin Radio Frequency Broad The set comprises two stages of radio frequency ampli- cast Receiver. fication, a detector and three stages of audio frequency amplification. The parts are mounted on a sub -base to which a Bakelite panel is attached. It is enclosed in a handsome solid mahogany cabinet.

The Giblin Audio -Frequency The Giblin Radio -Frequency Amplifying Transformer Amplifying Transformer Price $4.50 Price $5.00

. Buy Giblin Products from your dealer II'rih' fnr descriptive circulars

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VOL. I, No. 2 APRIL 1, 1924 15e. PER COPY, $3 PEL.i. YEAR How to Make Your Ground Better What Reason Have You for Think- ing Yours is a Good Ground

By HORACE V. S. TAYLOR

ALMOST every radio set must have There are two objections to this prac- Underwriters Forbid It a ground. Perhaps you think you tice. As you know, gas is under a very Another good reason against using a are operating your set without one when small pressure in the pipes. As a gas pipe for a ground is that the fire listening to a local station if you have insurance companies prohibit it. Their taken the ground wire off, but you are theory is that if a gas pipe should hap- not. You are really using a capacity pen to spring a leak, and at the same ground. A capacity ground uses the time any large current should happen condenser action of the set itself to get to go down the wire and make a spark, the electric waves to earth. This is the it would perhaps ignite the gas with way it works; the whole set is one plate resultant fire or explosion. Of course, of a condenser, the earth the other, and no such danger attends grounding on a the waves go through the air between water pipe. them in the same manner as they go Another mistake along the same lines through the variable condenser you use is illustrated as Fault No. 2. Here we when you tune in your set. The same have hot and cold water faucets. You action occurs when you use a counter- will notice the ground wire is attached poise-the counterpoise is connected to to the hot rather than the cold water the ground post of the set, and the con- faucet. The objection to this form of denser action (as described above) car- ground is that the electric waves will ries the waves across the intervening air Fault No. 1 have to go to the hot water heater and space, and so the set really is grounded. perhaps to the kitchen range before The only style of set which really matter of fact, the pressure is so low they find the cold water connection and does not require a ground is the one that you can easily blow backward using a loop aerial; we mean a real through a gas pipe and by filling it with loop aerial, one that has two terminals, air can blow out the lights in adjoin- both brought to the set. Many ama- ing rooms. This delicate attention to teurs use a wire wound on a square or one's neighbor often occurs in a college diamond shape form, and connect the dormitory where one fellow will put out outside end only to the aerial post of the light of his roommate at a critical their set. However, euch coil does not point in the evening's work. On the constitute a real coil aerial. The essen- other hand, water pipe has to stand tial difference is that a real coil aerial very heavy pressure. For this reason always has both ends connected to the the joints of the water pipes are usually set and no ground connection at all. screwed up a great deal tighter than the joints in a gas pipe. Of course a Some Common Mistakes lot of the electrical resistance in a pipe Fault No. 2 One of the common faults with the may easily occur at a joint not properly are able to run through the cold water ground system of a radio set is illus- tightened, and this is one very good pipes out into the ground. You will trated as Fault No. 1. This shows a reason why a water pipe is better for realize that the electric waves ere not ground wire attached to a gas pipe. a ground than a gas pipe. interested in the pipe or the wire itself, 6 RADIO PROGRESS APRIL 1, 1924 but are only intent on reaching the real, cause it runs so much higher than the Evidently in installing this set the wire solid ground, and so have to wander set that it has the tendency to act as was a little short and had to be pieced around the piping in your house until an aerial and robs the set of some of to enable it to reach down to the cellar they are able to reach the service en- the energy it would otherwise have. If to the water pipe. Of course, such a trance of the water pipe in your cellar at all possible, the ground wire should thing often happens, but when it does, and go directly to the earth. For this run down from the set and should not reason, be sure that you always ground rise above its level at any time before on the cold water pipe rather than the going down into the cellar. If neces- hot water. sary, a bare braided copper wire may be J_ run under the carpet from one side of Don't Wrap the Pipe the room to the other. Then you won't After you have found the correct pipe have to go up to the ceiling at all. The on which to ground, perhaps you have braided wire will be flattened out CELLAR made mistake No. 3. This may seem enough so that it will not damage the like a simple trouble, but it sometimes carpet nor be injured itself by people causes serious difficulty in the operation walking over it. Fault No. 4 of a set. You will notice the wire is Have you seen a radio installed with wrapped around the pipe several times Fault No. 5? You will observe that the joint should not be wrapped only, and then twisted back on itself. Such the aerial and ground wire run side by as shown in the picture; after wrapping a method will sometimes make a good side for a considerable distance before it should be soldered. The reason for ground which will last for a short separating. This is like the mistake this requirement is that the underwrit- while, but eventually it is very apt to we depicted in the article on aerials in ers specify that all joints in the ground fail through corrosion of the pipe or the our last issue. Where the ground ap- wire must be soldered unless fastened wire. proaches so close to the aerial wire the by some sort of approved clamp. Their condenser action between the two will attitude is that the same ground wire steal a large proportion of the music is usually connected to the lightning ar- which comes in through the air. In the rester, and if lightning should strike illustration shown, if the ground wire your house you naturally want the had been run straight down to the floor, ground wire as near one hundred per then along the floor to the left hand cent. perfect as possible, so as to make corner, it would have separated the two sure that all electricity will be brought wires several feet apart and this would to ground and none of it be left to have caused no trouble. wander around your rooms to set fire to your furniture. One Wire Per Hole Also, be sure that you do not make Moonlight Rambles Bad for Ground the mistake, which is seen so often, of Fault No. 7 shows how a ground wire Fault No. 3 running both wires through the same often rambles all around a house before hole in the wall or partition. If you do, reaching the cold water pipe. This is The only satisfactory way to attach you are throwing away a good deal of quite undesirable. The more direct and your ground wire to the pipe is to use your energy. short a ground can be made the better a copper ground clamp. Such a clamp Now look at Fault No. 6. Here we have your set will operate. When you have can be obtained at the cost of eight or a set connected quite properly to the such a long wire as is shown in the pic- ten cents, and it is foolish to attempt water pipe in the cellar, but you will ture it adds considerably to the re- to make a homemade device do the work notice that the wire is not continuous. sistance of the circuit, and this is a two - of such a cheap piece of apparatus. Of course, if the wire had been soldered to the pipe, it would have made a satisfactory connection, but if you have ever tried to solder to a pipe with AerQ water in it, you will know it is almost an absolute impossibility, and it is quite a lot of bother to draw the water off is o fore attempting to solder. It o better to use the clamp. zer Do You Go Up to Ground? Some installations look like picture No. 4. You will notice here the ground wire does not run straight down, but first goes up to the ceiling and across Ground the room before going down cellar to the water pipe. This is a mistake, be- Fault No. 5 APRIL 1, 1924 RADIO PROGRESS 7 If you are using this style of clamp fold disadvantage. In the first place it direct wire ground running down to the do not make 'mistake shown in Fault No. reduces the loudness of the broadcasting, water pipe, and they will not pay your 9. This mistake consists in using a and in the second place it makes it more fire losses when the house burns if they pipe driven in as described. Such difficult to tune out undesirable stations. find you used the radiator 'for a ground. single to its short length, has a If your set does not reach out as far a pipe, owing If you are using as your neighbors, make sure that your Just Where Should Ground Be Con- high resistance. ground, at least two ground wire ie direct and as short as nected to Pipe? driven pipes for used, and three would be bet- possible. By the underwriters' rule the place should be they are spaced as far as If you find trouble in running the wire to attach your ground clamp and wire ter still. If resistance is reduced direct to the cellar, the difficulty usually is on the cold water pipe just as close five feet apart, the or one-third, but even if they is that you can not get through some as possible to the point where it enters to half only couple of feet apart, the sec- floor or wall. So you must run the wire your cellar. This is usually right by are a ond helps quite a lot in reducing the to some actual opening like a. door or a the water meter. If your house is wired so improving the opera- crack which already exists. But this for electricity, you will doubtless find resistance and your set. In connecting up two is unnecessary. For about ten cents you that the lighting people have used the tion of a wire to each pipe, can buy an electrician's auger, which is same place as a ground for their equip- or three pipes, run these two or three wires about one foot long, and with it you can ment. If such is the case, it does no and then solder to the ground wire run- drill a hole through the wall or floor harm for you to ground an inch or so together and to set. This will make quite quite quickly and easily. The size of away from these connections, and right ning your the hole is so small, smaller than the on the same pipe. a satisfactory installation. diameter of 'an ordinary telephone cord, that it is very unobtrusive. Through If You Have No Running Water such a hole you can run your bare But let us suppose you are in tiro ground wire without experiencing diffi- country and have no running water. culty, and by doing so the wire will be What is the best method of making a short and direct, as it is necessary for ground under such conditions? Some best reception. exhaustive tests on grounds have lately been conducted by the Electrical World issues. 0 0 and reported by them in recent 0 00 Should you have no city water supply coming into your cellar, the best method w RA PP E D SET is to drive some pipes down into the Jo iNT ground and connect to them. However, do not make the mistake illustrated in Fault No. 8. You will notice this pipe is not driven very deep. In order to make a good ground, it should enter per- manently moist soil to a depth of three Fault No. 6 or morn feet. Since the permanently Fault No. 7 moist soil is usually found at least four Fault No. 10 is difficult to illustrate. Oftentimes grounding on your radia- feet below the surface, it means that It consists of attaching a ground clamp tor is a case of rambling. Before you your pipe should be driven to a depth to your pipe without properly attending ground on your radiator, make sure that of seven or eight feet. In driving it is to its surface. When a pipe has been the radiator pipes are pretty straight not necessary to buy a special tip, as it in use for some time it becomes dirty down to your cellar, and that the cold is found that a pipe with an open end and oftentimes rusty or corroded. Such water pipe running to your furnace is will penetrate most soils that are not a coating on the outside is a pretty good not unduly long and winding. You see, too stony in character. In case your insulator to prevent radio waves getting the radiator itself is not a ground, nor land contains too many small stones it from the clamp to the pipe itself. The is the furnace. It is only because the becomes rather difficult to force a pipe only good method of removing this scale radiator pipes connect to the furnn e, down to such a depth. Here the best is to take a piece of sandpaper and and the furnace connects with the cold method is to get a sharp pointed steel polish the outside of the pipe for the water pipe that it is satisfactory to use rod and drive it down first, then rem -we length of a couple of inches. When it the radiator at all. If these pipes are it and drive the pipe in the same hole. has been brightened up so it shines all comparatively short and direct, then no Care should be taken to use a steel rod the way around, you can put the ground harm can be done to your reception, but smaller in diameter than the iron pipe clamp on. If you screw it down tight, if they ramble around the house before because it is quite necessary that the you will find the good contact you get getting to the cold water outlet, you will pipe fit tight in the hole to give a good will last over a long term of years. get better operation if you run a ground contact to the surrounding earth. The This may seem like a small point, but wire direct to the water pipe. A further upper end of the pipe may be left pro- many a radio set is crippled somewhat abjection. to grounding on the radiator jecting as far as you like. It should in its operation by carelessness in this is that if you have an outside aerial the be attached to the ground wire by a cop- regard. underwriters require that you have a per ground clamp. Continued on Page 8 Most Important Part in Building Set Story of Flow One Radio Builder Nearly Came to Grief Through Oversight An Interview with Mr. Montmorency, the Boston Banker ANY people in building sets use the thing to do was to start with a sin- most anywhere, so he quickly filled the some unnecessary parts while oth- gle tube set using a regenerative hookup. order which I gave him. He told me the ers perhaps leave out some items which That would make it a lot easier to locate single circuit regenerative was an easy would be a distinct improvement to the any troubles which might develop and one to hook up and he thought I should set. A ease of this kind was recently ex- then we could afterwards add two stages not have any trouble with as plained by O. Albert it I had all Montmorency of of audio amplification, so on this basis the necessary parts. Beacon street, Boston. Mr. Montmo- we got down to work and made a list of rency is a banker in the daytime but 'in the various parts which we should need. Easy to Forget the evenings he has been (building crys- We found the advertising pages of the 'When I arrived home late that af- tal sets with the help of his son. Re - radio magazines quite helpful in making ternoon I was met at the door by the recently he decided to try building a tube a choice. After the list was done my family, who cried in chorus, 'Did you get set but when he got the apparatus ready son asked if I had put down the most it?' I instantly knew what they meant. he found that-but let him tell it: important thing of all. I told him that I 'By Jove, I forgot it at that,' I ex- "I have tried out most every kind of hadn't, as there was no chance at all of claimed. Well, you will have to turn a crystal set," said Mr. Montmorency, forgetting that. `Well, don't you come right around and go back and get it,' "and I have had pretty good success with back without it,' he said. said my wife. When I reached the store all of them. The one that worked best of "As I left on ,nly way down town my the dealer was apologetic. `Of course I all was modeled after a set described as wife handed me a list of things that I thought you had one,' he said, 'or I would a fool proof radio in one of the new was to get for her and incidentally have called your attention to the omis- radio magazines.* she asked if I liad made out my own list of sion when you were buying the rest of Getting the Distant Stuff radio parts as otherwise she knew that I the parts. It is the most important thing "But I finally decided that I wanted would forget something. 'I have down to get when building a set.' to get broadcasting out of the city and everything, but the one thing that I can't "I now hurried home the second time. so looked around to see what kind of forget,' I told her. `I know what you Again the family was waiting. 'Here it apparatus to buy. Should it be a one, mean,' she replied, `and don't come home is,' I said as I handed them the last two, or three tube set, or should I build without it.' `Not a chance,' I said. When copy Of RADIO PROGRESS." one of those big eight tube outfits, and I reached the radio store I found the then how about radio frequency and dealer had everything in stock that I *Editor's Note. He evidently refers to audio frequency. Here my son was able wanted. The dealer explained that it "A Fool Proof Radio" in the March 15 to help me considerably. He said that was easy to get the advertised parts al- number of RADIO PROGRESS.

IIOW To MAKE YOUR GROUND use for the ground. The idea is the superfluous. Dry wood or plaster, you BETTER radio waves come in through your aerial known, is a good insulator. With noth- Continued from Page 7 and do their best to get to ground. The ing to lose and the possibility of gain, aerial for this reason must be insulated there is no reason why bare wire should (either by using insulated wire, or by not be used. But if you already have supporting bare wire on insulators) if insulated wire installed, there is no IIIII1 IPIIuY you want the waves to go through your particular advantage in tearing up, --, it hi4l set; but after they have gone through but on new work, use bare wire. Or- and made music in your phones, you dinarily, No. 14 is recommended by the want them to reach hóme (ground) as fire insurance companies, unless it is soon as possible. How unnecessary it connected to the lightning arrester, in is, then, to cover the ground wire with which case No. 10 wire is specified. insulation. Lf this wire should happen On the whole, if you will look over to touch any piece of metal, like a fur- your wiring with the idea of getting the nace pipe, for instance, it would improve electricitiy Faults Nos. 8 and 9 from your set to a good moist the operation, if it had any effect at all, ground just as quick and direct as pos- What About Insulated Wire? because it would give the radio waves sible, you may find that you can improve Many amateurs use insulated wire for an even shorter path to ground. On the the operation of your set at a very small the ground. There is no real objection other hand, if it did not happen to touch outlay of money and time. to this practice. However, it is going any metal, then it would be insulated, In the next issue we shall discuss to unnecessary expense to put an in- even though bare wire, and any further some of the ordinary errors we find in sulated coating on the wire you are to insulation on the wire would be entirely the installation of lightning arresters. gRegenerativeNon-Squealin Radio "Teledyne" Circuit is One of the Recent Developments in the Non -Radiating Sets By H. S. WILLIAMS, Radio Engineer

(EDITOR'S NOTE: If you have fol- ent time, but practically all use the plan it excels in range, volume and selec- lowed recent discussions in the technical of substituting radio frequency for re- tivity. papers, you will notice that the 'burning generation. However, it is not neces- Mr. H. S. Williams, Radio Engineer, question of the hour is the non -radiat- sary to sacrifice regeneration. One of has written a series of two articles on ing set. In some congested districts it the first radios to retain this feature the "Teledyne." The first one explains is practically impossible to get any kind and yet omit the squeals is the so-called the circuit and tells how to build a set; of decent reception from distant stations "Teledyne;" "tele" meaning distance and. the second discusses the best aerial and until eleven or twelve o'clock at night, "dyne" meaning power. ground for use with this set and de- when most of your squealing neighbors This set was designed and built by scribes the method of tuning and opera- have gone to bed. Several non -radiating Dr. Bowden Washington of the Cutting tion.) hook-ups are on the market at the pres- & Washington Radio Corporation, and THE "Teledyne" was designed with experiments it was found by Dr. Bow- regeneration was a great step forward two primary objects in view. The den Washington that it was possible in radio reception. It made a vacuum first was tó produce a powerful and to eliminate "re -radiation" from re- tube almost a hundred -fold more effi- simple regenerative receiver that would generation. This accomplishment, in cient, bringing about considerable econ- not "transmit" or "re -radiate." The itself, will appeal to the radio fan who omy in tubes, coupled with greatly in- second was to increase the range, volume, is continually annoyed by squeals and creased sensitivity and selectivity. clearness and selectivity of four -tube catcalls from neighboring receivers as When radio -phone broadcasting swept receivers. one of extreme importance. over the country, regenerative receivers Both of these objectives have been The average fan may ask why is re- fairly "rained down upon the listen- obtained. By a series of engineering generation necessary. The discovery of ing public." Unfortunately, insufficient

A Delight to the Eye, as Well as to the Ear 10 RADIO PROGRESS APRIL 1, 1924 through the conventional beat or whistle 3*. method without the necessary hunting 28 for the stations. Once this carrier is located, all that is necessary to bring in distance signals is to tune the antenna control until the signal or beat is loudest. The regenera- tive control may be turned back slightly if necessary and the signals left clear and loud. The set therefore has only two major controls, comprising the secret of easy and simple tuning. The Teledyne also uses a four and one- half volt "C" battery, which is intended to give "B" battery economy along with zg C2o x 24-.,(D. x.3¿f ' or t7JQM/CA OR 8/il(EL/TE TUd/N(, /¡17dfA,G loud speaker volume. Materials Needed Fß.1. The following 'list of materials should Primary Coil is Wound on This Tube be followed as closely as possible, and thought and foresight were used in the frequency, the circuit being so developed where any alterations or substitutions beginning, and the radio fan was pre- as to be very selective and give coast to are necessary, equally as good parts sented with what has turned out to be coast loud speaker volume under good must be secured. the curse of the ether-the single circuit conditions. Primary Coil Tube regenerative receiver. It was this type There is just sufficient regeneration One Bakelite tube two and seven - of receiver with its many drawbacks intended in the antenna circuit to mini- eighths outside diameter, one -sixteenth that brought regeneration into such dis- mize to a marked extent ill -constructed inch wall and three and one-half inch repute. antennae. The minimizing of antenna long. Preventing a "Spill" resistance aids volume and selectivity. Secondary Coil Tube It was not regeneration, however, The tuned radio frequency stage One Bakelite tube four inch outside which was at fault, but, rather, the way is coupled in a peculiar manner to diameter, one -sixteenth inch wall and in which it was used. It is a force, a the grid of the detector, which, with both two and one -eighth inch long. very potent force, which, when intelli- tuning and regeneration, gives enormous gently utilized, opens up infinite pos- amplification with greater selectivity. Regeneration Coil Tube sibilities in the field of broadcast Under ordinary conditions the radio fre- One Bakelite tube three and one-fqurth reception. The problem in regener- quency stage amplifies the very weak in- inch outside diameter, one -sixteenth inch ating radio frequency amplifiers is coming signals nearly 10 times. This wall and three -fourths inch long. the tendency to spill over into amplified oscillation is then impressed Four UV 190 tube sockets. These oscillation. Neutrodyning prevents the upon the grid of the detector, where, should preferably have shock absorbers. tubes from oscillating, but with a through means of controlled regeneration One Du'billier grid condenser, type 801, sacrifice in sensitivity, for iit also pre- it is again amplified as much as one G capacity, .00025 mfd. vents the tubes from regenerating. hundred times. One phone condenser, capacity .002 The problem of utilizing regeneration Whistles Don't Disturb Neighbors mfd. with its unquestionable advantages with- Two by-pass condenser, capacity .1 The amplification out danger of self -oscillation was solved in the detector cir- mid. cuit is a material aid to ease in tuning. by Bowden Washington by taking the One spool No. 26 double silk covered principle The detector èircuit can be made to os- that when a resonant circuit, magnet wire, 1,/4 lb. cillate without antenna "re -radiation" consisting of an inductance and capacity One variable condenser capacity (11 in parallel, is placed in series with the and therefore pick up distance carriers plate). plate circuit of a vacuum tube, the grid 1p5TuRti,- IND N6 TO GENTRALY LO(ATE, circuit of which is also resonated to 5 r iw0 4n.w. on romE the same frequency, the resonant plate circuit will produce oscillations, and just of ^ off this resonant point, negative resist- OrC STRIP woe nWBr ance or regeneration. The research race rNeq 6 Sat OM ] GLOSi ro !OM SOYBR finally was simplified down to the point W(rN 11L.5P44NCTr/ where the coupling was made at a certain START critical value, thus oscilla- COIL preventing //ERE tion. LEA o our ON INSIDE UF ruBE J/ FU. 2. The Teledyne comprises four tubes, LEAD OI/T WIRES 6 TAP namely, LEAO OOr wate ON tuned radio frequency, regenera- 00T310E aP rum ro ßE 6- coryc tive detector and two stages of audio 026 BE.S. GA. 4REEN Li.5.0 CopPER WiRE APßIL 1, 1924 RADIO PROGRESS 11

FIRST TORY TUBE DYER _+L ' turns. Loop the wire at this turn and iNSUUT/Mi T/RSTTORN OTLOIID'.N COl3Z 5TR,P1 take off a tap, leaving about six inches for connecting to the switch point. Con- tinue in the same direction until 40 more turns are wound on. Anchor this as indicated, leaving as before about six inches for connecting. A diluted solu- . I 1 ! r tion of collodion, procurable at a drug store, may then be used to coat the wiring so that there will .be no pos- sibility of the wire coming loose or sliding off the coil.

Secondary Coil FREE ENO 2- 3 -WIRE WOuNO RIGHT RANO Fig. No. shows a complete sketch WIRES To BE COATED W IpB COLLODION 11G. 3 of a Teledyne Secondary. There are two windings on this coil, the lower one One variable Vernier condenser (11 Painstaking care in assembling is being the detector grid coil, or the plate). a most important thing in building -a secondary, while the small four turn coil Two All-American amplifying trans- Teledyne for results. The winding of wound over this is the plate delivery coil The formers, high impedance, ratio 5 to 1, or the coils is probably the most difficult of the radio frequency tube. latter equivalent. operation of the process, but even that is especially critical and should be as in Two Carter switching rheostats, resist- should not be alarming if instructions wound and placed exactly the these two coils is ance 30 ohms. are followed carefully. drawing. 'Separating One plain rheostat, resistance 20 The following formula is intended to a thin piece of bakelite or impregnated ohms. take the builder through the work, step cardboard. If the latter is used, it then One two spring jack. by step, in proper order of assembly and should be thoroughly dried and impregnated in a diluted solution of col- One Bakelite panel, approximately 3 wiring. If it is followed closely, the lodion. This prevents absorption of by 18 inches (depending on space avail- work is simplified considerably. able). moisture and assures better operating The should not be One shield plate slightly smaller than Primary Coil conditions. strip inch panel or at least large enough to cover As accurately as possible, lay out the more than a thirty-second of an the condensers and coils. The trans- location of the holes for the beginning thick and about / 'inch wide. A strip formers and rheostats need not be and end of the primary winding as per 123/4 inches long will just go around the winding. shielded. Fig. No. 1. A No. 55 drill is commonly secondary coil over the other Five or more dials, depending on used to drill these holes, but other sizes Lay out the holes for the secondary whether or not separate Verniers are are permissible, depending on what is tube according to Fig. No. 4. The three be used. handy. Too large a hole is not to be holes marked 13/64 inch drill may recommended, however. Referring to Fig. omitted if the circular bracket as found One switch contact arm of conven- 2, 10-5 the 26 double silk in the Cutting & Washington set is not tional design with two switch contact No. turns of No. covered wire are to be wound on this used. A different form of mounting will points. coil. Starting at the left end of the of course require a different bracket ifor coils Miscellaneous brackets the coil, as in Fig. No. 2, and turning the and hence different -holes. To those who and tube sockets, transformers, etc., and coil in the direction indicated by the have not had experience in reading blue- for regeneration coil a suitable shaft the arrow, wind on, aIs close as possible, 65 prints, Fig. No. 3 will probably suffice. will be left to the builder's discretion. They may be of anything, preferably zir -- brass or bronze, and may be shaped to suit the particular style of layout that the builder contemplates. Either hard or soft wire may be used for connecting the various units. Eleven binding posts will be required, one each for the Antenna, Ground, Nega- tive A, Positive A, Negative B, Detector B Positive, Amplifier B Positive, Nega- tive C, Positive C, and two for the horn. If flexible leads are used, as in the Cutting & Washington Teledyne, all but the first and last two may be discarded, and soldering lugs used in their place FiG. 4. to which the flexible leads are soldered. q'o.s.or LN ALL 9LACH aAKELITETueu 12 RADIO PROGRESS APRIL 1, 1924 The anchor holes may be drilled ap- proximately correct or as near as can 11G.5. be judged. The only holes Which must be at all accurate are the two holes through which the regeneration coil shafts run. These, of course, should be quite ac- curate, otherwise the dials will prob- ably wobble when attached to the shaft. Winding is Important Winding the secondary is next. Start at the left at Fig. No. 3. Wind in the direction shown in the drawing and continue until 45 turns of the No. 26 double silk covered wire are closely wound. Anchor as before, leaving sev- eral inches for connecting. Coat the coil 34OS.DIAli WALL BLACK with collodion as was the primary. Pro- 6 BAKELIrI;TUBTL cure the bakelite or cardboard strip. The two No. 17 holes are for the shaft. remembered is that the regeneration coil Fasten close to the right-hand end of Fig. No. 6 will show the method of must be swung inside the secondary coil secondary coil with collodion or a rub- winding. The same size wire is used at the end opposite to the one carrying ber band. This is illustrated in the as on the other three coils. Care should the plate delivery coil of the radio fre- sketch. Once the wire is wound in place be exercised here as before to see that quency tube. The assembly of this com- over this strip, it will hold itself. In the windings are close together and plete assembly in turn will depend upon the meantime, if the rubber band or properly placed. It likewise should he the particular style of panel layout that collodion is not sufficient to hold the coated with collodion and allowed to dry the builder is using. strip, a drop Of glue may be used before handling. on Panel Layout the ends. As shown in the drawing, this With the aid of a few shafts and bolts delivery coil, as 'it is called, is com- the secondary and regeneration coils While the assembly and panel layout prised of four turns of the same size may be assembled somewhat as in Fig. of the Teledyne will depend upon the wire as used before. Tt is wound in the No. 7. The inside of the regeneration particular kind and quantity of appara- same direction and very carefully placed coil should be that side having the wind- tus on hand, still there are certain so that the last turn of the delivery coil ing on it. If this is true and all the fundamental principles which must be is over the last turn of the secondary winding directions are as given in the borne in mind while this work is going winding. This is quite important. To prints, the rear connection or that one on. A general idea of this can be gained aid in holding the wire small pieces of marked "P" will go to the plate of the by glancing at the accompanying photo- graph of the Cutting & cloth tape -nut t. be inserted under the detector tube, while the remaining one Washington windings, the ends of the coils slipped or that one marked "B" will go to the Teledyne. Here you will note that the through the loops and the loops pulled outside winding of the audio transformer primary condenser is mounted at the left tight. The coil is then coated with col- primary and thence to the detector "B" with the primary coil fastened directly lodion as before and allowed to dry. battery. The experimenter will undoubt- to it. The coil is exactly vertical. This edly have many ideas as how to assem- is important. To the right of this Is Regeneration Coil ble the regeneration and secondary coils the secondary and regeneration coil as- Reference to Fig. No. 5 will show how so that part will be left entirely to the sembly with the regeneration dial work- the coil is to be prepared before winding. builder's discretion. All that must be ing to the regeneration coil by means of a train of gears. The radio frequency START WINPING tube socket is mounted directly between these coils. This makes short and direct leads possible. To the right of the sec- ondary regeneration coil assembly is mounted the secondary tuning 11 plate condenser. The vernier in this case is separate and actuated by a separate con- trol to the right of the main control. This is not essential, as any type of vernier condenser is suitable. \ i Use Shock Absorber D.15122 In the rear on a. special shook absorber mount are placed the grid condenser and ®-- D7720\ leak to the left, while the detector and FREE ENDZ° .q3xj6 RN.BPI.SCR\[- DLT two audio frequency amplifier tube WIREE TO BECOATE0 WITH DILUTED SOLUTION OF COLLODION sockets are to the right. A patented APRIL 1, 1924 RADIO PROGRESS 13 switching condenser used in place of the primary condenser make the ordinary iD-i H 1E END OF T/CKLER use of a switch lever and points un- necessary. These are not procurable on the 'market, so it, becomes necessary to use the switch lever and points instead. Lt These should be mounted at the left of the panel so as to make short leads from the primary coil possible. The rheostats may conveniently be mounted to the right, since this is the audio side. Like- wise might be advisable to mount the it aM-sCR.LnK. P1.Tuj *1-31 x4 RN audio frequency amplifying transformers to the right close to the tube sockets. This also makes for short leads. The mounting of the separate units is also left to the builder's ideas. It may be well to use a base board to which the front panel can be mounted so as to mounted more allow the units. to be -+ B-END oF conveniently. For instance, the primary TICKLER coil can be mounted directly on the pri- mary condenser. The radio frequency tube socket can then be mounted on the short leads base alongside of it, making Be Very Careful Not to Get These Wires Crossed, or It Will Reverse possible. The secondary regeneration Their Polarity coil assembly next to this either to the base or to the panel, but at right angles to it and with the center line of the CALIBRATING YOUR WAVE completed a long series of experiments to primary winding exactly on a line with METER see which broadcasting stations do hold fixed value. So far they have certi- the center of the secondary. This is Many amateurs have bought or built to a fied only, KDKA Bast Pittsburg important. In other words, the two coils wave meters which work very satisfac- two at The former should be exactly in line both ways, but torily in general, but which are not cali- and WGY at Schenectady. find, holds to 326 meters at right angles to each other. The brated to read accurately in wave length. station, they with an error of less than one meter up secondary variable condenser can then be One way of overcoming this defect is to or down; the latter has a wave length mounted to the right of this assembly send the wave meter to the Bureau of of 379 with a variance of not with both the amplifying transformers Standards in Washington. There they meters more than one meter up or down. You and tube sockets near by. The jack is will mark the dial for you, and of course will notice in the newspapers this sta- conveniently mounted at the extreme such data as they give will be absolutely tion is called 380 meters. Work is still right of the panel. correct and accurate. But this entails proceeding at the bureau to check other A word of caution here. Care should some time and expense. popular broadcasting stations, and when be taken when arranging the apparatus Another way of checking the wave they find the wave lengths hold to a fixed to see that all connecting wires will be meter is to murk on it the wave length value over a long period of months, they as short as possible and at the same of the various stations you hear, looking will make further announcements of time not come too close to one another. up their figures in meters on page 31 such stations. This applies especially to the radio fre- in this issue of RADIO PROGRESS, but quency' leads. When the binding posts here we run into a difficulty. Notice and other odds and ends are connected how many stations are scheduled for 360 YOU LIKE TO BE and assembled, the set is ready for wir- meters, and you know by experience that HOW WOULD ing, as shown in the next issue. they do not all come in at the same place THE MAIL MAN? on your dials. The reason is that any If you get several letters a day per- station which is nearly 360 meters is haps you think you have a heavy mail. AS TO THAT PRIZE CONTEST written down at that exact figure, so the How would you like to be a big broad- We are getting in some very choice real value of the wave length may 'be casting station and get more than stories of the marvelous operations of 355 or 365 meters, and still it is called 170,000 letters inside of a couple of various sets and other kinds of radio 360 meters. A further reason is that weeks? This is the mail one big broad- equipment. The contest closes April 5, most stations are so inaccurately oper- casting station received recently. Among so hurry in your own story or prize lie. ated that the wave length will often these letters were applause cards for the To the one sending the largest lie or fluctuate as much as three or four various performers, requests for favorite the strongest story will be awarded a meters up or down. numbers to be played again, and last, year's subscription to Racro PROGRESS, To overcome this trouble the Bureau but not least, a good many "mash" notes as announced in the last issue. of Standards at Washington has recently for the announcer and his company. 14 RADIO PROGRESS APRIL 1, 1924

RADIO AND PHONOGRAPH GET TOGETHER AN announcement of importance to both the public and the radio. and phonograph industry was made by David Sarnoff, Vice -President and General Manager of the Radio Corporation of America, recently as follows: "Through an agreement just signed between the Radio Corporation of Amer- ica and the Brunswick-Balke-Collender Company, phonograph manufacturers, millions of radio fans throughout the United States will receive for the first time operatic and musical programs rendered by famous artists whose ser- vices hitherto- have not been available to the broadcasting companies. "Although sporadic attempts have been made to combine radio and the phonograph, the announcement made to- day by the Radio Corporation of Amer- ica of a contract which not only will effect a marked improvement in future broadcasting programs, 'but which in- volves the sale of combined Radiola- Brunswick phonographs, is accepted as the first definite indication that large interests in the phonograph industry have now determined to combine the best features of radio and the phonograph in a single instrument. "Under the contract recently. con- cluded the phonograph company gains the right to install Radiola receiving sets in combination with Brunswick phonographs. In turn, the phonograph -Underwood & Underwood company will add its share to the public This Clock is Standard of the World. service now rendered by the principal broadcasting stations and aid the de- In the picture above you see the stand- will be broadcast over the whole Brit- velopment of free broadcasting to the ard clock of the world. This clock is so ish Isles and will be relayed by various public, by permitting the stations of the accurate that the sunrise and sunset is local stations, so that anyone with a Radio Corporation of America and those timed by it. A year ago the moon arose crystal set within range can set his of its manufacturing associates to broad- two minutes too soon and they had to watch accurately. This will cause a lot cast from the laboratories of the Bruns- hold it back until the clock caught up. of hardship to the fellows whose excuse wick Company during the periods when This clock is located at the Royal for being late is "my watch was slow." its artists are recording for phonograph Observatory, Greenwich, England. On reproduction, and to encourage these your maps you have no doubt noticed artists to aid the programs at other that all longitude is reckoned from the HONDURAS NOT BEHIND THE times as well. meridian at Greenwich, so much east or TIMES west longitude. The zero line is the One of the largest radio commercial "The areas that will benefit particu- meridian which runs ithru this observa- stations using vacuum tubes for trans- larly by this new arrangement are those tory and is known the whole world mission has been started at Tegucigalpa, served by the broadcasting stations of over as the place where time starts. The Honduras. This broadcaster is using a 20 the Radio Corporation of America, the Astronomer Royal of Great Britain has kilowatt power tube. The station is one General Electric Company and the West- arranged with the British Broadcasting of several of a similar nature which are inghouse Electric and Manufacturing Company, so that in the future this clock being installed all through Central Company, in New York, Washington, will keep time for the British Isles the America by the United Fruit Company. Chicago, Hastings, Neb., Springfield, same way that NAA (Arlington) does You see, they are taking care never to Mass., Schenectady, N. Y., Pittsburg, for the United States. The time signals run out of bananas again. Pa., and Oakland, Cal. What Happens When You Oscillate Maybe Your Set Has Been Doing It All This Time and You Didn't Know It By Vance

IN the last issue of RADIO PROGRESS it profanity among the neighbors than any ful than this, violent oscillations will was promised that a discussion would other part of radio. be continued indefinitely. be given of the term "oscillation." Some Your vacuum tube is just like a pistol. people mistake this word for "oscula- Like an Automatic Pistol The grid circuit is the trigger. That is, tion." The difference between the two To understand the operation of the the input to the tube is always con- is that the latter causes a vibration to feedback, suppose we have an old pistol. nected to the grid, as it is the point of run up and down the spine, while with The trigger is very stiff and rusty, and control. The plate circuit is the muzzle, the former the vibration is confined to it requires a pull of ten pounds in order as it is the output of the tube. Here is the wires. to make the gun shoot. As this is too where the telephones are always con- When anything oscillates it vibrates stiff for comfort when shooting a series nected, and, as in the case of a revolver, back and forth quite rapidly; thus of rounds at a target, we devise a way a small amount of energy applied to the musicians speak about the sound from of making the recoil of the gun- help grid (trigger) causes a large amount of a violin causing oscillations in the air. pull the trigger the next time. Perhaps energy to come out of the plate (muz- As a matter of fact, it is the oscillation we rig it up so that as the gun kicks zle) . The way you connect the muzzle of the particles of air which conveys on the first shot, that kick gives a, pull to the trigger is through the feedback the tone from the violin to our ears. of five pounds on the trigger. All we or tickler. In the most popular form of Suppose, for instance, we have an alarm shall have to do is to pull five pounds hook-up the tickler is a coil connected clock. When the alarm goes off our more to make it go off again, and we in the plate circuit between the tube and ears are strongly affected, as we all know have a feedback of 50 per cent. in this the telephone. This coil is placed close at seven o'clock every morning. But case. But perhaps this is still too stiff to another coil which is connected to suppose this same alarm clock is put in for easy operation, so we increase the the grid (trigger). ,So you see that a glass case and connected to an ex- coupling between the trigger of the pis- when the energy shoots out of the plate haust pump. While the alarm is ring- tol and the recoil cawed by the explosion it goes through the plate coil or tickler ing, set the exhaust pump going so that so that it kicks back on the trigger with and affects the grid coil, so feeding back it will suck the air out of the glass case a force of nine pounds. Now a one part of its energy to start the action all and leave a vacuum. As the pressure of pound pull of our finger on the trigger over again. . When you turn the tickler air keeps falling we note that the sound will ;be sufficient to fire the next shot. it merely rotates the plate coil so that of ringing gets fainter and fainter, and This, then, is a 90 per cent. feedback. it is farther away from the grid coil or in a short time we do not hear the alarm If we increase the coupling to the trigger else points it another direction, so that at all, although we can see the hammer again and let the recoil pull with a its action on the grid coil is greatly buzzing back and forth against the bell pressure of 9.9 pounds, we shall have to reduced. one -tenth of a as we look through the glass. Here we exert a force of only Something for Nothing have a case of the vibration being sup- pound to make up the 10 pounds on the Of course, something for nothing can pressed because no air is left to vibrate. trigger, so here we have a feedback of be had only in buying oil stock, so in 99 per cent. This, you see, would be a present instance we must look for a Electrical Oscillations Similar rather desirable adjustment if we wish the source of power. When you shoot off a When electricity vibrates back and to make the operation of the pistol easy. forth in a wire we call it oscillation, just pistol this source is the gunpowder is of the exactly as we did in the case of the air. Making it Automatic which explodes, and it part which is fed Any piece of apparatus which makes Now let us go one step farther. Let energy of this gunpowder the trigger the electricity vibrate is termed an oscilla- the recoil be connected tight enough to back to help you pull the tor. The most usual form of oscillator the trigger so that it supplies an even next time. In your tube set source is a dectector tube in a regenerative cir- 10 -pound pressure. In such a case you of energy is the "B" battery. Sometimes cuit when improperly adjusted. It is can see that once you start the pistol this is called the phone battery because these oscillations which cause the squeal- operating it will pull its own trigger the current operating the phones comes takes 10 ing which so often comes in over the and continue to fire shots as long as the from it. Assume, then, that it of air during the evening. The trouble is ammunition lasts. We have then a full - millivolts (a millivolt is the unit elec- of that the regeneration is turned on too automatic pistol. It is just at this point trical pressure) to operate the grid much; Another name for this regenera- that the gun begins to operate auto- your detector. If you have 'the tickler tion is feedback, or tickler. No one matically, the trigger going back and adjusted so the electricity coming from knows why it was ever called a tickler, forth continuously once it gets started; the plate feeds ;back five millivolts to the for no one is ever tickled with it. On and if the coupling between the muzzle grid, then your signal strength must be the contrary, it is claimed it causes more and the trigger is made any more power- five millivolts to be heard. If you in- 16 RADIO PROGRESS APRIL 1, 1924 crease the feedback to give nine milli- oscillate, just as the pistol oscillated want it to. The same thing applies to volts, then you can hear a signal which when we fed 10 pounds or more back to the detector. Id we increase the feedback ¡miles in with the strength of only one the trigger. And once it starts oscillat- to a point where the tube oscillates millivolt. And if, as before, we feed- ing it will continue to do so until it (squeals) and then turn it down one or back 9.9 millivolts, your signal has to runs out of ammunition ("B" battery two divisions until the squeal just dis- have only one -tenth of a millivolt voltage) . These oscillations are revealed appears, we shall have a similar condi- strength to operate your telephone. Per- to us by the squeals which are heard in tion, namely, the tickler doing most of haps you have never had the pleasure the telephone. the work, but leaving just enough for of shaking hands with a millivolt, but The next question is how to stop it. the broadcasting waves to do, so that you realize that it is a unit of measur- Getting back to our pistol, the obviouz they, and not the tickler, will eperite ing electrical pressure on your grid just way of stopping its continuous operation the set. By this adjustment you will as a pound is a unit of measuring is to reduce the connection between the not only stop squealing in your neigh- medhanical pressure on the trigger of muzzle and the trigger. The most de- bor's radio, but you will also get the your pistol. sirable amount of connection is naturally most sensitive point of adjustment for Now the Tube Oscillates around 99 per cent. or so; enough feed- your own reception. You will see that if we increase our back so that the recoil from the muzzle In the next issue of RADIO PROGRESS feedback once again so that 10 or more will do practically all the work, but will will be discussed the real meaning of the

. millivolts are fed to the grid from the leave just enough for our finger so that inductance of a coil and the capacity of plate, we will immediately make the tube the gun will not go off except when we a condenser.

A Lifetime in a Second ANY radio expert will tell you how fast radio waves travel; that they go seven times around the earth be- tween two ticks of a clock. The cor- responding time taken to travel any moderate distance is, of course, very small indeed, and so the listener -in is familiar with the idea of a very short length of time, but it has remained for Mr. J. F. Peters to go to the limit. Mr. J. F. Peters is an electrical engineer at the Westinghouse Electric Company at East Pittsburg. He has invented a form of camera called a klydonograph, which is able to take a picture of an electrical discharge which lasts for 2/100,000,000 of a second. To get an idea of how small a time this is just notice that the relation of this instant to a minute is about the same as the relation of one second to a lifetime of sixty years. Pictures in the Dark This instrument itself is shown in the photograph. It consists in general of a specially designed camera holding a sensitive photographic plate. Above this are located aseries of surge receivers. These receivers are so spaced that they conduct the electric disturbance to be photographed down into intimate con- tact with the sensitized plate. The klydonograph is connected to the cir- cuit to be tested through the medium of a condenser or else a transformer coil depending on the type of test desired. One peculiar thing about the operation is that no flash of light is visible at all, although tlhe photographic plate is affected. This means either that the Fig. 1. Westinghouse Engineer Takes Pictures in the Dark APRIL 1, 1924 RADIO PROGRESS 1.7

Fig. 2. Pictures Showing How Lightning Arrestors Work impluses have some peculiar form of trie lights alive during the thunder but every coil has wine condenser action wave motion which will affect a plate, storms which occur in summer time. as well. This is undesirable. This con- or, what seems more likely, the human Another important use for an arrestor denser action is caused by the various eye is too slow acting to catch such is to protect your aerial. The fire in- turns of wire, which are separated by lay- infinitesimal flash. surance underwriters require that every ers of insulator. Look at the variable outside aerial be so protected. It is by condenser in your set and you will notice Like Snowflakes testing out the effects of strokes of that it consists of a lot of pieces of The photographs which are obtained lightning on an instrument like this that metal separated by an insulator, in this by this method resemble snowflakes in the design of arrestors is improved from case air. Now the same effect which the multitude of beautiful shapes. But time to time. As a matter of fact, so you get in your variable condenser, there is this difference. Whereas snow- efficient is modern lightning protection namely, that of metal pieces with insu- flakes vary in their shapes, the picture that it is reported that during the last lator between them, obtains in the coil, which Mr. Peters shows de- obtains a two years not a single case is on record and that is why we get what is called cided tendency to fall into definite in the city of New York where any distributed capacity. groups. In the illustration for instance, house so protetced has been damaged we see three is Now to get back to our varnish. It is different sets. One style -by lightning in any way. that displayed by alternating currents, found by experiment that if you have a condenser and have varnish for the in- while the other two show the picture of VARNISH YOUR SET, BUT NOT direct current flashes, positive sulator between the plates instead of air and nega- YOUR COILS tive. The intensity of the pho1'ograph that the capacity measure of the con- We all know that a nice coat of var- is a pretty good indication of the in- denser is several times as great as it was nish improves the appearance of your tensity of the causing with air. So, you see, when you varnish voltage the flash. do realize that radio very much, but you your coils you are filling the little air Helps Protect Your Set when painted on your It the same varnish, spaces up with varnish and so increasing set? To under- Although this invention was intended coils is a detriment to the the distributed capacity by several times. principally to be used in testing trans- stand why such is the case you must mission lines, it is of considerable in- consider what goes on in the coil. As If you want to use something that terest to the radio fan. By means of you are doubtless aware, a coil of wire, will hold the wire in place, then a solu- the data obtained it is possible to im- whether in the form of a honeycomb or tion of collodion is about as good as prove the existing form of lightning spider web winding, is intended to slow anything. Even this is not as good as arrestors tò a great degree. Arrestors down the speed of vibration of the radio leaving the coils unimpregnated and just are used on all transmission lines and waves; that is, the bigger the coil the fastening down the ends of the wires are very necessary to keep your elec- slower the set will vibrate or oscillate; with a little sealing wax. What Will Broadcasting Be in 1925 ? Many Present Stations Will be Closed, but the President Will Talk to the Whole Nation

ALL indications point to the gradual over which the music goes from New which your set picks up quite easily, elimination of small stations. York is specially selected for its freedom in the ordinary way. When you listen in on the air tonight from noise and its clear transmitting This system of primary transmission and have difficulty in separating station powers. However, there are two objec- at high frequency and secondary trans- PllQ from station XYZ you are likely tions to the system. In the first place, mission at ordinary frequency (or wave to broadcast a few choice remarks your- it is quite expensive to lease a long dis- length) has the very great advantage self to your listening friends. You very tance telephone line and hold it out of in that a single pick-up station can send likely consign one of the stations to a service so long, and in the second place, its program all over the United States place where the wires would melt, and such a relaying scheme is rather limited and into Canada and Mexico, and even you are probably quite right, as there in extent, as it is not practical to have to England. Such a system was tried are altogether too many broadcasting the toll line from the parent station to out for the first time in history, on stations in the United States at the the local station too long. March 7. On that evening the Tech- present time. nologyClub, composed of graduates of the Radio Radioing the Massachusetts Institute of Tech- Not Enough Talent The second possible method of relay- nology, held its annual dinner at the As a matter of fact there is not ing is the one which is being developed Waldorf Astoria in New York. Station enough good talent in the country to now by the Radio Corporation. It con- WJZ, the local broadcaster of the keep all the stations supplied with pro- sists in carrying the program from the American Telephone and Telegraph, grams which are good and interesting, parent broadcaster to the various local picked up the program and sent it by and the result is that a great deal of stations, not by a toll line but by special long distance to WGY at Schenectady. rather inferior entertainment goes on high frequency radio waves. This might WGY broadcasted it in two ways. The the air. If all this poor stuff could be be called radioing the radio. The actual ordinary way was at 380 meters, such as eliminated, and only the highest class method of operation is like this. Some they do regularly with all their pro- entertainers be supplied to your favorite one station, located at a strategic point, grams, and if you were listening at that broadcasting station, wouldn't you think gets from the best talent in the country wave length that night you heard it was a tremendous improvement. But a performance of unusual interest. This the whole performance, but in addition the question is, How can it be done? program is not put on the air as or- to that, a second sending apparatus was With their customary foresight the dinary radio waves of 250 meters to 550 putting the same program on the air Radio Corporation of America has in meters, such as you receive on your own through the ultra short waves. In the the past year been attempting to solve radio set. The waves used are the ex- meantime KDKA at East Pittsburg had this very problem. Their attitude is tremely high frequency oscillations of set their ultra short receiving apparatus that if a few high powered stations three to four hundred million per sec- to pick up Schenectady, and had con- throughout the country could send out ond with a wave length less than 100 nected it with their transmitting station programs to a host of smaller sending meters long. Such waves make no im- at 326 meters, and sothey were putting stations, then they could easily afford pression at all on your radio, but do the same program on the air at the to serve you with the best talent in the have the very unusual tendency of going same time on their usual wave length. country, and you would be able to re- through static without being materially In addition to the 326 meter wave, an- ceive with an ordinary set instead of affected. Furthermore, they are not dis- other sending instrument was radiating trying to use a super-radio-hetro-neutro- turbed at all by interference from other high frequency waves at a speed of over dynamo-dyne set with 71/8 tubes in it. stations nor from code stuff. three million a second to stations KFKX are two ways of sending out at Hastings, Nebraska, 2AC There What Can You Do with Three Hun- and Station might be called a parent at wave from what dred Million Vibrations? Manchester, England. The exact broadcasting station. One is to relay length for this connecting link was 94 the programs by long distance telephone. What can you do to hear this high meters, whereas the first jump to East on your radio? The answer Then local stations broadcast this ma- frequency Pittsburg was at 100 meters. This is you can not do anything, but a broad- terial received over the phone. Such a slight change was desirable so that the casting station near you with special system is in regular operation at Station two sending stations would not interfere York. This studio sends receiving equipment can get these vibra- WEAF New with each other. A similar thing hap- Roxy programs every Sunday eve- tions just as plainly as if the perform- out pened at the Westinghouse station ning to Station WCAP in Washington ers were singing into their own micro- KFKX at Hastinge, Nebraska, and and WJAR in Providence. On the whole, phones. This special receiving appara- Hastings sent it on in the same manner such a method of relaying is very satis- tus in turn transfers the music to an factory. The reception is surprisingly ordinary broadcasting transmitter and to the new California station of the good as the long distance telephone line so goes out on the air as regular radio General Electric KGO, at Oakland. APRIL 1, 1924 RADIO PROGRESS . 19

04 c 3 ° l- -- ...... r .00- ---f G Y : > sc W.J.Z. AIÑ=sMse r.EwYORK .. wtat,' ?A .0 Y:h Y -yy.... ( 'Pf1Ket1ìG11 ' a»- rrM,,C V.,ß0 . >Ç ,57/Y/EJ ÿ_,q .._,'i;-.11111111.

This is the Road Map the Radio Waves Used

All Going at Once out through the air. For these reasons come in from the nearest secondary Here then were six stations all going it was thought advisable to use a toll sending station. at once, tied together by these new ultra line to Schenectady and use this pow- Such a system is not necessarily far short waves on the primary side, and erful General Electric Company sending in the future. The technical develop- yet each sending out its characteristic station as the parent broadcasting sta- ment is practically finished on it already wave length or tone to the listening pub- tion in the series. as proved by this first successful test by lic who tuned in to their usual meter Looking Forward to Future Years the Radio Corporation of America. wave length. For instance, in the East- It does not seem hard to look for- ern part of the United States, with a ward to the time when most of the small CENSORING BEDTIME STORIES reasonably good set, it was possible to one-horse sending stations in the United Big broadcasting stations get some queer mail, get the same speech at the same instant States will be suppressed, and a few and some requests written in first in exactly the same tone of voice from powerful broadcasting stations will be that at sight seem to be rather fool- three or possibly four different stations located at strategic points throughout ish. Here is a comment from a "listener - merely by turning the tuning knobs on America, say one every few hun- in" which is unusual, but seems reason- your set. If static or code happened to dred miles. The stations could all able when explained. interfere with the reception at one 'fre- receive relayed programs coming from This letter was written by Mr. F. J. quency, all you had to do was to switch some one or a few points in the United Lee of Lee Valley, Canada, and addressed the dials and the speaker kept right on States. Furthermore, each station could to the General ElectricStation, WGY, talking from a different State hundreds send out several programs at the same Schenectady. Lee Valley is in New On- of miles away. time at different frequencies, just as tario, Canada, and is a very wild coun- try. Big game abounds and A Howling Success WJZ and WJY are now doing in bears are quite plentiful. Not the tame kind you Perhaps we should not say "howling" New York. These two stations, as you see in a zoo, but the wild and woolly in this connection, as no "howls" were no doubt know, are in the same build- variety which thinks nothing of eating to be heard at all, only a clear, smooth ing and are really the same station, but a child or even a man when hungry reproduction d: the various speakers in give two simultaneous programs at en- enough. their natural tone of voice. But it cer- tirely different wave lengths.. The way "I want to file a protest," writes Mr. tainly was a wonderful success. During it would work out would be something Lee, "against the bedtime stories for the the evening congratulatory telegrams like this. There might be, say, half a children about bears eating up little were read from people all over the dozen programs going on at the same boys or wanting to. Remember, that United States, and two from England, time which could be heard 'anywhere in stuff goes to this new country where where the local British Westinghouse the United States by a set costing not there are bears. There are few children Company was relaying the program to over ten to fifteen dollars. Such a scheme going to school who haven't seen a bear. the British Isles. would involve sending simultaneously, Boys eight or ten years old only laugh You will notice that the connection perhaps, the following: at such stuff here, but the little tots are between WJZ (New York) and WGY 1. Grand opera and classical operatic made afraid." (Schenectady) was made over a wire. music. So, you see, the director of a broad- The reason for using a wire for this con- 2. Light opera and musical comedies. casting station not only has to have a necting link is that there are so many 3. Jazz and dance music. good voice and a pleasing personality, local broadcasting stations in New 4. Sports and baselball news. but he also must have a good idea of the York, and also so many amateurs ex- 5. Readings, plays and dramatic re- parts of the country which his programs perimenting, that it was feared some citals. reach. slight interference might occur. A fur- 6. Political speeches and addresses of ther reason was the presence of such an eminent men. immense number of steel skyscraper The average radio set would need only EAR PHONES FREE structures in the vicinity of WJZ which some six or eight marks- on it, and by See offers on page 32 of this issue would have a considerable absorbing turning your dial to any one of these explaining how you may secure an effect on the high frequency waves sent labels, the corresponding program would Ear Phone or Transformer free. RADIO PROGRESS APRIL 1, 1924

UP IN THE AIR ABOUT RADIO You do not have to get in on the ground floor to understand about radio, as is proved by the picture of an experi- mental station built by two boys of Oak- land, Cal. They wanted to know how reception would differ on the ground from up in the air, and so first tried out their set in the 'bungalow shown at the bottom on the picture, then afterward raised it to the shanty up in the top of the tree. Here they are twenty-three feet above ground level. Although this is a novel scheme and certainly is good advertising for the set, still we do not recommend that you try it with your own radio. The reason is that the ground wire running up to your set will be so much longer than your aerial and the aerial itself will not be very high above the ground. This will cause some loss of efficiency. You will note that the picture shows a loud speaker mounted in the roof of the shanty. When some of the loud stations are going, they are able to receive jazz music on a loop and the volume from the horn is sufficiently loud so that they hold dances on the veranda of the bungalow below. The only objection is that when one has particularly enjoyed a dance with his best girl, it does no good to en- core the music, because, unfortunately, the broadcasters do not hear it and play no encores.

MIKE IN THE MICROPHONE Anyone who follows the fortunes of champion boxers (and what redllooded This Set Always Runs "In High" -Keystone View man does not) will realize that it is something big to knock out Mike Mc Tigue, the world's light heavyweight RADIO PROGRESS champion boxer, yet when he recently 8 Temple St. (P. 0. Box 728) visited the General Electric Broadcast- Providence, R. I. Date ing Station at Schenectady he was com- pletely floored. Mr. Hager, chief an- You may enter my subscription to RADIO PROGRESS nouncer at this station, recalls it as onr of the outstanding humorous events of r 1 year $3.00 year j 2 years the two years that the station has been $5.50 in existence. "He was scheduled to deliver a few ,Signature words on boxing," explained Mr. Hager. "Naturally he was the last man in the Send it to this address world that we expected would suffer a Paid by (PRINT) case of `microphone fright;' but he did. He stepped up to the pick-up device, but

Check 1 I he could not talk `I would rather face Cash !1 Dempsey than talk into that thing,' he said. The result was that his trainer, Money order who accompanied him to the studio, was compelled to read the written address." WHEN any new idea is sprung In this connection may we sug- which carelessly have dropped on an astonished world or gest that it would be well to order down to the broadcasting band. a new enterprise is launched, your copy of RADIO PROGRESS from These latter will be taken care of some people will send roses and your newsdealer in advance, or, shortly by the radio department others will heave rocks; As this better yet, send in a subscription, of the government. A movement second issue of RADIO PROGRESS as many newsstands ran out of is on foot for the first time to curb goes to press we are happy to tell the first issue a couple of days the trouble of such ship code inter- you that we have received a good after it appeared. ference. many roses and also some rocks. But how can we get rid of the As a sample of the former, here is HAM AND FAN troublesome "ham ?'" We disagree one of a number of letters re- with the majority of radio maga- ferring to the crystal set de- One of the mysteries of radia zines in thinking that we want to scribed on page 17 in our last which we cannot explain is this : get rid of him. So many people issue. With Mr. Walker's permis- Why is the listener to code called take the attitude that in the past sion, we reproduce it : a "ham" and the same chap when the code worker has aided a great RHODE ISLAND TEXTILE ASSOCIATION listening to music and broadcast- deal in the development of the Providence ing called a "fan?" Whatever the science of radio, and that for this GENTLEMEN: I built a crystal set reason may be, there is doubt that reason we should cater to him in after the idea. suggested in your first the two classes are not on the best the future, but this is a mistake. number using a spider web ooil with of terms with each other. The Amateurs who have so little en- of five eight taps and a switch instead "hams" are sore ' because the gineering ability that they are not taps and a clip. It took me about two "fans" have succeeded in pushing able to adjust their sets in accord- hours including the time necessary to through legislation requiring that ance with the law, certainly are wind the coil. they keep off the air with their not smart enough to help much I have built and operated about every code sending between the hours in developing a very technical kind of a radio receiver including a super of eight to ten -thirty every eve- science which is already advanced hetrodyne but this little hookup has ning, and the "fans" are disgusted to a position far beyond them. So them all skinned. I can put WJAR on because, in spite of this legisla- we advise you to find out Who it the loud speaker as well as WEAN and tion, some hardy spirits persist in is who is disturbing you with code by the addition of a .0005 variable in the sending out dots and dashes dur- during the broadcasting period, antenna eau tune very sharply. I use a ing these hours. Furthermore, either by reading his signature or Music Master loud speaker, so you see they do not hold their wave length getting some friend who knows there is no amplification added. I con- down to 200 meters and below as- the code to tell you. Then write sider that a rather remakable perform- required by law. As a result, we to the radio inspector of your dis- ance. I live in Providence albout a mile hear a rich tenor voice singing trict and ask that the offending in direct line from WJAR. "You Wonderful Girl, You Dah operator be required to adjust his Very truly yours, de dah dah-dah de dah." set correctly or else keep off the E. F. WALKER, Of course, the code interference air. It is only by concerted action Secretary, R. I. T. Assn. is caused very largely by amateurs of the radio listeners that this Several of the rocks came from whose sets are implroperly ad- nuisance can be eliminated. people who think that publishing justed. In the endeavor to get as a magazine twice a month is not much radiation as possible so as THE AIR DOES NOT BREAK. advisable. Some. recommend mak- to be heard at long distances, they As we approach the spring and ing it a weekly, while others pre- overload their apparatus and so summer seasons all the listeners - fer a monthly. What do you think destroy the sharp tuning neces- in who have had a year or more about it yourself ? We would ap- sary to keep the radiation at a experience will sigh regretfully at preciate a postal card from every short enough wave length so as the thought of all the trouble from one of our readers expressing an not to interfere with broadcast- static which may be in store for opinion as to how often such a ing. 'Some of the interference us. Thev then think regretfully magazine' as this should be pub- comes from ship stations supposed of the telephone and electricity lished. to be radiating at 600 meters, but which continue to operate smooth- 22 RADIO PROGRESS APRIL 1, 1924 ly day after day and wish that was possible in the middle of immense joy found that, while all static could be eliminated to bring March. And when we started to the other wires were broken, the radio into the same class. But call up the electric light company air was unbroken. Floods of beau- when you begin to think such dis- to report we could not see, we tiful melodies rolled in through mal thoughts, just remember what found the telephone wires were all the loud speaker and solaced our happened during this last severe down and we could not hear. On -soul. storm which affected a large part top of this the oil burner in the For the first time the realiza- of the whole United States. cellar, which is driven by electric tion struck home that, although When we looked out the window power, stopped working, the tem- radio has the disadvantage that at the results of the first day's perature in the living room it is affected by outside disturb- storm we said, "What, a blizzard dropped to zero (as measured by ances like static and interference, in the middle of March? Impos- the chills up and down our spine) it has the balancing advantage sible." But the next night when and we realized that we could not that it cannot be put out of busi- all the lights went out and refused feel. ness by snowstorms and blizzards to return by coaxing with new Under these dismal conditions severe enough to cripple all other fuses we decided that a blizzard we turned on our radio and to our kind of electrical utilities. Station H V ST signing off --Good night Lines for Lady Listeners Edited by Miss Opal A. Mowry,

Contributions for this department will be accepted if they are of special interest to women

Housewives Now Pick Hampshire, Connecticut, all parts of cast, but also some child from the broad- Their Menus from, Massachusetts and all outlying towns in casting station will speak, sing or tell Rhode Island. some interesting story. In this way the the Air. Many letters are received from in- children are quieted and then are nicely valids, shut-ins and a large number of prepared for sleep. This entertainment If Your Husband Gets Tired of children.. for the children every evening is on the Your Cooking, Here's Your Mrs. Wood usually 'broadcasts about air early enough for them to listen to all Chance to Get a New Line. four to five recipes each time, and all of it and yet retire at their usual hour. In one well known city where broad- An Interview with Mrs. Wood are pronounced a success. Some are from very fine cooks and housewives of casting is done the names and birthdays Mrs. Wood of Station WJAR, the of 35 years and more experience, who are all the children under a certain age Outlet Company, Providence, R. I., much interested. are kept account of, and on each one's broadcasts recipes every Monday, Wed- birthday a "Happy Birthday" is broad- nesday and Friday morning of each Bedtime Stories for the Kiddies cast to him, calling him by name and week, beginning at 10 a. m. and lasting Every mother would like to have her making some little remark about the for one hour. The talk consists of an child quiet and calmed down from the child which pleases the kiddies very introduction, recipe, then a poem or joke day's excitement as bedtime draws near, much. to end the talk. She established this thereby making it easy for her to get the Each one is always listening in on his to sleep; for if child is exchange of ideas and recipes for women child a excited it birthday (as well as other days) , anx- about one year ago. Since then, from is much harder for sleep to overtake iously wafting to hear just what the receiving two or three letters a day, it him than if he is ' not. The child is voice at the other end is going to say has grown to 80 and 90 letters per day. called in from play for supper, and then, about him. It is thrilling for the child It evidently has been a helpful source of course, is kept in for the rest of the to hear his own name called over the of knowledge to women folks, as they evening. He becomes restless and un- radio. all seem to be so enthusiastic about it. easy after a while, and usually starts Mrs. Wood also receives letters from playing some game or games which in gentlemen listeners occasionally, telling time become more or less exciting for Dumb Luck her of the new things that they have the youngster, making it very hard to Professor-What is ordinarily used as been given to eat, and at times they quiet him down when Mother thinks it's a conductor of electricity? seem to be interested in the introduc- time for bed. Radio in the home is a ,Student (all at sea)-Why-er- tory talk. great help to mothers, as bedtime stories Professor-Wire. Correct! Now tell On account of daytime broadcasting, are broadcast every evening for the me, what is the unit of electric power? the area covered is not so large as in the kiddies, and any child is willing to sit Student (still at sea) -The what, sir? evening; but she has heard from New quietly and listen to the stories. Some- Professor-Exactly, the watt. Very York State, all through Maine, Neu times not only bedtime stories are broad- good. That will do.-Pep. AI'ftIL 1, 1924 RADIO PROGRESS 23

DIALS ARE DYING Some of the sets coming through have a rather unusual operation. That is, they have no dials to be turned. This is quite' an innovation, and looks like a step in the right direction. Instead of a dial, the knob chrries a pointer which travels over a cardboard scale. When you first hear your favorite broad- casting station on this set, you imme- diately write its call letters on the card- board opposite the pointer, so the next time you want to tune to that station you swing the pointer to cover this call. This is done with all of the stations you hear. At the end of a few days you will find twenty or more calls recorded, and so when your friends come in and ask to listen to Station PDQ, instead of apologizing for the static, the condition of your battery and the size of your gridleak, you just turn your knob around to PDQ and immediately get a flood of glorious music. Of course, it is unnecessary to state that such a system cannot be used ex- cept on modern sets which require only one or two controls.

WHAT TO EAT BY RADIO Of all the good things to eat which havehave been reported to us as coming in over the radio, this one is the best: Radio Peanut Butter Fluff Two cups granulated sugar, 2 squares grated chocolate, 1/2 cup sweet milk. Boil slowly together until mixture makes a soft ball in cold water. Remove from fire and add 2 tablespoons butter, 2 tablespoons peanut butter, 2 table- spoons marshmallow cream, pinch salt; -Foto Topics flavor with vanilla. Pour into buttered This Village is Lighted by Radio pan, and cut when nearly cold. Mrs. M. W. S., of Providence, who con- WILL CITIES OF THE FUTURE High is experimenting with the sending tributes this, says if you cannot make a BE LIGHTED VIA RADIO? of waves of energy by radio frequency, success of this you're no cook. Can you imagine your future home and has succeeded in sending current a lighted and heated by Radio? This seems few feet lighting the lamps in the mini- NEWS BY EAR AND EYE almost out of the question but many ature houses, and even running tiny mo- 'Many' newspapers are coming to the things which have been thought of as tors. By using a small variométer, he conclusion that they can disseminate impossible have been done so that we al- can raise, lower, put on and off the va- news by the ear as we'll as by the eye. most believe that everything is possible rious lights at will, as each unit has a Up to the present time fifty-five differ- in this age of inventions. If this sys- fixed condenser attached acting as a ent newspapers in the United States tem can be actually carried out on a miniature receiving station, attuned to have installed broadcasting stations and small scale then there is no question a varying wave length. Mr. High hopes supplemented their printed pages with aibout it working on a large scale. How to develop the transmission of radio oral radiograms. The chief complaint strange it would seem to have your power, and sees in the future whole com- of their patrons seems to be that the house lighted and heated by energy which munities lighted, heated, and run by radio furnished no comic page. If you knew came from many miles away. radio energy generated by a central sta- "Spark Plug," 'Tolly" or "Mutt and This is an interesting photograph of tion perhaps hundreds of miles distant. Jeff" could be made to appear through the miniature "wireless city" of John Photo shows the radio village of John the air, then the newspapers would High, Jr., constructed in his laboratory High, Jr., his 1000 -watt transmitter be- probably he superseded 'immediately. at Station 2GR in Riverdale, N. Y. Mr. ing seen in the background. Behind the scenes at station WGY Do You Know How a Broadcasting Studio Works? You Will Know if You Read This An interviewrwith Mr. Kolin Hager

AM.1. people think that the chief as all Wallingford stories are. Not long the speaker, singer or player is ready requirement of a 'broadcasting an- after the play was broadcast the studio to start, the announcer takes his place, nouncer is to have a sweet and melodious received a visit from a. woman who ap- turns the small lever to the left and voice. (However, that is not nearly peared very much excited. makes his announcement. After doing enough. Brains of a high order are just "You have exposed my secret," she so he takes a final look over the room as essential, and, although you can not said. "I have been working for a con- to be sure that all is arranged and then hear them over the radio, you will real- siderable length of time on this proposi- moves the lever to the extreme right, ize their need when you see some of the tion, and just as I get it perfected I cutting out his microphone and cutting things the announcer has to take care of. hear you broadcasting it to the world, in the one in front of the artist. The Perhaps a better title for the article telling every one about it." concert is on. Not one sound-other would be "Director of Broadcasting." "Absolute silence in the studio is most than the sounds which are, supposed to One of the most popular stations in essential," said Mr. Hager, "and it is occur, must be made. The red light is the United States is that of the General with the utmost difficulty that we are glowing. Electric Company at Schenectady. This able to impress this upon the artists or A Lead Covered Booth station is now in its second year. Mr. speakers who may be on the program. Leaving the table, the announcer goes Kd1in Hager has been in charge of sta- This silence must be maintained after across the studio to a booth in one cor- tion WGY since it started. the song or speech has been finished ner. This booth, built on the style of "I made my first announcement on until the power has been cut off. But those used by telephone companies, is the night of February 21, 1922, with very often a vocalist will turn about, covered with felt and sheet lead and is many misgivings," says Mr. Hager. immediately after finishing a song, and as near sound proof as is mechanically "I had rehearsed just what I was while standing in front of the micro- possible. Windows enable him to see going to say, 25 or 30 times, and then, phone say, 'Did I sing that all right?'" everything that is going on in the room. when the time for the announcement A small radio set enables him to re- arrived, I said something altogether dif- Green and Red Lights ceive from the air just what is being ferent from that which I had intended." High up on the wall, in plain 'view of spoken, played or sung in the studio. any one who happens to be in the studio, An ordinary telephone connects with the No Scenery to be Seen are two lights, one green and the other control room adjoining. His small set The WGY studio is a. comfortably red. Mr. Hager explained that the green enables him to hear just what is going furnished suite of rooms on the first light indicated power on the antenna, on in the same manner in which it is floor of a new office building. The room while the red light indicated that the being heard hundreds of miles away. from which come the songs and selec- microphone was open for broadcasting. Back at his table, as the number draws tions, the speeches and the readings, the The microphones do not come into near to its completion, the announcer is comedies and the dramas is furnished view at the first survey of the studio. ready to make the switch to his own with nothing in the way of scenery such The first thought of the uninitiated per- microphone just as soon as the last word as is found in theatres, yet it was only son upon stepping into the studio is is spoken or sung, or the last note is a few days ago that the studio officials that a considerable number of floor struck. The red light dies out, the green received a call from a traveling scenic lamps are used. Several of them with one comes on and when the program is who artist had been told that he might small ornate silk shades are located in completed and the power turned off in land a job at WGY painting scenery various sections of the room. Closer the control room adjoining, this light for the radio. inspection, however, discloses the fact also is extinguished. "One day the phone rang rather vigor- that instead of electric lights, the fringe "The 'Good night' of the announcer ously," said Mr. Hager. "I answered it of the shade conceals the microphone. does not mean that we have completed and received this message: 'My husband On one side of the room, just under our work," said Mr. Hager. "But when is dead, thank God, and I wish you the red and green lights, is a mahogany we say it we mean it and try to convey would broadcast the fact.'" table on which rests a small leather - to our thousands of friends a friendly Not so long ago the WGY Players, a covered box with a small lever projecting thought." dramatic organization built up for the from it. A small microphone sits along- Have You a "Broadcasting Voice?" broadcasting of plays delivered the side of the box -like arrangement. The All of the entertainment which goes comedy "Get Rich Quick Wallingford" artist stands in front of the "floor - out over the WGY radio station is volun- in a most excellent manner. The story lamp;" the announcer-when he is an- tary. The services of the artists are of the play has to do with the exploit- nouncing-sits at the table with the donated. "Very often," said Mr. Hager, ing of an invention for "carpet covered microphone and switdh 'box in .front of "after the regular program has been carpet tacks," and it is really amusing, him. When everything is arranged and completed we must start in trying out APRIL 1, 1924 RADIO PROGRESS

singers or entertainers who have come in during the course of the evening. It is the only time that most of them .can come, as many of them are employed or otherwise engaged during the day. We give them a try -out. ,Often it is found that a person with a wonderful voice is not at all suited for radio broad- casting. This all takes time. We go from one thing to another." Requests to broadcast personal mes- sages are frequent. "These requests are just as diversified as the classified col- umns of a newspaper," said the an- nouncer, "and many of the requests cover exactly the same subjects as are contained in the newspaper want, lost and found ads. Not so long ago a man came in with a request that we broad- cast the fact that he was an expert watchmaker out of work. He thought that he might be able to get a good job if we would only do that. We have been requested to of broadcast all kinds -Underwood & Underwood lost and found articles." Shall Have to See This Show When it Comes to Town Not All Joy from WGY "DAILY DOZEN" BY RADIO to do their stuff on the stage for the next Of all the hundreds of news bulletins One fellow on seeing this picture asked performance. which have been broadcast from WGY, Judging from the of exercise, we us when they were going to transmit form Mr. Hager pointed to those announcing should say that the music coming in sight by radio as well as sounds. He the deaths of President Harding and for- must be a lively foxtrot. In fact, a very mer -President Woodrow Wilson as the said he wanted to .be on the air when lively, lively fox-trot. We do not know saddest. '`We did very important work, they bróadcast from this studio. ' This how good the performance is of the radio I think, during the Japanese disaster," shows the studio of the "Topsy and Eva" shown in the picture, but we want to said Mr. Hager, referring to the many Company of Chicago. Three of the cho- congratulate the director of the chorus messages which had passed through the rus are limbering up so they will be able on being a very good picker. station during that tragic period. "News of the finding of Verner Alex- of a moving picture production. You the slightest whisper of the director. andersoii, the youngest child of E. F. W. can realize how he has to strain his The only objection which the directors Alexanderson, the man who has done so voice during rehearsals if he is to get have to this system is that they much to make long distance radio'broad- all the players, musicians, stage hands must be particularly careful in mak- casting possible, was the most joyful and property men to hear him at once. ing side remarks as they used to be able message ever sent out of the station, I When it comes to making a moving pic- to, as they find some of the actors object think," reflected Mr. Hager. ture, however, and the company is "on to having the director's opinion that Mr. Hager is assisted in his work of location" (as we believe they call it) they are dumbbells broadcast to the arranging the details of the work of making any one of these movies that whole company. arranging programs and in making the cost two million dollars, according to Those who have heard "Roxie" speak announcements by a staff of assistant their press agents, you can see that the from New York will be interested to announcers. These include Robert Wie- director has even more trouble. How is know that the first use the Capitol daw, "R. W. announcing;" Carl Jester, he going to throw his voice so that each Theatre made of these microphones was tenor soloist, "C. J.;" Asa Coggershall, of the ten thousand performers who are to assist Mr. Rothafel in giving his di- "A. C.," who gives particular attention advertised to take part will know when rections to his performers at rehearsal. to the humorous numbers, and E. H. to look pleasant and when to cry? The system worked out so well that now his concerts from Smith, "E. H. IS.," who directs the Here is where broadcasting steps in. are broadcast three "WGY Players." Instead of hollering at the top of his big cities, New York, Washington and voice, the director merely stands in front Providence. of the microphone and talks in an ordi- THE MAN WITH ONE THOU- nary tone. The transmitting set sends RADIO FANS SAND BULL POWER VOICE out waves to the various loud speakers You can get parts or sets in return If there 'is one man who needs to installed every one hundred or two hun- for a little work on your part. See bellow about one thousand times as loud dred feet apart, and not one of the per- the advertisement on nage 32 of this as any mortal speaks, it is the director formers (unless dead) can fail to hear issue. Radio Reported in Best of Health Radio Corporation Annual Report Shows Reduced Prices and a Bright Outlook

THE great strides made by radio in er ate rates for Trans -Atlantic messages. tioned is pursuant to our policy of elim- the past twelve months and its rise From the pressure of our competition inating interference with radio broadcast to a leading national industry, are re- undoubtedly resulted the reduction in programs, caused by marine spark trans- flected in the annual report of the Radio rates to Great Britain and France, which mitting apparatus, by using only contin- Corporation of America for 1923, made was announced by the cable companies uous wave tube transmitters in shore public recently. The report shows a total in April, 1923. Their rates were re- to ship service." of $26,394,789 in gross income for 1923, duced to agree with those already main- "The free medical service made avail- as against $14,830,856 for 1922. Its net tained by us and similar reduction was able on ships at sea through measures income for period of 102.3 is given as soon made to other European points. inaugurated by your officers in co-opera- $4,737,774, as compared with $2,974,579 The subsequent operation of our Trans - tion with the U. S. Public Health Ser- for 1922 and $426,799 for 1921. Atlantic circuits indicates that compe- vice, and the Seamen's Church Institute The Corporation's financial position tition with the cables on even terms is of New York has rendered urgent emer- has been further strengthened during being successfully met. By a rearrange- gency aid on many occasions during the 1923. Current assets have increased ment of the Central Radio Office in New year," the report continues. Approxi- $3,531,791 and exceed current liabilities York, it is now possible to handle over- mately 75 passenger vessels are now reg- by $8,000,467. seas message traffic by twelve distinct ular subscribers to the nightly press ser- circuits. Outstanding Developments of the vice which the RCA maintains through "The great value of radio communica- their coastal stations. Year tion over other methods in emergencies," At the beginning of the year the Cor Two says the report, "has been demonstrated additional radio communication poration furnished radio apparatus on a on various occasions." During five days circuits were opened for commercial ser- rental and service basis to 705 ships. By in March, when severe interrupted vice during the year, the report declares. storms the close of the year these had been in- the land lines to the Pacific Coast, we These connect the United States with creased to 759. "A feature of the year's assisted the news suc- Italy and Poland, making in all nine associations and activity," says the report, "was a con- cessfully channels ,of international message traf- handled a large volume of press tract for furnishing the S.S. Leviathan fic. Nine radio circuits are now in op- matter between New York and San Fran- with radio equipment, and its operation eration to Great Britain, Norway, Ger- cisco. by your Corporation." many, France, Italy, Poland, Japan, "In October, during the World's Series Hawaii, and Hawaii to Japan. "The baseball games in New York, wires to Sales service thus rendered to American busi- San Francisco were again interrupted The report speaks of the phenomenal ness interests and the enterprise of the and, for the first time, a baseball game growth of broadcasting and of public Corporations in developing new interna- was described play by play, by radio interest therein and adds: Dur- tional radio connections," the report con- from New York to San Francisco. "During the year 1923 about 450 radio tinues, "means much in developing for- ing the Japanese disaster in September, broadcasting stations have been in opera- was eign trade and in preserving friendly uninterrupted radio communication tion in the United States. The develop- relations with other nations." Plans for maintained with the stricken Empire and ment of non -radiating receiving appara- was high -power trans -oceanic stations in the worry of an anxious world al- tus of greater selectivity will make this Brazil have been approved. Service to layed by our service." great numlber of stations a real asset to the Argentine, on a deferred rate basis, the radio broadcast listener, pending the Marine Radio Communication through the medium of the high -power time when natural evolution of the art station at Buenos Aires, was inaugurated The Radio Corporation operates ma- may bring fewer stations more efficiently in February of the present year. rine coastal stations which communicate distributed and of better grade and high- The exchange of traffic with the Repub- with ships at sea. These stations are er power." lic of China is expected to prove profit- now located at: Chatham, Mass., New Distribution of Radio Corporation able according to the report and will York, N. Y., Cape May, N. J., San Fran- products is accomplished through 116 serve to foster trade between that coun- cisco, Cal., Los Angeles, Cal. distributors with 57 branches, making try and the United States. Preliminary "Our service between ships and shore 173 wholesale outlet points. Many surveys for the erection .of stations in has undergone considerable change dur thousands of retail dealers serve as a' China has already begun. In this enter- ing the year," says the report. "Im- link 'between these large distributors and prise the Federal Telegraph Company of proved types of apparatus have enabled the consumer. California invited the participation of us permanently to close our coastal sta- "There are still many problems to be the Radio Corporation and the Federal tions at New London, Conn., and Sia- solved in the broadcasting situation," Telegraph Company of Delaware was sconset, Mass. The service formerly ren- the report says, "and your engineers are formed. dered by them is now performed with devoting themselves to their solution Since its inauguaration, the Radio greater efficiency by the Chatham, Mass., with the ambition of perfecting the ser - Corporation has been the pioneer in mod - station. The closing of the stations men- Continued on Page 27 The Fight is Still On Shall Broadcast Music be Taxed, or shall it be as Free as Air? THE fight is still being continued be- ing station pay the composer for the pri- theatres, hotels, dancing academies, tween the National Association of vilege of advertising his song? dance halls, schools of music, outdoor Broadcasters and the American Society Having Your Cake and Eating It shows and radio broadcasters. of Composers, Authors, and Publishers. During the year 1922 the broadcast- At this meeting the National Associa- This latter society has been collecting ing stations of the United States were tion disclosed the effective and practical taxes from motion picture theatres, going peacefully along their way, 'broad- plan which they had evolved during the hotels, dancing academies, dance halls, casting whatever good music seemed to past year for providing radio broad- schools of music, etc., for some time for be desired by the listening public. From casting stations with "tax free" musi.!. permission to use the music copyrighted out of a clear sky came a demand by Broadcasters Have Plan by their society, but the National Asso- the American Society that they forth- The meeting was unanimous in its de- ciation of Broadcasters thinks that in- with be paid a substantial sum of money cision to adopt the broadcasters' plan of stead of paying for their service the for the privilege of broadcasting a num- obtaining relief from the taxation now performers and broadcasters should re- ber of selections, the copyrights of which imposed by the American Society 21 ceive a commission from the music pub- were claimed to be under the society's Composers, Authors, and Publishers, as lishers. control. This demand surprised the the interests of all in this meeting were broadcasters beyond expression, because found to be identical. It was, there- The Best Kind of Ad they always considered that a distinct fore, decided to support the broadcast- Their position is, briefly, this: When service was being given these publishers ers'.program by sending a letter to each a new piece of music is brought out, no- when their musical numbers were broad- organization representing the above pub- one at first asks for it, as, of course, it cast, and if there was any paying to be lic performers of music, inviting co- is not generally known. If the com- done, the publisher should pay the broad- operation and pointing out the objects poser is willing to spend thousands of caster. to be attained. dollars, he can make it known fairly The First Meeting Most of the broadcasting stations are well to the general public, but even at A meeting of the broadcasters was now members of the National Associa- that the public may not want to buy. called at Chicago in April, 1923, on tion of Broadcasters. They do not play But if the composer can get one of the which occasion they organized the Na- any pieces unless licensed to do so by big broadcasting stations to put the new tional Association of Broadcasters, one the publishers. This is the reason some song on the air, then millions of people of its objects being protection against of your favorite selections which come will hear it first hand, and if it has any the demands of the American Society, under the control of the American So- merit, they will be influenced to buy a which were considered unfair. ciety of Composers can not be put on copy of the sheet music. Why should A second meeting was held in Febru- the air. This perhaps explains why you this form of advertising be given free to ary, 1924. This meeting was attended never hear certain pieces for which you composers? Why should the broadcast- by representatives of motion picture have sent in many requests.

HOW IS THIS FOR SPEED? Radio in Best of Health This picture shows Mr. A. E. Gerhard, Continued from Page 26 of the Radio Corporation of America, receive code faster than the vice to the satisfaction and benefit of the who can American public?' sender can think up words to transmit. was to get ordinary Gross sales of radio receiving appara- He actually able of 59% words tus amounted to $22,465,000. code messages at the speed every minute, topping the previous rec- General ord of 56 words a minute by a comfort- speed was The report states that the Radio Cor- able margin. This unusual Convention poration has recently been made the ob- shown at the Fourth Annual ject of a complaint by the Federal Trade of the Second District Executive Radio Hotel, Commission and adds, "The position of Council at the Pennsylvania the Corporation, with regard to this, has New York, March 7. this speed been that it welcomes the opportunity to You can appreciate what that the make a complete review of its history, means better when you realize to shore organization and policies to that body." ordinary message sent from ship words min- The Directors of the Radio Corporation comes in at about twenty per deserves are confident that when the investigation ute. It appears that he well by the is fully completed and finally consid- the beautiful trophy awarded of the con- ered, the position of the 'Corporation will Breaks World's Record Radio Council to the winner be found to be entirely sound and proper. test. r R' *I\PStRI'D

NOTE: In this section the Technical Editor will answer of special interest to the questioner alone, or if a personal questions of general interest on any radio matters. Any of answer is desired, a charge of fifty cents will be made for our readers may ask not more than two questions, and if each answer. This will entitle the questioner to a personal answer by letter. the subjects are of importance However, if the question requires consid- to most radio fans they will erable experimental or development be answered free work, )higher rates will of charge in the magazine. If they are be charged, which may be obtained upon application.

Question. Why is it that some sta- United iStates. If you will run your consume one ampere out of your storage tions come in better at night and others eye down the wave length column of battery continuously. This, of course, is in the daytime? the list of stations as found on Page quite a drain on its capacity. But by Answer. Radio transmission at night 31 of this issue, you will notice that winding it with fine wire to a resistance is about three times as good as in the this particular wave length is repre- of 400 ohms, the current consumption is daytime. This is probably caused by sented by several times as many broad- cut down to less than 1/50 of an ampere, the fact that when the sun shines the casters as the next most popular one. which is so small that it is almost unap- high frequency light waves (the so- During the daytime most of the other preciable. This small current is plenty called ultra violet rays) cause a form stations are silent, and so we get no big enough to operate the potentiometer. interference, of interference with the waves from the and the program sent out The chief use of such a stablizer is in from broadcasting station. The precise man- Medford Hillside reaches Provi- controlling the tubes for the radio fre- dence ner in which these waves react is not with sufficient loudness to be quency amplification. There is a pro- heard, known, but it is thought that away up but at eight o'clock in the eve- nounced tendency for these tubes to oscil- ning in the atmosphere, twenty to fifty miles pandemonium breaks out. Any late with the objection that reception number above the earth, an action takes place of 360 meter stations are going is very mushy and difficult to control. something like what occurs inside your at once, and while they may be so faint When such a condition occurs in your vacuum tubes. At such a height the air that your set does not pick them up in set it means that you should turn the is so rarified that it is nearly a perfect sufficient quantities to be heard dis- dial of your stablizer. This will change vacuum. Whatever the mechanism of tinctly, still they are there strong the grid potential of your tubes and by enough operation, no doubt exists as to the to interfere with the faint re- the proper adjustment will kill off the fact-the sunlight has a disturbing in- ception coming in from WGI. So, of oscillation. You wild know when this course, fluence on broadcasting. This explains you report that you can not get occurs right away, because the mush of why you can hear most stations much this station. the signal will disappear and the music farther at night than you can in the Question. What is meant by a sta- will be much improved. daytime. blizer ? A stalblizer is usually not used on a On the other hand, an occasional re- Answer. The term stablizer is used to set with audio amplification. Sometimes port will be made of reversed condi- describe a potentiometer when used on you see a hook-up calling for one, but if tions: that is, a station will come in a radio frequency hook-up. The poten- you do you will know that it has not during the daytime and yet not be heard tiometer looks very much like a rheostat been well designed, as a potentiómeter at night. A well known illustration of except for two things. In the first place, in such a set is entirely unnecessary. this is the reception of WGI, Medford it always has three terminals, one for To be sure, you can vary the signal Hillside, Massachusetts, as heard in strength by the plus of the "A" battery, one for the such a control, but exactly Providence. This station is very diffi- the same variation can be minus of the "A" battery, and the third obtained by cult to pick up in Providence at any changing the gridleak, and since this connected to the sliding arm for con- time, owing to a dead spot in the air latter must be used, anyway,' it, is en- nection to the tuning coil. The between the two cities. Powerful sets sec- tirely superfluous to have two controls ond difference in the potentiometer are able to get the afternoon broadcast- is both doing the same thing. On the audio ing from WGI, but it is very rare that that it always uses very fine wire and amplification set the oscillating condi- even the best sets can obtain them in is wound to a resistance of around 400 tion of the tubes is controlled by the the evening. ohms. If you used a six or thirty ohms tickler or feedback. The reason for this unusual condition potentiometer it would work just as Question. I have recently added one is to be found in the wave length of weal, but would waste a great deal of tube of radio amplification to my set this station. They send out 360 meters, electricity from your "A" battery. A and find it does not work any better than the most popular wave length in the six ohm rheostat, for instance, would it did when it used a regenerative hook- Amu, 1, 1924 RADIO PROGRESS 29 the left or right. Notice particularly up without radio amplification. What is the charges until they have a sufficient the tone of the squeal. If you find that the trouble? amount of the electricity for a sudden and destructive bolt. It is very much the slight shift in your dial changes the Answer. This is the general experi- the same idea as a dam. Suppose you pitch of the squeal note by making it ence obtained by changing the regenera- have a dam across a river and there is either a slightly higher or a slightly tive set into a single radio amplification some danger of its breaking in a flood. lower note, then the fault is all yours, set. When your set is regenerative you To such an occurrence you open and you should proceed to adjust your get amplification through the feedback prevent a sluice-gate in the dam and let the set by reducing the amount of feedback of about five to one at an average value. water run out slowly at the same time it or regeneration. Turn your tickler dial If you take this feedback off and sub- runs in, and so it does not accumulate several notches down toward zero and etitute a radio frequency amplification, any supply of water behind the dam. try shifting your tuning dial again. This you will gain the amplification of the However, realizing that people are for- action should be repeated until the radio frequency, but will lose that of the underwriters specify that in squeal has disappeared from your set. regeneration, but it so happens that the getful addition to a grounding switch a light- If, on the other hand, when you turn multiplication of the radio is just about ning arrestor must be used, so that if your tuning dial one degree to the left five to one, so what you have done is to the switch is forgotten and left open or to the right, it does not change the substitute one form of multiplication by a thunder storm the lightning pitch of the note, but merely makes it five for another form of the same thing, during arrestor will automatically take care of louder or softer with the same tone, then and so, of course, the final result is not As a farther step, if you are out of luck. The squeal is caused very different from what it was at the the discharges. arrestor is so good that it entirely by some kind friend in your start. the lightning will operate instead of a grounding neighborhood who has adjusted his set This is the reason why you will switch when the latter is forgotten (and wrong by leaving the regeneration dial usually find at least two stages of radio only lightning arrestors approved by the turned up too high. Unfortunately, there amplification on most com- frequency underwriter's laboratories are allowed) is no remedy for this condition short of mercial sets. To be sure, some of the then it seems entirely unnecessary to getting the offending fan on the 'phone hook-ups use radio amplification hewer put the grounding switch on at all. That and asking him to cut down his feed- end regeneration 'together. In that case is the reason why the insurance people back. a positive gain will ho obtained, but the do not require a ground switch but do Question. Please publish the hookup set le much harder to construct and demand an approved lightning arrestor. for the two -tube Harkness set with the Question. When my radio squeals how diode tube. Question. Is there any possible dan- can I tell whether it is a neighbor that Answer. The circuit is shown here- ger frein lightning from an aerial if it is to blame, or that my own set is out with. Instead of a diode vacuum tube a k grounded during electrical storms? of adjustment? crystal may be substituted with similar The advantages of a crystal are ;I newer. According to the late Charles 1 newer. This is a rather popular ques- results. I'. Steinmetz of the General Electric Co., tion, as it has been asked by various that it takes no battery to operate; is and is easily replaced in t hr foremost authority on lightning in fans. It is a simple matter to tell very cheap, the world, an aerial, if grounded during whether you are squealing in your neigh- case of accidental damage. The advan- n storm is not a source of danger, but on bor's ear or whether he is doing the same tages of the diode are that there is no the other band is a positive preventive to you. The sure test is as follows: cat whisker to fuss with, it stays in per- of a lightning stroke reaching the house. Turn the principal tuning dial, the one manent adjustment, cannot be put out of This is because the thunder clouds dis- connected to your variable condenser or commission by a heavy static disturb- is) and is charge their voltage slowly and harm- your grid variometer s (depending on ance (as a crystal sometimes a crystal. lessly to the aerial instead of collecting what style of set you use) . one degree to slightly more sensitive than CIRCUIT FOR TWO -TUBE HARKNESS

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1 1 1 °--1I4I,I, r 30 RADIO PROGRESS APRIL 1, 1924 UNITED STATES BROADCASTING STATIONS W.L. K.C. W.P. ARRANGED WBAN Wireless Phone Corp., Paterson, N. J 244-1230- 100 ALPHABETICALLY BY WBAP Wortharn -Carter Pub. Co. Fort Worth, Tex 476- 630- 750 CALL LETTERS WBAV Erner & Hopkins Co., Columbus, Ohio 390- 770- 500 Abbreviations: WBAW Marietta College, Marietta, Ohio 246-1220- 250 W.L. wave length in meters; K.C., frequencies in WBAY American Tel. & kilocycles; Tel. Co., New York, N. Y 492- 610- 500 W.Y., watt power of station. WBL T. & H. Radio Co., Anthony, Ks 261-1150- 100 W.L. K C. W.P. WBR Penn State Police, Butler, Pa 286-1050- 250 KDKA Westinghouse Elec. & Mfg. Co., East Pittsburgh 326- 920-1000 WBT Southern Radio Corp., Charlotte, N. C 360- 833- 500 KDPM Westinghouse Elec. & Mfg. Co., Cleveland, 0 270-1110. 250 WBU City of Chicago, Chicago, Ill 286-1050- 500 KDYM Savoy Theatre, San Diego. Cal 280-1070- 100 WBZ Westinghouse Elec. & Mfg. Co., Springfield, Mass 337- 890-1000 KDYQ Oregon Institute of Technology, Portland, Ore 360- 833- 100 WCAD St. Lawrence University, Canton, N. Y 280-1070- 250 KDYX Star Bulletin, Honolulu, Hawaii 360- 833- 100 WCAE Kaufmann & Baer Co., Pittsburgh, Pa 462- 650- 500 KßZB Frank E. Siefert, Bakersfield, Cal 240-1250- 100 WCAJ Nebraska Wesleyan Univ., Univ. Place, Neb 360- 833- 500 KDLE The Rhodes Co., Seattle, Wash 455- 660- 500 WCAL St. Olaf College, Northfield, Minn 360- 833- 500 KDZF Auto. Club of So. Cal., Los Angeles, Cal 278-1080- 500 WCAM Villanova College, Villanova, Pa 360- 833- 150 KFAD McArthur Bros. Mercantile Co., Phoenix, Ariz 360- 833- 100 WCAP Chesapeake & Potomac Tel. Co., Wash'gt'n, D. C 469- 640- 500 KFAE State College of Washington, Pullman, Wash 360- 833- 500 WCAR Alamo Radio Elec. Co., San Antonio, Tex 360- 833- 150 KFAJ University of Colorado, Boulder, Col 360- 833- 100 WCAS W. H. Dunwoody Ind. Inst., Minneapolis, Mino 246-1050- 100 KFAQ City of San Jose, San Jose, Cal 360- 833- 250 WCAT S. Dakota State Sch. of Mines, Rapid City, S. D 240-1250. 100 KFAR Studio Lighting Service Co., Hollywood, Cal 280-1070- 200 WCAU Durham & Co., Philadelphia, Pa 286-1050- 100 KFAU In. Sch'I Dist. of Boise City, Boise H. S., Boise, Id 360- 833- 150 WCAY Kesselman-O'Driscoll Co., Milwaukee, Wis 261-1150- 250 KFBK Kimball -Upson Co., Sacramento, Cal 283-1060- 100 WCBD Wilbur G. Voliva, Zion, III 345- 870- 500 KFCM Richmond Radio Shop, Richmond, Cal 360- 833- 100 Stix, Baer & Fuller Dry Goods Co.. St. Louis, Mo 360- 833- 100 KFCZ Omaha Central High School, Omaha, Neb 258-1100- 100 wCM University of Texas, Austin, Tex ...360. 833- 500 KFDH University of Arizona, Tucson, Ariz 360- 833- 150 WCX Detroit Free Press, Detroit, Mich 517- 580- 500 KFDV Gilbreth & Stinson, Fayetteville, Ark 360- 833- 200 WDAE Tampa Daily Times, Tampa, Fla 360- 833- 250 KFDX First Baptist Church, Shreveport, La 360- 833- 100 WDAF Kansas City Star, Kansas City, Mo 411- 730- 500 KFDY So. Dakota State College, Brookings, So. Dakota 360- 833- 100 WDAG J. Laurance Martin, Amarillo, Tex 263-1140- 100 KFEQ J. L. Scroggin, Oak, Neb 360- 833- 150 WDAK The Courant, Hartford, Conn 261-1150. 100 KFEV Felix Thompson Radio Shop, Casper, Wyo 263-1140- 250 WDAP Board of Trade, Chicago, III 360- 833- 500 KFEX Augsburg Seminary, Minneapolis, Minn 261-1150- 100 WDAR Lit Brothers, Philadelphia, Pa 395- 760- 500 KFEZ Amer. Society of Mech. Engineers, St. Louis, Mo 360- 833- 100 WDAU Slocum & Kilburn, New Bedford, Mass 360- 833- 100 KFFQ Markehoffel Motor Co.. Colorado Springs, Col 360- 833- 100 WDAX First National Bank, Centerville, Iowa 360- 833- 100 KFFX McCray Co., Omaha, Neb 278-1080- 100 WEAF American Tel. & Tel. Co., New York, N. Y 492- 610- 500 KFFY Pinous & Murphey, Alexandria, La 275-1090- 100 WEAI Cornell University. Ithaca, N. Y 286-1050- 500 KFGC Louisiana State University, Baton Rouge, La 254-1180- 100 WEAJ University of S. Dakota, Vermillion, S. Dak 283-1060- 200 KFGH Leland Stanford University, Stanford Univ., Cal 360- 833- 500 WEAM Borough of N. Plainfield, N. Plainfield, N. J 252-1190- 100 KFGJ Mo. Natl. Guard, 138th Infantry, St. Louis, Mo 266-1130- 250 WEAN Shepard Co., Providence, R. I 273-1100- 100 KFGX First Presbyterian Church, Orange, Tex 250-1200- 500 WEAO Ohio State University, Columbus, Ohio 360- 833- 500 KFHD Utz Electric Shop Co., St. Joseph, Mo 226-1330- 100 WEAP Mobile Radio Co., Mobile, Ala 360- 833- 100 KFHF Central Christian Church, Shreveport, La 266-1130- 150 WEAS Hecht Co., Washington, D. C 360- 833- 100 KFHJ Fallon & Co., Santa Barbara, Cal 360- 833- 100 WEAU Davidson Bros. Co., Sioux City, Iowa 360- 833- 100 KFHX Robert W. Nelson, Hutchinson, Ks 229-1310- 150 WEAY Iris Theatre, Houston, Tex 360- 833- 250 KFI Earle C. Anthony, Inc., Los Angeles, Cal 469- '640. 500 WEB Benwood Co., St. Louis, Mo 360- 833- 500 KFIF Benson Polytechnic Institute, Portland, Ore 360- 833- 100 WEW St. Louis University, St. Louis, Mo 261-1150- 100 KFIX R. C. of Jesus Christ of L.D. Sts.. Ind'p'nd'n'e, Mo.240-1250- 250 WFAA Dallas News & Dallas Journal, Dallas, Tex 476- 630- 500 KFIZ Daily C'm'nw'lth & O.A.Heulsm'n, Fond d'L'c,Wis.273-1100. 100 WFAB Carl F. Woese, Syracuse, N. Y 234-1280- 100 KFJC Seattle Post Intelligencer. Seattle, Wash 233-1290- 100 WFAH Electric Supply Co., Port Arthur, Tex 236-1270- 150 KFJK Delano Radio and Electric Co., Bristow, Okla 233-1290- 100 WFAN Hutchinson Elec. Service Co., Hutchinson, Minh 360- 833- 300 KFJM University of N. Dakota, Grand Forks, N. Dak 280-1070- 100 WFAV Univ. of Nebraska, Dept. of E. Eng., Lincoln, Neb.275-1090- 500 KFKB Brinkley -Jones Hospital Association, Milford, Ks 286-1050. 500 WFI Strawbridge & Clothier, Philadelphia, Pa 395- 760- 500 KFKQ Conway Radio Laboratories, Conway, Ark 224-1340- 150 WGAQ Glenwood Radio Corp., Shreveport, La 360- 833- 150 KFKX Westinghouse Elec. & Mfg. Co., Hastings, Neb 286-1050- 500 WGAW Ernest C. Albright, Altoona, Pa 261-1150- 100 KFLR University of N. Mexico, Albuquerque, N. M 254-1180- 100 WGAY Northwestern Radio Co., Madison, Wis 360- 833- 100 KFMQ University of Arkansas, Fayetteville, Ark 263-1140- 100 WGI Am. R'd'o & Res'ch Corp., Medf'rd Hillside, Mass.360- 833- 150 KFMS Freimuth Dept. Store, Duluth, Minn 275-1090- 100 WGL Thomas F. J. Rowlett, Philadelphia, Pa 360- 833- 500 KFMX Carleton College, Northfield, Minn 283-1060- 500 WGR Federal Tel. & Tel. Co., Buffalo, N. Y 319- 940- 500 KGN Northwestern Radio Mfg. Co., Portland, Ore 360- 833- 100 WGV Interstate Electric Co., New Orleans, La 360- 833- 100 KGU Marion A. Mulreny, Honolulu, Hawaii 360- 833- 500 WGY General Electric Co., Schenectady, N. Y 380- 790-1000 KGW Portland Morning Oregonian, Portland, Ore 492- 610- 500 WHA University of Wisconsin, Madison, Wis 360- 833- 500 KHJ Times-Mirror Co., Los Angeles, Cal 395- 760- 500 WHAA State University of Iowa, Iowa City, Iowa 283-1060- 100 KHQ Louis Wasmer, Seattle, Wash 360- 833- 100 WHAB Clark W. Thompson, Galveston, Tex 360- 833- 200 KJR Northwest Radio Service Co., Seattle, Wash 270-1110- 100 WHAD Marquette University, Milwaukee, Wis 280-1070- 100 KJS Bible Institute of Los Angeles, Los Angeles, Cal 360- 833- 750 WHAG University of Cincinnati, Cincinnati, Ohio 222-1350- 100 KLS Warner Brothers, Oakland, Cal 360- 833- 250 WHAH Rafer Supply Co., Joplin, Mo 283-1060- 250 KLX Tribune Publishing Co., Oakland, Cal 360- 833- 250 WHAM University of Rochester, Rochester, N. Y 283-1060- 100 KLZ Reynolds Radio Co., Denver, Col 360- 833- 500 WHAS Courier -Journal & Louisville Times, Louisville, Ky 400- 750- 500 KNT Grays Harbor Radio Co., Aberdeen. Wash 263-1140- 250 WHAZ Rensselaer Polytechnic Institute, Troy, N. Y 380- 790- 500 KNV Radio Supply Co., Los Angeles, Cal 256-1179- 100 WHB Sweeney School Co.. Kansas City, Mo 411- 720- 500 KNX Electric Lighting Supply Co., Los Angeles, Cal 360- 833- 100 WHK Radiovex Co., Cleveland, Ohio 283-1060- 100 KOB N. M. C. of Agri. & Mech. Arts, State Col., N. M 360- 833- 500 WHN George Schubel, New York, N. Y - 360- 833- 100 KOP Detroit Police Dept., Detroit, Mich 286-1050- 500 WIAC Galveston Tribune. Galveston, Tex 360- 833- 100 KPO Hale Bros., San Francisco, Cal 423- 710- 500 WIAJ Fox River Valley Radio Supply Co., Neenah, Wis 224-1340- 100 KQV Doubleday -Hill Electric Co., Pittsburgh, Pa 360- 833- 250 WTAK Journal-Stockman Co., Omaha, Neb 273-1080- 200 KSD Post Dispatch, St. Louis, Mo...:. 546- 550- 500 WIAO School of Eng. of Milwaukee. Milwaukee, Wis 360- 833- 100 KTW First Presbyterian Church, Seattle, Wash 360- 833- 750 WIAR Paducah Evening Sun, Paducah, Ky 360- 833- 100 KUO Examiner Printing Co., San Francisco, Cal 360- 833- 150 WIAS Home Electric Co., Burlington, Iowa... y,.. 360- 833- 100 KUS City Dye Works & Laundry Co., L. Angeles, Cal 360- 833- 100 WIK K. & L. Electric Co., McKeesport, Pa 234-1280- 500 KWG Portable Wireless Tel. Co., Stockton, Cal 360- 833- 100 WIP Gimbel Brothers, Philadelphia, Pa 509- 590- 500 KWH Los Angeles Examiner, Los Angeles, Cal 360- 833- 500 WJAB American Electric Co., Lincoln, Neb 360- 833- 500 KYW Westinghouse Elec. & Mfg. Co.. Chicago, Ill 536- 560-1000 WJAD Jackson's Radio Eng. Laboratories, Waco, Tex 360- 833- 150 KZN The Deseret News, Salt Lake City, Utah 360- 833- 500 WJAG Norfolk Daily News, Norfolk, Neb 283-1060- 250 WAAB Valdemar Jensen, New Orleans, La 268-1120- 100 WJAN Peoria Star, Peoria, Ill 280-1070- 100 WAAC Tulane University, New Orleans, La 360- 833- 400 WJAQ Capper Publications, Topeka, Ks 360- 833- 100 WAAF Chicago Daily, Drovers Journal, Chicago, Ill 286-1050- 200 WJAR The Outlet Co., Providence, R. I 360- 833- 500 W.AAM I. R. Nelson Co., Newark, N. J 263-1140- 250 WJAS Pittsburgh Radio Supply House, Pittsburgh, Pa 360- 833- 500 WAAW Omaha Grain Exchange, Omaha, Neb 360- 833- 200 WJAX Union Trust Co., Cleveland, Ohio 390- 770- 500 WAAZ Hollister-Miller Motor Co., Emporia, Ks 360- 833- 100 WJAZ Chicago Radio Laboratory, Chicago, Ill 448- 670-1000 WABA Lake Forest College, Lake Forest, Ill 266-1130- 100 WJX Deforest Radio Tel. & Tel. Co., N. Y., N. Y 360- 833- 500 WABE Young Men's Christian Assn.. Washington, D. C 283-1060- 100 WJY R. C. A., New York, N. Y 405- 740- 500 WABL Conn. Agri. College, Storrs, Conn 283-1060- 100 WJZ Broadcast Central, New York, N. Y 455- 660- S00 WABM F. E. Doherty Auto. & R'dio E. Co., Saginaw, M 254-1180. 100 WKAA H. F. Paar, Cedar Rapids, Iowa 268-1160- 100 WARN Ott Radio, Inc., La Crosse, Wis 244-1320- 250 WK AF W. S. Radio Supply Co., Wichita Falls, Tex 360- 833- 100 WARP Robert F. Weinig, Dover, Ohio 266-1130-. 100ß WRAP Dutee W. Flint, Cranston, R. I 360- 833- 250 WABT Holliday -Hall, Washington, Pa 252-1190- 100 WKAQ Radio Corp. of Porto Rico, San Juan, P. R 360. 833- 100 W i't TUT Victor Talking Machine Co., Camden, N. J 226-1330- 100 WKAR Michigan Agri. College, E. Lansing, Mich 280-1070- 250 wtRX Henry B. Joy, Mount Clemens, Mich 270-1110- 150 WKY WKY Radio Shop, Oklahoma, Okla 360- 833- 100 WRA.A Purdue University. West Lafayette, Ind 360- 833- 250 WLñG Cutting & Wash. Radio Corp., Minneapolis, Min 417- 720- 500 100 WR41) St"rling Electric Co . Minneapolis, Minn 360- 833- 100 WLAH Samuel Woodworth, Syracuse, N. Y. 234-1280- WBAH The Dayton Co.,- Minneapolis, Minn 417- 720- 500 WLAJ Waco Electrical Supply Co., Waco, Tex 360- 833- 150 APRIL 1, 1924 RADIO PROGRESS ;1

RADIO FREQUENCY AMPLIFICATION with the BALLANTINE VARIOTRANSFORMER How to get increased distance with your crystal set YOUR crystal set is the starting point on which to build a good distance receiver. For authorities agree that there is nothing finer than a good crystal for clean-cut detection-not so loud as a tube, perhaps, but much clearer. By all means, keep this element with which you are already familiar. Use tubes to best advantage Tubes, Complete radio frequency of course, are needed for amplification-to build up weak amplifier unit with $ .00 distant signals so that they may operate your crystal detector. socketandrheostat 15 But, by putting your money for tube equipment into one or more Transformer only $9,60 stages of radio frequency amplification, tuned with BALLAN- for panel or base TINE VARTOTRANSF0RMER Units, you will get increased At dealers or postpaid distance. Try this instrument. Then, if there's anything you don't under- stand, our staff will help you out. Booklet tells how to improve crystal sets "Radio Frequency Amplification with the BALLANTINE VARIO - TRANSFORMER," is the title of our 25 -page booklet, packed with useful data, charts and diagrams. Send for your copy now.

óQ0 0 TO 1J sBB21% a Co. Pioneers in Bakelite Moulding 824 Fanny Road, Boonton, N. J.

RADIO FREQUENCY AMPLIFICATION with the BALLANTINE VARIOTRANSFORMER

W.L. B.C. W.P. WQAM Electrical Equipment Co., Miami, Fla 360- 833- 100 Pa 280-1070. 100 WLAK Vermont Farm Machine Corp., Bellows Falls, Vt.360- 833- 100 WQAN Scranton Times, Scranton, 360- 833- 100 WQAO Calvary Baptist Church, New York, N. Y 360- 833- 100 WLAL Naylor Electrical Co., Tulsa; Okla Reporter, Abilene, Tex 360- 833- 100 WLAN Putnam Hardware Co., Houlton, Me 283-1060- 250 WQAQ Abilene Daily N. Y 360- 833- 500 WQAS Prince- Walter Co., Lowell, Mass 266-1130- 100 WLAW Police Dept. City of N. Y., New York, Co., Peoria, Ill 360- 833- 100 WLW Crosley Mfg. Co., Cincinnati, 0 309- 970- 500 WQAX Radio Equipment 360- 833- 100 WRAA Rice Institute, Houston, Tex 360- 833- 200 WMAB Radio Supply Co., Oklahoma, Okla Power Co., St. Croix Falls, Wis 248-1210- 100 WMAC Clive B. Meredith, Cazenovia, N. Y 261-1150- 200 WRAL No. States Mass..360-833- 100- 500 WRAM Lombard College, Galesburg, Ill 244-1230- 250 WMAF Round Hills Radio Corp., Dartmouth, Yellow Springs, Ohio 360- 833- 100 WMAH General Supply Co., Lincoln, Neb 250-1180- 100 WRAY Antioch College, 275-1090- 250 WRAX Flexon's Garage, Gloucester City, N. J 268-1120- 100 WMAJ Drovers Telegram Co., Kansas City, Mo Scranton, Pa 280-1070- 100 WMAK Norton Laboratories, Lockport, N. Y 360- 833- 500 WRAY iRadio Sales Corp., 246-1220- 150 WRC Radio Corp. of America, Washington, D. C 460- 640- 500 WMAP Utility Battery Service, Easton, Pa Electric Co., Hamilton, Ohio 360- 833- 200 WMAQ Chicago Daily News, Chicago, Ill 448- 670- 500 WRK Doren Bros. 266-1130- 250 WRL Union College, Schenectady, N. Y 360- 833- 500 WMAT Paramount Radio Corp., Duluth, Minn Illinois, Ill 360- 833- 500 WMAV Alabama Polytechnic Institute, Auburn, Ala 250-1200- 500 WRM University of Urbana, Mo 280-1070- 100 WRW Tarrytown Radio Research Lab., Tarrytown, N. Y.273-1100- 1S0 WMAY Kingshighway Presbyterian Church, St. Louis, T'chers' Coi., Cane Girardeau, Mo.360- 833- 100 WMC "Commercial Appeal," Memphis, Tenn 500- 600- 500 WSAB S. E. Mo. State 278-1080- 100 WSAC Clemson Agri. Col., Clemson C&lege, S. C 360. 833- 500 WNAC Shepard Stores, Boston, Mass Foster Co., Providence, R. I 261-1150. 150 WNAD University of Oklahoma, Norman, Okla 360- 833- 100 WSAD J. A. Y 286-1050- 100 WSAH A. G. Leonard, Jr., Chicago, Ill 248-1210- S00 WNAN Syracuse Radio Telephone Co., Syracuse, N. Ohio 309- 970- 500 WNAP Wittenberg College, Springfield, Ohio 360- 833- 100 WSAI U. S. Playing Card Co., Cincinnati, Tex.360- 833- 100 WSAJ Grove City College, Grove City, Pa 360- 833- 250 WNAS Tex. Radio Corp. & Austin Statesman, Austin, N. Y 275-1190- 100 WNAT Lenning Brothers Co., Philadelphia, Pa 360- 833- 100 WSAW Curtis & McElwee, Canandaigua, 236-1270- 500 WSAY Irving Austin, Port Chester, N. Y 233-1290- 100 WNAV People's Tel. & Tel. Co., Knoxville, Tenn Ga 429- 700- 500 WNAX Dakota Radio Apparatus Co., Yankton, S. D 244-1230- 100 WSB Atlanta Journal, Atlanta, & Co., Utica, N. Y 273-1100- 100 WOAG Apollo Theatre, Belvidere, Ill 224-1340- 100 WSL J. M. Electric WS -Y Alabama Power Co., Birmingham, Ala 360- 833- 500 WOAH Palmetto Radio Corp. Charleston, S. Q 360- 833- 100 385- 780- 500 WTAM The Willard Storage B'tt'ry Co., Cleveland, 0 390- 770-1000 WOAI Southern Equipment Co., San Antonio, Tex Mattoon, Ill 240-1250- 100 WOAL William E. Woods, Webster Groves, Mo 229-1310- 500 WTAN Orndorff Radio Shop, & Son, Osseo, Wis 226-1330- 100 WOAN Vaughn C'nserv't'ry of Music, Lawrenceb'rg, Tenn.360- 833- 150 WTAQ S. H. Van Gorden_ Erie, Pa 242-1240- 100 WTAR Reliance Electric Co.. Norfolk, Va 280-1070- 100 WOAV Penn. Nat'l Guard, 2d Bat, 112th Inf., E. Erbstein, Elgin, Ill., near 286-1050- 500 WOAW Woodmen of the World, Omaha, Neb 526- 570- 500 WTAS Charles 240-1250- 500 WTAT Edison Electric Ilium. Co., Boston, Mass 244-1229- 100 WOAX Franklyn J. Wolff. Trenton, N. J State Agri. Col., Manhattan, Ks 360- 833-1000 WOC Palmer Sch. of Chiropractic. Davenport, Iowa 484- 620- 500 WTG Kansas & Philadelphia, Pa 360- 833- 100 WOI Iowa State College, Ames; Iowa 360- 833- 100 WWAI7 Wright Wright, Inc., 360- 833- 500 WWAE Alamo Dance Hall, Joliet, Ill 227-1320- 500 WOK Pine Bluff Co., Pine Bluff, Ark 236-1270- 100 509- 590- 500 WWAF Galvin Radio Supply Co., Camden, N. J WOO John Wanamaker, Philadelphia, Pa of Mines. Houghton, Mich 244-1230- 250 WOO Western Radio Co., Kansas City, Mo 360- 833- 500 WWAO Michigan College 405- 740- 500 WWT Détroit News. Detroit. Mich 517- 580- 500 WOR L. Bamberger & Co., Newark, N. J New Orleans, La 280-1070- 100 WOS Mo. State Marketing Bureau, Jefferson City, Mo 441- 680- 500 WWL Loyola University, WPAB Pennsylvania State College, State College, Pa 283-1060- 500 WPAC Donaldson Radio Co., Okmulgee, Okla 360- 833- 200 DEPENDABLE ADVERTISING 360- 833- 250 WPAH Wisconsin Dept. of Markets. Waupaca, Wis PROGRESS is WPAK North Dakota Agri. Col., Agri. College, N. D 360- 833- 250 Advertising in RADIO accepted from only WPAL Avery & Loeb Elec. Co., Columbus, Ohio 286-1050- 100 those firms who are known to be reliable. You can buy WPAZ John R. Koch (Dr.), Charleston, W. Va 273-1100- 100 with confidence anything advertised in any issue of this WOAA Horace A. Beale, Jr., Parkesburg, Pa 360- 833- 500 WQAC E. B. Gish, Amarillo, Tex 360- 833- 100 magazine. RADIO -FANS! Here's an opportunity to get PARTS SETS Anything you want in the Radio Line without cost to you if you will do a little work for us

If you think we have the right idea in subscribe. Then write his name and address, RADIO PROGRESS,-if you like the magazine and your own name and address PLAINLY on (and remember, this is only the second issue), a sheet of paper and mail, with money -order you will want to receive it regularly. And if for $6.00 to cover the two subscriptions to you think well enough of our effort to sub- SUBSCRIPTION DEPARTMENT, RADIO scribe yourself, you surely will be willing PROGRESS, 8 Temple Street (Post Office Box to ask your next-door neighbor to subscribe 728. Providence. R. I.) . We'll ship the Trans- with yon. Therefore, here's former or Ear Phones prepaid by return mail. (Be sure to show clearly which address is yours, so we will know where to send the Transformer 1 or Ear Phones, and be sure to tell which article Offer No. you want.)

If > ,,u will send in your own subscription for one year to RADIO PROGRESS (the subscrip- tion price is $3.00 a year) and the subscription Offer No. 2 of one friend, we will send you by return mail Get your choice of a fine Radio frequency or Audio one more yearly subscription, making frequency three in all (including your own), and we'll send you BOTH THE TRANSFORMER AND Transformer THE EAR PHONES ! ! or a pair of High -Grade, Guaranteed WRITE TO -DAY! Ear Phones Address: SUBSCRIPTION DEPT., RADIO PROGRESS, Speak to one of your radio friends to -day! Show him this copy of RADIO PROGRESS. 8 Temple Street, P. O. Box 728, You won't have any trouble in getting him to Providence, R. 'I...... ;..:..:..;..;..;..:..:..:..;..;..:.:..:..:..:.:..:.:..:.:..:.:..;..;..:.:..:.;.., :..:..; .::..::..:.:..; .:.:.:..:..:..;..;..:.:.:.:..:.:.:..:.:..;..;..:..:..:.:..:.:.:..:. DO .:. .:. .:. .:. .:. .:. Announcing the .:. .:. .:. .:. WIZARD ARISTOCRAT.:... .:. .:. ( All that the name infers ) THE "B" BATTERY SUPREME

Fashioned by experts-from the best materials the market affords-

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TO DEALERS-You can't afford not to sell the "WIZARD ARISTOCRAT." WRITE TO -DAY for full information ti and dealer proposition.

WIZARD BATTERY CORPORATION Factory-Laboratories-Executive Offices

381 North Main St. P. 0. Box 238 Pawtucket, R, I.

I.; :.,.;..,.,.;..;..:e:.,..;....:-:....;.... "Built First to Last."

Now is the Time to Build your New Portable Set for Radio Outings \\ hen the spring sun gets warm and your old automobile just naturally turns out into the country road and the far hillsides beckon to you, you will want to take your radio with you. So get ready. A Coto compact radio set made ac- cording to your favorite hook-up will give you wonderful results wherever you may happen to string your aerial. You can box set, batteries and all neatly in small space if the parts you use are Coto built.

See the Honeycomb Stator Coils Coto Apparatus is all Guaranteed "Built First to Last" and al- ways built to uphold our repu- tation for radio apparatus of a quality second to none. Every Coto part is Laboratory Tested before shipment. Your dealer is authorized to make im- mediate replacement for any defects that may develop in shipment, or ordinary use. So it is wise to buy Coto.

Coto Compact Manufacturers of Variometer wins Fine Radio Sets wide Popularity Turn to Coto The Coto compact Variable Air Its small size, 2/x1/x33/4. Condenser with vernier which is makes it best of all adapted only 2% inches square is now for portable sets. But wide specified for two high, grade radio use in sets of standard size sets, the makers of which de- has proved it to be equal to mand the very highest efficiency the best. Range is 200 to 600 in an air condenser. Plates are meters. Connections to rotor soldered in place and SILVER by pigtail, assuring positive PLATED. .00025 Mfd , $4.50. contact. Very handsome in Type .0005 Mfd., $5. .001 Mfd., $6. appearance in polished brown 9000 bakelite. $5.50

It is Coto Compact Variocoupler Turn Ratio Tapped A companion piece of the variometer is Type and possessing all .its features of ex- cellence. With eight taps for use 5 to 1 5000A with primary condenser. $7.50 For Loop Aerial COTO -COIL CO. 87 Willard Ave., Providence, R. I. Rich, Full Toned Reception with Port- BRANCH OFFICES: Audio Amplification Los Angeles, 329 Union League Bldg. Coto compact Audio Amplify- able Set Minneapolis, Geo. F. Darling, 705 Ply- ing Transformer may be de- The Coto tapped Radio Fre- mouth Bldg. pended upon to give unusual quency Amplifying Transformer Atlanta, C. P. Atkinson, Atlanta Trust quality of amplification. The will operate with marked effi- Co. Bldg. ratio is low enough to avoid ciency. Write for folder of 8 CANADIAN DISTRIBUTOR: distortion and high enough to Radio Frequency diagrams in Perkins Electric Co., Ltd. give ample volume. Type 4000. one. Range 180 to 750 meters. Montreal, Toronto, Winnipeg $5. r I risirairnvuut IRWR la 1 ià