From A Treatise on Wireless Telegraphy

The Electrical Experimenter, vol. 1, no. 1–2, May–June 1913

Part Two: Wireless and the Layman

Receiving Wireless Messages

The question we hear from most beginners is:—“What outfit do you advise me to use? I know nothing about wireless.”[1]

We advise the use of ANY honestly built receiving outfits. Which one to choose depends upon yourself, your taste and your pocketbook. This is where YOU must decide. Of course the lower priced outfits have naturally a short range—they won’t catch messages hundreds of miles away, and those without tuning coils cannot be used to “cut out” one of the messages when two of them are in the “air” at the same time.[2] It is self-evident though, that you can start with the very cheapest outfit,—say an E. I. Co. detector and a pony telephone receiver.[3] With such an outfit messages can be picked up astonishingly well indeed. Many of our enthusiastic young friends started with such an outfit and kept on adding instruments till they finally had up-to-date stations.

The next question hurled at us is:—“How can I receive messages if I don’t know the codes?”

A wireless telegram, no matter if it is in Chinese or English, “comes in” in dots and dashes. When you have the telephone receivers to your ear and a message is coming in, you hear a series of long and short, clear, distinct buzzes. A long buzz is a dash, a short buzz is a dot. The E. I. Co. sell a 10¢ code chart by means of which the dots and dashes are translated into letters. Thus (in the Morse code), dash, dash, dot, stands for the letter G; dash, dash means M, dash, dot, dash, dot means J and so forth. Any person with a few weeks’ practice “listening to the wireless” can master the code, and read the messages with ease.

Remember that there are over two thousand high powered wireless stations in this country alone, each being able to transmit messages of over a thousand miles distance!

There are almost at any minute, during night and day, messages in the air, no matter where you are,—sending YOU messages, only waiting to be picked up by you. It is truly wonderful; it is the cheapest as well as the most elevating diversion known to modern man, the most inspiring example of the triumph of mind over matter.

“How about the Wireless Law?”, you want to know next.

The law does not apply for stations used for receiving only. There is no law which forbids you to receive all the messages you wish. You can receive as many and as long as you please,—Uncle Sam doesn’t mind. But you MUST preserve the secrecy of the message. You must not make use of any information you receive by wireless, if this information is of such a nature that makes it private property. Your own conscience will tell you which message to keep secret and which one you can make use of.[4] Here is the text of the Law:

Secrecy of Messages

“Nineteenth. No person or persons engaged in or having knowledge of the operation of any station or stations shall divulge or publish the contents of any messages transmitted or received by such station, except to the person or persons to whom the same may be directed, or their authorized agent, or to another station employed to forward such message to its destination, unless legally required to do so by the court of competent jurisdiction or other competent authority. Any person guilty of divulging or publishing any message, except as herein provided, shall, on conviction thereof, be punishable by a fine of not more than two hundred and fifty dollars or imprisonment for a period of not exceeding three months, or both fine and imprisonment in the discretion of the court.”

Of late a great many stations are beginning to use the wireless telephone. This art is rapidly being perfected and is the coming thing in “Wireless.” There is hardly a week that you do not read about some new wireless telephone and some new distance record established.

It is of course understood that any receiving apparatus that can receive wireless telegraph messages, 90 times out of 100, can receive wireless telephone messages. Of course, in that case no code is required as the voice comes through the receiver the same as through the regular telephone. (For further details on Wireless Telephony, see “The Wireless Telephone,” by H. Gernsback, at 25¢; also Lesson No. 18 of the E. I. Co. Wireless Course.)

Distance

The question asked mostly by the layman is: “How far can I receive with such and such an outfit, my aerial being so high and so long?”

Nobody can correctly answer such a question. You can reason it out as well as we can. For example: Would you ask us: “How far away can I hear the steam whistle of the X & Y Cotton Mill?” No, you wouldn’t, for it all depends. First, how hard the whistle blows, second, how good your hearing is, third, how the wind blows, and fourth, how many and how great are the intervening objects between the whistle and your ear. Some days you may hear the whistle two miles off with the wind blowing your way. Or if you are way down in the cellar you may only hear it faintly, although you are but two blocks away from it. It all depends. The one thing you are sure of is that the whistle blows with about the same strength each day. The same reasoning holds true for wireless to a very great extent.

As a rule, the higher up and the bigger your aerial, the better the wireless reception will be. Naturally if you are a thousand miles off from a station that can but send 500 miles, you won’t hear it, no matter how good your instruments are. It’s like trying to hear the sound of a whistle 10 miles away from you, that can at the very best be heard only within a radius of 5 miles.

Just use a little horse sense and you can do your own deducting: no wireless expert is required. It is also evident that the messages cannot come in with the maximum loudness unless the instruments are well in tune, and unless well designed instruments are used. Thus a loose coupler will give louder signals than a small tuning coil. It also depends a lot on the detector and its adjustment.[5]

This is the way the detectors range according to their sensitiveness:

1st. The Audion (the most sensitive detector to date); 2nd, The Electrolytic; 3rd, The Peroxide of Lead; 4th, The Perikon; 5th, Zincite and Bornite; 6th, Silicon and Galena; 7th, Iron Pyrites (Ferron); 8th, Carborundum; 9th, Molybdenite. (See Lesson No. 10, of the E. I. Co. Wireless Course, on Detectors.)[6]

If you are entirely surrounded by high mountains or steel buildings, you naturally will not expect to receive messages as well as if you were on the top of a mountain. Also remember that wireless waves travel twice as far over water as over land, and that you can reach twice as far after sundown than during the daytime.[7]

Wave Lengths and Tuning

This seems to be the greatest stumbling block for most beginners. Again let us make a comparison. Take two pianos and place them in the same room. Or two violins will do as well. Tune two strings, one on each instrument, so both will give exactly the same note. Pick one of the strings in order to sound it, and the other “tuned” string, although 10 feet away will sound in unison, although you did not touch it. Both are now in tune. Both give out the same (sound) wave length. No mystery here. The secret lies in the fact that both strings ARE OF THE SAME LENGTH, and have the same tension, roughly speaking. Make one string longer than the other and both are “out of tune.”

The same in wireless. Nearly all commercial stations operate on a wave length of from 300 to 600 meters. (A meter measures 39.37 inches.) Now in order that you can hear such a station, you must be able to tune up to 600 meters; roughly speaking your aerial should be 600 meters long electrically. That, however, would be a pretty expensive and cumbersome aerial. Besides it isn’t required. We simply wind, roughly speaking, 600 meters of wire on a coil or drum and our aerial can now be quite small, within certain limits of course, and we can for this reason “catch” the station having a 600 meter wave length, providing our other instruments are sensitive enough. Thus, for instance, it will be seen that the E. I. Co. No. 8486 tuning coil, as well as their No. 12002 loose coupler have sufficient wave length capacity to catch 700 meter waves. As they are both provided with adjusting sliders, more or less wire can be put into the circuit and therefore both these instruments can be used to catch wave lengths from 100 up to 700 meters, but not over this amount.

Therefore, if we should want to hear a station having 1400 meters wave length, we would connect two No. 8486 tuning coils in series, which would give us 700 + 700 = 1400 meters wave length. Or we would connect one No. 8486 tuner in series with the primary of the No. 12002 loose coupler and we would get the same effective wave length. As a rule only stations doing long distance work use excessive wave lengths, thus the Marconi Transatlantic station at Glace Bay has a wave length of about 7100 meters, while the new Government station at Washington, which sends messages over 3,000 miles, has a wave length of about 4,000 meters.[8] By consulting the “Wireless Blue Book” the wave length of all important wireless stations can be found, as each station normally uses a certain prescribed wave length. (See Lessons No. 4, 5, 6, 7, 8, 9, of The E. I. Co. Wireless Course.)

The best all around aerial is about 75 feet long, composed of four strands E. I. Co. “Antenium” wire No. 14, or stranded “Antenium” cable. One of the best forms is shown herewith. We recommend E. I. Co. No. 10007 insulators, although others can be used. For a 75 foot aerial, the strands should be about two to three feet apart. For a 150 foot aerial from three to four feet apart and so on. The strands should never be less than 1½ feet apart even for a very small aerial. All connections should be soldered if possible. Use as many insulators as feasible, remember you have but little energy when receiving; few and poor insulators waste 50 per cent. of the little incoming energy. If you have a good spacious roof it is not necessary to use poles to hold up the aerial. It may be stretched between two chimneys, etc. The spreaders to hold the wire strands apart may be of bamboo, wood, metal pipe, etc. If metal is used, the wire strands should be insulated from the former. (See Lesson No. 11, of the E. I. Co. Wireless Course, on Aerials.)

The ground is quite important. The best wire to use is a No. 12 copper wire run from the instruments to the water or gas pipe using one of the E. I. Co. No. 10003 ground clamps to make an efficient connection. If no water or gas pipe is to be had, bury a metal plate, copper preferred, not less than three feet square, in a good moist ground; a number of these plates connected to the ground wire would be preferable. It should be buried at least six feet deep. Another good ground is a six to ten feet long iron pipe rammed into moist earth, the ground wire being connected to it, either soldered, screwed, etc. The ground wire running from ground to instruments should never be less than No. 16 B. & S. copper, and can, of course, be bare. Insulation on a ground wire is just that much waste.

Connections and Hook-Ups

The diagrams given in the E. I. Co. catalogue No. 11 show how to connect most of these instruments. Their $.25 book “Wireless Hook-Ups” and their Wireless Course (Lessons 12 and 13), gives hundreds more of them, while their Engineering Department, on receipt of 10¢ to cover postage, will be only too glad to furnish any hook-up to be used in connection with their instruments. Connections should be made with nothing finer than No. 18 B. & S. copper wire (Annunciator wire). All connections must be as short and straight as possible. Avoid all wire crossings as far as practicable, if you can’t avoid crosses, the wires should cross each other at right angles; and NEVER wind the connecting wire in coils (“curls”) which may look pretty, but kills all wireless messages. Make all connections as tight as possible, a loose connection is worse than no connection at all.

Reception of Messages

We presume you have a complete receiving set. You proceed thus:

First, you must know if your detector is adjusted to its best sensitiveness. If no message comes in you don’t know if your detector is in its best receptive condition. For this reason, the up-to-date wireless man uses the “Buzzer test.” Aside from giving imitation wireless buzzes, the buzzer may be used to practice telegraphy. It consists of three things: 1st—Any buzzers, such as the E. I. Co. No. 954, or better No. 965 or No. 950: 2nd—E. I. Co. No. 1118 key; 3rd—A dry cell. Connections MUST be made as shown. Now every time you press the key you will get a perfect imitation of a wireless signal and it becomes child’s play to adjust the detector to its greatest efficiency. The buzzer test can of course be used with ANY detector. It saves lots of time and bother and is quite necessary. Sometimes a detector may have a “dead spot” and you will be “listening in” for hours, without being able to catch as much as one dot. The buzzer test makes such an occurrence impossible.

In order that the buzzer itself is not heard directly, it is usually wrapped in absorbent cotton or wadding which muffles its sound effectively, or it may also be placed in another room.

When the detector is adjusted the tuning coil (or loose coupler) is regulated by moving the slider or sliders back and forth till the sliders are heard the loudest. If the loose coupler is used the secondary is moved back and forth in addition, till the best position is reached. Now the variable condenser (or condensers) are adjusted if required.[9]

The variable condenser is of the greatest use during excessive “static,” which sometimes interferes seriously, during summer weather, especially when “taking” a long distance message. It is also of invaluable help to “cut out” unwanted messages when two or more are “coming in” simultaneously. Thus by adjusting the tuner (or loose coupler) in conjunction with the variable condenser it is often possible to cut out all interference from unwanted stations.

It is an excellent idea to have several detectors in a station, arranged in such a manner that by means of a multi-point switch any one of them can be thrown into the circuit. It will thus be found that some stations, especially during interference, can be heard better on a certain detector than on another. Some will be found to work best for long distance work, others work best for medium distances, etc., etc. (See also E. I. Co. Wireless Course, Lessons No. 8 and 9.)

Sending Messages

Let us quote the law, as far as the amateur is concerned, before going any further:

Let us explain in plain English just what this means: As you notice from the first paragraph, the part which we underlined, it is pointed out to you that the law does not concern you unless you send messages from one state into another. You therefore do not require a license as long as your messages do not reach over the border of your state and if you do not interfere with a station’s business (in your state) which receives messages from another state. Of course, you want to know how you can tell what your transmitting range is. We will explain.

It has been proved by experience with spark coils, that in almost all cases a one-inch spark cannot possibly reach over eight miles. From this information the following table has resulted:

Spark transmitting range.

Suppose you live in the city of Columbus, Ohio. The nearest state line is Kentucky, about 86 miles in a direct line from Columbus. If you do not wish to be licensed you can use any spark coil up to 10-inch spark, or a ½ K.W. close core transformer.

Suppose your home is in Austin, Texas. The nearest state line is Louisiana, a distance of 230 miles. Thus you could with perfect safety use, for instance, an E. I. Co. No. SO 200 outfit, which does not reach more than 200 miles.

It is also pointed out that if you live within five miles of a Government wireless station you cannot use more than ½ K.W. power, though the next state border might be 100 miles or more distant.

Of course if you live close to another state, as for instance, in New York City, you are required to take out a license for any size transmitter.

What the License Is

The license has not been created to muzzle you; it is the other way around. Uncle Sam gives you a written order telling you that you can send messages to your heart’s content, and no one can tell you to stop sending, as long as you do not create mischief.

The license is free, it costs not a penny. All that is required of you is that you are familiar with the law and that you can transmit messages at a fair degree of speed.

The law does not require that you take an examination in person if you are located too far from the next radio inspector. All you have to do is to take an oath before a notary public that you are conversant with the law and that you can transmit a wireless message. If you wish to be licensed—and we urge all amateurs to do so, as it is a great honor to own a license—write your nearest Radio Inspector (See below), and he will forward the necessary papers to you to be signed.

Radio inspectors are located at the following points: (Address him at the Customs House):

Boston, Mass., New York, N. Y., Baltimore, Md., Savannah, Ga., New Orleans, La., San Francisco, Cal., Seattle, Wash., Cleveland, Ohio, and Chicago, Ill. Also the Commissioner of Navigation, Department of Commerce and Labor, Washington, D. C.

In an interview with the New York Times, W. D. Terrell, United States Radio Inspector for the port of New York, said in discussing the new law:

So much for the law. Everybody will now understand that the law is just and fair and that it gives the amateur a distinct standing in America, a standing which he does not enjoy in any other country. He knows what he can do and what he can’t do, and no one can come to him and boss or abuse him, as Government or Commercial wireless operators were wont to do before the enactment of the law.

With sending outfits the reasoning is almost the same as with the receiving outfits.

In order to select an outfit you must, of course, know where and how far you wish to send. Upon all this depends.

As a rule two or more friends get the “Wireless bug” and order two or more complete transmitting sets. Of course, the outfits selected must necessarily be powerful enough to cover the intervening distance between the houses of the friends, and this only you know.

Therefore if you and your friend decide to converse by wireless and if the distance between your two houses is 10 miles you will buy either the E. I. Co. outfits No. SO-10 or SO-15 (SO stands for Sending Outfit, the number indicates the mileage that the outfit will cover). Of course, a more powerful set may be used, although there is no particular advantage in doing so, except, perhaps, that the incoming signals of necessity will be louder with the more powerful sets. It goes without saying that almost ANY receiving outfit which the E. I. Co. list can be used with ANY of the sending outfits. Bear in mind that the selections which they give with their sending outfits do not have to be used if not wanted. Thus their “Interstate” outfit or even their “Transcontinental” receiving outfit can be used with their SO-¼ set. For if you and your friend live one-quarter of a mile apart and both of you have SO-¼ Sending outfits, you probably want to have a receiving outfit with which both of you can pick up messages 2,000 miles distant. In that case you would order two SO-¼ sending outfits only, and two RO-2000 outfits, or else two “Transcontinental” receiving outfits. If either you or your friend feel that you cannot afford such a set, why then get the set that you can afford best and that suits you best. As you see there is no hard and fast rule about the relation of sending and receiving outfits. On the other hand we don’t have to tell you that if you wish to obtain two SO-200 outfits you require of necessity a good receiving outfit, else you couldn’t hear the station 200 miles off. A little common sense will help everyone decide just what combination to order.

Like receiving sets, the transmitting sets are divided into two groups. The untuned (open circuit) and the tuned (closed circuit) ones.

The untuned ones have, 1st—a spark coil, 2nd—source of power, usually dry cells or a storage battery, 3rd—the spark gap, 4th—the key.

Such outfits can be used only for very short distances and should never be used above three miles. When connections are made by following the blue prints, which is supplied with all sets, the pressing of the key gives a strong spark in the spark gap. The spark gap (the open space between the zinc plugs) from the smallest to the largest sets, must never be more than one-eighth to three-sixteenths of an inch. A bigger gap does not work. Pressing the key long gives a dash, pressing it but for a fraction of a second gives a dot. Combinations of these represent the telegraphic characters; the code can be learned in a few weeks, practicing twice a day from one-half to one hour. (See Lesson No. 15, of the E. I. Co. Wireless Course.)

In the tuned outfits, we have in addition to the above enumerated apparatus: 5th—The Leyden jars, or condenser; 6th—The Helix, or oscillation transformer. The Leyden jars change the red spark obtained from a spark coil, into an intense blue-white crashing spark. The Leyden jars also create a train of fast oscillations and go to make the outfit far more powerful although no more battery power is required. The Leyden jars also give better “carrying power,” as the signals can be heard more distinctly and not “mushy” as if no Leyden jars were used. For each outfit the best jars or condensers have been selected by the company and no changes should be made here.

The helix as well as the oscillations transformer, are, to the sending outfit, what the tuner and the loose coupler respectively, are to the receiving outfit.[11] The helix or the oscillation transformer is the tuning coil pure and simple for the transmitting station. Like the tuning coil the helix and the oscillation transformer have sliders or else clips by means of which more or less wire convolutions can be put in the circuit of the aerial. Therefore more or less wire, and consequently more or less wave length is added to your aerial. Again there is not much of a mystery here. Anyone understands it. (See E. I. Co. Wireless Course Lesson No. 14.)

In the larger sets where the battery power is insufficient as well as un-economical we have two methods open to fill the gap. One is the Gernsback electrolytic interrupter working on 110 volts Direct or Alternating current, which supplies the spark coil (transformer coil) with the power;[12] the other method requires the use of a closed core transformer operating without any kind of interrupter direct from the alternating current supply. This kind of transformer, however, does not work on the direct current, not even in connection with the electrolytic interrupter. The choice, for this reason lies entirely with you.

The aerial switch is an absolute necessity where both a sending and receiving set is used in one station. If you are through receiving a message from your friend, you, of course, wish to answer him. You therefore, must switch the receiving set off from your aerial and switch the sending set onto the aerial. The aerial switch does all this in one operation.

For sets using nothing higher than a 2½-inch spark coil an ordinary double pole, a double throw switch may be used. For heavier sets using more power the E. I. Co. Antenna switch No. 8100 must be used, as the smaller switch cannot carry the necessary power.

Sending a Message

In order to send messages it goes without saying that you must know how to “tap the key.” The easiest way to learn and the cheapest way at the same time, is to get a buzzer set as explained under “Reception of Messages.” With this set, which represents a first class learner’s outfit, you can send yourself dots and dashes to your heart’s content until your wrist has limbered up sufficiently to do rapid sending. After a few weeks’ practice it will be as easy to send a telegraphic message as to write on a typewriter.[13]

If your friend has a wireless and starts learning the code with you, it becomes very simple for both of you to soon become proficient in the art. Each will send to the other, the Morse or Continental alphabet, which is sent back and forth till the right speed is obtained. After this certain words are exchanged between the stations; later on short sentences are sent and so forth, till it becomes possible to converse freely by wireless.

There is but little adjusting to do when sending. As a rule amateurs converse with only one, seldom two, and rarely three stations. For this reason much adjusting is unnecessary. When using a small set comprising spark coil, Leyden jars, and helix it becomes necessary to adjust the Leyden jars. Either more or less jars (which adds more or less capacity to the circuit) are used till the spark sounds loudest in the spark gap and appears most powerful. A little experimenting will quickly tell when the right capacity is used. It is important to understand that the capacity should be adjusted only when the spark gap is connected to aerial and ground. (See Lesson No. 14, E. I. Co. Wireless Course.)

The next important adjustment is in the helix (or oscillation transformer if this is used in place of a helix). To change the clips around on the helix (or on the oscillation transformer) it is necessary that a small gap is first made in the aerial circuit. This is done best by driving two nails in a piece of very dry wood, and connecting the aerial wires to each nail as shown in sketch. The two wires, A and B are brought close together now and when the key is pressed down a small spark will jump from A to B showing that you are changing the aerial and that energy is radiated from same. Now change the adjustment on the helix (or oscillation transformer) till the longest and fattest sparks jump between A and B. To do this A and B are separated until a point is reached where the spark cannot jump any further. You know now that you are radiating the maximum of energy and the point on the helix (or adjustment on the oscillation transformer) should be carefully marked so you will know at any time just where the maximum is. It goes without saying that you should also note how many Leyden jars (or how many condensers) you are using when making the test and you should write this information down, for if you were to use more or less Leyden jars (or condensers) you would have to change the adjustment on the helix (or oscillation transformer) as explained above. Now after the maximum “radiation” has been ascertained, the test block with the nails is discarded and the break in the aerial wire connected again. You know now that your station is radiating the maximum energy and adjustments of the sending set will not be required for some time to come. Indeed they may be left undisturbed indefinitely.

We believe that we have made everything as plain as possible and that by reading this treatise the elementary points of “Wireless” must become plain to even the layman. If, however, you desire additional information, we will be only too glad to answer your questions promptly and explicitly. Now it’s up to you to get busy and “start something”!!

Notes