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How to enjoy popular radio broad- casting. With complete instructions and description of apparatus.
For those who desire to be entertained with radio concerts, lectures, dance music, and for the radio amateur and experimenter.
PRICE THIRTY-FIVE CENTS
June 1, 1922
SALES DEPARTMENT
233 Broadway New York City
DISTRICT OFFICE
10 South La Salle Sc. Chicago, 111.
UNIVERSITY Of ILLINOIS LIBRARY
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RADIO CORPORATION OF AMERICA
Completing Sets at the Westinghouse Electric and Manufacturing Company's Radio Works, Springfield, Massachusetts
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Introduction
Radio Enters T3 ADIO has placed a the Home X\. new, inspiring and powerful resource at the disposal of civilization.
With magic touch it has relieved isola- tion and neglect on land and sea.
It has given the voice of hope and sal- vation to ships and passengers whose despair and tragic fate formerly were shrouded in silence.
It has brought new romance into the world to replace the exploits of Paul Re- vere and John Paul Jones. It travels swift as light, not through one valley, or on one lonely sea, but to the world at large on the wings of the ether.
Radio answers the call for more liberal education of nations and peoples, and per- meates the remote places of the earth with the cultivating influence of music.
Radio telephony, following closely up- on the heels of radio telegraphy, is sweep- ing the country, carrying into the homes of rich and poor alike a modem facility of pleasure and education which is binding the people together in a new and demo- cratic brotherhood.
A richer and more complete home-life, with mental stimulus and pleasant relaxa- tion, has been made possible through broadcasting and its receiving corollary, the radio telephone receiver.
First Taste To the Westinghouse
of Electric & Mfg. Company
Broadcasting is accredited the first
successful attempt at or- ganized broadcasting. This took place on November 2, 1920, at Pittsburgh, Pa., when “KDKA” broadcasted the Harding- Cox Presidential returns to thousands of expectant citizens.
Later, at the New York Electrical Show of October, 1921, a prominent artist sang to an audience of listeners in thousands of homes in and around New York. She was amazed when there came back through the ether to the concert room immediate requests for an encore. While the major-
ity, with their telephone receiving sets, merely listened, the request for the encore came from many amateurs who were equipped with sending sets.
In a like manner, nearly 200,000 radio enthusiasts, located hundreds of miles away from the ringside at Jersey City, received reports, round by round, of the Dempsey-Carpentier bout.
From a national standpoint, however, the full significance of radio telephony be- comes apparent when it is possible for the President of the United States to address the people of the country clearly and im- pressively on special occasions. The sug- gestion has already been made in Congress that the debates of both upper and lower houses be broadcasted by radio.
In the great centers where broadcasting is in full swing, where theatrical stars and famous speakers have been heard by fam- ilies sitting, miles away, around their own fireside, life has literally been made over for boy 8 and girls, their fathers and mothers, the strong and well, the blind and the bedridden. Radio concerts have become the order of the evening in tens of thousands of American homes within the radius of the broadcasting stations.
Advanced scientific and engineering efforts have simplified radio receiving of concerts to the point where anyone, with- out experience or study, can enjoy the new national resource.
Not only have home concerts become a national pastime, but dancing to the music of famous orchestras playing in person for the benefit of radio "fans,” has established itself as a permanent recre- ation.
From the oldest to the youngest — fathers and sons listening to baseball scores — mothers and daughters to the brief fashion talks — the whole family to some church service — farmers to the crop and weather reports — lawyers, doctors, clerks, messengers, captains of industry — all equipped for some feature of this new and amazing thing called radio broad-
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casting. No art or science has ever, nor probably ever can, touch the lives of all the people more intimately.
With broadcasting rapidly reaching a national and comprehensive stage, the time is not far distant when every home in the United States, from hut to mansion, will be equipped to “listen in” while the Government makes its reports of crop and weather conditions, while the news of the day is briefly recited, while statesmen plead for united action, while famous ar- tists sing to a larger audience than they have ever known, while splendid bands and orchestras inculcate the taste for music.
Today, clocks and watches are being checked by the U. S. Navy radio, while
both the Department of Agriculture and Post Office Department are communicat- ing with the whole nation through radio.
These reports, like the fashion talk to women, bedtime stories for children, base- ball scores and concerts constitute at the various broadcasting stations a definite program, running on a schedule an- nounced in newspapers and usually cov- ering the day from ten o’clock in the morning until ten at night. And when the- listeners want to retire they merely turn off a switch.
For the sick in hospitals small watch- case telephone receivers are placed near each bed, and the patient “listening in" may enjoy broadcasting without disturb- ance to a neighbor.
WHAT EVERYONE OUGHT TO KNOW ABOUT
BROADCASTING
The American Boy has taken to Radio with an enthusiasm probably greater than any
other subject of the day.
THESE pages are designed to show you how you can have musical entertainments in your home, the things you ought to know about broadcasting, what a radiophone broad- casting receiving set consists of, how to install and operate one, the things you ought to know so that you can select the type of set suited to your purse and your particular locality.
For the novice, who knows nothing of the technique of radio and simply wants to enjoy
the popular advantages of listening to news, lectures and concerts, the only question which he needs to settle for himself is whether his home is near a broadcasting station. These stations already spot the whole country, but, naturally, the radius of none of them is na- tional.
At the time of this writing there are active, licensed high-powered broadcasting stations in Newark and Jersey City, N. J., New York City,
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N. Y.f New Haven and Hartford, Conn., Springfield and Medford Hillside, Mass., Washington, D. C., Pittsburgh and Philadel- phia, Pa., Indianapolis, Ind., Toledo and Cin- cinnati, Ohio, Detroit, Mich., Chicago, 111., Madison, Wis., Omaha and Lincoln, Nebr., Minneapolis, Minn., Kansas City, Mo., Denver, Colo., Los Altos, Pasadena, Los Angeles, Hollywood, Oakland, Sacramento, San Fran- cisco, San Jose, Stockton and Sunnyvale, Calif., and Seattle, Wash. More stations are being opened every day.
The Government operates the stations that send crop and weather reports, while others are operated by manufacturers, newspapers, department stores, public spirited bodies, mu- nicipalities, etc.
It is a very simple matter to ascertain whether you are within reasonable radius of one of these stations. Wherever you see * Radio Corporation of America sets or appara- tus in a window or advertised over a dealer's name, you can get a quick answer to this simple, but at present, important question.
Variable Range All the stations, in the Versus Reliable present state of develop- Range ment, have a variable range
and a reliable range. There have been many amazing achievements in transmitting, as, for instance, when amateurs flashed messages from this country to Scotland. Amateurs have been responsible in large measure for the present development of the art, but while they, with their thorough knowl- edge, based upon experimentation, are daily achieving the extraordinary, those interested in reception of popular broadcasting are naturally more concerned with the average, reliable transmission from the broadcasting stations.
The number of miles any receiving set will cover in its operating radius is subject to varia- tions caused by such factors as the location of the station itself — whether, for instance, it is located in the open country or is surrounded by buildings with steel frame works. Where this is the case, the range of a given receiver is found to be somewhat shorter than under the above conditions. For this very reason, in the catalogue sections of this book, the ranges given for receiving sets are conservatively estimated.
Formed in response to a suggestion of repre- sentatives of the United States Government, the Radio Corporation of America has steadfastly pursued a policy based upon a sense of responsi- bility to the public. The distributors of R.C.A. sets and apparatus have been selected care- fully and these distributors, as well as the dealers through whom they sell to the public, may be relied upon to give expert advice in the matter of selecting suitable equipment for every need.
No Technical Between the “amateur0 — a Knowledge term that has become synony- Is Required mous with experimenter, en- thusiast, expert — and the nov-
ice— the latter constituting the very large part of the public keenly interested, but interested only in the telephonic, non-technical reception of broadcasting — there is a considerable gulf. The amateur who, after studying the code, re- ceives his first intelligible message in tele- graphic code, thrills to a sense of scientific or mechanical proficiency. Technical portions of this book and catalogue are for the amateur.
The family group, unconcerned and unin- terested in code or technical study, thrills in its turn to an entirely different emotion — an emo- tion responsive to the dramatic realization that it is now possible to spend an evening in your own home with great artists entertaining you “in person;" with news of the day coming to you before it is printed in a newspaper; with statesmen and lecturers replacing each other in the program designed to please you.
While it is possible to use the smaller, in- expensive telephone receiving sets when near a broadcasting station, the larger sets give greater radius. With some sets, there is no more need for study or adjustment than in the case of a phonograph. It is merely a matter of moving an indicator until you hear what you want to hear — a resume of the day’s news, weather reports, time signals from a central observatory, such as the one located in Wash- ington, D. C., market reports, special lectures by medical authorities on sanitation and hy- giene, lectures by Government officials, time- ly political discussion, opera, music — whatever the program may happen to be.
Brushing up Occasionally, you may hear Conversationally someone say that the con- cert last evening was not quite up to standard, because of “static."
Stripped of technicalities, “static" is a nat- ural atmospheric interference. Radio waves in their passage through the ether travel in waves similar to the waves at the seashore. Short wave lengths are used for short distance, low power work. Long wave lengths are em- ployed for long distance, high power work. “Static" is caused by stray, natural, electrical discharges, traveling* through the same me- dium. It is difficult to tune them out of the way. They are natural little violators of man- made traffic laws. Science is working hard to harness them. They are more prevalent by day than by night, far more troublesome in summer than winter.
One difficulty, which has previously been experienced in radio broadcasting when ap- plied to concert work, was that of securing proper loud-speaking devices — devices which would give forth sufficient volume of sound so as to be heard in a large room by a great num- ber of people. In this connection, a new class of amplifying and loud-speaking apparatus is now finding favor in radio concert work.
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THE BROADCASTING STATION
A famous star sinking to the **unseen audience*' from radio receiving station.
AT present there are perhaps 125 to 200 , radio telephone broadcasting stations in the United States which are regularly sending out news and entertainments to the hundreds of thousands of listeners who have receiving apparatus. They are located in the larger cities, which is essential for two reasons: that their programs may reach the largest num- ber of people possible and that artists of rec- ognized ability may be secured to join the other entertainers.
A broadcasting station is generally divided into two or more rooms. The studio, with its piano, phonograph and other equipment for the artists, resembles the music room to be found in a home, except that the ceiling and walls are generally covered with some cloth or material which will eliminate any reverber- ating sounds or echoes.
One or more small “pick up” instruments known as microphones, mounted on standards, are usually the only pieces of electrical ap- paratus to be found in this room. Wires from these convey the voice or music into another room, which in many cases is at quite a dis- tance from the studio. The latter resembles a laboratory with its various pieces of electrical apparatus, transmitting vacuum tubes, panel boards, storage batteries, etc. Here the music or speech is put through a number of steps of amplification by means of smaller vacuum tubes which increases the volume of the sound waves thousands of times. The amplified speech currents then enter another bank of vacuum tubes, known as modulators or molders of the electric waves sent through the ether.
Vacuum tubes, made in the same manner
and containing the same number of elements as the small tubes used for receiving, but much larger and therefore capable of handling more power, usually are used for radio broadcasting.
Direct current at a high voltage is necessary for the operation of a transmitting station. To obtain this, a low voltage alternating current, such as used for lighting purposes in the home, is boosted to a high voltage by means of a motor-generator. This voltage is then applied to a number of vacuum tubes. The electric power supplied to these tubes causes electrical oscillations in the aerial wire system known as the antenna, and the antenna in turn radiates electrical waves which are molded to the form of the inflexions of the voice or of music, by other tubes termed modulators.
The power used at a broadcasting station is measured by the energy delivered to the an- tenna system, rather than the energy taken from the power lines. For this reason the rated power of a broadcasting station seems rather low to the uninitiated.
Many of the broadcasting stations employ 500 watts of radiated energy, which is equiva- lent to nearly one horsepower. However, one of the largest broadcasting stations in the United States, located in Schenectady, New York, and owned by the General Electric Com- pany, has facilities for greater power, but this is used only for special experimental tests. The masts used to support the antenna at this sta- tion are 183 ft. high and have been erected on the roof of a five story building.
Operators at broadcasting stations must possess the faculty of clear diction; they must be able to carry on a conversation in moderate tones sufficiently modulated and at low enough speed to insure correct and fault- less reception at all the receiving stations.
A comer of the Radio Corporation — Westinghouse Station ‘•WJZ,#.
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The average range of the several high power broadcasting stations now in ^existence is 100 to 500 miles, although the stations main- tained by the Westinghouse Electric and Mfg. Co., the General Electric Co. and the Radio Corporation of America have been heard over several thousand miles. In one instance an operator on board a ship more than a thousand miles at sea received a complete concert from a broadcasting station near New York with great enough intensity to pass it over the ship's telephone lines to 25 different staterooms at the same time.
It is estimated there are between 500,000 and 750,000 receiving sets in use, and artists at the larger broadcasting stations have had their entertainment heard by more than one hundred thousand people simultaneously.
As previously explained, the range of a receiving station depends upon a number of variable factors and the distances pointed out here have been covered by receiving stations employing sensitive apparatus, involving sev- eral stages of vacuum tube amplification. These facts should be considered in purchasing radio receivers.
THE FIVE FUNDAMENTALS OF RADIO RECEPTION
MOST of us know that there are various types of apparatus for the reception of radio broadcasting. Some of these "sets," as they are called, are more sensitive than others. Sensitivity, in the sense we apply it to receiving sets, is a quality analogous to power in transmitting apparatus. Most re- ceiving sets, have five distinct functions — in- tercepting, tuning, detecting, amplifying and reproducing. It will be helpful to us later, when we consider receiving sets as complete units, if these functions are understood.
Intercepting
"Antenna" and "Ground," the externals of a radio receiving set, intercept the broadcasted signals and lead such energy as they collect to the receiving set by means of wires. In prac- tice the ground usually consists of a wire con- necting a certain binding post or terminal connection on the set with a water pipe, or other metallic conductor which leads to the ground. The antenna, in its simplest form, may consist of a single bare wire, thoroughly insulated from adjacent objects, seventy- five to one hundred and twenty-five feet long and raised horizontally to the earth as high as pos- sible. This also is connected with the receiv- ing set by means of a wire called the lead-in; details for the installation of the ground and erection of antenna are furnished in printed directions which accompany every set sold by the Radio Corporation of America.
Tuning
AH radio broadcasted speech or other sig- nals arrive at the receiving antenna on a defi- nite radio wave length, that is, the wave length to which the broadcasting station is adjusted or "tuned." Every sound we hear, therefore, is carried through space by electrical waves, but these electrical waves are not audible to the human ear until, first, they have been "tuned in" at the receiver, and second, made audible by the "detector" and the head tele- phone. Tlie radio transmitting station does
Every living room of the average home become* a radio receiving station.
not radiate fa. "sound wave." It radiates an electrical wave which serves to carry through space the inflexions of the human voice or of music or of telegraph signals.
Tuning, as applied to radio, means the ma- nipulation of wave changing controls on the re- ceiving set so that the apparatus may be adjusted for a maximum signal from the broad- casting transmitting station. Once the receiver has been tuned to the wave length of the dis- tant station, no further tuning manipulation is necessary for the reception of the entire con- cert. Nor is tuning a difficult operation for the beginner; all that has to be done is to turn the controlling knobs or levers on the tuning elements until the signal is heard loudest.
Detecting
The detector rectifies or "changes" the energy received by the radio set into a form of energy which will produce an audible sound in a reproducer such as the head telephone or loud speaker. There are two classes of de- tectors, mineral crystals, and vacuum tube de- tectors. A vacuum tube detector is better
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than the crystal detector because it is much easier to adjust and it performs its functions with greater efficiency as it amplifies incoming radiophone signals many times.
A receiving set equipped with a crystal de- tector is known as a “crystal receiver*’; a receiving set which employs a vacuum tube detector is called a “vacuum tube receiver**; a receiving set using a vacuum tube detector which has special means for amplifying signals is called a “vacuum tube regenerative receiver.**
Amplifying
Amplifying devices are used when the re- ceiving set is far removed from the broadcast- ing station, or when it is desired to have the received signals actuate a loud speaking device.
The essential of an amplifying device is the vacuum tube. Each vacuum tube utilized in such apparatus (not to be confused with the detector tube) is known as one “step** of am- plification.
Amplifier tubes operate on an electrical principle analogous to the mechanical princi- ple of a firearm. Pulling the trigger of a gun requires very little physical energy, yet it re- leases a terrific energy stored in the shell in the form of powder. When energy is impressed on the amplifier tube, it “triggers off,** from a battery storing electrical energy, a given signal having many times the energy of the original.
In some receiving sets, the tubes are so placed as to amplify the signal before it is fed to the detector tube. This is called “radio fre- quency amplification.” In other sets, the tube
is made to amplify the signal after it has passed through the detector. This is known as * ’audio frequency amplification.'* Where extreme amplification is desired, the set may contain amplifier tubes in both positions.
Reproducing
The function of the reproducer is to con- vert the energy which has been passed through the various apparatus described above from electrical pulsations into sound waves. A pair of head telephones constitute one type of re- producer. Another is the loud speaker, con- sisting of a sensitive telephonic reproducer at- tached to a suitable sound chamber or horn.
A very slight vibration from the head tele- phone will suffice to convey the sound to the ear. On the other hand, a loud speaker, to make the signal audible over an entire room, must have a diaphragm vibrating vigorously. Obviously, a loud speaker requires a signal of much greater intensity than a telephone head- set, and it is one of the functions of amplifica- tion to furnish this louder signal.
General Remarks
The strength and quality of the audible sound made by the reproducer is directly de- pendent upon how well each of the five func- tions is performed by the receiving set.
Crystal receivers do not amplify signals; they simply tune, and rectify or change the energy at the detector and pass it directly to the reproducer, which is invariably a head tele- phone set.
The Radio Concert becomes a reality by the use of a combination receiver-amplifier unit in conjunction with
loud speaker.
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CLASSES OF APPARATUS AND THEIR APPLICATION
ONCE any of the telephone receiving sets, intended for concert reception, is in- stalled in your home, there is no need for technical knowledge. The usual questions that are asked can be briefly answered here:
“How much will it cost and what distance will it carry?’* “ Do city conditions differ from those of the country in regard to radio recep- tion?”
In general it may be said that there are four classes of radio apparatus, each one designed at a specific price and for a specific use. These are:
( 1 ) The simple circuit crystal type re- ceiver which may cost from $18 to $50, and which may receive effec- tively from five to twenty- five miles, according to skill in setting up an- tenna, and atmospheric conditions.
Crystal detector apparatus necessitates the use of an outdoor aerial, and reception is accomplished by means of head tele- phone receivers.
(2) This class of apparatus may be said to be practically the same as Class 1, except in this instance we depart from the simple crystal detector to the vacuum tube detector, with an improvement in receiving qualities. The cost in this instance may range from $65 to $100.
It is also necessary to employ the outdoor antenna, as well as the head telephone receivers. It is not possible in this in- stance to make use of loud-speaking de- vices, for the energy received by the sin- gle vacuum tube detector is not strong enough to handle the loud speaking de- vice unless the set is located within 2 or 3 miles of the transmitting station.
The "Man in the Moon" in action at "WDY" Broad- casting Station formerly at Roselle, N. J.
Bed time stories and music by radio have delighted thousands of little tots within a radius of several hun- dred miles from Newark, N. J. and New York.
(3) In this class, it is also necessary to use the antenna and ground contact of the other systems mentioned. But much greater efficiency is obtained because vacuum tube amplification is employed. Receivers of this type usually consist of a receiving or tun- ing unit, a vacuum tube detector and two stages of vacuum tube amplifi- cation. This type of receiving equipment may cost from $150 to, possibly, $300. It has a much greater range of operation than the other types, and will function quite well up to 100 miles, although un- der exceptional receiving conditions, as much as 1 000 miles may be ob- tained, employing the head tele- phone receivers.
It is also possible, in this instance, to em- ploy a loud speaker and thus eliminate the head telephone receivers, thereby permitting a roomful of people to hear radio. The extra two stages of amplifi- cation permit this, for they increase the original intensity of a signal to such a point as to effectively operate the loud speaker.
(4) This is the de luxe type of radio re- ceiver, usually embodied in a com- plete cabinet, similar to that of the phonograph. All necessary instru- ments are enclosed in the cabinet and the tuning and adjusting de- vices are greatly simplified. It is designed for the use of the techni- cally uninformed general public. A unit known as the “Aeriola Grand” is now on the market which in- corporates these desirable features, and which is sold for $350.
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RADIO BROADCASTING RECEIVING OUTFITS
AERIOLA JR. RECEIVER, MODEL RE
Aeriola Jr. is compact, inexpensive, requires no bat- teries, and is easy to operate
tuner control arm with relation to the cali- brated dial. With Aeriola Jr. there is no main- tenance cost Once the antenna has been erected and the ground connection made ac- cording to the instructions given, it is only necessary to adjust the detector and rotate the tuner control arm until radio signals are heard in the head telephone receivers. The wave- length range of Aeriola Jr. is particularly adapted to broadcasting reception on the 190- 500 meter wavelength band.
Reliable and Inexpensive
Aeriola Jr. includes everything necessary for this type of receiver — a tuner, a fixed con- denser, a supersensitive crystal detector, and a high grade set of head telephones. In order to secure the best results from this outfit it is but necessary to follow the directions given in another section of this book and devoted to the erection of the antenna and securing the ground connections.
AERIOLA JR. is a complete Radio receiv- ing outfit designed and manufactured by the Westinghouse Electric and Manufacturing Company. Its range varies from ten to twenty miles. Any one who can operate a talking machine or a camera can operate an Aeriola Jr.
Simple Adjustments
No technical knowledge is required. The only adjustments necessary include the occa- sional finding of a 'sensitive spot** on the crystal detector and the simple turning of a tuning control arm to obtain the maximum in- tensity of reception.
The complete receiver is built in a very sub- stantial and attractive wood cabinet which has a compartment for storing the telephone re- ceivers when .the set is not in use.
The tuning elements and the crystal detec- tor are mounted on a black panel which forms the top of the receiving set when the cover is lifted. All the metal parts are finished in nickel. Under the tuning control arm, there is a calibrated dial. Where the receiving sta- tion is within range of several broadcasting stations operating on different wave lengths, it is possible to determine just what setting is necessary in order to hear any of the stations at a given time by noting the position of the
The entire design assures a degree of se- lectivity and reliable operation not usually found in this type of receiver.
Aeriola Jr. may ordinarily be employed for receiving from the broadcasting stations up to a maximum distance of 20 miles. Under some circumstances this range may be increased; often the Aeriola Jr. will pick up broadcasting over distances up to 35 miles.
The farmer located within easy distance of a broad- casting station may use Aeriola Jr. to advantage for the reception of market and weather reports.
Aeriola Jr. Makes an Ideal Set for the Beginner. It is Portable, Compact and Inexpensive.
Requires no Batteries of any Kind.
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OPERATING INSTRUCTIONS FOR AERIOLA JR
Text numbers correspond with above diagram.
No. 1. First, refer to accompanying sketch, adjustment, rotate tuning handle (6) slowly
then erect antenna and place protective over the scale, listen until sound is heard
device in position as described on page 56. in the telephone receivers. Temporarily
No. 2. Connect a wire leading from terminal ?toP adjustment of detector and manipu-
marked R on protective device to binding late tuning handle until maximum strength
post indicated by arrow for stations below 18 obtained. Leave tuning handle m this
.350 meters. position and readjust detector. After a
.. ’ _ . short time, the operator will become skill-
No. 3. For stations between 350 and 500 ful in finding delicate adjustments on thia
meters, connect the above wire to this crystal detector. Various stations may be
P°8t* heard by simply rotating the tuning handle
No. 4. Connect this post with terminal G of over scale.
protective device. Note: As crystals are rubbed together, a
No. 5. Connect telephone receivers to these black deposit appears on the movable crys-
two posts. Adjust detector by pulling tal, decreasing the sensitivity of the set. TTiis
movable crystal away from stationary crys- deposit may be scraped off lightly with a knife,
tal and then allowing it to come in contact Further precautions regarding the care of crys-
again at various points. While making this tals are pointed out in part 4 of this book.
Complete Aeriola Jr. Broadcasting Receiver, Model RE, 190-500 Meters, with Head Tele-
phone Receivers, Spare Crystals, Antenna Equipment and Full Instructions $32.50
Aeriola Jr. Broadcasting Receiver, Model RE, as above, less Antenna Equipment $25.00
Dimensions: 7 in. x %Yi in. x 7J4 in.
Weights: Net, 5 lb.; Shipping, 10 lbs.; with Antenna Equipment, 17 lbs.
NOTE: For Prices of other Complete Receiver Combinations , see page 35.
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RADIO BROADCASTING RECEIVER, MODEL ER-7S3
ALL that radio broadcasting has to offer from the opera to dance music, from dis- courses by world-famed lecturers to bed-time stories for the youngsters, is brought into your home by this simple receiving set. You listen to the news of the day, market reports and time signals sent out by United States Gov- ernment stations; you hear popular entertain- ers in person singing their hits of the day, or telling jokes; in a word, the world’s celeb- rities become visitors to your home and friends of your family. And best of all you need learn no code or have any electrical knowledge — simply run a wire into the air and connect another in the ground and you have at your command, news, instruction and enter- tainment.
Compact and Portable
The unit may be used with the antenpa equipment described in the following pages and which may be installed by either novice or expert in a very short time.
The front panel is made of a high-grade in- sulating material radially embossed as shown in the accompanying illustration. By merely sliding this panel from its normal position, the metal cabinet may be opened to receive the telephone headset supplied. This arrange- ment makes the set completely portable. When it is not in use, it may be closed up so that there are no exposed loose wires.
An indicator on the front of the panel is turned when it is desired to hear signals from different stations. By means of this simple control you change from one station to an- other and bring in signals from any station at
their greatest strength. At the same time pos- sible interference from other stations is avoided.
This practical receiver covers a band of wave lengths from 180 to 700 meters in two steps. The antenna connections for these two ranges are clearly indicated on the front panel. These ranges are from 180 to 400 and 300 to 700 meters respectively.
This outfit is sold with one pair of telephone receivers, but several pairs may be employed in conjunction with the four point telephone jack UD-486. Where this jack is used each pair of telephone receivers should be Con- nected with a telephone plug UD-824. The method of employing this jack and plug sys- tem is fully described elsewhere.
Easy to Install and Operate
Radio receiver ER-753 may also be used in conjunction with the amplifying apparatus de- scribed in this book. When the proper antenna is used and the distance from a broadcasting station does not exceed 20 or 25 miles, the addition of vacuum tube amplifying apparatus in this instance, permits the use of a Vocarola loud speaker or the phonograph attachments described on page 55.
This receiving outfit is complete and is so simple that even a child can easily learn to operate it. Within its range amateur and commercial stations can be heard, but its greatest application is found in securing at a very small cost all the enjoyment radio broad- casting makes possible.
This compact receiver is a product of the General Electric Company.
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Radio Receiver Model ER-753 is furnished with a pair of high grade Head Telephone Receivers.
A compact and effec- tive receiver for short distance reception.
Ideal for use in cities served by a local broad- casting station.
OPERATING INSTRUCTIONS FOR RADIO RECEIVER ER-753
No. 1 . First, refer to accompanying sketch, then erect antenna and place protective de- vice in position as described on page 56.
No. 2. For 180 to 400 meter range, connect a wire from terminal R of protective device to this binding post.
No. 3. For 300 to 700 meter range, connect this post to terminal R of protective de- vice.
No. 4. Connect this post with terminal G of protective device.
No. 5. Adjust detector movable arm and thumb screw until minerals just touch each other. Slowly move large knob pointer over scale. When signals are heard make further adjustment of the movable con- tact on the detector.
Note: As crystals are rubbed together, a black deposit appears on the movable crystal, decreasing the sensitivity of the set. This de- posit may be scraped off lightly with a knife. Further precautions regarding the care of crystals are pointed out in Part 4 of this book.
Complete Radio Broadcasting Receiver, Model ER-753, 180-700 meters, with Head
Telephone Receivers, Antenna Equipment and Full Instructions $25.50
Radio Broadcasting Receiver, Model ER-753, as above less Antenna Equipment $18.00
Dimensions: 8 in. x 5J4 in. x 5 in.
Weights: Net, 5 lbs.; Shipping, 10 lbs. with Antenna Equipment, 17 lbs.
NOTE: For Prices of other Complete Receiver Combinations , see page 35.
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RADIO
CORPORATION
AMERICA
RADIO CONCERT RECEIVER, MODEL AR-1375
A High Grade Crystal Receiver of superior workmanship
Operates on all practical wavelengths of amateur and broadcast stations
Wavelengths 170 to 2650 meters
THIS receiver was designed by the Wireless Specialty Apparatus Co. to fill the need for a high-class crystal receiver covering a wave- length range of 1 70 to 2650 meters, thus per- mitting the reception of broadcasted concerts as well as daily time signals sent by Arlington (Radio, Va.) on a wavelength of 2500 meters. The entire unit is built in an artisti- cally finished metal case, having a bakelite dilecto front panel. The set is sold complete with a pair of highly sensitive telephone re-
Wave Changing Switch
A wave change switch having three posi- tions is mounted on the left hand side of the panel, providing three distinct wavelength ranges; 170-410, 350-965, 925-2650 meters. Variations between the lower and upper por- tions of these three ranges can easily be ob- tained by manipulating the tuning knob found in the center of the front panel.
The tuning knob is provided with an indi- cator which moves over a graduated dial engraved directly upon the front panel itself.
This knob is used to bring in desired, and to cut out undesired stations.
The crystal detector employed with this outfit is mounted directly on the front panel and is of the “catwhisker” type, provided with a very sensitive crystal.
Binding Post Feature
The binding posts on this outfit are of unique design. To connect external wires, it is merely necessary to push down on the top, insert the end of a wire and then release the top. The wire is then automatically held in place by a strong tension spring. This type of post is the simplest and most effective brought out to date.
The receiver is provided with a metal cover which is held in place by two snap catches. One end of the receiver case is removable and forms a suitable receptacle for the telephone receivers when the set is not in use, or when it is being carried about.
An added feature of Receiver AR-1375 is that provisions are made to connect a vacuum tube amplifier unit for loud speaker operation.
OPERATING INSTRUCTIONS FOR RADIO CONCERT RECEIVER
MODEL AR-1375
Numbers Correspond to Diagram
No. 1. First, refer to accompanying sketch, then erect antenna and place protective device in position as described on page 56.
No. 2. Connect a wire leading from terminal marked R on protective device to binding post marked ANT.
No. 3. Connect a wire leading from terminal G on protective device to terminal marked GND on receiver. Connect telephone cord tips to terminals marked TEL.
No. 4. For wavelengths between 170-410 meters, place wave change switch at point A. Most broadcasting reception will be heard with the switch in this position.
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RADIO CORPORATION OF AMERICA
OPERATING INSTRUCTIONS ( Continued )
El
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-v -jpi
No. 7. After wave change switch has been set for the desired wavelength range, adjust detector by pulling movable spring-point away from crystal and then allowing it to come in contact again at various points. While making this ad- justment, rotate tuning knob (8) slowly over the scale, listening until sound is heard in the telephone receivers. Tem- porarily stop adjustment of detector and manipulate tuning knob until maximum sound is obtained. Leave tuning knob in this position and readjust detector. After a short time the operator will be- come skillful in finding delicate adjust- ments on this crystal detector. Once the detector is properly set various sta- tions may be heard by simply rotating the tuning handle over scale.
Note: A black deposit sometimes forms
on detector crystals, decreasing the sensi- tivity of the set. This deposit may be scraped off lightly with a penknife.
Complete Radio Concert Receiver, Model AR-1375, 170-2650 Meters, with Head
Telephone Receivers, Spare Crystals, Antenna Equipment and Full Instructions $47.50
Radio Concert Receiver, Model AR-1375, as above, less Antenna Equipment 40.00
Dimensions — 9% in. x 7 in. x 7 in.
Weights — Net, 7 lbs.. Shipping, 1 2 lbs. With Antenna Equipment, 1 8 lbs.
Note— For prices of other Complete Receiver Combinations see page 35.
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RADIO CORPORATION OF AMERICA
AERIOLA SR. RECEIVER, MODEL RF
Aeriola Sr. has become famous as a highly satis- factory and easily operated vacuum tube receiver.
LIKE the Aeriola Jr.t the Aeriola Sr. is a West- inghouse product designed to fill the popu- lar demand for an inexpensive set for broad- casting reception with a greater range than that of Aeriola Jr. Aeriola Sr. makes use of the Regenerative Circuit. This circuit in con- junction with a vacuum tube detector amplifies radiophone signals many times beyond the strength obtainable with a simple circuit. The outstanding feature of Aeriola Sr. is the fact that the filament of the vacuum tube may be operated from a single dry cell, the telephones being energized by what is termed a “B" or plate battery #f 20 volts or more.
Aeriola Sr. for the Farmer
Aeriola Sr. will be found especially useful to the farmer for the daily reception of market and weather reports. These messages are sent out by the U. S. Government stations on a wavelength of 485 meters and are received like regular telephone conversations. It is not necessary for the farmer to know the telegraph codes. Thus this instrument proves of great value to the great farming centers of the United States which are served by local radiophone broadcasting stations.
In addition to its longer receiving range, Aeriola Sr. possesses the added feature of a more delicate tuning adjustment. This reduces the possibility of interference from undesired stations. Aeriola Sr. is portable. The upkeep
expense is very small. Like Aeriola Jr. its wavelength range is from 190 to 500 meters.
Aeriola Sr. includes the receiver or tuner, an Aeriotron detector tube and a pair of head telephone receivers.
Aeriola Sr. for the Boy Scouts
Aeriola Sr. receives over comparatively long distances from low-powered transmitting stations and lends itself particularly for com- municating between Scout troops and head- quarters or sections of the same troop located in different places.
The set may be carried by one Scout without overburdening him, whether he is on a long hike or not. The Aeriola Sr. with the neces- sary batteries for its operation, the insulators and wire for making the antenna as well as the wire used for the ground connection may all be placed in a haversack. The total weight is less than 15 pounds.
In addition to being very sensitive, this out- fit is easy to operate and is not subject to irreg- ularities sometimes found in fragile receivers.
A well-trained troop can set up the antenna, make the ground connection and have a receiv- ing station in operation in a few moments.
Erecting the Antenna
The simplest way to erect an antenna when afield is the following: Attach an insulator to a long piece of string. This insulator and string is then used as a sling and hurled by a Scout over a branch of a tree or any other convenient object. When the insulator reaches the ground on the opposite side of the tree, it
It is easy for the Boy Scout Signal Officer to erect a temporary aerial over a tree branch.
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is merely necessary to attach the antenna wire and pull on the string. When the antenna is high enough simply fasten the string to the trunk of the tree or other convenient support.
For communicating over short distances, the ground connection may be made by mere- ly laying a piece of rubber-insulated copper wire along the ground for a distance of about 40 or 50 feet. This arrangement does away with the necessity of driving rods into the earth.
However, where the station is to be set up near salt water or in a salt marsh, it is more effective to connect the ground wire with a piece of metal of large surface and to place the metal either in the water or the damp earth. The length of the aerial for such a receiving set may be from 50 to 150 feet.
Easy to Install Antenna
In one of the accompanying illustrations a Scout is shown casting an insulator attached to a string over the branch of a tree. In another illustration a group of Scouts are gathered about a receiving station using the antenna sus- pended from the tree.
The Aeriola Sr. has been used by Scout Troops with entire satisfaction. Because it is sensitive, compact anjd inexpensive, it is the ideal receiving outfit for use in connection with their outdoor manoeuvres.
A
RADIO
CORPORATION
O F
AMERICA
OPERATING INSTRUCTIONS FOR AERIOLA SR.
Text numbers correspond with above diagram.
Numbers Corresponding to Diagram
No. 1 . First, refer to accompanying sketch, then erect antenna and place protective device in position as described on page 56.
No. 2. Connect a wire leading from terminal marked R on protective device to binding post indicated by arrow for stations below 350 meters.
No. 3. For stations between 350 and 500 meters, connect the above wire to this post.
No. 4. Connect this post with terminal G of protective device.
No. 5. Connect telephone receivers to these two posts.
No. 6. Turn rheostat as far as it will go to- ward tail of arrow.
No. 7. Connect to posi- tive (center) terminal of the single 1.5 volt dry cell.
No. 8. Connect to nega- tive (outside) termi- nal of the single 1 . 5 volt dry cell and neg- ative terminal ( — ) of 22.5 volt plate bat- tery.
No. 9. Connect to posi- tive terminal marked ( + ) of 22.5 volt plate battery.
No. 1 0. Insert Aeriotron Vacuum tube in re- ceptacle provided. Note that the four holes in base which re- ceive prongs of tube are not all alike, one being larger than the rest, thus permitting insertion of tube in but one way. Be sure prongs register with holes and then press in (irmly.
No. 1 1 . Place “Tickler” pointer at zero point of scale.
No. 12. Turn rheostat (6) toward point of arrow until vacuum tube shows dull red. Do not try to bum too brightly as this materially reduces the life of the filament.
No. 1 3. Rotate tuning handle slowly over the scale, meanwhile listening until sound is heard in the telephone receivers. Adjust to best position, then increase “Tickler** (11) until maximum strength of signal is obtained. If tickler is turned too far toward maximum position, signals will lose their natural tone and reception of telephone signals may become difficult.
Note: This terminal is also connected to
terminal G of the protective device.
Complete Aeriola Sr. Broadcasting Receiver, Model RF, 1 90-500 Meters, with One Aeri- otron WD-ll-D Vacuum Tube, One Filament Dry Cell, One Plate Dry Battery,
Head Telephone Receivers, Antenna Equipment and Full Instructions $75.90
Aeriola Sr. Broadcasting Receiver, Model RF, As Above, Less Batteries and Antenna
Equipment $65.00
Dimensions: 7 in. x 8 Vi in. x 7% in.
Weights: Net, 6 lbs.; Shipping, 12 lbs.; with Antenna Equipment and Batteries, 25 lbs. NOTE: For Prices of other Complete Receiver Combinations , see page 35.
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RADIO
CORPORATION
AMERICA
SHORT WAVE REGENERATIVE RECEIVER, MODEL RA
THIS short-wave tuner, a product of the Westinghouse Company, has been designed to meet the needs of those who require the best form of receiving set available for broadcast re- ception. Particular attention has been paid to the fact that some Radio enthusiasts desire to carry on experiments of their own, and to in- corporate various parts of their receiving equip- ment. For this reason the terminals are so arranged that either a crystal detector or a vacuum tube detector may be employed. For the former, type DB crystal detector, described on page 52, is recommended, for the latter, type DA Vacuum tube detector and two stage amplifier unit described on page 2 1 .
Wide Variety of Uses
It has been customary for the novice in Radio to begin with a crystal detector, later adopting vacuum tube detection. As the type RA Receiver will give satisfaction with either method, it forms an ideal unit. The type RA tuner, as used in connection with the average antenna, has a wavelength range of 180 to 700 meters. This range therefore includes prac- tically all that the average person cares to hear — in a word everything from amateur messages and broadcasted music to ship signals.
This receiver requires but one major ad- justment in order to bring in desired stations and cut out undesired stations. Tuning, as this operation is called, is effected by turning the tuner knob. A minute adjustment of this cir- cuit is obtained by what is known as a '‘vernier*’ condenser, which is connected in parallel with the antenna condenser. When a vacuum tube detector is used with this tuner advantage is taken of the amplifying qualities of the Arm- strong regenerative circuit. In this case the degree of amplification is controlled by a small knob marked “ticker.”
.
f r
L ft
Tuner RA, with Crystal Detector DB and Head Telephones
Receiver.
Model RA Tuner is a high grade Westinghouse product.
SPECIFICATIONS
Panel — Micarta, finished in black matte.
Cabinet — Natural polished mahogany.
Dials — Polished black micarta with beveled edges. Markings filled in white.
Knobs — Moulded black composition.
Condensers — Rotary plate type, air dielectric. Stationary plates are soldered to three sup- ports, thus making excellent electrical con- tact and insuring permanent alignment.
Coils — Single layer wound on micarta tubes. Movable part of variometer connected to stationary coil through wire “pigtail.”
Tickler Coil — Wound on same tube as sta- tionary coil of variometer, and suitable taps are insulated with varnished cambric tubing and brought out to a dial switch.
Binding Posts — Moulded insulated posts, brought out at rear.
Fittings — Exposed metal _ _ parts on front of pan-
el are bra88» nickel-
I w -v plated. All other
h screws are black fin-
ished.
Wiring Diagram — A wir- ing diagram showing all connections is fur-
e. UD-790 complete the ni»he<|- together with
complete instructions.
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RADIO CORPORATION OF AMERICA
OPERATING INSTRUCTIONS FOR MODEL RA TUNER
When Used With Wettinghoute Crystal Receiver Combination No. 5
Text numbers correspond to above diagram.
No. 1. First, refer to accompanying sketch, then erect antenna and place protective de- vice in position as described on page 5 6.
No. 2. Make connections as shown above, tak- ing care that the two wires leading to the protective device do not lie close together. These wires should be as short as possible. All wiring may be made with No. 1 8 rub- ber-covered copper wire. Carefully re- move the cover from both ends of each wire used, scraping clean with a knife, plac- ing the end thus cleaned under the terminal caps shown and tighten cap.
No. 3. Connect head set as shown.
No. 4. Place dial switch in position shown.
No. 5. Adjust pressure type crystal by clasp- ing black handle and pulling the movable crystal away from the stationary one and let it come in contact with it at various points. Crystals should come together with firm pressure. While trying various points,
turn the tuner knob (6) slowly over the scale, listening at the same time for sounds in the telephone receivers.
No. 7. By changing the dial switch (4) to the other position this detector may be used. The flexible wire with special tip should be brought into contact with the various points on the stationary crystal, at the same time manipulating the tuner handle (6) as ex- plained under (5) until the sound is loud- est.
No. 8. Vernier knob may be used as a fine adjustment on tuner knob (6).
No. 9. This knob is not used in this set and should be placed at minimum.
Text numbers correspond to above numbers.
Note— Terminals A, B, C, in upper diagram correspond to antenna, detector, detector- ground. D and E to tickler and plate when the unit is used with amplifier Model DA.
Complete Short Wave Regenerative RA, with Crystal Detector, Model DB, Head Tele- phone Receivers, Antenna Equipment and Full Instructions $90.00
Short Wave Regenerative Tuner Only (Model RA), with Instructions $68.00
Dimensions of Tuner: 9!/2 x 8*/2 x 6 in.
Weights: Net, 6 lbs.; Shipping, 1 0 lbs.; with Complete antenna equipment as above, 25 lbs. NOTE: For Prices of other Complete Receiver Combinations , see page 35.
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RADIO CORPORATION OF AMERICA
DETECTOR AND TWO-STAGE AMPLIFIER, MODEL DA
THIS unit is designed along advanced engi- neering principles and is especially adapted for the use of those who have not made an ex- tensive study of radio but who desire to receive over ranges greater than those of Aeriola Jr., or the RA receiving sets when used without any external amplifying units. Within a very attractive mahogany cabinet equipped with a hinged cover all the elements necessary for a vacuum tube detector and two-stage audio fre- quency amplifier are found. This device when used in conjunction with the type RA short- wave regenerative tuner described on page 2 1 , forms a combination for radio reception of a very high order for the non-technical user.
Three Vacuum Tubes Are Employed
The amplifier acts as a magnifier of the signals received by the detector. With each stage of amplification the incoming signals are magnified many times, so that with this detec- tor and two-stage amplifier, signals which at times cannot be heard with simpler sets, may be received with ease on a loud speaker.
Vacuum tubes require two batteries for their operation, one for the heating of the filament, known as the “A” battery (in this case a stor- age battery of 6 volts with a capacity from 40 to 1 30 ampere hours), and the other a dry bat- tery of 40 to 60 volts known as the “B" bat- tery. For the best results it is necessary to reg- ulate the amount of current supplied by the storage battery to the filament of the vacuum tube. In type DA unit are two rheostats, one of which regulates the current in the detector tube, and the second that regulates the supply to both amplifying tubes.
Three Controls Provided
Three telephone jacks are mounted on the panel and are arranged to control the internal circuits according to the desire of the operator. Thus, by inserting the telephone plug in the first jack the signal is received with the detector tube alone. With the plug in the second jack we have one stage of amplification. The second stage of amplification is made available by in- serting the plug in the third jack.
A screened window is provided in front of the panel in order that the operator may ob- serve the brilliancy of the vacuum tubes. All the vacuum tube sockets are mounted on the same base which in turn is mounted on heavy rubber shock absorbing supports.
Amplifier DA is the logical graduating step for owners of Tuner RA previously described.
The cabinet is mounted on rubber feet to prevent scratching of the table or desk upon which it is placed.
This instrument will be found entirely sat- isfactory for amplifying weak radio signals and producing loud signals when used in conjunc- tion with a Vocarola loud speaker (Model LV) for entertainment.
SPECIFICATIONS.
Panel — Micarta finished in black matte. An opening protected by metal gauze is provided for ventilation and to give a visual indication of the tubes in operation.
Cabinet — Natural mahogany, varnished and polished. Door provided in top for ready inspection and replacement of vacuum tubes.
Knobs — Moulded black composition.
Rheostats — Continuously1 variable type with open circuit po- sition. Polished nickel pointers.
Sockets — Metal on micarta base with tangential contacts. Shock-proof mounting.
Binding Posts — Moulded insulated posts, brought out at rear. Amplifying Transformers — Closed core type, designed for maximum efficiency with standard tubes.
Wiring — Covered with varnished cambric tubing. All wiring neatly done. All connections soldered.
Shielding — Instrument completely shielded on all sides, elimi- nating capacity effects from operator's body.
Wiring Diagram — A wiring diagram showing all connections is furnished, together with complete instructions.
Detector and Two-Stage Amplifier, Model DA, less Vacuum Tubes, Batteries and
Telephone Plug $70.00
Dimensions: 9 1/2 in. x 8 1/2 in. x 6f/2 in.
Weights: Net, 10 lbs.; shipping, 15 lbs.
NOTE: For Prices of other Complete Receiver Combinations , see page 35.
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RADIO c CORPORATION OF AMERICA
A Highly Sensitive Long Distance Receiver
SHORT WAVE REGENERATIVE RECEIVER, MODEL RC
Combining RA Tuner and DA Amplifier in One Cabinet
For Broadcast- ed news, music, concerts
THE radio broadcast enthusiast or amateur who desires a modern, compact, portable and efficient receiver for general reception, will nnd these requisites in Model RC short wave regenerative receiver. It is an ideal instrument ror use with loud speaking devices and has already found great favor throughout the entire country.
Long Distance Features
This receiver comprises a combination of the RA short wave regenerative tuner, and type DA detector and two stage audio fre- quency amplifier described on preceding pages. Distant radio telephone, amateur and ship stations may be received on any wavelength within the range of 1 80 to 700 meters. The addition of Load Coil, model CB, allows the
u?nr?tlOIj ?LTa*8 on 'wavelengths between loUU and 2800 meters where an average ama- teur outdoor antenna is used. This makes the set suitable for the reception of Arlington (Radio, Va.) time signals, which are broad- casted on 2500 meters at noon and 1 0 p. m., Standard 7 5 Meridian time, each day over distances of several hundred miles.
Broadcasting may be received on either de-
tector alone or with one or two stages of amplification by simply changing the head telephone plug connection. Where a Voca- rola loud speaker is employed, the entire family may enjoy radio concerts without the use of telephone receivers. The set is metal- lically shielded so as to prevent undesired noises caused by capacity effects between the set itself and the operator's body.
The specifications for this receiver are iden- tical to those of the RA tuner and DA de- tector and amplifier, with the exception that both units have been incorporated in one cab- inet. All binding posts are mounted on the rear of the panel, permitting connections to be readily made. A wiring diagram and com- plete instructions accompany each instrument.
Dimensions — Height, 9J4 in.; depth, 8!/2 in.; width, 18 in.
Weights — Net, 1 5 lbs. ; shipping, 22 lbs.
Radiotrons Give Best Results
It is recommended that the Radio Corpora- tion’s detector and amplifying tubes Radiotron UV-200 and Radiotron UV-201 be used with these instruments.
OPERATING INSTRUCTIONS FOR MODEL RC RECEIVER
Numbers Correspond with Diagram
No. 1. First, refer to accompanying sketch, then erect antenna and place protective de- vice in position as described on page 56.
No. 2. Connect a wire leading to this post from terminal R of protective device.
No. 3. Connect a wire between this post and terminal G of protective device.
No. 4. Turn rheostats as far a s they will go toward tail of arrow.
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RADIO CORPORATION OF AMERICA
No. 5. Connect positive ( + ) terminal of 6 volt storage battery to terminal (-}-A — B. BAT.) of receiver.
No. 6. Connect negative ( — ) terminal of storage battery to terminal marked ( — A. BAT.) of receiver.
No. 7. Connect one positive and one negative terminal of 22.5 volt dry batteries to- gether.
No. 8. Connect remaining negative terminal of 22.5 volt batteries to terminal (+A. — B. BAT.) of receiver.
No. 9. Connect remaining positive terminal of 22.5 volt battery to terminal marked +AMPL. B. BAT.
No. 1 0. Connect terminals marked +DET. B. BAT. and terminal +AMPL. b. BAT., together.
No. 1 1 . Open door in top and insert three radiotron type UV-201 amplifier tubes in sockets. Catch pin inside of tube base with slot in socket, press down and turn into place.
No. 12. Insert telephone plug in right hand jack and turn both rheostats (4) toward point of arrow until all tubes bum brightly.
No. 1 3. Rotate tickler midway between stops.
No. 14. Rotate tuner knob slowly over scale, listening for sounds in telephone receivers. Receiver is very sensitive to adjustments of the tuner knob and care should be taken not to move it too rapidly or the signal will be lost. Signals on short wave lengths will be received near the lower end of the scale, whereas the wave length increases toward the upper end of the scale. Broad- casting stations are generally tuned in be- tween 20 and 40. When the signal is heard its intensity may be increased by
Text numbers correspond with above diagram.
Text numbers correspond to above diagram.
manipulating "Vernier” in one direction or the other and by adjusting the tickler (13). Further adjustment may be made by manipulation of the filament rheostats
(4).
For those who desire to operate with a soft type detector tube, radiotron UV-200 may be inserted in the socket at the rear of the cabinet instead of the UV-201, but it is then necessary to alter the connections as illustrated below.
Method of connecting Filament and Plate Batteries.
Complete Short Wave Regenerative Receiver with Detector and Two-Stage Amplifier, 170-700 meters, Model RC, with Load Coil, one Radiotron Detector Tube, two Radio- tron Amplifier Tubes, one six-volt Storage Battery Model 6HR-9, Telephone Plug, two “B” Plate Batteries, Vocarola Loud Speaker, Rectigon Battery Charger (5 ampere size), Receiving Antenna Equipment, and Full In- structions $261.75
Short Wave Regenerative Tuner,
Model RC, less all above Equipment,
$132.50
Dimensions — 9]/i in. by 8j/2 in. by 8 J/© in.
Weights — Net, 15 lbs.; shipping, 22 lbs.; with above Equipment, 150 lbs.
NOTE — For prices of other Complete Receiver Combinations , see page 35
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RADIO CORPORATION OF AMERICA
RADIO RECEIVER, MODEL AR-1300
case and arrangement of terminals to suit the various standard amplifier and detector instruments.
The variable air condenser is a special type arranged to operate an automatic switch which changes the inductance in the circuit. There- fore a continuous rotation of 360° is utilized for the entire wavelength range.
A rugged, compact and efficient unit for crystal or vacuum tube reception.
THIS compact and highly efficient receiver is of the single-circuit type, with a continuously variable air condenser for tuning. Because it is provided with regenerative coil for amplifi- cation and oscillation, it is suitable for the re- ception of all types of radio signals over the wavelength range of 180 to 700 meters. This meets the requirements of present day broad- casting.
The receiver, which is manufactured by the General Electric, is built upon the standard EZKASE plan, which determines the size of
Crystal or Vacuum Tube Detection
A sensitive crystal detector is pro- vided on the receiver, and a jack for plugging in the telephone receivers. For crystal detector operation, there- fore, the unit is complete in itself, and needs no further units except the telephone receivers and the antenna.
Receiver AR- 1 300 can be used in connection with an external ampli- fier unit as embodied in Detector Amplifier, Model AA-1400, described on the following pages. When so used, the crystal detector is switched off and the intensity knob is turned to control amplification by regeneration.
The receiver is enclosed in the EZKASE, which serves the dual purpose of an electro- static shield and a protection against me- chanical injury.
Rear section of case is readily detached after pressing release button on top of case.
Receiver AR- 1300, when used in combination with amplifier AA-1400 and the Vocarola loud speaker, furnishes ail that the aver- age home requires for Broadcast re- ception at medium cost of installation and operation. Moreover, the en- tire family may “listen in.”
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RADIO CORPORATION OF AMERICA
DETECTOR- AMPLIFIER, MODEL AA-1400
Detector-amplifier aa-moo is a
compact and easily operated amplifier unit. It is also a product of the General Elec- tric Co. and consists of a vacuum tube detector and two stages of audio frequency amplifica- tion enclosed in a neat metal EZKASE.
It is especially adapted for use with Radio Receiver AR-1 300 when it is desired to greatly increase the strength of the broadcasted con- certs such as would ordinarily be received with the simple crystal type detector.
Individual Filament Control
An important feature of Model AA-1400 is the individual filament control system, that is, the three vacuum tubes employed here (a de- tector and two stages of amplification) are fur- nished with separate rheostats, thus enabling the operator to obtain individual stage control of the received energy.
Plug and Jack Selection
Another operating feature is the selectiveness furnished by the three telephone jacks. The left hand one is for plugging in on the detector tube only, the middle jack furnishes detection and one stage of audio frequency amplification, while the right hand jack gives maximum am- plification output, i. e., detection with two stages of amplification.
This feature will be found useful where it is desired to decrease the intensity of signals when receiving from high powered stations over short distances.
Detector-Amplifier AA-1400 has unusual features of amplification.
Reception may also be continued in emerg- ency with the detector, or the detector and one stage of amplification when the battery has be- come discharged to such an extent that it will not properly operate the filaments of the three tubes, although this practice should not be generally followed. Means are provided by which the loud speaker is automatically dis- connected from the circuit when the telephone plug is placed in a jack.
Distortion Practically Eliminated
Distortion of broadcasted music or speech and consequent lack of tone qualities so com- mon with many receiving systems is practically eliminated by AA-1400.
The electro-static shielding afforded by the metal case of this instrument as well as the AR- 1 300 eliminates all disturbances caused by the proximity of the hand or body to the instru- ments.
Complete Regenerative Radio Broadcasting Receiver, Model AR-1 300 and Detector, Am- plifier Model AA-1400, One Radiotron Detector Tube, Two Radiotron Amplifier Tubes, Head Telephone Receivers, Six Volt Storage Battery Model 3LXL-9, Three Plate Batteries, Vocarola Loud Speaker, Tungar Battery Charger (5 Ampere Size) Telephone Plug, Receiving Antenna Equipment and Full Instructions $250.25
Regenerative Radio Broadcasting Receiver Model AR-1 300, 170-700 Meters, Less All
Above Equipment - $50.00
Detector-Amplifier, Model AA-1400, Less Tubes $75.00
Dimensions: 11 in. x. 9Yz in. x 9 in.
Weights: Net, 13 lbs. Spring, 25 lbs.
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AMERICA
Text numbers correspond to above numbers.
OPERATING INSTRUCTIONS FOR RADIO RECEIVER AR-1300
Numbers Corresponding to Diafram
No. 1. First refer to accompanying sketch, then erect antenna ana place protective device in posi- tion as described.
No. 2. Connect receiver as shown in accompanying illustration.
No. 3. Insert telephone plug in jack at right hand side of receiver.
No. 4. Adjust crystal detector and rotate tuner arm until signals are heard.
No. 5. Make further adjustment of crystal detector so as to obtain the most sensitive position.
No. 6. Intensity control does not function with this receiver when a crystal detector is used and it should therefore be left at the zero position.
Note: As crystals are rubbed to- gether, a black deposit appears on the movable crystal, decreasing the sensitivity of the set. This deposit may be scraped off lightly with a knife.
G. E. Regenerative Radio Broadcasting Receiver Model AR-1300, leu Head Telephone
Receivers and Telephone Plugs $50.00
OPERATING INSTRUCTIONS FOR DETECTOR-AMPLIFIER AA-1400 USED WITH RADIO RECEIVER AR-1300
No. 1. Make connections as shown in illustration.
No. 2. Separate crystal detector minerals.
No. 3. Insert a Radiotron UV-200 in the left hand socket, and two Radiotrons UV-201 in the re- maining two sockets.
No. 4. Turn filament control knobs almost entirely around to the left, bringing the filaments to their proper temperature.
No. 5. Insert telephone plug in left hand jack and set intensity knob on receiver at zero posi- tion.
No. 6. Tune with wavelength knob on receiver until signals are heard with maximum intensity.
No. 7. Slowly rotate intensity knob until a maximum signal strength is obtained.
Note: A loud speaker may be
connected to the output terminals on right hand end. The loud speaker is automatically disconnected when using head telephones.
G. EL Detector- Amplifier, Model AA-1400, Less Tubes and Batteries
$75.00
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RADIO CORPORATION OF AMERICA
THE AERIOLA GRAND
An instrument which may well be accorded a place in the most discrimi- nately equipped apartment
Simplicity of manipulation and elegant appearance make the Aeriola Grand a popular receiver
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RADIO
CORPORATION
AMERICA
Aeriola Grand offers all that may be desired of modern radio telephone broadcasting. Its use makes possible the radio dance, the radio concert, the radio party.
HERE indeed is the ideal radiophone receiver for home entertainment. For simplicity of operation and compactness, it is unequaled and holds a leading position in the held of radio broadcast reception. Any man, woman or child can easily operate it without the slightest technical knowledge. A simple snap switch starts or stops it and a single tuning lever con* troU the wave length range. This high grade * instrument is a product of the Westinghouse Electric and Mfg. Co.
Combines All Radio Essentials
The Aeriola Grand has been especially de- signed to receive broadcasting stations operat- ing on the standard wave of 360 meters, but provision is made for an additional range up to 550 meters.
All the essentials of radio detection, ampli- fication and loud speaking are embodied in this popular instrument. By means of the loud speaking chamber the entire family may hear broadcasted music and other entertainments.
In fact, the complete outfit is arranged in a cabinet very similar to that of the conventional phonograph cabinet.
With Aeriola Grand it is only necessary to
connect the antenna and ground wires, turn the current on by means of a small snap switch and tune in the desired signals with a single control handle. A special plug is provided for reducing the volume of the incoming signals when the broadcasted concerts are too loud.
Automatic and uniform heating of the fila- ment of the detector and three amplifier vac- uum tubes used for reception in the Aeriola Grand is obtained by means of four ballast „ tubes.
The workmanship of the Aeriola Grand is unsurpassed. Its parts are housed in a highly polished mahogany cabinet, artistically con- structed. Indeed, the instrument forms a val- uable addition to the furnishings of any home.
Aeriola Grand is shipped complete with one detector tube, three amplifier tubes, four bal- last tubes and the necessary “B” battery. To complete the installation, a 6 volt, 80 ampere- our storage battery and a Model AD Antenna Outfit are required.
1 ** Anyone Can Install Aeriola Grand
Suitable stands are furnished for Aeriola Grand if desired. These stands are richly fin- ished and harmonize in every way with the Aeriola Grand.
AERIOLA GRAND BROADCASTING RECEIVER, MODEL RG
Introducing a De Luxe Design in Broadcasting Receivers •
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RADIO
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NOTES ON OPERATION OF AERIOLA GRAND
THE Aeriola Grand is a complete radio re- ceiver and loud speaker combined, in a high grade mahogany cabinet. It is designed for use in homes near high power broadcasting sta- tions operating on wave lengths below 500 meters. The distance from such a station, under average conditions, should not exceed 50 miles.
The instrument is well adapted for use by the novice. A push button switch, for turn- ing the current on and off the vacuum tube filaments, and a single tuning lever completes the control. The method of amplifying has been developed to a degree where practically no distortion exists. The reproduction of c^ear speech and music is one of the outstand- ing features of the Aeriola Grand.
The Batteries
The vacuum tubes employed in the Aeriola Grand are designed for use with a six volt storage battery for lighting the filaments. The small dry batteries used for supplying the nec- essary plate voltage for the vacuum tubes are mounted within the cabinet of the Aeriola Grand itself. These dry batteries will give
The specially designed mahogany cabinet holds the storage battery and spare parts.
* As a home entertainer, Aeriola Grand has no equal.
several months of service, after which, replace- ment is easily accomplished. There are four of them connected in series and secured by a retaining clamp.
Ballast Tubes
Ballast tubes are used in this receiver instead of the ordinary filament rheostats. The char- acteristics of the ballast tube filament is such as to automatically maintain a constant value of voltage on the vacuum tubes, thus doing away with four rheostat controls which would otherwise be necessary.
The Battery Charger
The storage battery used for the Aeriola Grand is not included with the set, but can be procured from the dealer. This storage bat- tery should have a capacity not lower than eighty ampere hours. Where alternating cur- rent is available a very convenient method for lighting the filaments of the Aeriola Grand is obtained by employing a suitable storage bat- tery and a Tungar or Rectigon battery charger.
An arrangement is possible by which a single switch may be used to connect the storage bat- tery with the filaments of the vacuum tubes, or to charge the battery or to cut it off entirely.
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RADIO
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Installation
If the Aeriola Grand is to be installed less than 1 0 miles from a broadcasting station it is not always necessary to use all three stages of amplification, for the sound intensity is apt to be too great. To offset this possibility the
" •
Simplicity of operation ha* made Aeriola Grand the most popular Receiver for use in large cities served by radio telephone broadcast transmission.
front, left-hand amplifier tube should be re- moved from its socket. In its place the socket plug found in the dummy socket at the rear of the panel should be inserted. The withdrawn amplifier tube may then be placed in the recep- tacle formerly occupied by the plug. This ar- rangement reduces the number of tubes acting as amplifiers as well as the volume of the re- ceived sound.
The Aeriola Grand performs most satisfac- torily in residential sections of cities where broadcasting stations operate. Caution should be used in attempting to make installations in the heart of large cities, for unless an antenna is relatively free from the screening effect of nearby buildings, especially steel-framed build- ings, a marked decrease in signal strength is apt to result. However, installations made within a few miles of a broadcasting station will, of course, function even under such un- favorable conditions.
The Antenna System
The satisfaction derived from the perform- ance of the Aeriola Grand depends largely on the care used in erecting the antenna system. The antenna should consist of a single wire 75 to 150 feet long, suitably insulated, as de-
scribed in Part 2. Other forms of antennae may be used, according to circumstances. In some locations indoor antennae may be em- ployed satisfactorily. For private residences the antennae should be at least 30 feet above the ground and in apartment houses this wire should be at least 1 5 feet above the roof. In any event, the antenna wire should not come closer than 1 0 feet from trees, smokestacks, towers, cupolas, etc. The antenna wire should not be strung above trees or behind tall build- ings if any other arrangement is possible.
The Ground Connection
The ground wire is as important as the an- tenna wire, and if possible, should be con- nected to a water pipe on the same floor as the instrument itself. In many cases equally good results may be obtained by connecting the ground wire to a steam or hot water radiator, rather than wiring a great distance to the water pipe.
Service by Local Dealer
The Aeriola Grand has been designed for people having little or no technical knowledge of radio, but nevertheless an arrangement should be made with the local radio dealer to have the equipment inspected at regular in- tervals. A service arrangement of this char- acter can be made with a responsible dealer and it offsets the possibility of overtaxing any part of the equipment, assuring at the same time satisfactory results under all conditions.
Testing of Vacuum Tubes
In purchasing vacuum tubes, either for the Aeriola Grand or any other type of receiving instrument, it is advisable to have these tubes I tested by the dealer in order to be perfectly sure they are in good condition and were not damaged during transportation.
An Interior View of the Aeriola Grand Receiver
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RADIO
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OPERATING INSTRUCTIONS FOR AERIOLA GRAND
Numbers Correspond with Diagram
No. 1. First, refer to accompanying sketch, then erect antenna and place protective device in position as described on page 56.
No. 2. Place Aeriola Grand on table or stand and connect wire as shown herewith. The two wires connecting the Aeriola Grand to the protecting device should be separated by at least one foot. No. 1 8 rubber-cov- ered wire may be used for connections. The rubber covering on each end should be carefully removed and the wire scraped with a knife until bright. The clean bare wire should then be placed under the ter- minal caps and these caps screwed tightly into position.
No. 3. The wire from terminal R of the pro- tective device connecting to terminal A of the Aeriola Grand should be removed and connected to terminal B when signals be- low 350 meters are desired.
No. 4. Press the black button of the snap switch, thus disconnecting the battery.
Text numbers correspond to above diagram.
Illustrating easy method of connecting aerial ground and filament storage battery.
No. 5. Insert Model WR-21-D Aeriotron de- tector tube into the right hand front socket so that stamped trade mark is facing toward front of cabinet. Tube should be pressed firmly into socket.
No. 6. Insert three Model WR-21-A Aerio- tron amplifier tubes in the remaining front sockets.
No. 7. Insert four Model WB-800 ballast tubes in rear sockets. Be sure that pins register with holes and press firmly into place.
No. 8. Press red button of snap switch (4) clear down. All Aeriotron filaments should now be lighted.
No. 9. Slowly rotate tuning handle over the scale until sound is loudest.
No. 10. This plug should be used to replace the front left-hand tube if the broadcast- ing station is so near as to make the sound abnormally loud.
Caution: Always press black button of
snap switch (4) when not using instrument, as this conserves battery energy.
Complete Aeriola Grand Broadcasting Receiver, Model RG, and Mahogany Stand, 150- 550 meters, with six volt Storage Battery, Model 6HR-9, Rectigon Battery Charger
(6 ampere size), Receiving Ajntenna Equipment and Full Instructions $409.50
Aeriola Grand Broadcasting Receiver, as above, less Stand, Storage Battery, Charger
and Receiving Antenna Equipment $325.00
With Stand $350.00
Mahogany Stand Only $35.00
Dimensions: Receiver Cabinet, 21 in. x 1 7 /i in. x 1 4 Yi in. Stand, 31 54 in. high x 22 J4 in.
x 1954 in.
Weights: Net 50 lbs.; Shipping 70 lbs., with Stand 140 lbs.
NOTE: For Prices of other Complete Receiver Combinations , see page 35 .
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COLLAPSIBLE LOOP ANTENNA MODEL HG-1380
(For Indoor Reception).
IN general, loop antenna reception is found advisable for use in 1 congested areas where interference from a number of trans- mitting stations operating at the same time, is experienced. The reason for this is that the loop antenna responds only to signals from stations in the direction in which the loop points.
One of the difficulties experienced in loop reception, is that the distance over which signals may be heard is considerably reduced, unless suitable amplifiers are employed.
Loop reception, however, in the highly perfected state it is found in to-day, is so simple of operation that it is merely necessary to point the loop in the direction of the desired trans- mitting station, turn on the current and control the reception by a single adjustment. This adjustment is performed by a condenser generally mounted on the base of the loop as shown ^ in the accompanying illustration.
The frame of the loop illustrated is artistically finished in mahogany and is entirely collapsible. The arms are rotated into position on hinges and the assembly is held rigidly in place by two metal hooks. The wire used for the winding of the loop is passed through bakelite cross arms fitted with milled slots. This wire is flexible and rubber covered. An outer covering of woven material is provided to resist wear when the loop is assembled, taken down, or carried about.
This loop has been designed for radio broadcasting reception and when used in conjunction with the UC-1820 variable con- denser and any of the detector-amplifier units described in this book with the necessary batteries, forms a complete short distance receiving station for broadcasting use, which marks a distinct advance in the radio art.
While it is possible that loud spealiing results may be realized over short distances with such combinations, it is not always to be expected when only audio-frequency amplification (as *1
supplied by all the amplifying units listed else- where) is employed. Such results, however, are common where the energy of the incoming signal is built up by means of radio frequency * I
amplification before it is passed on to the de- tector tube to be rectified and thence amplified by audio frequency units. The construction of radio frequency amplification circuits from It, j*|
component parts is fully described on pages which follow. flHlB
Interference from static is greatly decreased { 911 J by the use of the loop antenna for reception. I 1 \\ R
To tnput O/Wijierjkj) or Detector
Upper figure shows loop in action.
Figure at left Figure a
•How. method right .how
of connection to receiving instruments.
Figure at right shows loop folded when not in use for recep- tion.
COLLAPSIBLE LOOP ANTENNA, MODEL HG-1380, less variable condenser $25.00
Dimensions: Height opened, 4 ft. 10 J/^ in.; closed 2 ft. 9 in.; base, 12x12 in.
Weights: Net, 4 lbs.; shipping, 10 lbs.
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COMPLETE RADIO TELEPHONE RECEIVER SETS
i 4
f l
Illustrating the general set up of receiver combinations. The extreme left hand cut show GE Receiver AR- 1300 as a crystal receiver, the next cut shows GE Receiver AR-1300 in combination with Amplifier AA- 1 400, the next cut shows the method of battery connection when using these two units. The extreme right hand cut shows GE Crystal Receiver AR-753 in operating position.
RECOMMENDED RECEIVER COMBINATIONS
IN determining the necessary equipment for a Broadcast Receiving Station the following combinations of apparatus wiki be found helpful. Any unit may be bought separately. The complete combinations are indicated merely to guide those who wish to purchase a complete receiving set. Thus the technically uninformed enthusiast avoids the risk of buying unnecessary parts.
Westinghouse Aeriola Grand Combination
No. 1
RG Aeriola Grand Receiver,
with Stand, 150-550 meters, comprising one Aeriotron Detector, three Aeriotron Amplifiers, four Ballast V a c u u m Tubes, and four “B" Bat- teries $350.00
6HR-9 Storage Battery, 6 volts,
100 A.H 24.00
AD Receiving Antenna Equip- ment 7.50
285168 Rectigon Battery Charger, 6
amperes 28.00
Total $409.50
Westinghouse Aeriola, Sr., Combination No. 2
RF Aeriola Sr., Receiver, 190-
500 meters, with Brandes Telephones and one W-D- 1 1 Aeriotron Detector
Tube 65.00
One Dry Cell for Aeriotron
Filament .40
One “B" Battery, 22.5 volts 3.00
AD Receiving Antenna Equip- ment 7.50
Total $75.90
Westinghouse Aeriola Jr., Combination No. 3
RE Aeriola Jr., Receiver, 1 50-
700 meters, with Brandes Telephones and spare crystals 25.00
AD Receiving Antenna Equip- ment 7.50
Total $32.50
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O F
AMERICA
Westinghouse Regenerative- Vacuum Tube Receiver Combination No. 4
RC Short Wave Regener-
ative Receiver, 170- 700 meters, less tubes $1 32.50
CB Load Coil 6.00
UV-200 One Radiotron Detector 5.00
UV-201 Two Radiotron Ampli- fiers 13.00
6HR-9 Storage Battery, 6 volts,
100 A. H 24.00
UD-790 Brandes Telephones. . . 8.00
UD-824 Telephone Plug 1.75
Two “B" Batteries. . . . 6.00
AD Receiving Antenna
Equipment 7.50
LV Vocarola (Loud Speak- er) 30.00
285168 Rectigon Battery Charg- er, 5 amperes 28.00
Total $261.75
Westinghouse Crystal Receiver Combination
No. 5
RA Short Wave (Regenera-
tive) Tuner, 1 70-700
meters $68.00
DB Crystal Detector 6.50
UD-790 Brandes Telephones. . . 8.00
AD Receiving Antenna
Equipment 7.50
Total $90.00
General Electric Regenerative-Vacuum Tube Receiver Combination No. 1 AR- 1 300 Radiophone Receiver,
1 70-700 meters. . . . $50.00
AA-1400 Detector — 2-step Ampli- fier, less Tubes 75.00
UV-200 One Radiotron Detector 5.00
UV-201 Two Radiotron Ampli- fiers 1 3.00
UD-790 Brandes Telephones. . . 8.00
^LXL-9 Storage Battery, 6 volts,
80 A. H 23.00
2156 Three “B" Batteries,
each 22.5 volts 9.00
LV Vocarola (Loud Speak- er) 30.00
219865 Tungar Battery Charg- er, 5 amperes 28.00
UD-824 One Telephone Plug. . 1.75
AG-788 Receiving Antenna
Equipment 7.50
Total $250.25
General Electric Crystal Receiver Combination
No. 2
AR- 1 300 Crystal Radiophone Re-
ceiver, 1 7 0- 7 00
meters, complete $50.00
UD-790 Brandes Telephones. . . 8.00
AG- 7 88 Receiving Antenna
Equipment 7.50
Total $65.50
General Electric Crystal Receiver Combination No. 3
ER-753 Crystal Radiophone Re-
ceiver, 300-700 meters, with Murdock Telephone Receivers $18.00 AG-788 Receiving Antenna
Equipment 7.50
Total $25.50
Wireless Specialty Crystal Receiver
Combination No. 1 AR-1375 Crystal Radiophone Re- ceiver, 170-2650 meters, with Tele- phone complete $40.00
AG- 788 Receiving Antenna
Equipment 7.50
Total $47.50
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tADIO CORPORATION OF AMERICA
PART TWO
Receiver Accessories
With Data on
Receiving Circuits Audio Frequency Amplification Radio Frequency Amplification Vacuum Tubes and Their Use Receiving Antenna Equipment Special High Grade Receivers And other information for the Radio Enthusiast desiring to assemble experimental units
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RECEIVING CIRCUITS
A Simple Vacuum Tube Circuit
CONTRARY to general opinion, receiving circuits in which vacuum tubes are em- ployed are quite simple. The following de- scriptions include several standard receiving circuits which have proved satisfactory after long usage and which may readily be made up by the experimenter who follows the simple directions.
Fig. 1 is a simple receiving set, wherein a loose coupler is used for tuning. As will be seen, there are two distinct coils in a loose coupler, one called the primary, L 1 , and the other the secondary, L 2. One end of the primary is connected to a binding post which in turn is connected to the antenna. The other end of the winding is free, but a sliding contactor is provided in order to con- nect as many turns between the binding post to which the end of the coil is attached and the free end as may be necessary. This slid- ing contact is indicated in the diagram by an
ous tubes require different values of resist- ance in this position. The Radio Corporation grid leaks (UP-509 to UP-527) with the mounting UX-543 are recommended for this work.
The opposite side of the loose coupler is connected to the negative side of the Filament of the vacuum tube indicated in the diagram by F — . Where a vacuum tube is used in conjunction with a Radio Corporation socket UR-542, this connection is made to one of the binding screws on the vacuum tube socket marked F. To this post, as will be seen, two other connections— one from the minus or neg- ative pole of the six volt storage battery, indi- cated by “A”, and the other from one outside terminal of the “A” Battery Potentiometer, R2, are made. The opposite side of the “A** Bat- tery is connected to one terminal of the Fila- ment Rheostat, R, the second terminal of the rheostat being connected to the vacuum tube socket, UR-542, at the point F+. The re-
Figure 1 A simple vacuum tube rece ivi n g circuit em-
J>loying a oose coup- led tuner.
C 1 — Variable condenser, .0006 mfd. max. UC-1820.
C 2 — Secondary tuning variable condenser .001, .005 mfde., UC-1810.
C 3 — Grid condenser (fixed or variable), .00025 mfd., UC-567 with UX-543 mounting or UC-1820 variable con- denser.
C 4 — Telephone condenser, fixed, value optional. UC-560 with UX543 mounting.
L 1 — Primary of any loose coupler (sometimes called re- ceiving transformer).
L 2 — Secondary of loose coupler.
R 1 — Filament control rheostat, PR-535.
R 2 — “A” battery potentiometer, PR-536.
R 3 — Standard grid leak resistance, .5 to 2 megohms, UP-S1& 510 or 523 with UX-543 mounting.
T — Telephone receivers. Western Electric No. 1002 -A.
arrow. A switch is often employed instead of the slider. Such a switch is made with many contact points, each point being con- nected to a different part of the primary or secondary winding. For the most satisfactory tuning, a variable condenser, C-1, should be inserted between this slider or switch and the ground connection.
A variable condenser, C-2, is placed be- tween the two terminals of the secondary. As indicated by C-3, a small condenser, called a Grid Condenser, because it is inserted in the grid circuit, is placed between the Grid ter- minal (marked “G") of the socket, UR-542, and one terminal of the secondary.
For the best reception some vacuum tubes require what is known as a grid leak resist- ance. This is shown in the diagram R-3. Vari-
maining outside terminal of the Potentiometer is connected to the positive or plus side of the “A” battery. This Potentiometer is pro* vided with a third terminal which is connected to the 18-volt tap of the “B" battery (Bur- gess No. 2156). The positive terminal of the “B” Battery is connected to one side of the condenser C-4 with the opposite side of this condenser being connected to the termi- nal P of the vacuum tube socket, UR-542. The tips of the telephone cords are also connected, one each to the binding posts of the con- denser C-4. This completes what is known as a straight vacuum tube detection circuit A great improvement over this circuit is obtained by using the arrangement shown in Fig 2* although it is not quite so simple.
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Figure 2 A simple vacuum tube circuit sim- ilar to Fig- ure I but employing a “tickle r“ coil for re- generation.
C 1 — Antenna tuning variable condenser, .0006 mfd. max. UC-1820.
C 2 — Secondary tuning condenser, .0001 -.005 mfds., UC-1819. C 3 — Grid condenser (fixed or variable), .00025 mfds., UC- 567 with UX-543 mounting or UC-1820 variable condenser.
C 4 — Telephone condenser, value optional, UC-569, with UX- 543 mountings.
L 1 — Primary of loose coupler.
L 2 — Secondary of loose coupler.
L 3 — Tickler coil.
“A" — 6-volt filament lighting battery. Exide, 3-LX-9-1.
“B” — 20 to 30- volt plate battery. Burgess No. 2156.
R 1 — Standard Filament rheostat, PR-535.
R 2 — Standard “AM battery potentiometer, 04-536.
R 3 — Standard grid leaks resistance .5 to 2 megohms, UP- 516, 19 pr. 23 with UX-543 mounting.
T — Telephone receivers, Western Electric No. 1002- A.
Note: Where the UC-1820 is used for the grid condenser no UX-543 mounting is necessary for inserting the grid leak resistance as this condenser is equipped with clips which will At any of the RC standard grid leak re- sistance.
A Simple Regenerative Circuit
In Fig. 2 it will be observed that all the im- portant elements are identical to those shown in Fig. 1 . However, this arrangement permits very much greater selectivity in receiving as well as providing for amplifying the incoming signals by what is known as the regenerative method.
The only difference between Fig. 1 and Fig. 2 is, that a coil of wire L3, is connected in the circuit between the two points indi- cated by X3 and X4. This coil is used to carry the current back to the secondary of the loose-coupler and when properly ad- justed causes amplification to take place. This coil is called a "tickler” coil. Its size depends upon the particular class of receiving to be
carried on. The size of this coil for these vari- ous applications may be obtained by referring to any good book written for wireless experi- menters. This circuit forms what is known as a standard regenerative receiver. In some in- stances the value of the "tickler” or feed-back circuit is made variable. There are several ways of varying this value. Regeneration is generally controlled in this type of circuit by changing the position of L3 with relation to L2, or varying the inductance of the circuit itself.
Amateur Regenerative Circuit Fig. 3 shows the circuit generally used where a vario-coupler and two variometers are employed as the variable tuning elements in regenerative receivers. This character of receiving equipment is more or less confined
Figure 3. Short wave rege nera- tive circuit employing a vario-coup- ler and two variometer* for control- ling wave length and regen e ra- tion.
C 1 — Antenna variable condenser, .0006 mfd. max., UC-1820. C 2 — Grid condenser, Axed or variable, .00025 mfd., UC-567 with UX-543 mounting or UC-1820 variable air con- denser.
C 3 — Telephone condenser, value optional, UC-569, with UX- 543 mounting.
** A”-— 6- volt Alament lighting battery, Exide, 3-LX-9-1.
B — 20 to 30-volt plate battery. Burgess 2156.
L 1 — -Primary of any vario-coupler.
U“2 — Secondary of any vario-coupler.
L 3 — Grid variometer.
L 4 — Plate variometer.
R 1 — Standard Alament control rheostat, PR-535.
R 2 — Standard “A” battery potentiometer, PR-536.
R 3 — Standard grid leak resistance, JL to 2 megohms, UP-516, 519 or 523 with UX-543 mounting.
T — Telephone receivers. Western Electric, 1002- A.
Note: Where the UC-1820 is used for the grid condenser it is not necessary to use the mounting UX-543 for the grid leak resistance, for the condenser is Atted with mountings for standard R.C. grid leak resistances.
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to short waves from 150 to 600 or 700 me- ters. It will be seen that the inductance, L-2, in this case is not shunted by a variable capacity as was the case in Figs. 1 and 2. However, the variometer, V-l, is employed which comprises one stationary and one mov- able coil, is arranged so that the rotation of the movable coil with reference to the station- ary coil has the effect of increasing or decreas- ing the wavelength of the circuit and permits a very selective control.
From the points indicated by X-l and X-2, by making a comparison of Figs. 2 and 3, it will be found that Fig. 3 differs from the first two only in that the condenser, C-2, is not used and the variometer V-3, is placed be- tween the upper terminal of the secondary of the loose-coupler and the grid condenser.
Hie third tuning circuit which controls the regeneration or amplification is also made vari-
or procuring the parts which go to make up the units and assembling them. For the bene- fit of those who desire to assemble their own equipment the circuit shown in Fig. 1 is very strongly recommended for use in sec- tions where receiving stations are closely lo- cated to one another. In congested city dis- tricts near the broadcasting stations, shunt a wire across the points X-3 and X-4, leav- ing out the tickler circuit. The circuit de- picted in Fig. 4 is quite similar to those shown in Fig. 2 and Fig. 3, but two stages of amplification have been added. As may be observed this form of amplifier circuit may be added to any form of receiving circuit and need not be confined to the arrangement shown in Fig. 4.
It should be observed from a comparison of the last three circuits under consideration that where the audio frequency amplifiers are
Figure 4. Standard re- generative rec e i v«i ng circuit em- ploying two stages of au- dio frequen- cy amplifi- cation.
C 1 — Variable antenna tuning condenser, .0006 mfd. max., UC-1820.
C 2 — Secondary tuning variable condenser, .0001 -.005 mfds., UC-1819.
C 3 — Standard tubular grid condenser, UC-567 with UX-543 mounting or UC-1820 precision variable sir con- denser.
C 4 — Bi-pass condenser, variable, UC-1819 or UC-1820
C 5 — Telephone condenser, value optional, UC-569, with UX- 543 mounting.
L 1 — Primary of loose coupler.
L 2 — Secondary of loose coupler.
L 3 — Ticker coil.
R 1, 2 and 3 — Standard R. C. Filament control rheostats, PR- 535.
R 4 — Standard R. C. grid leak resistance unit, 2 to 5 meg- ohms UP-516, 519 or 523, with mounting UX-543.
S — Standard R. C. Vacuum tube sockets, UR-542.
AFT — Standard R. C. Audio- frequency amplifying transform- ers, UV-712.
T — Telephone receivers. Western Electric, 1002 -A.
"AM — 6-volt filament lighting battery, Exide, 3-LX-9-1.
— 20 to 100- volt plate batteries, made of several Burgess 2156 units connected in series, with a tap taken off at the 18- volt point for operation of the detector tube.
Note: When UC-1820 precision variable air condenser fta used for the grid condenser no mounting UX-543 is needed for the grid leak, for the mounting is made as a part of the condenser. It will accommodate any of the R. C. Standard grid leak resistances.
able by means of a variometer, V-4. This variometer is placed in the circuit between the points marked X-3 and X-4. It takes the place of the coil L-3 in Fig. 1, and forms one method of changing the value of this tertiary or plate circuit.
Where it is desired to use some form of loud-speaking device or where the distance over which signals are to be received is ex- ceptionally long, the experimenter must use some method of increasing the intensity of the received signal. The most common method for accomplishing this is found in what is termed, “audio frequency amplification.’*
Where the experimenter wishes to take ad- vantage of audio frequency amplification, there are two means at his disposal, namely: purchasing the amplifying units fully wired and ready for connecting them in the circuit.
brought in play, the place ordinarily occupied by the telephone receivers is taken by the in- put circuit of the first stage of amplification, and a variable condenser is substituted for the fixed condensers shown in the other three circuits, to increase the stability of operation. In other respects the fundamental parts of all three circuits are identical.
Regeneration, in this system, is obtained and controlled by the same method described in connection with Figs. 2 and 3. In Fig. 4 a standard method of regeneration is illustrated, but the arrangement shown in Fig. 3 may be employed. The circuit as in Fig. 4 shows a pair of telephone receivers in use, but it is often desirable to use a loud speaking device in their stead.
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In order to employ a loud speaker it is merely necessary to remove the telephone re- ceivers from the circuit and connect the two terminals of the loud speaker in their place. Adjustment of the variable condenser, C-4, may be used to clarify the tone of the signals. Some loud speakers require a battery for their operation, but the vast majority will function directly from the amplifier. Where the loud speaker does require such a battery, the di- rections which accompany the device must be strictly adhered to, in order to prevent the possibility of ruining the internal mechanism and connection may generally be made to the six-volt storage battery marked “A”.
The effect of using two stages of amplifi-
speaker” is employed or where extraordinary distances are being covered.
Where such amplifiers are used it is often found desirable to use less than the maximum amplification. To accomplish this ordinarily, it is necessary to alter several of the connec- tions. An automatic system has been devised utilizing multi-bladed telephone jacks function- ing with the conventional telephone plug. The blades and the jacks are so connected to the circuit that the necessary units are included when the plug is inserted in position.
Amplifier Circuit with Plug and Jack Control
The circuit arrangement shown in Fig. 5 is one employing standard Radio Corporation
cation is to increase the intensity of the in- coming radio signal, whether it be speech, mu- sic or code, many times. Each step of amplifi- cation increases the signal a certain number of times, depending upon the design and use of the amplifier, so it may be seen that where each step amplifies from six to ten times, the result of using two stages is an increased energy of from approximately 36 to 100 times its original value. In estimating the amplification factor of audio frequency devices it is safe to assume that the higher the voltage applied to the plates of the amplifier tubes, the greater is the resultant amplification. This does not hold true with detector tubes.
Regenerative Amplifier Circuit
The arrangement illustrated in Fig. 4 may be used for obtaining satisfactory results over very long distances and it is recommended because it is simple to assemble and operate. This system is now being used by a great many experimenters throughout the world and one need have no fear of its dependability, where the values for the different units comprising the layout are properly followed.
Many modem receiving equipments include one or two stages of audio-frequency amplifi- cation. This is especially true where a “loud
amplifying parts, with Western Electric tele- phone jacks. When the plug is inserted in the first jack the detector tube alone functions; when the plug is inserted in the second jack the detector tube and the first amplifying cir- cuit function together; when placed in the third jack three tubes are made to operate. As may be seen from the diagram, the Filament as well as the other circuits are operated by merely inserting the plug.
Where this layout is desired, the circuit should not be made to include the batteries indicated in the diagram, but should be made to run to a series of terminals or binding posts indicated by the dotted lines in the diagram.
Regulation of the voltage on the plate of the detector tube is accomplished by means of a Potentiometer shunted across the “A” battery with the arm connected to the negative terminal of the “B“ battery. This Potentiometer when connected to the 1 8 volt tap of a Standard Bur- gess No. 2156 plate battery permits a voltage regulation of from 18 to approximately 24 volts. With some detector tubes it is necessary, in order to obtain best results, to connect to the 22.5 volt lead of the plate battery instead of the 1 8 volt lead. This is especially so with bat- teries which have been in use for a considerable period. Ip this case the voltage range is from approximately 22.5 volts to 28 volts.
4!
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RADIO
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FOR GENUINE AMPLIFICATION
TONE FREQUENCY INTERVALVE AMPLIFYING TRANSFORMER
Ideal for Broadcast Amplification
IT is a well known fact that for maximum am- plification the characteristics of an inter- valve tone frequency amplifying transformer must be such as to fit the output impedance of the preceding tube in a cascade amplifying set. There is an allowable variation of the constants of the transformer when loaded on the second- ary by an amplifying tube, but nevertheless, the maximum signal is obtained from a trans- former designed especially to fit the output impedance of the tubes with which it is used.
Designed for Radiotron Vacuum Tubes
Prior to the introduction of Transformer Model UV-712, amateur experimenters were compelled to employ intervalve transformers of various characteristics!, none of which had been designed specifically for the Radio Cor- poration’s detector tube, Radiotron UV-200, and the amplifier tube, Radiotron UV-201. Transformer UV-712 not only has been de- signed to fit these vacuum tubes, but special
care has been taken to reduce the transformer losses to the lowest possible minimum.
Thousands Now in Use
The accompanying illustration shows the new amplifying transformer, of which there are several thousand now in daily use. Trans- former UV-712 has been designed and manu- factured strictly on a quality basis. It is pre- cisely the same type used in the Corporation’s commercial types of radio receiving sets. It is not to be compared with other types in which efficiency has been sacrificed to obtain compactness or to reduce manufacturing costs. Many experimenters report that the introduc- tion of UV-712 into their receiving sets, has resulted in such a marked increase of signal audibility as to be nothing short of marvelous.
In general, a tone-frequency amplifier trans- former should occupy the same position in the output circuit of a vacuum tube as the receiv- ing telephont. The terminals P and F of Transformer UV-712 may be connected to the plate circuit terminals which ordinarily are con- nected to the telephone receiver. The secon- dary terminals should connect to the grid and filament of the following tube of a multi-stage amplifier.
In radio amplifier circuits using Trans- former UV-712, the insulation of all appar- atus connected to the secondary must be as perfect as possible. Leakage from the grid to the filament of amplifier tubes through the socket, mounting, panel, wiring or otherwise, will decrease the amplification. The lead from terminal G should be kept reasonably short and in cascade amplifier sets adjacent transformers should not be mounted too close; a separation of at least four or five inches should be allowed.
PHYSICAL CHARACTERISTICS
1. Totally enclosed 4. Overall length, 3% in.
2. Net weight, 1 lb. Al/2 oz. 5. Overall height, 2^ in.
3. Shipping weight, 1 lb. 7 oz. 6. Base area, 2 x 2% in.
ELECTRICAL CHARACTERISTICS
1. Ratio of Secondary to Primary Turns, 9/1.
2. Useful frequency range, 60/3000 cycles.
3. Allowable current on each winding, 10 mQliamperes. .
4. Test voltage between windings and between core and windings, 300 volts at 60 cycles.
5. Terminal voltage limit of secondary winding, 300 volts.
Model UV-712 is the only transformer designed specifically for use with Radio trons. AMPLIFYING TRANSFORMER, MODEL UV-712 $7.00
Dimensions: 2 ^ in. x 3% in. x 2 in. Shipping Weight: I lb. 7 oz.
42
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RADIO FREQUENCY AMPLIFICATION
With The RCA Radio Frequency Intervalve Transformer*
Greater
Receiving
Range
with
Less Distortion
Model UV-1714,
range
200 to 5000 meters
A MPLIFICATION in radio reception means ** increased signal audibility. The current developed in a radio receiving set from a distant transmitting station is not always of sufficient intensity to operate a telephone or a loud speaker. It is for this reason that radio fre- quency. audio frequency amplification or a combination of both must be resorted to. The radio frequency amplifier consists of a group of vacuum tubes in cascade, interconnected by specially designed transformers which increases the intensity of the signalling current in its original form. The audio frequency amplifier, on the other hand, amplifies the output of a detector tube which has changed the amplified high frequency current to a form which will op- erate a telephone receiver.
Where receiving sets are located within a comparatively short distance from a broad- casting station, ample signal strength may be secured by the use of a vacuum tube detector and a two-stage audio-frequency amplifier. However, where the receiving station is more remote, the incoming signal must be built up in order to properly actuate the detector tube. This building up of signal energy is accom- plished by radio frequency amplification.
Ordinarily, very weak signals influence the detector so slightly that there is little or no rectification. Under this condition, audio fre- quency amplification is not always effective.
In general, more than two stages of audio frequency amplification proves unsatisfactory, for there is then a tendency to over-amplify tube noises and inductive disturbances from nearby lighting circuits.
The radio frequency method of amplification described here increases the strength of the in-
Modal
UV-1716,
range
5000 to 25000 maters
coming antenna current through successive stages until it becomes of sufficient intensity to enable detection to take place. Then with the addition of one or two stages of audio fre- quency amplification a current of sufficient strength will be generated which may be used to actuate either telephone receivers or loud speaking devices.
The design, however, of a radio frequency transformer suitable for amplification of sig- nals at both long and short wavelengths has always presented a difficult problem, and it id only with the introduction of the Radio Cor- poration of America’s new radio frequency transformers that amateurs and experimenters may take advantage of this means of ampli- fication.
The radio frequency amplifier circuits illus- trated and described here have been fully tested, and with the apparatus listed the broadcast enthusiast, the amateur and experi- menter can at once enjoy radio reception with- out the necessity of using a high antenna, at the same time insuring minimum of interference from undesired stations. *
Radio frequency amplification also permits the use of frame or loop aerials and provides, even with such limited antennae, a signal of great enough intensity to function properly with audio frequency amplifiers for the opera- tion of loud speakers, within certain limits. It is particularly suited to the reception of radio music and speech for it tends to eliminate the distortion resulting from the use of several stages of audio frequency amplification. For the longer wave lengths, two or three stages in cascade will produce a very strong signal from foreign stations using an average ama- teur antenna for receiving.
In former attempts to obtain radio frequency
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RADIO CORPORATION OF AMERICA
“A” — Storge battery (6V-80 ampere-hour size or larger). L 1 — Simple tuning coil, either tapped or fitted with a slider.
“B” — Standard 22.5 volt plate batteries, with 18 volt tap. R 1, R2 — Standard filament rheostats, PR-535.
C — Variable antenna series condenser, UC-1820 (.0006 mid. R 3, R 4 — Standard "A” battery potentiometers, PR-536,
max.).
NOTE: — The circuit within the dotted lines is a standard regenerative circuit.
amplification, it has been impossible to obtain maximum results on certain wave lengths with- out sacrificing on others. This is because trans- formers with characteristics which would be desirable for the long waves would not function properly on the shorter waves and vice versa. With Model UV-1 714, a range of 200 to 500 meters is provided. To permit this very broad range, a tap has been made on each winding and connected to the terminal marked “2.” For short wave reception, that is, from 200 to 500 meters, the connections illustrated in the accompanying diagrams are to be used. For the longer range of 500 to 5000 meters, the metal strap on each side of the transformer is disconnected and the entire windings from the terminals “1” to the terminals “3” are used.
2-Stage Radio Frequency Amplifier Circuit
Fig. 1 illustrates a satisfactory circuit for use in connection with several stages of radio fre- quency amplification for the reception of con- tinuous waves.
In this case the antenna is tuned to the wave length of the desired signal and this selected signal is amplified through the primary of a
standard receiving set connected to the plate circuit of the last frequency amplifier tube. It is then transferred through the secondary cir- cuit to the detector tube, in which regeneration may be controlled as desired.
One decided advantage of using the circuit shown in Fig. 1 is that the oscillations in the detector tube circuit cannot find their way back through the radio frequency amplifier to the antenna circuit, therefore the antenna cannot radiate energy. If potentiometer R-3 is not used, the filament rheostat should be placed in the positive leg of the filament circuit instead of the negative.
Combined Radio-Audio Frequency Circuit
For general reception when an aver age out- door amateur antenna and radio frequency amplification are used, the circuit shown in Fig. 2 is most highly recommended. This arrange- ment is quite similar to that shown in Fig. I. but instead of the standard regenerative re- ceiver, a vario-coupler and twin variometer receiver is employed, and two stages of audio- frequency amplification have been added for operating a loud speaker.
m/* (/, f-S42 Soc/br/3 -
OOSnfd
Fig. 2
"A” — Storage battery (6V-80 ampere-hour size or larger). “B” — Standard 22.5 volt plate batteries, with 18 volt tap.
C 1 — Variable antenna series condenser, UC-1820 (.0006 mfd. max.).
C 2— Variable condenser, UC-1819 (.0001 - .005 mfd.).
C 3 — Grid condenser (fixed or variable) .00025 mfd., UC-567 with UX-543 mounting or UC-1820.
C4 — Telephone condenser, size optional, UC-567 to UC-570, with mounting, UX-543.
C 5 and C 6— .005-. 01 mfd.
L 1 — Simple tuning coil, either tapped or fitted with a slider. L 2 — Primary of vario-coupler.
L 3 — Secondary of vario-coupler.
L 4 — Grid variometer.
L 5 — Plate variometer.
R 1, 2, 3, 4, 5— Standard filament rheostats, PR-535.
R 6— Standard grid leak, .5 to 2 megohms, UP-516, 519 or 523, with UX-543 mounting.
T — Head telephones.
R 7 and R 8 — Standard “A” battery potentiometers, PR-539*
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RADIO CORPORATION O F AMERICA
«A” storage battery (6V-80 ampere-hour size or larger).
“B”— Standard 22.5 volt plate batteries, with
C l— Variable loop tuning condenser » UC- 1 UO. .M06
C 2— Grid condenwr ( fixed or variable) 00025 mfd., UC-567,
C 3 Telephone* cond«wer* UC-567 to UC-570, with mountin,
UX-543. The use of this condenser is optional.
Loop— Fully described above.
R 1, R 2, R 3 — Standard filament rheostats, PR-535.
R 4, R 5— Standard “A” battery potentiometers, PR-536.
R6 — Standard grid leak .5 to 2 megohms, UP-516, 518 or 523, with UX-543 mounting.
T — Head telephones.
As is the case with the former circuit, the circuit shown in Fig. 2 utilizes separate antenna tuning, by means of the simple tuning coil Lr This tuning coil permits the antenna circuit to be adjusted to resonance with the desired in- coming signals, and the signal, thus selected, is carried through the radio frequency amplifier circuit and the primary of the vario-coupler to the detector tube circuit, where it is rectified and brought to an audible frequency. This audio-frequency current is then passed through two stages of audio frequency amplification.
In using this circuit, the first two tubes should not be permitted to oscillate, but merely to amplify the incoming signal, for the oscillation and regeneration is most satisfactorily con- trolled by tuning the detector tube plate van- ometer in the customary mannen mere this circuit is employed DO N°T GROUND the negative lead of the 6- volt A battery. If potentiometer R-7 is not used, the filament rheostat should be placed in the positive leg of the filament circuit instead of the negative.
Loop Antenna and 3-Stage Radio Frequency Amplifier
Fig. 3 shows a method of reception using a loop antenna and three stages of radio fre- quency amplification. This type of receiving set will bring in signals over several hundred miles and interference is considerably reduced, as the loop possesses properties which enable signals to be received from a given direction to the exclusion of unwanted stations. Static is also considerably reduced.
A very satisfactory loop for this purpose may be made by using a frame three feet square wound with five or six turns of No. 14 b. cc 5. lamp cord, each turn being spaced Vi to % of an inch. A tap should be provided on each turn. The loop should be shunted by a vari- able condenser (UC-1820) having a capacity of .00004 to .0006 mfd.
With this arrangement, the incoming signals are of an intensity slightly greater than is ob-
tained with an ordinary amateur antenna and a single detector tube. By the addition of two stages of audio frequency amplification, we have a method of obtaining a greater signal in- tensity than is possible with the outdoor an- tenna, while the interference from undesired stations is considerably reduced. For fine tuning, the condenser shunted across the active turns of the loop should be equipped with a vernier, although this is not absolutely essential.
Where a radio frequency amplifier of two or more stages is desired, it should be built in a metal box, or in a box lined with metal, and should preferably have a separate compart- ment for each radio frequency amplifier tube and its transformer. In completing such an amplifier, it is also important to ground the negative side of the filament battery, except with single circuit tuners, to the metal case or metal lining. This insures stability.
In general, the foregoing instructions also apply to the radio frequency intervalve trans- former, UV- 1716, which is designed for use in connection with long wave reception. The turn ratio, however, in this transformer is ap- proximately 1 to 3 for the reason that a step- up is advantageous for the long wave range. No intermediate tap is used on this transformer as it functions satisfactorily over the entire wave length range of 5000 to 25,000 meters.
Note: In figures 1, 2 and 3 it will be ob- served that there are two additional condensers each designated with a capacity of .005 mfd. It has been found that the use of these consid- erably improves radio frequency amplification.
Features of Both Models
1 . Receiving ranges may be doubled and even
tripled.
2. News and music broadcasted by distant
stations are received with remarkable clearness.
3. Distortion is greatly reduced.
4. Selectivity is considerably increased.
45
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5. Vacuum Tube noises are practically elim-
inated.
6. These transformers are designed especially
for, and will function at maximum effi- ciency only, when used with Radiotron Amplifier Tube UV-20 1 .
Physical Characteristics Model UV-1714
1. Base Dimensions 2 9/16" x 1 1 1/16".
2. Overall Height 2^4".
3. Net Weight 7 oz.
4. Shipping Weight 1 0 oz.
Model UV-1716
1. Base Dimensions 2 9/16" x 2!4".
2. Overall Height 224".
3. Net Weight 12 oz.
4. Shipping Weight 1 lb.
Electrical Characteristics Model 1714
1. Ratio of primary to secondary turns, 1 to 1.
2. Tap on each winding provides for two wave
length ranges: 200 to 300 meters and 500 to 5000 meters.
3. Especially designed for use with Radiotron
amplifier tube UV-20 1.
Model 1716
1. Ratio of primary to secondary turns, 1 to
3 (approximate).
2. Entire wave length range 5000 to 25,000
meters available without taps.
3. Especially designed for use with Radiotron
amplifier tube UV-20 1.
Radio Frequency Amplifying Transformer, 200 to 5000 meters. Model UV-1714. . . . $6.50 Radio Frequency Amplifying Transformer, 5000 to 25,000 meters, Model UV-1716. . 8.50
GRID LEAKS FOR RECEIVING SETS
The grid of any vacuum tube, whether employed as a detector or an amplifier, is the controll- ing member of the tube, that is ^
to say, it controls the current flowing between the plate and filament. The character of the control depends directly upon the bias potential maintained upon the grid. Thus one value of grid po- tential will be found most suitable for radio detection, while still another value must be maintained to secure maximum amplification. The requisite bias potential for varied con- ditions of use may be obtained in several ways, the most common of which are: (a) to insert in series with the grid circuit a small bat- tery usually called a “C” battery; (b) to tap one terminal of the grid circuit from a fixed resistance in series with the filament rheostat through which the filament current flows; (c) to employ a GRID LEAK connected across the grid condenser or the grid and the filament.
The function of the grid leak is to present a leakage path across the grid condenser so that the potential of the grid member in respect to a terminal of the filament may be maintained at some desired value. The potential main- tained on the grid is computed by Ohm's Law and it is therefore equal to the grid current times the grid resistance. With a grid resist-
ance of two megohms (2,000,- 000 ohms) and a grid current of ^ one microampere, the bias nega-
WtM tive potential will be two volts.
Different detection and ampli- fication circuits require grid leaks of different values and in order that the experimenter may have access to a complete line of re- sistance units from 100,000 ohms to 6,000,-
000 ohms, the Radio Corporation has standard- ized a number of different values which are certain to meet all the requirements for radio reception.
The proper capacity for the grid condenser should be determined by experimenting with different values between .0002 and .0004 microfarad.
The grid leak unit which will give the proper biasing potential on the grid may vary between Yi megohm (500,000 ohms) and 3 megohms (3,000,000 ohms). Various values can be obtained by purchasing three of the Radio Corporation grid leak units, approximating /i,
1 and 2 megohms, respectively. The experi- menter can then try three values by employ- ing them singly, in series, in parallel or in series-parallel. Eight or more different val- ues between Yl to 3Yl megohms may in this way be obtained.
|
Model |
Ohms |
Megohms |
Model |
Ohms |
Megohms |
|||
|
The Radio Corporation Grid |
Leak Units |
UP-512 |
200,000 |
.2 |
UP-520 |
1,250,000 |
1.25 |
|
|
are |
manufactured in |
the |
UP-513 |
250,000 |
JZS |
UP-521 |
1,500,000 |
1.5 |
|
following sizes: |
UP-514 |
300,000 |
.3 |
UP-522 |
1,750,000 |
1.75 |
||
|
UP-515 |
400,000 |
.4 |
UP- 523 |
2,000,000 |
2. |
|||
|
Model |
Ohms |
Megohms |
UP-516 |
500,000 |
.5 |
UP-524 |
2,500,000 |
2.5 |
|
UP-509 |
50.000 |
.05 |
UP-517 |
600,000 |
.6 |
UP-525 |
3,000,000 |
3. |
|
UP-510 |
100,000 |
.1 |
UP-518 |
750,000 |
.75 |
UP-526 |
4,000,000 |
4. |
|
UP-511 |
150,000 |
.15 |
UP-519 |
1,000,000 |
1. |
UP-527 |
5,000,000 |
5. |
Grid Leak Moimting, Model UX-543
Grid Leak Units, Models UP-509 to UP-527.
$0.50
.75
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RADIOTRONS FOR RELIABLE RECEPTION
RADIOTRONS form the center of a system of radio com- munication which would be en- tirely impossible without them.
These vacuum tubes are manufac- tured by the General Electric Co. and the Westinghouse Lamp Com- pany for the Radio Corporation of America. There are so many shin- ing examples of great distances covered by Radiotron reception and transmission thai enumeration here would be impossible. With a single Radiotron, experimenters in Florida and another in Cuba have listened to the concerts sent out by a radio broadcasting station located in the vicinity of New York City.
The Radiotron detector tube was used by Mr. Paul F. Godley in his successful attempt to hear American amateur transmitting stations at the station he erected in Ardroasan, Scotland.
The electrical characteristics of all Radiotrons are practically uni- PR1C
form. This is made possible by 0veralI dimen. the highly standardized method of in. Shippin production utilized by the manu- facturers at their various factories for the pro- duction of Radiotrons. For this reason, the experimenter, in using Radiotrons, is assured of a uniform reliability, as every tube is made to pass a severe test and is rejected unless the high standard set for it is obtained.
There are many functions for the Radiotron to perform in connection with radio reception and only its great versatility permits it to be confined to two forms which cover perfectly the varied tasks they are called upon to per- form. These two forms are the detector and amplifier Radiotrons UV-200 and UV-201, respectively.
THE UV-200 DETECTOR TUBE
Radiotron UV-200 may be called upon to perform a great variety of duties as shown in the accompanying illustrations. In any receiv- ing circuit either simple or complex, Radiotron UV-200 is the detector which embodies all the characteristics necessary for faultless perform- ance. The circuits which appear throughout this book show some of the common uses made of this wonderful vacuum tube which has made communication over thousands of miles a fact by means of the code and speech to say noth- ing of music. Where long distances are to be covered, where stability of operation is de- sired, where long life and its resultant low cost are desired, where detector tubes of uniform characteristics are required for critical receiv- ing adjustments, in fact wherever real results
m
m
PRICE— $5.00
Overall dimensions, 1% in. x 4% in. Shipping weight, 1 lb.
are sought, there is but one an- swer to the detector tube question — Radiotron UV-200.
The Radiotron UV-200 is made with a standard four prong bayo- net base designed to fit the Radio Corporation standard VT sockets UR-542, and UP-552.
How to Use Radiotron UV-200
In using Radiotron UV-200 for a detector, a grid condenser of approximately .00025 mfd. or thereabouts should be connected in series with the grid. Many ex- perimenters prefer a variable grid condenser which is of value in regenerative circuits. In addition to the grid condenser one of the Radio Corporation's standard grid leaks should be connected across the grid condenser as shown in diagrams. In this case the Radio Corporation's standard Grid Leak and Condenser Mountings, UX- 543 should be employed.
»ight, i lb. Note: Where a variable grid-
condenser ia used, the UC-1820, fully described on page 50f is recommended; with this condenser no grid leak mounting is required, for the condenser is fitted with a mounting which will hold any of the Radio Corporation's standard grid leaks.
Where the desired voltage is not more than 22|/2. the “A" Battery Potentiometer PR-536 permits an extension of the life of the “B" battery. When the normal voltage of the 1 8 volt tap is too low, the connection from the potentiometer may be made to the 22Yi volt tap, thus using the cells between the 18 volt tap and the 22Yl volt tap previously idle.
It is sometimes necessary to use more than 22/i volts with the UV-200 and when this is the case, instead of connecting the lead through the potentiometer to the 18 volt tap of the plate battery it should be connected to the negative or 22Yl volt terminal of the plate battery. This permits an adjustment of from 22Yl to about 28 volts on the plate circuit.
Voltages in excess of 28 to 30 should not be applied to the plate of a Radiotron UV-200.
If the experimenter prefers to adjust the fila- ment by indicating instruments, it should be done by a voltmeter and not by an ammeter. All tungsten filaments show a decrease of cur- rent during their life and if constant current is maintained in the filament rather than constant voltage across it, the life will be greatly de- creased and no better signals obtained. The normal voltage to be maintained at the fila- ment terminals of RADIOTRON UV-200 lies within the range of 5 to 5.4 volts.
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RADIOTRONS FOR SATISFACTORY AMPLIFICATION
Radiotron UV-201
WHERE it is desired to use loud speakers, in order to eliminate the necessity of listen- ing to radio with the head tele- phones, sufficient energy must be provided to actuate the loud speaking device. A most suitable means for providing this energy is found in audio frequency am- plification, which is the combina- tion of Radiotrons and amplifying transformers functioning with a local source of current.
The incoming radio signals af- fect the vacuum tube in such a way as to draw current from the local source; this local current is then used to actuate the loud speaking device.
As may be seen from the fol- lowing description, the amplifica- tion factor ordinarily obtained where this method is employed is between 6 and 1 0 ; so that for each stage of amplification, the incom- ing signal is multiplied from 6 to 1 0 times. Where several stages are used, the signal may reach 36 to 100 times its original intensity.
PRICE— $6.50
Overall dimensions, 1% in. x 4 Vs in. Shipping weight, 1 lb.
RADIOTRONS FOR AUDIO AND RADIO FREQUENCY AMPLIFICATION
Radio frequency amplification differs great- ly from audio frequency amplification in that the increase of the signal intensity takes place before it has been reduced to suitable charac- teristics for operating a telephone receiver or loud speaker. Both radio and audio fre- quency amplification and circuits illustrating their most valuable uses, may be found in the section of this book devoted to receiving circuits.
For such circuits, the Radiotron UV-201, may be counted upon for reliable performance. Radiotron UV-201 may be used in any circuit where vacuum tubes are used as amplifiers. This remarkable amplifying tube has been de- signed to function with the Radio Corporation's audio frequency transformer UV-712 and the radio frequency amplifying transformers UV- 1714 and 1716, both described elsewhere in this book.
The normal plate voltage of Radiotron UV- 201 is 40, although increased amplification is possible with plate voltage up to 1 00. With 40 volts on the plate, the amplification constant
varies between 6.5 to 8, but with 100 volts on the plate, this con- stant is from 8 to 10. The output impedance of Radiotron UV-201 varies in value from 1 5,000 to 25,000 ohms, with 40 volts on the plate and from 10,000 to 15,000 with 100 volts on the plate, the normal filament current for Radio- tron UV-20i is approximately one ampere. The filament is de- signed for operation from a 6-volt storage battery with a standard filament rheostat in series.
To obtain maximum amplifica- tion with UV-201, means should be provided for imposing nega- tive potential on the grid although good amplification may be se- cured without this special provi- sion. The requisite negative grid potential for this purpose may be secured by connecting a “C“ bat- tery of 2 or 3 volts in the grid cir- cuit shunted by a 200 to 400 ohm potentiometer, or by placing a 2 -$6.50 ohm resistance in series with the
, i SA in. x 4 Vi negative terminal of the filament eight, l lb. and connecting the “low poten- tial" terminal of the tuner secondary to include this resistance in the grid circuit.
Important Facts Concerning UV-201
Because the UV-201 has been designed for use especially with the Radio Corporation s audio and radio frequency transformers, cir- cuits employing these standard units are found to give absolute satisfaction, even under se- vere operating conditions. The Radiotron UV-201 permits very great amplification with- out distortion. This feature is especially de- sirable where reception is carried on at short wavelengths. Heretofore, it has been a very difficult problem to obtain vacuum tubes and radio frequency amplifying transformers which would give satisfaction on the wavelengths used for amateur communication. The per- fection of the Radiotron with its allied units now permits radio reception over distances hitherto considered impossible, on all wave- lengths.
Circuits and data fully covering the applica- tion of Radiotron UV-201 to both Radio Fre- quency and Audio Frequency Amplification as well as various combinations of both have been presented at length in previous pages.
Digit[zed by
RADIO
CORPORATION
AMERICA
AERIOTRON VACUUM TUBES
(Westinghouse Products)
Aeriotron Amplifier Tube Model WR-21-A, for Use with Aeriola Grand Receiver
This is a specially designed and carefully selected tube for use in the amplifying circuits of the Aeriola Grand and may be placed in any of the three front receptacles from left to right.
The filament current for this tube is approxi- mately .8 of an ampere and the drop across the filament is about 4 volts. A six volt stor- age battery with a rheostat or ballast tube con- trol will, therefore, furnish satisfactory power for heating the filament to its normal operat- ing temperature.
The plate impedance of this tube is from 60,000 to 80,000 ohms, making it adaptable to resistance coupled amplification.
WR-21-A Amplifier Tube for Aeriola Grand
Receiver $7.50
Dimensions: 4 Vi in. x 1 14 in.
Weights: Net, 4 oz.; Shipping, 1 lb.
Aeriotron Detector Tube. Model WR-21-D, for Use with Aeriola Grand Receiver
This tube is designed especially for use with the Aeriola Grand Receiver and when so used gives excellent receiving results. It is provided with a special base which prevents its being used in equipment with which it will not prop- erly function. Aeriotron WR-2 1 -D has a green tip marking and is designed for use as the detector tube in Aeriola Grands, and should be placed in the right-hand front receptacle.
The filament current for this tube is approx- imately .8 of an ampere and the drop across the filament is about 4 volts. A six volt stor- age battery with a rheostat or ballast tube con- trol will, therefore, furnish satisfactory power for heating the filament.
Aeriotron Detector Renewal Tube, Model WR- 21-D for Aeriola Grand Receiver. . .$7.50 Dimensions: 4 /i in. x 1 14 in.
Weights: Net, 4 oz.; Shipping, 1 lb.
tmoTPOl
[PE WD (
Pc. 3195*
Aeriotron Ballast Renewal Tube Model WB-
800 for Aeriola Grand Filament Circuits
This vacuum tube has been especially de- signed for use with the Aeriola Grand Re- ceiver. It functions as a control element in the filament circuit of the detector and ampli- fier tubes. By the use of these control tubes, accurate adjustment of the filament current is automatically taken care of and filament rheo- stats are not required.
Aeriotron Ballast Renewal Tube, Model WB-
800 for Aeriola Grand Filament Circuit,
$3.50
Dimensions: 4 Vi in. x 1 14 in.
Weights: Net, 4 oz. ; Shipping, 1 lb.
Aeriotron Detector Tube Model WD-11, For Use with Aeriola Sr. Receivers
Aeriotron Detector tube, Model WD- 11, is designed for use with the Aeriola Sr. Receiver. It is provided with a special base to preclude the possibility of its being placed in a circuit other than that for which it has been designed.
The filament current consumed by this tube ia .25 of an ampere which may be supplied from a single 1.5 volt standard dry cell. However, it is inadvisable to connect the tube directly across the terminals of such a battery, and for this reason a suitable rheostat for controlling the filament temperature is provided with the Aeriola Sr.
The WD-1 1 Aeriotron tube operates quite satisfactorily as a detector when 22.5 volts are applied to its plate.
Aeriotron Detector Renewal Tube, Model WD-11 for Aeriola Sr. Receiver $8.00
Dimensions: 4 14 in. x 114 in. Weights: Net, 4 oz. ; Shipping, 1 lb.
Caution : The Aeriotron WD- 11 has a special coated filamentand must not be burned brighter than a DVJ.T. FF.D.
Digitized by 1
RADIO
CORPORATION
VARIABLE CONDENSERS FOR RECEIVING CIRCUITS
General
A VARIABLE condenser is an essential ele- ment for sensitive reception.
In general, variable condensers afford a reliable and simple method of altering the val- ues of receiving circuits in order to bring about a point of resonance, thus enabling one to select, at will, stations operating on different wave lengths.
When two or more circuits are in resonance they are of the same electrical wave length and the altering of the values of capacity or induc- tance in them to secure a certain wave length is called tuning.
When one desires to receive from a trans- mitting station, it is necessary to tune the re- ceiving instrument to resonance with the wave length of the station one wishes to hear — whether it be radio telephony or radio teleg- raphy.
There are so many types of variable con- densers, each designed for a certain purpose and a few remarks may be of value in assisting the experimenter to make a correct selection for the various types of receiving circuits com- monly employed.
Different usages require condensers of va- rious designs and the types described here are of unusual construction, providing a degree of accuracy and reliability hitherto unattained, and may be relied upon to fill every need.
Illustrating the use of two Faradon UC-1820 nested on a single shaft for controlling two circuits simul- taneously
FARADON PRECISION VARIABLE CON- DENSER MODEL UC-1820
In any radio circuit where a variable capacity from .00004 to .0012 mfd. is required, the Faradon Condenser UC-1820 will be found indispensable. This condenser has a capacity range from .00004 to .0006 mfd., but it is so constructed that it is possible to join two condensers together controlling them from a single dial knob. By such an arrangement, three distinct maximum capacities may be found by the condenser units of .0003, .0006, and .0012 mfd. respectively, as shown in the accompanying sketches.
Faradon UC-1820
Adding Other Capacities
Additional capacity variations may be ob- tained by adding to the variable condenser unit the Radio Corporation's tubular condens- ers UC-567-8-9-70 having capacities of .00025, .0005, .001, and .0025 respectively, the variable condenser acts as a vernier in this instance. The UC-1820 is provided with clips into which these fixed condensers may be placed. With these condensers it will be seen that the capacity range of the UC-1820 com- bination cannot be duplicated by any other condenser or combination of condensers now on the market.
There are quite a few important properties that may be obtained by the chain connected condensers. One very marked advantage is that the system will permit simultaneous tuning of two circuits with one knob.
If the circuits have a common lead an induc- tance may be connected between the fixed sys- tem of one condenser to the common movable system and a second equal inductance system may be connected between the fixed system of the second unit to the movable system as shown
50
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RADIO CORPORATION OF AMERICA
in the figure on previous page. If the dial is rotated the periods of both circuits will vary simultaneously.
Construction
The movable and fixed elements comprising the UC-1820 are die castings exact to 1/1000 of an inch. The housing of the condenser is likewise cast with great exactness. The mov- able element is fastened to a steel shafting. This shafting is fitted with bronze bearings and a suitable arrangement is provided for the cen- tering of the fixed and movable elements. The spacing between the plates is 10/1000 of an inch. The insulation between the fixed and movable systems for their relative support has been reduced to a minimum area in order to avoid dielectric losses. Connection from the movable system is made from a double split brush fitted to one of the base insulators.
Clip Mounting Feature
The clip mounting, in addition to furnishing possible variations of capacity by the use of fixed condensers as previously described, fur- nishes a ready means for inserting a standard Radio Corporation grid leak resistance. (UP- 507 to UP-509) where the UC 1820 is used as a variable grid condenser. This method per- mits a rapid change of grid leak resistance as well as a variable grid capacity, making for very accurate control of this circuit.
This condenser may be mounted in any position and provision is made to allow for panel thickness up to 5/16 of an inch, or on a base of any thickness.
Faradon Condensers have an efficiency of over 99 — 7/10% and they represent a standard of quality and efficiency that is rarely attained in any electrical device.
Faradon Precision Variable Condenser
Model UC-1820 $7.50
Capacity: .00004 — .0006 mfd.
Dimensions: 4 in. by 3 54 in.
Weights: 1 0 oz. Shipping 2 lbs.
FARADON VARIABLE MICA CONDENSER MODEL UC-1819
It is impossible to realize without having used one of these condensers, the satisfaction it makes possible in any form of receiving cir- cuit for accurate, reliable and selective opera- tion. A very marked difference between vari- able condensers of the older type and this new condenser is the fact that the capacity from minimum to maximum is increased in a uniform manner dependent upon the position of the variable element with respect to the fixed or stationary element. This relation is controlled by rotating a single calibrated control knob.
Wide Range of Capacities
Faradon UC-1819 for fine receiving work
Another and equally astounding fact con- cerning the Faradon UC-1819 is the very great range of capacity it covers — from .0001 to .005 mfd., which is a ratio of 50 to 1. No other condenser of similar size covers any such range as this.
A special grade of selected mica forms the dielectric of this condenser which is vastly dif- ferent from the forms of mica condensers here- tofore used, in that the capacity is continuously variable while the older types were variable in certain fixed steps, necessitating changes in the wiring or operated by a switching device.
Scientifically Constructed
The Faradon UC-1819 is the embodiment of advanced construction methods coupled with supreme engineering technique. Every detail has been scientifically considered and the completed unit marks a new period in radio reception. Here, at last, is a condenser which may be counted upon to perform satisfac- torily under the most trying receiving con- ditions.
The Faradon UC-1819 condenser is of the form shown in the accompanying illustration. It lends itself to any style of mounting, for it may be attached to the surface of any panel up to 5/16 of an inch in thickness with the shaft projecting through or it may be screwed to a base where that form of mounting is preferred. In either case an indicator is included to facili- tate the lining up of the rotary element with the calibrated dial knob.
Faradon UC-1819 Variable Mica Condenser*
$8.75
Capacities: .0001 — .005 mfd.
Dimensions: 4j/z in. x 6 in. x 4j4 in.
Weights: 14 oz. Shipping 2 lbs.
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RADIO CORPORATION OF AMERICA
COMPONENT PART TWO STAGE AUDIO- AMPLIFIER MODEL AA-485
Special Stabilizer Control eliminates distortion of speech and music.
HERE is the ideal instrument for the ad- vanced amateur who wishes to carry on experiments in amplification and thus study at first hand the action of various forms of radio receiving circuits.
Audio-Amplifier AA-485 is exceptionally well adapted for this purpose, for it is an open- wired set of very simple make-up incorporat-
ing unusual features of design and workman- ship. It consists of two stages of audio fre- quency amplification and is made up of stand- ard RCA receiving units, designed to function in perfect accord.
All the units are mounted on a strong bake- lite dilecto panel, which in turn is supported by heavy legs. Hie units are placed in posi- tions which are scientifically correct.
Terminals for the connection of the storage and plate batteries, as well as the input and out- put circuits, are conveniently located and dis- tinctly marked, so as to preclude the possibility of making wrong connections. An "A" battery potentiometer is provided in order that the grid bias potential may be controlled, avoiding dis- tortion, and to adapt it to various operating conditions.
Two Stage Component-Part Audio Frequency Amplifier, Model AA-485 $45.00
Dimensions: 12f/2 In. x 7% in. x 5in..
Weights — Net, 5 Vi lbs. ; Shipping, 7 lbs.
Note— For prices of Complete Receiver Combinations, see page 35.
TYPE DB CRYSTAL DETECTOR, STYLE NO. 307216
IN the base of this detector what is known as a blocking condenser is connected across the telephone terminals, thus making a very compact and complete unit.
The two types of detectors used on this unit are what is known as the “Pressure** type and the “Cat Whisker** type. In the former two selected minerals are held in pressed contact with each other. In the second type but a single crystal is used, the adjustment being made by means of a fine wire which may be moved about the crystal to locate sensitive spots.
Westinghouse Supersensitive Crystal Detector,
Model DB ...$6.50
Dimensions: 4% in. x 4|4 in. x 2 in. Weights: Net, l lb.; Shipping, \l/2 lbs. Spare Crystals (Pressure Type) Model DE,
$1.00
Spare Crystals (Cat Whisker) Model DD,
* $1.00
Note: Crystal Detector, type DB, may be very satisfactorily employed with any standard receiving outfit and it has been specially designed for use with the type RA Tuner, described in the nrst part of this book.
PORCELAIN SOCKET UR-542
THIS socket has been specially designed to meet the need for a reasonably priced sock- et which should at the same time be constructed of the very best insulating material obtainable, and should bear the stamp of quality through- out. It is a direct duplicate of the type used in commercial radio sets.
Porcelain is the ideal material for use in these devices, on account of its low specific in- ductive capacity and its high insulating qual- ities. Production in great quantities enables us to keep the selling price unusually low.
Model UR-542 is designed to accommodate RADIOTRONS UV-200, UV-201 and UV- 202, as well as KENOTRON UV-216.
PORCELAIN SOCKET, UR-542 $1.00
Size: 2^4 in. x 2 in.
Shipping Weight: 8 oz.
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52
RADIO CORPORATION OF AMERICA
“A” BATTERY POTENTIOMETER PR-536
It is impossible to over-estimate the desira- bility of using a potentiometer in connection with the Radio Corporation's gas-content de- tector, Radiotron UV-200. Only in this way can proper detector action and resulting in- crease of signal audibility be obtained.
It is inadvisable to use any type of potentiometer across a standard **B" battery, as it will exhaust the cells in a relatively short time. To overcome this diffi- culty the Radio Corporation developed this instrument.
In appearance, POTENTIOMETER PR-536 closely resembles the Radio Corporation's Rheostat PR-535. It is provided with three contacts. Two of these are shunted across the "A” battery, while the third is con- nected to a tap on the negative side of the plate battery, giving eighteen volts. This connection gives a plate voltage variation from eighteen to twenty-four volts.
“A” Battery Potentiometer $2.00
Dimeiuions: 2 in. x \/i in. x 2 7/16 in.
Shipping Weight, 1 lb.
BAKEUTE SOCKET UP-552
Some amateurs may prefer to use a Bakelite socket rather than our standard porcelain sock- et, Model UR-542, described on page 52. This socket has enjoyed unusual popularity for several years past. It is durably constructed and of fine appearance. One particular fea- ture is the ease with which connection may be made, since the connecting clamps are unusual- ly accessible and provide ample space for per- manent contacts. Socket UR-542 will take Radiotrons UV-200, UV-201 and UV-202.
Bakelite Socket, UP-552 $1.50
Dimensions: I Yi in. x I J/J in. * \/i in.
Shipping Weight, 1 lb.
TUBULAR GRID AND PLATE CONDENSER
There has been an insis- tent demand in the amateur held for fixed condenser units of various capacities, suitable for amateur receiv- ing sets. The Radio Cor- poration of America has evolved the four models herein listed, which are de- signed to fit its Standard Grid Leak Mounting. These condensers are recommend- ed for use in the grid cir- cuit, or as a by-pass con- denser in the plate circuit, of standard vacuum tube receiving sets. They are es- pecially useful as a unit of fixed capacity to be shunted to any standard variable air condenser.
The complete condenser unit is sealed in a glass tube fitted with end caps, in the same manner as the Stand- ard Grid Leaks. Every amateur station should have at least one complete set for general experimental purposes. Nothing equally satisfactory to the four models listed here has been produced for mounting in receiving set cabinets, for if one value of capacity is found unsatisfactory for the purposes at hand, another suitable value may be imme- diately inserted in its place. Dimensions: 1^ in. x %
m.
Shipping Weight: 4 oz.
AN INDIVIDUAL COLOR FOR EACH CAPACITY
Condenser, UC-570— .0025 Mfd., White $2.00
Condenser, UC-569 — .001 Mfd., Orange l.S©
Condenser, UC-568— .0005 Mfd., Green 1.35
Condenser, UC-567— .00025 Mfd., Black 1.20
Condenser Moimting, UX-543 SO
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RADIO
CORPORATION
AMERICA
THE FOUR POINT TELEPHONE JACK MODEL UD-486
© ©
ONCE a radio broadcasting receiving set has been installed, it does not take long for one* 8 friends to hear of it and they are wont to drop in of an evening to hear something of the concerts and news .which may be received from the ether. In such cases, it is desirable to pro- vide some means to permit these friends to listen without interfering with one’s own pleas- ure. A more convenient way for connecting several sets of radio head receivers than the UD-486 cannot be made.
As may be seen from the illustration, this little unit is merely connected to the receiving set by two wires. There are little openings on its face through which the sets of head receiv- ers may be plugged in.
Ordinarily, the connecting of more than one pair of telephones is a rather difficult task for the cord tips cannot be joined together very readily. By connecting each pair to the tele- phone plug UD-824, however, any desired number of head sets up to four may be put in operation by using the four point telephone jack.
The interior connections on this jack are so arranged as to permit connection of one to four pairs of telephones at will. The UD-486
will accommodate four plugs; each plug is in turn connected to a pair of receivers so that four sets may be used. As each set is made up of two individual receivers, it may be seen that eight persons may listen simultaneously using a single receiving set
When one or more plugs are withdrawn from the four point jack the circuit is auto- matically rearranged to leave the telephone receivers connected to the remaining plugs in an operative condition.
Four Point Telephone Jack,
Model UD-486 $7.25
Dimensions: 4j/2 in. x 2|4 in. x 2 in. Weights: Net 5 oz. ; Shipping, 1 lb.
SINGLE AND DOUBLE TELEPHONE PLUGS, MODELS UD-824 AND UD-825
Single Plug, Model UD-824
By using the four-point jack and double plugs illus- trated here, many persons may listen in.
Double Plug, Model UD-825
THESE telephone plugs are so connected that ordinary telephone cords may be in- serted in them without having to take off the cord tips. The plugs are particularly useful in connection with radio where multi-stage ampli- fiers are used, for, without the necessity of making special soldered connections, the user has at his disposal a ready means for applying any pair of telephone receivers to a plug and jack system.
There are two models: one for connecting a single pair of telephone receivers, one for use with two pair. To apply these plugs it is merely necessary to place the cord tips in the openings provided and locking them in place by moving the tip sleeve.
Single Telephone Plug,
Model UD-484 $1.75
Double Telephone Plug,
Model UD-485 $2.60
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RADIO CORPORATION OF AMERICA
“ VOCAROL A”— THE LOUD SPEAKER
WHERE broadcasted music and speech is being received and it is desired to have volume enough to (ill a room so that many per- sons may hear, the Vocarola may be employed to advantage. It is but necessary to remove the plug of the telephones from the jack in the amplifier unit, placing the loud speaker plug in its place.
Vocarola is equipped with a supersensitive sound producing device which changes the in- coming electrical impulses into sound waves. This sounding element is attached to an at- tractively finished tone chamber in the form of a horn from which the sound emerges.
The Vocarola, when used with suitable am- plifying equipment, furnishes music and speech with a tone clarity identical to that of the trans- mitted music or speech.
Vocarola Loud Speaker, Model LV
Dimensions — 10 in. x 8 in. x V/i in.
Vocarola, Model LV.
$30.00
Weights — Net, 2. lbs., Shipping, 5 lbs.
PHONOGRAPH LOUD SPEAKER ATTACHMENTS
These attachments are pro- vided with a six-foot telephone cord and an attachment plug which may be inserted in the jack of the amplifier.
Where these loud speaker attachments are employed, it is necessary to use amplifiers just as it is necessary to do so in using the Vocarola described above.
BY employing a phonograph attachment it is possible to convert your phonograph into a loud speaking device for radio reception where the music is to be heard by a number of people throughout the room.
In order to use this new attachment it is but necessary to remove the reproducer or “ 'sound box** as it is called, from the tone arm of the talking machine, replacing it by the phono- graph attachment which is designed to easily slip into place. There are two models, one for Victrolas and the other for Graphonolas. The Victrola model, in addition to fitting Vic- tor machines, will fit any other talking machine having the same size tone arm.
Victrola Loud Speaker Attachment, Complete with Cord and Plug, Model LS $18.00
Graphonola Loud Speaker Attachment, Complete with Cord and Plug, Model LS 18.00
Dimensions: in. x 3 in.
Weights: Net 1 lb.; Shipping, 1 Vi lbs.
Note: In ordering , the make of phonograph should be specified.
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RADIO
CORPORATION
AMERICA
RECEIVING ANTENNA OUTFITS
(With Complete Instructions For Installation)
rtS h> " _
lp*ii
Fig. I — Illustrating method of installing a one or two wire antenna for broadcast reception.
THESE antenna outfits have been espe- cially designed for the radio broadcast- ing sets described in this catalog. Hie following instructions apply in general to all classes of receivers but especially to broad- casting reception.
Selecting the Location
The number of miles over which a given broadcasting receiving outfit will respond de- pends upon a number of important factors. In order to get the most satisfactory results with any of the receiving outfits described here the antenna, or aerial, as it is sometimes called, should consist of one or two wires 50 to 150 feet long. Good reception often can be ob- tained with two wires of a shorter length, sep- arated from each other by three- foot wooden spreaders. See Fig. 3. Care should be taken to keep the antenna as far as possible from trees and buildings, especially where the latter have a steel frame-work, and the lead-in wire should never be brought down a narrow air- shaft. Where an antenna is supported by a house at one end and a tree at the other end, care should be taken to have an insulator, such as provided with Model AD outfit, extend a distance of at least 10 feet beyond the tree's branches. Where one end of the antenna is fastened to a building having a metal roof this same precaution should be followed, for should the antenna come in contact with the objects mentioned, the incoming signals will be re- duced in strength by electrical leakage.
Raising the Antenna
The method of raising the antenna after the location has been decided upon, where a single wire antenna is to be used, is as follows : Take one of the screw eyes furnished with the antenna equipment in the building or tree, which is to support the free end of the antenna, that is, the end away from the receiving out-
fit. A piece of copper wire is passed through this screw eye as shown in Fig. 2. This wire is then left long enough to extend 1 0 feet beyond the roof of the building or the branches of the tree holding the screw-eye and to it is at- tached an insulator. The other end of this in- sulator is used for fastening the end of the an- tenna wire itelf as shown in Fig. 2.
The wire is then run from this point to a point directly beneath that section of the house in which the receiving set is to be placed. This end of the antenna is put in place by inserting another screw eye in some part of the house, preferably as high as pos- sible. In this instance the insulator is attached to the antenna wire at a point estimated to be approximately 1 0 feet from the side or roof of the house. To the opposite end of this in- sulator is connected another tie wire as illus- trated in Fig. 2. The opposite end of this tie wire is then drawn through the screw eye on the house, and fastened by twisting. In this way by tightening the second tie wire the an- tenna is raised above the ground. It should not be drawn too tight, but a certain amount of slack should be permitted.
The Lead-In Wire
The end of the wire leading to the receiv- ing set must be fastened to the end of the an- tenna wire before the antenna is raised from the ground. The connection between these two wires is made as follows:
/ te> /J Copper W&
rf/t'e'/Mu,' iV.re
/tot M Copper Wa fie mre
ffo /4 /PsvA7/ea
Cower Hire
Afo. /4 Capper We/0 7/e W&r
\te./4 (typer m/f A/toMff Wire
Fig. 2 — To the left shows method of connecting the antenna to the lead-in wire. To the right shows the free end of the antenna and manner of fastening to support.
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CORPORATION
AMERICA
A metal connector is supplied with this type of antenna outfit. In its original condition it resembles two hollow, metal tubes fastened to- gether. Through one of these tubes the end of the antenna wire passes in one direction while the end of the insulated lead-in wire, from which six inches of the insulation has been removed, passes through the other tube in the opposite direction. By grasping each end of this connector with a pair of pliers and twisting, the two wires are bound together in this metal sleeve in the manner shown in Fig. 2 eliminating the necessity of soldering.
The lead-in wire should run in as near a direct line as possible from the antenna to that part of the house in which the receiving set is to be placed. Right angle turns in the lead-in wire should be avoided, in so far as possible. Where it is necessary to have the lead-in wire run along the side of a building it should be raised on porcelain knobs as shown in Fig. 4. This wire should be isolated from surrounding objects as far as possible.
Where the lead-in wire is to enter the build- ing it is essential to bore a hole in the wall (if the building is frame), or through the window casing in other types of buildings. This hole may be drilled with a ^-inch bit. The insulating bushing furnished with these outfits is then inserted in this hole through the build- ing. The hole through the building should be made on an angle as shown in Fig. 4. The lead-in wire is then passed through the tube from the outside and a small loop should be left outside the building to permit the rain water to drop off both the lead-in and the in- sulating bushing.
Description of Window Board
A suitable method for making connections from a radio receiving antenna is illustrated by Fig. 4. This method is especially desirable in apartment houses for the reason that it ob- viates the necessity of drilling holes through the wall or window frames.
Fig. 3 — Illustrating a method of installing an antenna on the roof of an apartment house.
A piece of board 1 0 or 11 inches wide and just long enough to extend across the window is held in place by a wedge placed at either side of the window casing as shown. A hole is drilled through the board and the lead-in in- sulator passed through this hole. The pro- tective device is screwed directly to this board in the position indicated and the lead-in wire is permanently attached to the terminal A of the protective device. The terminals R and G of the protective device are used for connec- tion to the receiving set and the latter is also connected to the ground wire as described elsewhere.
Where this method is employed, the win- dow may be opened or closed without inter- fering with the lead-in wire or the wires run- ning to the receiving apparatus, and the pro- tective device may be attached to the board without in any way mutilating the window cas- ing or walls of the house.
The Installation of the Protective Device
This device is used to protect the receiving instruments as well as the house itself from possible damage caused by lightning flashes. It is a combination of a very small spark gap and fuse. It should be placed in some incon- spicuous place, either on the wall or under the window frame, not far from the point at which the lead-in wire enters the building. The lead- in wire is fastened to one terminal of the pro- tective device as shown in Fig. 4. To the other two terminals are connected the wires which run to the receiving set. It will be no- ticed in Fig. 4 that one of these two termi- nals is made to carry two wires. The second wire is called the ground wire and is made from a portion of the 50 feet of rubber-cov- ered ground wire, supplied with the antenna equipment. This wire may be run through the house by using some of the insulated staples supplied with the outfit.
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CORPORATION
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Attaching the Ground Clamp and Running the Ground Wire
The ground clamp is a strip of metal made to fasten around a pipe and held in place by a clamping device. It is important that the pipe itself be scraped very clean, either by a knife, file or a coarse grade of sand-paper. After being sure that the pipe to which the clamp is to be attached is thoroughly cleaned, the ground clamp may be installed. It must fit over the pipe as tightly as possible. The ground wire, which runs from one terminal of this clamp to the protective device, as shown in Fig. 4, should be as short as possible. As is the case with the antenna lead-in wire, the ground wire should be as free from angles as possible, the ideal condition being found when the ground wire is very short and straight. With these instructions and references to the accompanying illustrations no difficulty should be experienced in erecting an antenna which will give satisfaction under almost any condi- tions.
The Protective Device
The protective device does away with the necessity of having a large antenna grounding switch on the exterior of the building and pre- cludes the possibility of the operator forget- ting to throw this switch when the receiving equipment is not in use. This protective de- vice is more thoroughly described on page 59.
In large cities it is sometimes difficult to find a location where either a single or double wire, as shown in Fig. 1 , can be erected. Fig. 3 gives a very good idea of the method which may be used in placing antennae on apartment houses or office build- ings. Where the building is 100 feet high or more and the receiving outfit is to be located on one of the lower floors, a single wire run- ning from the roof to a point opposite, the location of the receiving apparatus will suf- fice to cover the ranges previously mentioned with regard to the sets described in this catalog. Where a building is lower than this it is some- times advisable to run a wire _
across the roof supported by any rfSi,
convenient object such as a water tower, a clothes pole, or }*** ™ a high chimney. This wire is then * r connected to the lead-in wire which may be run to the receiving outfit. Where this method is em- ployed care must be taken to keep both the flat-top section of the antenna as well as the lead-in wire as far as possible from adjoining buildings.
The details of any receiving antenna may be worked out from observation of the fore- going instructions and no difficulty should be experienced in getting satisfactory results.
The following antenna outfits comprise everything essential for installation. The out- fits are packed complete with full instructions.
Westmghouse Receiving Antenna Outfit
Antenna Outfit Model AD $7.50
Includes 150 feet No. 14 Copper Weld Antenna Wire. 50 ft. No. 18 Copper Ground Wire.
50 ft. No. 14 Copper Lead-in Wire.
I PA Protector.
1 Entrance Bushing.
2 Antenna Insulators.
2 Screw Eyes.
I Ground Clamp.
3 Porcelain Knobs.
I Connector.
I 2 Insulated Staples.
G. EL Receiving Antenna Outfit
Antenna Outfit, Model AG-788 $7.50
Includes 175 feet No. 14 Copper Weld Antenna Wire. 50 feet No. 14 Copper lead-in wire.
25 feet No. 14 Copper Ground wire.
I Protector.
I Porcelain Entrance Bushing.
3 Antenna Insulators.
3 Screw Eyes.
I Ground Clamp.
3 Porcelain Knobs.
12 Insulated Staples.
8 Wood Screws.
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RADIO
CORPORATION
AMERICA
RECEIVING ANTENNA PROTECTIVE DEVICES
THESE devices are standard units supplied with R. C. receiving antenna outfits. How- ever, they may be used satisfactorily with any other type of receiving antenna equipment. Their purpose is to supply a means for pro- tecting the receiving station as well as the building in which it is located from any serious effects which might be caused by lightning.
The G. E. Vacuum Type Protector Model UQ- 1310
Heretofore, it has been necessary to have a large switch mounted on the outside of the building with a heavy wire running to an out- side ground connection. Although this switch formed a satisfactory method for carrying elec- trical charges to the earth, there was always the possibility of the operator forgetting to throw the switch after he had finished receiving. With the protective device no such possibility as this can arise, for there is no switch to be thrown. Once it has been installed it func- tions wihout further attention.
Two types of antenna protective devices are available. Model UQ- 1310, illustrated above, is the vacuum type; Model PA, shown below, is the fuse type. Both are suitable for receiv- ing purposes, but not for transmission.
The Westinghouse Fuse Type Protector Model PA
G. E. Receiving Antenna Protective De- vice, Model UQ-1310 $2.50
Westinghouse Receiving Antenna Protec- tive Device, Model PA .$2.00
Dimensions: 7J4 in. x ll/2 in. x 1 y2 in. Weights: Net, 10 oz. ; Shipping, 1 lb.
LOAD COIL MODEL CB (1800-2800 METERS) FOR USE WITH RC RECEIVER OR RA AND DA COMBINATION
BY using this coil in conjunction with the RC Receiver or the RA tuner, and DA ampli- fier previously described, it is possible to re- ceive signals on wave lengths up to 2800 meters. This is particularly valuable as it en- ables one to hear the time signals from the United States Navy Station at Radio, Va. for distances of several hundred miles. Watch repair shops and jewelers will find this twice-a- day service from the United States Observatory in Washington invaluable for checking watches and clocks as the time may be received with less than one-tenth of a second error. Dealers throughout the country are availing themselves of this service, some going so far as to arrange small time balls for their windows by which passers-by are given an opportunity to check their watches.
mmm*.
Illustrating the method of connection for CB Load Coil in conjunction with Model RC Receiver
For wavelengths between 170 and 700 meters the switch arm shown in the center of the picture should be raised. For wave lengths between 1800 and 2800 meters it is but nec- essary to push down on this arm. The CB Load Coil is arranged to supply the necessary inductance for both the antenna and tickler circuits.
Caution — It is essential that the ground wire (G & D) be connected exactly as shown in the accompanying illustration.
Load Con, Model CB, 1800-2800 Meters,
$6.00
Dimensions: 6 in. x 4 in. x 5 in.
Weights: Net, 8 oz.; Shipping, 2 lbs.
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RADIO
CORPORATION
AMERICA
STORAGE BATTERIES FOR RADIO USE
Exide Battery, Model 3LXL-9
WHERE vacuum tubes are used for receiv- ing, the filaments must be heated by a storage battery. It has been common practice among Radio Amateurs to use almost any type of storage battery they can lay hands on, re- gardless of its capacity or design. Storage bat- teries, like every other electrical device, in order to function satisfactorily, must be de- signed with a given purpose in view. A very heavily constructed storage battery is not suit- able for radio service as it is too heavy to be transported conveniently to a charging station, and a battery of too light construction, such as the automobile starting, lighting and ignition battery, will not give satisfactory life in this type of service.
Especially Designed for Radio Work
In vacuum tube receiving sets, the number of tubes generally employed is from one to three. The normal current consumption of each tube is approximately one ampere. It is obvious, therefore, that a storage battery for most satisfactory operation with radio must be capable of delivering the required ampere hour capacity at the rate of one to three amperes when in use. Most amateur stations are used intermittently and for this reason the duration of a single charge in the storage battery is con* siderably increased.
In order to provide a suitable storage bat- tery for radio work, the Radio Corporation of America offers to the field the Exide bat-
tery, which has given entire satisfaction in ma- rine service since wireless equipments were first installed on ship board.
This battery — the Exide — has behind it 34 years of battery-building experience. Its man- ufacturer, The Electric Storage Battery Com- pany, since the beginning of the storage bat- tery industry, has built storage batteries for every purpose, and this knowledge and exper- ience have been put to good use in designing a battery especially for vacuum tube operation.
In this class of service batteries must be cap- able of withstanding numerous complete cycles of charge and discharge at low and intermit- tent rates.
The separators are made of a selected qual- ity of hard and durable wood subjected to a special '‘treating process" which eliminates elements which would injure the batteries.
The jars and covers are made of the tough, semi-flexible "Giant Compound Rubber" and are practically unbreakable under service con- ditions.
Service Station Advantage
A very distinct advantage of this battery for radio work is that the user may call upon any of the Exide Service Stations, which thorough- ly cover the United States and Canada, and extend into all civilized foreign countries, to have his battery properly charged, or for other service.
For domestic use the Exide batteries are shipped assembled, sealed and charged, and all ready to go into service. For export use, these batteries are especially packed for ex- port shipment and are shipped assembled, sealed but unfilled, and they can readily be filled and put into service at destination.
The ampere hour capacity of the Exide Ra- dio Battery varies as it does with all storage batteries, according to the current being con- sumed. The following table shows what may be expected of these batteries in vacuum tube work:
Ampere-Hour Capacity Rate of Discharge
Type Intermittent
3LXL-5 40 Amp. Hrs.
3LXL-9 80 Amp. Hrs.
3LXL-13 120 Amp. Hrs.
Specifications
Charging Charging rate rate
Type Length Width Height Weight at start at finish
3LXL-5 5-11/16" 7-5/16" 9-5/8" 24^ lb. 6 amp. 3 amp.
3LXL-9 9- 1/16" *• ** 42i4‘* 13 “ 6 “
3LXL-I3 12- 7/16" “ #* 59 M 18 M 9 M
Storage Battery, Model 3LXL-5 $17.50 Storage Battery, Model 3LXL-9 .
Storage Battery, Model 3LXL-13 $30.00
.$23.00
Prices packed for Domestic Shipment, f.o.b. Factory, Philadelphia.
C jtized by
RADIO CORPORATION OF AMERICA
THE WESTINGHOUSE UNION RADIO “A” BATTERY
THE Radio Corporation of America takes pleasure in offering to the Radio public the Westinghouse Type H.R. Radio Battery, and feels warranted in backing the claims made by the Westinghouse Union Battery Company for their product.
It was decided, after an extensive investiga- tion and research in the radio field in conjunc- tion with the largest manufacturers, to produce series of special radio batteries of entirely new design, rather than a conversion of previous types.
These Radio Batteries embody the most ad- vanced engineering principles and the finest materials and workmanship possible in a bat- tery. They are backed by the immense re- sources of the Westinghouse Air Brake Com- pany, and affiliated Companies, and are built to meet and live up to the standard of quality and service established by its sponsors during the last 50 years.
Features of Design
Heavy positive plates — 3/16" thick — are used to insure ample capacity and long life. High rests to insure ample mud space and acid space are provided in order that the battery may function longer without recharging, while wide plate spacing reduces to a minimum the internal discharge. This feature alone justifies a special design as it helps limit the loss of power when the Radio equipment is not in service.
To prolong the life of the Radio Battery — rubber sheets are used on both sides of the positive plates — thereby retarding the break- ing down of the separators. A rubber covered cable is moulded into the post thereby enabling connections to be made several inches from the battery and eliminating poor connections and corrosion.
Acid will settle in a fine spray on the top of the cells while the battery is being charged and in most batteries will seep between the jars, through the case and then on to the table or desk^-destroying the finish or covering — but Westinghouse engineers have eliminated this on the type “HR” by completely sealing all cells together at the top so that the acid may be seen at once and wiped away.
Westinghouse Battery Model 6-HR-9
Westinghouse Service
“Westinghouse Attention” is the improved type of service available at Westinghouse Bat- tery Service Stations.
It is founded on Westinghouse ideals and guided by the experience of experts. Being based upon a fundamental plan, it is uniform everywhere.
It is co-ordinated by a comprehensive, fac- tory-operated service organization which cov- ers the entire country and insures that there shall be no falling away from the rigid stand- ards.
Type “HR“ Batteries ordered from the Radio Corporation will be delivered fully charged from the nearest Westinghouse distrib- utor, thus insuring the user a battery that has been freshly charged and is instantly ready for use.
Ampere Hour Capacity
|
Amp. Hra. at 3 Amps. |
||||
|
Type |
Volta |
Intermittent Rate. |
||
|
6-HR-5 |
6 |
50 A. H. |
||
|
6-HR-9 |
6 |
100 A. H. |
||
|
6-HR-I3 |
6 |
150 A. H. |
||
|
Length |
Width |
Charging rate Height Weight Start riniah |
||
|
6-HR-5 |
iff |
7% |
9 13/16 |
30 4 1.75 |
|
6-HR-9 |
73/s |
9 13/16 |
46 7.75 3.5 |
|
|
6-HR-l 3 |
73/g |
9 13/16 |
65 11.75 5.25 |
Storage Battery Model 6-HR-5. .... .$18.00 Storage Battery Model 6-HR-9 $24.00
Storage Battery Model 6-HR-13 $33.50
Prices, packed for domestic shipment, f.o.b. nearest Westinghouse Battery Distributor.
61
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RADIO CORPORATION OF AMERICA
RADIO BATTERY CHARGERS
TUNGAR BATTERY CHARGERS RECTIGON BATTERY CHARGERS
MANY vacuum tube receiving seta require a storage battery for illumination of the tube filaments. When only a source of alter- nating current is available, the simplest and least troublesome device for battery-charging is the General Electric Company’s Tungar Rectifier. Two sizes are recommended.
The 2 -ampere Tungar has a capacity of 1 5 watts and will charge a 3-cell storage bat- tery at 2 amperes or a 6-cell storage battery at one ampere.
The 1 -battery Tungar has a capacity of 45 watts and will charge a 3-cell storage bat- tery at 5 amperes, or a 6-cell, or two 3-cell batteries at 3 amperes.
2-AMPERE TUNGAR, Model No. 195529 $18.00
1-BATTERY TUNGAR, Model No. 219865.. .$28.00 RENEWAL BULB No. 195528 for Tungar Model No.
195529 $4.00
RENEWAL BULB No. 189048 for Tungar Model No.
219865 $8.00
Weights: No. 195529. .8 lbs.— No. 219865. . 15 lbs.
No. 195528. .4# lb .—No. 189048. . 3 lbs.
THE Rectigon Battery Charger, manufac- tured by the Westinghouse Elec. Mfg. Co., forms a very satisfactory means of charging the filament storage battery from an alternating current source. There are no moving parts to this instrument and it is simple, safe and economical.
Style No. 282395, the 2,/2-ampere capacity Rectigon, is suitable for charging a 40-ampere- hour storage battery from 1 1 0-volt, 60-cycle mains. All the larger batteries should be charged with Style No. 285168, which is capable of delivering six amperes.
2 H -AMPERE RECTIGON, Model No. 282395. $18.00 6-AMPERE RECTIGON, Model No. 285168. $28.00 RENEWAL BULB No. 277681 for Rectigon No.
282395 $4.00
RENEWAL BULB No. 289414 for Rectigon No.
285168 $8.00
Weights: No. 282395. .9*4 lbs. — No. 285168. .21 lbs.
No. 277681 . . % lb. — No. 289414. . 3 lbs.
It is only necessary to connect the Chargers to any 60- cycle alternating cur- rent (110 volts) electric light socket, and attach the low voltage direct current terminals to the bat- tery.
Illustrating the simplicity of battery charging when A. C. is available.
The outfits are so designed as to give rated normal cur- rents at normal line voltage to 3 cells and about 2/3 this cur- rent at normal line voltage to 6 cells.
62
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RADIO RECEIVING APPARATUS OF QUALITY
-THE Radio Corporation of America is in a position to present ^ to Experimenters and to the Laboratories of Colleges, Univer- sities and High Schools, equipment which incorporates the highest quality of material and workmanship and the latest technique in radio design.
The radio receivers and accessories listed in the following pages were designed and manufactured under the supervision of one of America’s foremost radio receiving experts. Experimen- ters desiring to purchase receiving apparatus of the last degree of refinement are urged to investigate this line of equipment. The wavelengths covered by these receivers range from 1 50 to 8,000 meters. By the use of the loading inductances listed, these Bets can be adapted for reception up to 20,000 meters. Appro- priate binding posts are mounted on the receiving cabinets and by removing a short circuit strap, these load coils can be inserted in both the primary and secondary circuits.
All controls are mounted on Bakelite panels and the complete apparatus is contained in an oak box. Suitable detector and amplifier units are also provided.
Radio engineers about to make precision measurements in laboratory research work should investigate the high class variable condensers described on the following pages. These represent the highest grade of workmanship and will retain their calibration with extremely slight variation throughout their operating life. Additional high grade apparatus will be added to this catalog from time to time to meet the demand for instruments of superior performance. All receiving apparatus and accessories described herein are licensed for amateur or experimental use only.
63
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RADIO CORPORATION OF AMERICA
RADIO RECEIVER, IP-500
THE IP-500 Receiver is one of the most effi- cient receivers manufactured. The circuits are designed to give the highest possible effi- ciency.
Normal wavelength range: 300 to 6,800 meters. This receiver is equipped with six binding posts, normally short-circuited for 300 to 6,800 meters to which loading coils may be attached for the reception of wavelengths up to 23,000 meters. The proper loading coils are: Primary, 50; Secondary, 50; Tickler, 30 milli- henries. This receiver possesses a high degree of selectivity, but it is also provided with an un- tuned or “standby” circuit. It is especially adapted for use in laboratories, and by ad-
vanced radio clubs, where a receiver is desired which is the last word in perfection of design and finish.
A switching mechanism permits the use of either of two tuned circuits on an untuned or tuned secondary.
The coils used in the receiver are bank- wound inductances of high-frequency cable, wound on threaded bakelite tubes. The as- sembled coils are impregnated in vacuum and baked. The individual sections are automati- cally connected, entirely disconnected and opened, or entirely disconnected and individu- ally short-circuited, by a mechanism operated by the inductance switch. By this means every coil in the receiver has a natural period when connected with its leads and switch points which is less than the shortest wavelength in the range of the receiver. This eliminates the re- ception of parasitic signals, reduces the absorp- tion of the desired signal by the coils, forces the energy into the detector, and minimizes inter- ference on all wavelengths.
The condensers are of the self-balanced plate type. Insulating bushings are entirely absent in their construction. Their calibration is constant and their losses extremely low.
The receiver is mounted under a J/^-inch Bakelite-dilecto panel. The containing box is of ^g-inch oak. A switch is provided for vac- uum-tube reception, and also to protect the detector during transmission.
RECEIVER, IP-500, INCLUDING HIGH GRADE CRYSTAL DETECTOR $595.00
Overall dimensions: 23 in. x II in. x 14J/2 in. Shipping weight: 87 Iba.
RADIO RECEIVER, IP-501
THE IP-501 Receiver shown in the accompanying illustration is a compact unit containing the radio frequency and detecting circuits in a single case.
Normal wavelength range: 300 to 7,500 meters.
This receiver is equipped with six binding posts (normally short-circuited for 300 to 7,500 meter reception) to which loading coils may be attached for the reception of wavelengths up to 21,000 meters. The proper loading coils are: Primary, 50;
Secondary, 100; Tickler, 30 millihenries.
The receiver is similar in mechanical design to the IP-500, with the untuned circuit omitted. The ca- pacity coupling between primary and secondary cir- cuits is eliminated in this type by heavy sheet copper boxes separately enclosing the two circuits.
The panel is of Bakelite-dilecto. The coils are bank -wound inductances, of high frequency cable wound on threaded Bakelite-dilecto tubes, impreg- nated and baked.
RECEIVER, IP-501, INCLUDING HIGH GRADE CRYSTAL DETECTOR $550.00
Overall dimensions: 20 in. x 11 in. x 9 in. Shipping weight: 55 lbs.
64
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DETECTOR AND ONE-STEP AMPLIFIER, TRIODE A
THE amplifier control box shown in the illustration contains vacuum tube detector and amplifier circuits and their con- trols. A switch permits the use of either the detector or the amplifier. Continuous control of the detector between the damped and undamped methods of reception is obtained by an adjustment in the receiver itself. Amplification is obtained by means of a transformer interlinking the detector and ampli- fier. Separate rheostats and ammeters are provided with each. The degee of amplification is controlled by the ampli- fier rheostat. The amplifier is of a type entirely new to the radio art, operating on the principle of low frequency reso- nance and variable input impedance.
The detector and amplifier have shock-proof mountings that entirely eliminate “noise” due to mechanical vibration.
These in turn are mounted on a Bakelite-dilecto panel, and the whole encased in an oak box.
The best of materials and workmanship are employed in the construction of this control unit. It is rugged, and with proper care will have an indefinitely long life in service. It presents the best solution of modern radio problems, and is designed and manufactured in accordance with the best radio engineering practice.
DETECTOR AND 1-STEP AMPLIFIER, TRIODE A $190.00
Overall dimensions: 14J/2 in. x 9J4 in. x 6J4 in.
Shipping weight: 20 lbs.
TWO-STEP AMPLIFIER, TRIODE B
THIS two-step amplifier is a compact unit of the resonance low-frequency type. It provides a maximum of amplifica- tion due to the transformer design, which is greatly superior for radio reception to other types on the market. The input impedance of each tube is automatically controlled by the filament rheostat.
The apparatus consists of two vacuum tube receptacles, two filament control rheostats, and two amplifying transformers. Shock-proof mountings protect the vacuum tubes from “noise** due to mechanical vibration.
The apparatus is mounted on the rear of a Bakelite-dilecto panel and enclosed by an oak box. At the bottom of the panel are terminals for connecting the 6-volt filament and the 40-volt plate batteries. At the lower left of the panel are the two input binding posts for connection to the receiver equip- ment. At the right of the panel are two binding posts for connecting telephones.
TWO-STEP AMPLIFIER, TRIODE B $95.00
Overall dimensions: 1 1 J's in. x 7 J/2 in. x 6 Ya in.
Shipping weight: 12 lbs.
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CONSTANT IMPEDANCE AUDIBILITY METER, IP-306
:7 V V:
•MW* t , , W
AN audibility meter is an essential piece of appa- ** ratus in all comparative tests of receivers and telephones, for the reason that it reduces the strength of signals to a definite standard basis of numerical comparison; thus, unit audibility, or an audibility of one, is the strength of a signal which is just audible. By means of a variable shunt around the telephones it is possible to reduce the strength of signal to unit audibility. If the proportional current passing through the shunt is known, the number of times audibility of the signals can readily be determined, provided that at the same time an impedance is in- troduced in series with the detector output, so as to maintain constant the total impedance across the detector.
The meter is beautifully finished in a hardwood box, with a bevelled Bakelite-dilecto top, on which the audibility is directly engraved. Connection is readily afforded by four binding posts, two for the receiver circuit, and two for the telephones. The taps and contact arm are of pol- ished nickel, so that the instrument makes an attractive, as well as an invaluable, addition to any radio station or laboratory.
AUDIBILITY METER, IP-306
Dimensions: 8 in. x 8 in. x 3/2 in. Weight: 4 lbs.
$135.00
RECEIVER LOAD COILS
Wi offer a high-grade, compact and efficient load coil in three different values, namely, 30, 50 and 100 millihen- ries. These coils consist of two Bakelite-dilecto side pieces, between which is mounted a highly efficient wave- wound coil of high-frequency cable. The electrostatic capacity of the coil is extremely low. The side pieces are finished square, forming a base for the coil. Close coupling between two or more load coils is possible, as their rear surfaces are flush and close to the plane of the coil.
The coils are ideal units for loading the receivers listed in this catalogue, and in fact any type, to long wavelengths, as they
are efficient and permit easy and very wide variation of coupling. A pair of these coils, used in conjunction with two variable air condensers of the types shown on page 67, constitute a receiver. Their values are constant and they may be used as standards and for general experimental purposes.
LOAD COIL — 30 Millihenries. Dimensions: 1 in. x 5*4 in. x 524 in $10.00
LOAD COIL — 50 Millihenries. Dimensions: 1 in. x 5*4 in. x 524 in 15.50
LOAD COIL — 100 Millihenries. Dimensions: 1 in. x 5*4 in. x 5 24 in. . 21.50
Shipping weight: 2 lbs.
Digitized by
RADIO CORPORATION OF AMERICA
PRECISION VARIABLE AIR CONDENSERS
TYPES
|
IP-300, |
.005 |
mfd. |
|
IP-301, |
.003 |
ii |
|
IP-302, |
.0015 |
a |
|
IP-303, |
.0007 |
a |
THESE condensers are built in the four dif- ferent capacities listed below. They are all of the balanced type and will hold any adjust- ment regardless of the position in which they are placed.
The .005 mfd. condenser shown in the illus- tration contains a total of 56 semi-circular Axed plates and 58 semi-circular variable plates. The smaller capacity condensers have a correspond- ingly smaller number of plates. The plates of the upper half of the condenser are mounted on the opposite side of the shaft from the sim- ilar lower plates, thus effectively balancing the system mechanically.
The plates are hard aluminum, 1/32 in. thick. The air space between plates is 3/32 in.
The plates are separated by aluminum washers accurately machined. The rods supporting the stationary plates are of brass. The movable plates are mounted upon a steel shaft. The system is fastened to two circular Bakelite- dilecto end pieces, the upper of which is, in turn, fastened to the Bakelite-dilecto top of the condenser. The unit may be easily lifted from the case by the removal of eight screws. On the Bakelite-dilecto top is the rotary control knob and pointer, which is provided with an engraved 180° scale. Two nickel-plated bind- ing posts are provided for making connections to the condenser.
These condensers are mounted in neat oak boxes, and are provided with calibration charts.
VARIABLE AIR CONDENSER — TYPE IP-300, CAPACITY .005 MFD $90.00
Dimensions: 7)4 in. x 7 54 in* x 7^4 in*
Shipping weight: 15 lbs.
VARIABLE AIR CONDENSER— TYPE IP-301, CAPACITY .003 MFD 72.00
Dimensions: 7J4 in. x 7*4 in. x 8 J4 in.
Shipping weight: 12 lbs.
VARIABLE AIR CONDENSER— TYPE IP-302, CAPACITY .0015 MFD 45.00
Dimensions: 5 54 in. x 554 in. x 8 Vs in*
Shipping weight: 7J4 lbs.
VARIABLE AIR CONDENSER— TYPE IP-303, CAPACITY .0007 MFD 41.50
Dimensions: 5 54 in. x 5 J4 in. x 4 34 in*
Shipping weight: 6 lbs.
67
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RADIO
CORPORATION
A M E R I C A
PART THREE
Vacuum Tube Transmission for the Radio Amateur and Experimenter
With Data on
Radiotron Transmission Kenotron Rectification Transmitting Tube Circuits Transmitting Apparatus
68
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RADIO
CORPORATION
AMERICA
RADIOTRON TRANSMISSION
THE USE OF RADIOTRONS IN EXPERIMENTAL CONTINUOUS WAVE TELEGRAPH AND TELEPHONE SETS
CURRENT literature devoted to amateur radio activities affords sufficient evidence that the era of continuous wave transmission has arrived. It has long been known that con- tinuous wave sending apparatus would provide a greater radio transmission range than a spark transmitter of the same power to the antenna, and also that the use of continuous waves would permit the adoption of more efficient methods of reception than the spark system.
The only suitable form of undamped wave generator for short wave transmission is the oscillating vacuum tube. The expenditure of large sums of money in pains- taking research conducted b y America’s fore- m o 8 t scientific experts has en- abled the pro- duction of relia- ble and efficient power tubes —
RADIOTRONS
— which may be employed as generators o f continuous os- cillations, of any frequency used
in radio com- Station "8ZG" of Salem, Ohio, municatio n. Vacuum Tube Tranami
The vacuum
tube is better adapted to radio transmission at wavelengths in the region of 200 meters than the spark system, for the spark system has cer- tain inherent characteristics which place a very definite practical limit upon the amount of energy that can be put into an antenna at short
Station *'8ZG” of Salem, Ohio, Equipped with a I 00-Watt Radiotron Vacuum Tube Transmitter Made Up of RCA Parts.
wavelengths and therefore at high frequencies.
The vacuum tube transmitter using the Radio Corporation’s Power Tubes is comparatively simple, both in point of construction and in operation. It is no more difficult to adjust and to maintain than a spark transmitter, and it has many points of advantage over the spark set. There are, however, certain precautionary measures which must be considered in vacuum tube operation, and it is one of the objects of this bulletin to place before the amateur such information as will enable him to secure the