The Operation of Rectifier Vacuum Tubes.--The vacuum tube rectifier is simply a two electrode vacuum tube. The way in which it changes a commercial alternating current into pulsating direct current is the same as that in which a two electrode vacuum tube detector changes an oscillating current into pulsating direct currents and this has been explained in detail under the heading ofThe Operation of a Two Electrode Vacuum Tube DetectorinChapter XII. In theC. W. Telegraph Transmitting Setsdescribed inChapter XVII, the oscillator tubes act as rectifiers as well as oscillators but for wireless telephony the alternating current must be rectified first so that a continuous direct current will result.
The Operation of Reactors and Condensers.--A reactor is a single coil of wire wound on an iron core, seeFig. 90andAinFig. 91, and it should preferably have a large inductance. The reactor for the plate and grid circuit of a wireless telephone transmitter where one or more tubes are used as modulators as shown in the wiring diagram inFig. 90, and the filter reactor shown inFig. 92, operate in the same way.
When an alternating current flows through a coil of wire the reversals of the current set up acounter electromotive forcein it which opposes, that isreacts, on the current, and thehigherthe frequency of the current thegreaterwill be thereactance. When the positive half of an alternating current is made to flow through a large resistance the current is smoothed out but at the same time a large amount of its energy is used up in producing heat.
But when the positive half of an alternating current is made to flow through a large inductance it acts like a large resistance as before and likewise smooths out the current, but none of its energy is wasted in heat and so a coil having a large inductance, which is called aninductive reactance, or justreactorfor short, is used to smooth out, or filter, the alternating current after it has been changed into a pulsating direct current by the rectifier tubes.
A condenser also has a reactance effect on an alternating current but different from an induction coil thelowerthe frequency thegreaterwill be the reactance. For this reason both a filter reactor andfilter condensersare used to smooth out the pulsating direct currents.
In the chapters onReceptorsyou have been told how to build up high-grade sets. But there are thousands of boys, and, probably, not a few men, who cannot afford to invest $25.00, more or less, in a receiving set and would like to experiment in a small way.
The following set is inexpensive, and with this cheap, little portable receptor you can get the Morse code from stations a hundred miles distant and messages and music from broadcasting stations if you do not live too far away from them. All you need for this set are: (1) acrystal detector, (2) atuning coiland (3) anearphone. You can make a crystal detector out of a couple of binding posts, a bit of galena and a piece of brass wire, or, better, you can buy one all ready to use for 50 cents.
The Crystal Detector.--This is known as theRasco babydetector and it is made and sold by theRadio Specialty Company, 96 Park Place, New York City. It is shown inFig. 96. The base is made of black composition and on it is mounted a standard in which a rod slides and on one end of this there is fixed a hard rubber adjusting knob while the other end carries a thin piece ofphosphor-bronze wire, called acat-whiskerTo secure the galena crystal in the cup you simply unscrew the knurled cap, place it in the cavity of the post and screw the cap back on again. The free end of the cat-whisker wire is then adjusted so that it will rest lightly on the exposed part of the galena.
Fig. 96.--Rasco Baby Crystal Detector.
TheTuning Coil.--You will have to make this tuning coil, which you can do at a cost of less than $1.00, as the cheapest tuning coil you can buy costs at least $3.00, and we need the rest of our $5.00 to invest in the earphone. Get a cardboard tube, such as is used for mailing purposes, 2 inches in diameter and 3 inches long, seeAinFig. 97. Now wind on 250 turns ofNo. 40 Brown and Sharpe gauge plain enameled magnet wire. You can useNo. 40 double cotton covered magnet wire, in which case you will have to shellac the tube and the wire after you get it on.
Fig. 97.--How the Tuning Coil is Made.
As you wind on the wire take off a tap at every 15th turn, that is, scrape the wire and solder on a piece about 7 inches long, as shown inFig. 99; and do this until you have 6 taps taken off. Instead of leaving the wires outside of the tube bring them to the inside of it and then out through one of the open ends. Now buy around wood-base switchwith 7 contact points on it as shown atBinFig. 97. This will cost you25or50cents.
The Headphone.--An ordinary Bell telephone receiver is of small use for wireless work as it is wound to too low a resistance and the diaphragm is much too thick. If you happen to have a Bell phone you can rewind it withNo. 40single covered silk magnet wire, or enameled wire of the same size, when its sensitivity will be very greatly improved. Then you must get a thin diaphragm and this shouldnotbe enameled, as this tends to dampen the vibrations of it. You can get a diaphragm of the right kind for 5 cents.
The better way, though, is to buy an earphone made especially for wireless work. You can get one wound to 1000 ohms resistance for $1.75 and this price includes a cord. [Footnote: This is Mesco, No. 470 wireless phone. Sold by the Manhattan Electrical Supply Co., Park Place, N.Y.C.] For $1.00 extra you can get a head-band for it, and then your phone will look like the one pictured inFig. 98.
Fig. 98.--Mesco 1000 Ohm Head Set.
How to Mount the Parts.--Now mount the coil on a wood base, 1/2 or 1 inch thick, 3-1/2 inches wide and 5-1/2 inches long, and then connect one end of the coil to one of the end points on the switch, and connect each succeeding tap to one of the switch points, as shown schematically inFig. 99and diagrammatically inFig. 100. This done, screw the switch down to the base. Finally screw the detector to the base and screw two binding posts in front of the coil. These are for the earphone.
Fig. 99.--Schematic Layout of $5.00 Receiving Set.Fig. 100.--Wiring Diagram for $5.00 Receiving Set.
The Condenser.--You do not have to connect a condenser across the earphone but if you do you will improve the receiving qualities of the receptor.
How to Connect Up the Receptor.--Now connect up all the parts as shown inFigs. 99and100, then connect the leading-in wire of the aerial with the lever of the switch; and connect the free end of the tuning coil with theground. If you have no aerial wire try hooking it up to a rain pipe that isnot groundedor the steel frame of an umbrella. For agroundyou can use a water pipe, an iron pipe driven into the ground, or a hydrant. Put on your headphone, adjust the detector and move the lever over the switch contacts until it is in adjustment and then, if all your connections are properly made, you should be able to pick up messages.
Unit Abbreviationampere amp.ampere-hours amp.-hr.centimeter cm.centimeter-gram-second c.g.s.cubic centimeters cm.^3cubic inches cu. in.cycles per second ~degrees Centigrade °C.degrees Fahrenheit °F.feet ft.foot-pounds ft.-lb.grams g.henries h.inches in.kilograms kg.kilometers km.kilowatts kw.kilowatt-hours kw.-hr.kilovolt-amperes kv.-a.meters m.microfarads [Greek: mu]f.micromicrofarads [Greek: mu mu]f.millihenries mh.millimeters mm.pounds lb.seconds sec.square centimeters cm.^2square inches sq. in.volts v.watts w.
Prefix Abbreviation Meaningmicro [Greek: mu]. 1 millionthmilli m. 1 thousandthcenti c. 1 hundredthdeci d. 1 tenthdeka dk. 10hekto h. 1 hundredkilo k. 1 thousandmega m. 1 million
Symbols for quantities
Quantity SymbolcapacitanceCconductancegcoupling co-efficientkcurrent, instantaneousicurrent, effective valueIdecrement[Greek: delta]dielectric constant[Greek: alpha]electric field intensity[Greek: epsilon]electromotive force,instantaneous valueEelectromotive force,effective valueFenergyWforceFfrequencyffrequency x 2[Greek: pi][Greek: omega]impedanceZinductance, selfLinductance, mutualMmagnetic field intensityAmagnetic flux[Greek: Phi]magnetic inductionBperiod of a completeoscillationTpotential differenceVquantity of electricityQratio of thecircumference of acircle to its diameter=3.1416[Greek: pi]reactanceXresistanceRtimetvelocityvvelocity of lightcwave length[Greek: lambda]wave length in meters[Greek: lambda]mworkWpermeability[Greek: mu]Square root[Math: square root]
No. of Turns Turns Ohms perWire, per per Cubic InchB.& S. Linear Square ofGauge Inch Inch Winding20 30 885 .74822 37 1400 1.8824 46 2160 4.6126 58 3460 11.8028 73 5400 29.2030 91 8260 70.9032 116 21,000 7547.0034 145 13,430 2968.0036 178 31,820 1098.0038 232 54,080 456.0040 294 86,500 183.00
W. L.--Wave Lengths in Meters.F.--Number of Oscillations per Second.O. or square root L. C. is called Oscillation Constant.C.--Capacity in Microfarads.L.--Inductance in Centimeters.1000 Centimeters = 1 Microhenry.
W.L. F O L.C.50 6,000,000 .839 .7039100 3,000,000 1.68 2.82150 2,000,000 2.52 6.35200 1,500,000 3.36 11.29250 1,200,000 4.19 17.55300 1,000,000 5.05 25.30350 857,100 5.87 34.46400 750,000 6.71 45.03450 666,700 7.55 57.00500 600,000 8.39 70.39550 545,400 9.23 85.19600 500,000 10.07 101.41700 428,600 11.74 137.83800 375,000 13.42 180.10900 333,300 15.10 228.011,000 300,000 16.78 281.571,100 272,730 18.45 340.401,200 250,000 20.13 405.201,300 230,760 21.81 475.701,400 214,380 23.49 551.801,500 200,000 25.17 633.501,600 187,500 26.84 720.401,700 176,460 28.52 813.401,800 166,670 30.20 912.001,900 157,800 31.88 1,016.402,000 150,000 33.55 1,125.602,100 142,850 35.23 1,241.202,200 136,360 36.91 1,362.402,300 130,430 38.59 1,489.302,400 125,000 40.27 1,621.802,500 120,000 41.95 1,759.702,600 115,380 43.62 1,902.602,700 111,110 45.30 2,052.002,800 107,140 46.89 2,207.002,900 103,450 48.66 2,366.303,000 100,000 50.33 2,533.204,000 75,000 67.11 4,504.005,000 60,000 83.89 7,038.006,000 50,000 100.7 10,130.007,000 41,800 117.3 13,630.008,000 37,500 134.1 18,000.009,000 33,300 151.0 22,820.0010,000 30,000 167.9 28,150.0011,000 27,300 184.8 34,150.0012,000 25,000 201.5 40,600.0013,000 23,100 218.3 47,600.0014,000 21,400 235.0 55,200.0015,000 20,000 252.0 63,500.0016,000 18,750 269.0 72,300.00
Many of the physical quantities use Greek letters for symbols. The following is the Greek alphabet with the way the letters are pronounced:Greek symbols
a alphab betag gammad deltae epsilonz zetaae etath thetai iotak kappal lambdam mun nux Xi(Zi)o omicronp pir rhos sigmat tauu upsilonph phich chips psio omega
In Air for Various Voltages between Needle Points
Volts DistanceInches Centimeter5,000 .225 .5710,000 .470 1.1915,000 .725 1.8420,000 1.000 2.5425,000 1.300 3.3030,000 1.625 4.1035,000 2.000 5.1040,000 2.450 6.2045,000 2.95 7.5050,000 3.55 9.9060,000 4.65 11.870,000 5.85 14.980,000 7.10 18.090,000 8.35 21.2100,000 9.60 24.4110,000 10.75 27.3120,000 11.85 30.1130,000 12.95 32.9140,000 13.95 35.4150,000 15.00 38.1
No. of Single Double Single DoubleB.& S. Cotton, Cotton, Silk, Silk, EnamelGauge 4-Mils 8-Mils 1-3/4-Mils 4-Mils20 311 298 319 312 32021 389 370 408 389 40422 488 461 503 498 50923 612 584 636 631 64224 762 745 800 779 81025 957 903 1,005 966 1,01926 1,192 1,118 1,265 1,202 1,28627 1,488 1,422 1,590 1,543 1,62028 1,852 1,759 1,972 1,917 2,04229 2,375 2,207 2,570 2,435 2,57030 2,860 2,534 3,145 2,900 3,24031 3,800 2,768 3,943 3,683 4,08232 4,375 3,737 4,950 4,654 5,13233 5,590 4,697 6,180 5,689 6,44534 6,500 6,168 7,740 7,111 8,09335 8,050 6,737 9,600 8,584 10,19736 9,820 7,877 12,000 10,039 12,81337 11,860 9,309 15,000 10,666 16,11038 14,300 10,636 18,660 14,222 20,27439 17,130 11,907 23,150 16,516 25,51940 21,590 14,222 28,700 21,333 32,107
TO BE USED FOR ALL GENERAL PUBLIC SERVICE RADIO COMMUNICATION
[Note: period denotes Morse dot, hyphen denotes Morse dash]
A .-B -...C -.-.D -..E .F ..-.G --.H ....I ..J .---K -.-L .-..M --N -.O ---P .--.Q --.-R .-.S ...T -U ..-V ...-W .--X -..-Y -.--Z --..Ä (German) .-.-Á or Å (Spanish-Scandinavian) .--.-CH (German-Spanish) ----É (French) ..-..Ñ (Spanish) --.--Ö (German) ---.Ü (German) ..--1 .----2 ..---3 ...--4 ....-5 .....6 -....7 --...8 ---..9 ----.0 -----Period .. .. ..Semicolon -.-.-.Comma -.-.-.Colon ---...Interrogation ..--..Exclamation point --..--Apostrophe .----.Hyphen -....-Bar indicating fraction -..-.Parenthesis -.--.-Inverted commas .-..-.Underline ..--.-Double dash -...-Distress Call ...---...Attention call to precede every transmission -.-.-General inquiry call -.-. --.-From (de) -.. .Invitation to transmit (go ahead) -.-Warning--high power --..--Question (please repeat after ...)--interrupting long messages ..--..Wait .-...Break (Bk.) (double dash) -...-Understand ...-.Error ........Received (O.K.) .-.Position report (to precede all position messages) - .-.End of each message (cross) .-.-.Transmission finished (end of work) (conclusion of correspondence) ...-.-
LIST OF ABBREVIATIONS TO BE USED IN RADIO COMMUNICATION
ABBREVIATION QUESTION ANSWER OR REPLYPRB Do you wish to communicate I wish to communicate by meansby means of the International of the International Signal Code.Signal Code?QRA What ship or coast station is This is....that?QRB What is your distance? My distance is....QRC What is your true bearing? My true bearing is....QRD Where are you bound for? I am bound for....QRF Where are you bound from? I am bound from....QRG What line do you belong to? I belong to the ... Line.QRH What is your wave length in My wave length is ... meters.meters?QRJ How many words have you to send? I have ... words to send.QRK How do you receive me? I am receiving well.QRL Are you receiving badly? I am receiving badly. PleaseShall I send 20? send 20....-. ...-.for adjustment? for adjustment.QRM Are you being interfered with? I am being interfered with.QRN Are the atmospherics strong? Atmospherics are very strong.QRO Shall I increase power? Increase power.QRP Shall I decrease power? Decrease power.QRQ Shall I send faster? Send faster.QRS Shall I send slower? Send slower.QRT Shall I stop sending? Stop sending.QRU Have you anything for me? I have nothing for you.QRV Are you ready? I am ready. All right now.QRW Are you busy? I am busy (or: I am busy with...).Please do not interfere.QRX Shall I stand by? Stand by. I will call you whenrequired.QRY When will be my turn? Your turn will be No....QRZ Are my signals weak? You signals are weak.QSA Are my signals strong? You signals are strong.QSB Is my tone bad? The tone is bad.Is my spark bad? The spark is bad.QSC Is my spacing bad? Your spacing is bad.QSD What is your time? My time is....QSF Is transmission to be in Transmission will be inalternate order or in series? alternate order.QSG Transmission will be in aseries of 5 messages.QSH Transmission will be in aseries of 10 messages.QSJ What rate shall I collect for...? Collect....QSK Is the last radiogram canceled? The last radiogram is canceled.QSL Did you get my receipt? Please acknowledge.QSM What is your true course? My true course is...degrees.QSN Are you in communication with land? I am not in communication with land.QSO Are you in communication with I am in communication with...any ship or station (through...).(or: with...)?QSP Shall I inform...that you are Inform...that I am calling him.calling him?QSQ Is...calling me? You are being called by....QSR Will you forward the radiogram? I will forward the radiogram.QST Have you received the general General call to all stations.call?QSU Please call me when you have Will call when I have finished.finished (or: at...o'clock)?QSV Is public correspondence being Public correspondence is beinghandled? handled. Please do not interfere.
[Footnote: Public correspondence is any radio work, official or private, handled on commercial wave lengths.]
QSW Shall I increase my spark Increase your spark frequency.frequency?QSX Shall I decrease my spark Decrease your spark frequency.frequency?QSY Shall I send on a wavelength Let us change to the wave lengthof ... meters? of ... meters.QSZ Send each word twice. I havedifficulty in receiving you.QTA Repeat the last radiogram.
When an abbreviation is followed by a mark of interrogation, it refers to the question indicated for that abbreviation.
Useful Information
Symbols
alternatorammeteraerialarcbatterybuzzercondenservariable condenserconnection of wiresno connectioncoupled coilsvariable couplingdetectorgap, plaingap, quenchedgroundhot wire ammeterinductorvariable inductorkeyresistorvariable resistorswitch s.p.s.t." s.p.d.t." d.p.s.t." d.p.d.t." reversingphone receiver" transmitterthermoelementtransformervacuum tubevoltmeterchoke coil
Theohmis the resistance of a thread of mercury at the temperature of melting ice, 14.4521 grams in mass, of uniform cross-section and a length of 106.300 centimeters.
Theampereis the current which when passed through a solution of nitrate of silver in water according to certain specifications, deposits silver at the rate of 0.00111800 of a gram per second.
Thevoltis the electromotive force which produces a current of 1 ampere when steadily applied to a conductor the resistance of which is 1 ohm.
Thecoulombis the quantity of electricity transferred by a current of 1 ampere in 1 second.
Theampere-houris the quantity of electricity transferred by a current of 1 ampere in 1 hour and is, therefore, equal to 3600 coulombs.
Thefaradis the capacitance of a condenser in which a potential difference of 1 volt causes it to have a charge of 1 coulomb of electricity.
Thehenryis the inductance in a circuit in which the electromotive force induced is 1 volt when the inducing current varies at the rate of 1 ampere per second.
Thewattis the power spent by a current of 1 ampere in a resistance of 1 ohm.
Thejouleis the energy spent in I second by a flow of 1 ampere in 1 ohm.
Thehorse-poweris used in rating steam machinery. It is equal to 746 watts.
Thekilowattis 1,000 watts.
The units of capacitance actually used in wireless work are themicrofarad, which is the millionth part of a farad, because the farad is too large a unit; and theC. G. S. electrostatic unit of capacitance, which is often called thecentimeter of capacitance, which is about equal to 1.11 microfarads.
The units of inductance commonly used in radio work are themillihenry, which is the thousandth part of a henry; and thecentimeter of inductance, which is one one-thousandth part of a microhenry.
Note.--For further information about electric and magnetic units get theBureau of Standards Circular No. 60, calledElectric Units and Standards, the price of which is 15 cents; also getScientific Paper No. 292, calledInternational System of Electric and Magnetic Units, price 10 cents. These and other informative papers can be had from theSuperintendent of Documents, Government Printing Office, Washington, D. C.
The Admiralty Manual of Wireless Telegraphy. 1920. Published by His Majesty's Stationery Office, London.
Ralph E. Batcher.--Prepared Radio Measurements. 1921. Wireless Press, Inc., New York City.
Elmer E. Bucher.--Practical Wireless Telegraphy. 1918. Wireless Press, Inc., New York City.
Elmer E. Bucher.--Vacuum Tubes in Wireless Communication. 1919. Wireless Press, Inc., New York City.
Elmer E. Bucher.--The Wireless Experimenter's Manual. 1920. Wireless Press, Inc., New York City.
Charles B. Hayward.--How to Become a Wireless Operator. 1918. American Technical Society, Chicago, Ill.
G. D. Robinson.--Manual of Radio Telegraphy and Telephony. 1920. United States Naval Institute, Annapolis, Md.
Rupert Stanley.--Textbook of Wireless Telegraphy. 1919. Longmans, Green and Co., London.
E. W. Stone.--Elements of Radio Telegraphy. 1919. D, Van Nostrand Co., New York City.
L. B. Turner.--Wireless Telegraphy and Telephony. 1921. Cambridge University Press. Cambridge, England.
Send to theSuperintendent of Documents, Government Printing Office, Washington, D. C., for a copy ofPrice List No. 64which lists the Government's books and pamphlets on wireless. It will be sent to you free of charge.
The Government publishes; (1)A List of Commercial Government and Special Wireless Stations, every year, price 15 cents; (2)A List of Amateur Wireless Stations, yearly, price 15 cents; (3)A Wireless Service Bulletinis published monthly, price 5 cents a copy, or 25 cents yearly; and (4)Wireless Communication Laws of the United States, theInternational Wireless Telegraphic Convention and Regulations Governing Wireless Operators and the Use of Wireless on Ships and Land Stations, price 15 cents a copy. Orders for the above publications should be addressed to theSuperintendent of Documents, Government Printing Office, Washington, D. C.
Adams-Morgan Co., Upper Montclair, N. J.
American Hard Rubber Co., 11 Mercer Street, New York City.
American Radio and Research Corporation, Medford Hillside, Mass.
Brach (L. S.) Mfg. Co., 127 Sussex Ave., Newark, N. J.
Brandes (C.) Inc., 237 Lafayette St., New York City.
Bunnell (J. H.) Company, Park Place, New York City.
Burgess Battery Company, Harris Trust Co. Bldg., Chicago, Ill.
Clapp-Eastman Co., 120 Main St., Cambridge, Mass.
Connecticut Telephone and Telegraph Co., Meriden, Conn.
Continental Fiber Co., Newark, Del.
Coto-Coil Co., Providence, R. I.
Crosley Mfg. Co., Cincinnati, Ohio.
Doolittle (F. M.), 817 Chapel St., New Haven, Conn.
Edelman (Philip E.), 9 Cortlandt St., New York City.
Edison Storage Battery Co., Orange, N. J.
Electric Specialty Co., Stamford, Conn.
Electrose Mfg. Co., 60 Washington St., Brooklyn, N. Y.
General Electric Co., Schenectady, N. Y.
Grebe (A. H.) and Co., Inc., Richmond Hill, N. Y. C.
International Brass and Electric Co., 176 Beekman St., New York City.
International Insulating Co., 25 West 45th St., New York City.
King Amplitone Co., 82 Church St., New York City.
Kennedy (Colin B.) Co., Rialto Bldg., San Francisco, Cal.
Magnavox Co., Oakland, Cal.
Manhattan Electrical Supply Co., Park Place, N. Y.
Marshall-Gerken Co., Toledo, Ohio.
Michigan Paper Tube and Can Co., 2536 Grand River Ave., Detroit, Mich.
Murdock (Wm. J.) Co., Chelsea, Mass.
National Carbon Co., Inc., Long Island City, N. Y.
Pittsburgh Radio and Appliance Co., 112 Diamond St., Pittsburgh, Pa,
Radio Corporation of America, 233 Broadway, New York City.
Riley-Klotz Mfg. Co., 17-19 Mulberry St., Newark, N. J.
Radio Specialty Co., 96 Park Place, New York City.
Roller-Smith Co., 15 Barclay St., New York City.
Tuska (C. D.) Co., Hartford, Conn.
Western Electric Co., Chicago, Ill.
Westinghouse Electric Co., Pittsburgh, Pa.
Weston Electrical Instrument Co., 173 Weston Ave., Newark, N. J.
Westfield Machine Co., Westfield, Mass.
A. ..............AerialA.C. ............Alternating CurrentA.F. ............Audio FrequencyB. and S. .......Brown & Sharpe Wire GaugeC. ..............Capacity or CapacitanceC.G.S. ..........Centimeter-Grain-SecondCond. ...........CondenserCoup. ...........CouplerC.W. ............Continuous WavesD.C. ............Direct CurrentD.P.D.T. ........Double Point Double ThrowD.P.S.T. ........Double Point Single ThrowD.X. ............DistanceE. ..............Short for Electromotive Force (Volt)E.M.F. ..........Electromotive ForceF. ..............Filament or FrequencyG. ..............GridGnd. ............GroundI. ..............Current Strength (Ampere)I.C.W. ..........Interrupted Continuous WavesKW. .............KilowattL. ..............InductanceL.C. ............Loose CouplerLitz. ...........LitzendrahtMfd. ............MicrofaradNeg. ............NegativeO.T. ............Oscillation TransformerP. ..............PlatePrim. ...........PrimaryPos. ............PositiveR. ..............ResistanceR.F. ............Radio FrequencySec. ............SecondaryS.P.D.T. ........Single Point Double ThrowS.P.S.T. ........Single Point Single ThrowS.R. ............Self RectifyingT. ..............Telephone or Period (time) of CompleteOscillationTick. ...........TicklerV. ..............Potential DifferenceVar. ............VariometerVar. Cond. ......Variable CondenserV.T. ............Vacuum TubeW.L. ............Wave LengthX. ..............Reactance
ABATTERY.--See Battery A.
ABBREVIATIONS, CODE.--Abbreviations of questions and answers used in wireless communication. The abbreviationof a questionis usually in three letters of which the first is Q. Thus Q R B is the code abbreviation of "what is your distance?" and the answer "My distance is..." SeePage 306[Appendix: List of Abbreviations].
ABBREVIATIONS, UNITS.--Abbreviations of various units used in wireless electricity. These abbreviations are usually lower case letters of the Roman alphabet, but occasionally Greek letters are used and other signs. Thusamperesis abbreviatedamp., micro, which meansone millionth, [Greek: mu], etc. SeePage 301[Appendix: Useful Abbreviations].
ABBREVIATIONS OF WORDS AND TERMS.--Letters used instead of words and terms for shortening them up where there is a constant repetition of them, asA.C.foralternating current; C.W.forcontinuous waves; V.T.forvacuum tube, etc. SeePage 312[Appendix: Abbreviations of Common Terms].
AERIAL.--Also calledantenna. An aerial wire. One or more wires suspended in the air and insulated from its supports. It is the aerial that sends out the waves and receives them.
AERIAL, AMATEUR.--An aerial suitable for sending out 200 meter wave lengths. Such an aerial wire system must not exceed 120 feet in length from the ground up to the aerial switch and from this through the leading-in wire to the end of the aerial.
AERIAL AMMETER.--SeeAmmeter, Hot Wire.
AERIAL, BED-SPRINGS.--Where an outdoor aerial is not practicablebed-springsare often made to serve the purpose.
AERIAL CAPACITY.--SeeCapacity, Aerial.
AERIAL COUNTERPOISE.--Where it is not possible to get a good ground anaerial counterpoiseorearth capacitycan be used to advantage. The counterpoise is made like the aerial and is supported directly under it close to the ground but insulated from it.
AERIAL, DIRECTIONAL.--A flat-top or other aerial that will transmit and receive over greater distances to and from one direction than to and from another.
AERIAL, GROUND.--Signals can be received on a single long wire when it is placed on or buried in the earth or immersed in water. It is also called aground antennaand anunderground aerial.
AERIAL, LOOP.--Also called acoil aerial, coil antenna, loop aerial, loop antennaand when used for the purpose adirection finder. A coil of wire wound on a vertical frame.
AERIAL RESISTANCE.--SeeResistance, Aerial.
AERIAL SWITCH.--SeeSwitch Aerial.
AERIAL WIRE.--(1) A wire or wires that form the aerial. (2) Wire that is used for aerials; this is usually copper or copper alloy.
AERIAL WIRE SYSTEM.--An aerial and ground wire and that part of the inductance coil which connects them. The open oscillation circuit of a sending or a receiving station.
AIR CORE TRANSFORMER.--SeeTransformer, Air Core.
AMATEUR AERIAL OR ANTENNA.--SeeAerial, Amateur.
ALTERNATOR.--An electric machine that generates alternating current.
ALPHABET, INTERNATIONAL CODE.--A modified Morse alphabet of dots and dashes originally used in Continental Europe and, hence, called theContinental Code. It is now used for all general public service wireless communication all over the world and, hence, it is called theInternational Code. Seepage 305[Appendix: International Morse Code].
ALTERNATING CURRENT (A.C.)--SeeCurrent.
ALTERNATING CURRENT TRANSFORMER.--SeeTransformer.
AMATEUR GROUND.--SeeGround, Amateur.
AMMETER.--An instrument used for measuring the current strength, in terms of amperes, that flows in a circuit. Ammeters used for measuring direct and alternating currents make use of themagnetic effectsof the currents. High frequency currents make use of theheating effectsof the currents.
AMMETER, HOT-WIRE.--High frequency currents are usually measured by means of an instrument which depends on heating a wire or metal strip by the oscillations. Such an instrument is often called athermal ammeter,radio ammeterandaerial ammeter.
AMMETER, AERIAL.--SeeAmmeter, Hot Wire.
AMMETER, RADIO.--SeeAmmeter, Hot Wire.
AMPERE.--The current which when passed through a solution of nitrate of silver in water according to certain specifications, deposits silver at the rate of 0.00111800 of a gram per second.
AMPERE-HOUR.--The quantity of electricity transferred by a current of 1 ampere in 1 hour and is, therefore, equal to 3600 coulombs.
AMPERE-TURNS.--When a coil is wound up with a number of turns of wire and a current is made to flow through it, it behaves like a magnet. B The strength of the magnetic field inside of the coil depends on (1) the strength of the current and (2) the number of turns of wire on the coil. Thus a feeble current flowing through a large number of turns will produce as strong a magnetic field as a strong current flowing through a few turns of wire. This product of the current in amperes times the number of turns of wire on the coil is called theampere-turns.
AMPLIFICATION, AUDIO FREQUENCY.--A current of audio frequency that is amplified by an amplifier tube or other means.
AMPLIFICATION, CASCADE.--SeeCascade Amplification.
AMPLIFICATION, RADIO FREQUENCY.--A current of radio frequency that is amplified by an amplifier tube or other means before it reaches the detector.
AMPLIFICATION, REGENERATIVE.--A scheme that uses a third circuit to feed back part of the oscillations through a vacuum tube and which increases its sensitiveness when used as a detector and multiplies its action as an amplifier and an oscillator.
AMPLIFIER, AUDIO FREQUENCY.--A vacuum tube or other device that amplifies the signals after passing through the detector.
AMPLIFIER, MAGNETIC.--A device used for controlling radio frequency currents either by means of a telegraph key or a microphone transmitter. The controlling current flows through a separate circuit from that of the radio current and a fraction of an ampere will control several amperes in the aerial wire.
AMPLIFIERS, MULTI-STAGE.--A receiving set using two or more amplifiers. Also calledcascade amplification.
AMPLIFIER, VACUUM TUBE.--A vacuum tube that is used either to amplify the radio frequency currents or the audio frequency currents.
AMPLITUDE OF WAVE.--The greatest distance that a point moves from its position of rest.
AMPLIFYING TRANSFORMER, AUDIO.--SeeTransformer, Audio Amplifying.
AMPLIFYING MODULATOR VACUUM TUBE.--SeeVacuum Tube, Amplifying Modulator.
AMPLIFYING TRANSFORMER RADIO.--SeeTransformer, Radio Amplifying.
ANTENNA, AMATEUR.--SeeAerial, Amateur.
ANTENNA SWITCH.--SeeSwitch, Aerial.
APPARATUS SYMBOLS.--SeeSymbols, Apparatus.
ARMSTRONG CIRCUIT.--SeeCircuit, Armstrong.
ATMOSPHERICS.--Same asStatic, which see.
ATTENUATION.--In Sending wireless telegraph and telephone messages the amplitude of the electric waves is damped out as the distance increases. This is calledattenuationand it increases as the frequency is increased. This is the reason why short wave lengths will not carry as far as long wave lengths.
AUDIO FREQUENCY AMPLIFIER.--SeeAmplifier, Audio Frequency.
AUDIO FREQUENCY AMPLIFICATION.--SeeAmplification, Audio Frequency.
AUDIBILITY METER.--SeeMeter, Audibility.
AUDIO FREQUENCY.--SeeFrequency, Audio.
AUDIO FREQUENCY CURRENT.--SeeCurrent, Audio Frequency.
AUDION.--An early trade name given to the vacuum tube detector.
AUTODYNE RECEPTOR.--SeeReceptor, Autodyne.
AUTO TRANSFORMER.--SeeTransformer, Auto.
BAKELITE.--A manufactured insulating compound.
B BATTERY.--SeeBattery B.
BAND, WAVE LENGTH.--SeeWave Length Band.
BASKET WOUND COILS.--SeeCoils, Inductance.
BATTERY, A.--The 6-volt storage battery used to heat the filament of a vacuum tube, detector or amplifier.
BATTERY, B.--The 22-1/2-volt dry cell battery used to energize the plate of a vacuum tube detector or amplifier.
BATTERY, BOOSTER.--This is the battery that is connected in series with the crystal detector.
BATTERY, C.--A small dry cell battery sometimes used to give the grid of a vacuum tube detector a bias potential.
BATTERY, EDISON STORAGE.--A storage battery in which the elements are made of nickel and iron and immersed in an alkalineelectrolyte.
BATTERY, LEAD STORAGE.--A storage battery in which the elements are made of lead and immersed in an acid electrolyte.
BATTERY POLES.--SeePoles, Battery.
BATTERY, PRIMARY.--A battery that generates current by chemical action.
BATTERY, STORAGE.--A battery that develops a current after it has been charged.
BEAT RECEPTION.--SeeHeterodyne Reception.
BED SPRINGS AERIAL.--SeeAerial, Bed Springs.
BLUB BLUB.--Over modulation in wireless telephony.
BROAD WAVE.--SeeWave, Broad.
BRUSH DISCHARGE.--SeeDischarge.
BUZZER MODULATION.--SeeModulation, Buzzer.
BLUE GLOW DISCHARGE.--SeeDischarge.
BOOSTER BATTERY.--SeeBattery, Booster.
BROADCASTING.--Sending out intelligence and music from a central station for the benefit of all who live within range of it and who have receiving sets.
CAPACITANCE.--Also called by the older name ofcapacity. The capacity of a condenser, inductance coil or other device capable of retaining a charge of electricity. Capacitance is measured in terms of themicrofarad.
CAPACITIVE COUPLING.--SeeCoupling, Capacitive.
CAPACITY.--Any object that will retain a charge of electricity; hence an aerial wire, a condenser or a metal plate is sometimes called acapacity.
CAPACITY, AERIAL.--The amount to which an aerial wire system can be charged. Thecapacitanceof a small amateur aerial is from 0.0002 to 0.0005 microfarad.
CAPACITY, DISTRIBUTED.--A coil of wire not only has inductance, but also a certain small capacitance. Coils wound with their turns parallel and having a number of layers have abunched capacitancewhich produces untoward effects in oscillation circuits. In honeycomb and other stagger wound coils the capacitance is more evenly distributed.
CAPACITY REACTANCE.--SeeReactance, Capacity.
CAPACITY UNIT.--SeeFarad.
CARBON RHEOSTATS.--SeeRheostat, Carbon.
CARBORUNDUM DETECTOR.--SeeDetector.
CARRIER CURRENT TELEPHONY.--SeeWired-Wireless.
CARRIER FREQUENCY.--SeeFrequency, Carrier.
CARRIER FREQUENCY TELEPHONY.--SeeWired-Wireless.
CASCADE AMPLIFICATION.--Two or more amplifying tubes hooked up in a receiving set.
CAT WHISKER CONTACT.--A long, thin wire which makes contact with the crystal of a detector.
CENTIMETER OF CAPACITANCE.--Equal to 1.11microfarads.
CENTIMETER OF INDUCTANCE.--Equal to one one-thousandth part of amicrohenry.
CELLULAR COILS.--SeeCoils, Inductance.
C.G.S. ELECTROSTATIC UNIT OF CAPACITANCE.--SeeCentimeter of Capacitance.
CHARACTERISTICS.--The special behavior of a device, such as an aerial, a detector tube, etc.
CHARACTERISTICS, GRID.--SeeGrid Characteristics.
CHOKE COILS.--Coils that prevent the high voltage oscillations from surging back into the transformer and breaking down the insulation.
CHOPPER MODULATION.--SeeModulation, Chopper.
CIRCUIT.--Any electrical conductor through which a current can flow. A low voltage current requires a loop of wire or other conductor both ends of which are connected to the source of current before it can flow. A high frequency current will surge in a wire which is open at both ends like the aerial.
CLOSE COUPLED CIRCUITS.--SeeCurrents, Close Coupled.
CLOSED CIRCUIT.--SeeCircuit, Closed.
CLOSED CORE TRANSFORMER.--SeeTransformer, Closed Core.
CODE.--
COEFFICIENT OF COUPLING.--SeeCoupling, Coefficient of.
COIL AERIAL.--SeeAerial, Loop.
COIL ANTENNA.--SeeAerial, Loop.
COIL, INDUCTION.--An apparatus for changing low voltage direct currents into high voltage, low frequency alternating currents. When fitted with a spark gap the high voltage, low frequency currents are converted into high voltage, high frequency currents. It is then also called aspark coiland aRuhmkorff coil.
COIL, LOADING.--A coil connected in the aerial or closed oscillation circuit so that longer wave lengths can be received.
COIL, REPEATING.--SeeRepeating Coil.
COIL, ROTATING.--One which rotates on a shaft instead of sliding as in aloose coupler. The rotor of avariometerorvariocoupleris arotating coil.
COILS, INDUCTANCE.--These are the tuning coils used for sending and receiving sets. For sending sets they are formed of one and two coils, a single sending coil is generally called atuning inductance coil, while a two-coil tuner is called anoscillation transformer. Receiving tuning coils are made with a single layer, single coil, or a pair of coils, when it is called an oscillationtransformer. Some tuning inductance coils have more than one layer, they are then calledlattice wound,cellular,basket wound,honeycomb,duo-lateral,stagger wound,spider-webandslabcoils.
COMMERCIAL FREQUENCY.--SeeFrequency, Commercial.
CONDENSER, AERIAL SERIES.--A condenser placed in the aerial wire system to cut down the wave length.
CONDENSER, VERNIER.--A small variable condenser used for receiving continuous waves where very sharp tuning is desired.
CONDENSER.--All conducting objects with their insulation form capacities, but acondenseris understood to mean two sheets or plates of metal placed closely together but separated by some insulating material.
CONDENSITE.--A manufactured insulating compound.
CONDUCTIVITY.--The conductance of a given length of wire of uniform cross section. The reciprocal ofresistivity.
CONTACT DETECTORS.--SeeDetectors, Contact.
CONTINENTAL CODE.--SeeCode, Continental.
COULOMB.--The quantity of electricity transferred by a current of 1 ampere in 1 second.
CONVECTIVE DISCHARGE.--SeeDischarge.
CONVENTIONAL SIGNALS.--SeeSignals, Conventional.
COUNTER ELECTROMOTIVE FORCE.--SeeElectromotive Force, Counter.
COUNTERPOISE. A duplicate of the aerial wire that is raised a few feet above the earth and insulated from it. Usually no connection is made with the earth itself.
COUPLED CIRCUITS.--SeeCircuit, Coupled.
COUPLING.--When two oscillation circuits are connected together either by the magnetic field of an inductance coil, or by the electrostatic field of a condenser.
COUPLING, CAPACITIVE.--Oscillation circuits when connected together by condensers instead of inductance coils.
COUPLING, COEFFICIENT OF.--The measure of the closeness of the coupling between two coils.
COUPLING, INDUCTIVE.--Oscillation circuits when connected together by inductance coils.
COUPLING, RESISTANCE.--Oscillation circuits connected together by a resistance.
CRYSTAL RECTIFIER.--A crystal detector.
CURRENT, ALTERNATING (A.C.).--A low frequency current that surges to and fro in a circuit.
CURRENT, AUDIO FREQUENCY.--A current whose frequency is low enough to be heard in a telephone receiver. Such a current usually has a frequency of between 200 and 2,000 cycles per second.
CURRENT, PLATE.--The current which flows between the filament and the plate of a vacuum tube.
CURRENT, PULSATING.--A direct current whose voltage varies from moment to moment.
CURRENT, RADIO FREQUENCY.--A current whose frequency is so high it cannot be heard in a telephone receiver. Such a current may have a frequency of from 20,000 to 10,000,000 per second.
CURRENTS, HIGH FREQUENCY.--(1) Currents that oscillate from 10,000 to 300,000,000 times per second. (2) Electric oscillations.
CURRENTS, HIGH POTENTIAL.--(1) Currents that have a potential of more than 10,000 volts. (2) High voltage currents.
CYCLE.--(1) A series of changes which when completed are again at the starting point. (2) A period of time at the end of which an alternating or oscillating current repeats its original direction of flow.
DAMPING.--The degree to which the energy of an electric oscillation is reduced. In an open circuit the energy of an oscillation set up by a spark gap is damped out in a few swings, while in a closed circuit it is greatly prolonged, the current oscillating 20 times or more before the energy is dissipated by the sum of the resistances of the circuit.
DECREMENT.--The act or process of gradually becoming less.
DETECTOR.--Any device that will (1) change the oscillations set up by the incoming waves into direct current, that is which will rectify them, or (2) that will act as a relay.
DE TUNING.--A method of signaling by sustained oscillations in which the key when pressed down cuts out either some of the inductance or some of the capacity and hence greatly changes the wave length.
DIELECTRIC.--An insulating material between two electrically charged plates in which there is set up anelectric strain, or displacement.
DIELECTRIC STRAIN.--The electric displacement in a dielectric.
DIRECTIONAL AERIAL.--SeeAerial, Directional.
DIRECTION FINDER.--SeeAerial, Loop.