GRINDERS.--The most common form of Static, which see. They make a grinding noise in the headphones.
GROUND.--See Earth Connection.
GROUND, AMATEUR.--A water-pipe ground.
GROUND, WATERPIPE.--A common method of grounding by amateurs is to use the waterpipe, gaspipe or radiator.
GUIDED WAVE TELEPHONY.--See Wired Wireless.
HARD TUBE.--A vacuum tube in which the vacuum is high, that is, exhausted to a high degree.
HELIX.--(1) Any coil of wire. (2) Specifically a transmitter tuning inductance coil.
HENRY.--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.
HETERODYNE RECEPTION.--(1) Receiving by the beat method. (2) Receiving by means of superposing oscillations generated at the receiving station on the oscillations set up in the aerial by the incoming waves.
HETERODYNE RECEPTOR.--See Receptor, Heterodyne.
HIGH FREQUENCY CURRENTS.--See Currents, High Frequency.
HIGH FREQUENCY RESISTANCE.--See Resistance, High Frequency.
HIGH POTENTIAL CURRENTS.--See Currents, High Potential.
HIGH VOLTAGE CURRENTS.--See Currents, High Potential.
HONEYCOMB COILS.--See Coils, Inductance.
HORSE-POWER.--Used in rating steam machinery. It is equal to 746 watts.
HOT WIRE AMMETER.--See Ammeter, Hot Wire.
HOWLING.--Where more than three stages of radio amplification, or more than two stages of audio amplification, are used howling noises are apt to occur in the telephone receivers.
IMPEDANCE.--An oscillation circuit has reactance and also resistance, and when these are combined the total opposition to the current is called impedance.
INDUCTANCE COILS.--See Coils, Inductance.
INDUCTANCE COIL, LOADING.--See Coil, Loading Inductance.
INDUCTIVE COUPLING.--See Coupling, Inductive.
INDUCTIVE REACTANCE.--See Reactance, Inductive.
INDUCTION COIL.--See Coil, Induction.
INDUCTION, MUTUAL.--Induction produced between two circuits or coils close to each other by the mutual interaction of their magnetic fields.
INSULATION.--Materials used on and around wires and other conductors to keep the current from leaking away.
INSPECTOR, RADIO.--A U. S. inspector whose business it is to issue both station and operators' licenses in the district of which he is in charge.
INTERFERENCE.--The crossing or superposing of two sets of electric waves of the same or slightly different lengths which tend to oppose each other. It is the untoward interference between electric waves from different stations that makes selective signaling so difficult a problem.
INTERMEDIATE WAVES.--See Waves.
IONIC TUBES.--See Vacuum Tubes.
INTERNATIONAL CODE.--See Code, International.
JAMMING.--Waves that are of such length and strength that when they interfere with incoming waves they drown them out.
JOULE.--The energy spent in 1 second by a flow of 1 ampere in 1 ohm.
JOULE'S LAW.--The relation between the heat produced in seconds to the resistance of the circuit, to the current flowing in it.
KENOTRON.--The trade name of a vacuum tube rectifier made by the Radio Corporation of America.
KICK-BACK.--Oscillating currents that rise in voltage and tend to flow back through the circuit that is supplying the transmitter with low voltage current.
KICK-BACK PREVENTION.--See Prevention, Kick-Back.
KILOWATT.--1,000 watts.
LAMBDA.--See Pages 301, 302. [Appendix: Useful Abbreviations].
LATTICE WOUND COILS.--See Coils, Inductance.
LIGHTNING SWITCH.--See Switch, Lightning.
LINE RADIO COMMUNICATION.--See Wired Wireless.
LINE RADIO TELEPHONY.--See Telephony, Line Radio.
LITZENDRAHT.--A conductor formed of a number of fine copper wires either twisted or braided together. It is used to reduce the skin effect. See Resistance, High Frequency.
LOAD FLICKER.--The flickering of electric lights on lines that supply wireless transmitting sets due to variations of the voltage on opening and closing the key.
LOADING COIL.--See Coil, Loading.
LONG WAVES.--See Waves.
LOOP AERIAL.--See Aerial, Loop.
LOOSE COUPLED CIRCUITS.--See Circuits, Loose Coupled.
LOUD SPEAKER.--A telephone receiver connected to a horn, or a specially made one, that reproduces the incoming signals, words or music loud enough to be heard by a room or an auditorium full of people, or by large crowds out-doors.
MAGNETIC POLES.--See Poles, Magnetic.
MEGOHM.--One million ohms.
METER, AUDIBILITY.--An instrument for measuring the loudness of a signal by comparison with another signal. It consists of a pair of headphones and a variable resistance which have been calibrated.
MHO.--The unit of conductance. As conductance is the reciprocal of resistance it is measured by the reciprocal ohm or mho.
MICA.--A transparent mineral having a high insulating value and which can be split into very thin sheets. It is largely used in making condensers both for transmitting and receiving sets.
MICROFARAD.--The millionth part of a farad.
MICROHENRY.--The millionth part of a farad.
MICROMICROFARAD.--The millionth part of a microfarad.
MICROHM.--The millionth part of an ohm.
MICROPHONE TRANSFORMER.--See Transformer, Microphone.
MICROPHONE TRANSMITTER.--See Transmitter, Microphone.
MILLI-AMMETER.--An ammeter that measures a current by the one-thousandth of an ampere.
MODULATION.--(1) Inflection or varying the voice. (2) Varying the amplitude of oscillations by means of the voice.
MODULATION, BUZZER.--The modulation of radio frequency oscillations by a buzzer which breaks up the sustained oscillations of a transmitter into audio frequency impulses.
MILLIHENRY.--The thousandth part of a henry.
MODULATION, CHOPPER.--The modulation of radio frequency oscillations by a chopper which breaks up the sustained oscillations of a transmitter into audio frequency impulses.
MODULATION, GRID.--The scheme of modulating an oscillator tube by connecting the secondary of a transformer, the primary of which is connected with a battery and a microphone transmitter, in the grid lead.
MODULATION, OVER.--See Blub Blub.
MODULATION, PLATE.--Modulating the oscillations set up by a vacuum tube by varying the current impressed on the plate.
MODULATOR TUBE.--A vacuum tube used as a modulator.
MOTION, WAVE.--(1) The to and fro motion of water at sea. (2) Waves transmitted by, in and through the air, or sound waves. (3) Waves transmitted by, in and through the ether, or electromagnetic waves, or electric waves for short.
MOTOR-GENERATOR.--A motor and a dynamo built to run at the same speed and mounted on a common base, the shafts being coupled together. In wireless it is used for changing commercial direct current into direct current of higher voltages for energizing the plate of a vacuum tube oscillator.
MULTI-STAGE AMPLIFIERS.--See Amplifiers, Multi-Stage.
MUTUAL INDUCTION.--See Induction, Mutual.
MUSH.--Irregular intermediate frequencies set up by arc transmitters which interfere with the fundamental wave lengths.
MUSHY NOTE.--A note that is not clear cut, and hence hard to read, which is received by the heterodyne method when damped waves or modulated continuous waves are being received.
NATIONAL ELECTRIC CODE.--See Code, National Electric.
NATIONAL ELECTRIC SAFETY CODE.--See Code, National Electric Safety.
NEGATIVE ELECTRICITY.--See Electricity, Negative.
NON-SYNCHRONOUS GAP.--See Gap, Non-Synchronous.
OHM.--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.
OHM'S LAW.--The important fixed relation between the electric current, its electromotive force and the resistance of the conductor in which it flows.
OPEN CIRCUIT.--See Circuit, Open.
OPEN CORE TRANSFORMER.--See Transformer, Open Core.
OSCILLATION TRANSFORMER.--See Transformer, Oscillation.
OSCILLATIONS, ELECTRIC.--A current of high frequency that surges through an open or a closed circuit. (1) Electric oscillations may be set up by a spark gap, electric arc or a vacuum tube, when they have not only a high frequency but a high potential, or voltage. (2) When electric waves impinge on an aerial wire they are transformed into electric oscillations of a frequency equal to those which emitted the waves, but since a very small amount of energy is received their potential or voltage is likewise very small.
OSCILLATION TRANSFORMER.--See Transformer.
OSCILLATION VALVE.--See Vacuum Tube.
OSCILLATOR TUBE.--A vacuum tube which is used to produce electric oscillations.
OVER MODULATION.--See Blub Blub.
PANCAKE OSCILLATION TRANSFORMER.--Disk-shaped coils that are used for receiving tuning inductances.
PERMEABILITY, MAGNETIC.--The degree to which a substance can be magnetized. Iron has a greater magnetic permeability than air.
PHASE.--A characteristic aspect or appearance that takes place at the same point or part of a cycle.
PICK-UP CIRCUITS.--See Circuits, Stand-by.
PLATE CIRCUIT REACTOR.--See Reactor, Plate Circuit.
PLATE CURRENT.--See Current, Plate.
PLATE MODULATION.--See Modulation, Plate.
PLATE VOLTAGE.--See Foliage, Plate.
POLES, BATTERY.--The positive and negative terminals of the elements of a battery. On a storage battery these poles are marked + and - respectively.
POLES, MAGNETIC.--The ends of a magnet.
POSITIVE ELECTRICITY.--See Electricity, Positive.
POTENTIAL DIFFERENCE.--The electric pressure between two charged conductors or surfaces.
POTENTIOMETER.--A variable resistance used for subdividing the voltage of a current. A voltage divider.
POWER TRANSFORMER.--See Transformer, Power.
POWER TUBE.--See Generator Tube.
PRIMARY BATTERY.--See Battery, Primary.
PREVENTION, KICK-BACK.--A choke coil placed in the power circuit to prevent the high frequency currents from getting into the transformer and breaking down the insulation.
Q S T.--An abbreviation used in wireless communication for (1) the question "Have you received the general call?" and (2) the notice, "General call to all stations."
QUENCHED GAP.--See Gap, Quenched.
RADIATION.--The emission, or throwing off, of electric waves by an aerial wire system.
RADIO AMMETER.--See Ammeter, Hot Wire.
RADIO FREQUENCY.--See Frequency, Radio.
RADIO FREQUENCY AMPLIFICATION.--See Amplification, Radio Frequency.
RADIO FREQUENCY CURRENT.--See Current, Radio Frequency.
RADIO INSPECTOR.--See Inspector, Radio.
RADIOTRON.--The trade name of vacuum tube detectors, amplifiers, oscillators and modulators made by the Radio Corporation of America.
RADIO WAVES.--See Waves, Radio.
REACTANCE.--When a circuit has inductance and the current changes in value, it is opposed by the voltage induced by the variation of the current.
REACTANCE, CAPACITY.--The capacity reactance is the opposition offered to a current by a capacity. It is measured as a resistance, that is, in ohms.
RECEIVING TUNING COILS.--See Coils, Inductance.
RECEIVER, LOUD SPEAKING.--See Loud Speakers.
RECEIVER, WATCH CASE.--A compact telephone receiver used for wireless reception.
REACTANCE, INDUCTIVE.--The inductive reactance is the opposition offered to the current by an inductance coil. It is measured as a resistance, that is, in ohms.
REACTOR, FILTER.--A reactance coil for smoothing out the pulsating direct currents as they come from the rectifier.
REACTOR, PLATE CIRCUIT.--A reactance coil used in the plate circuit of a wireless telephone to keep the direct current supply at a constant voltage.
RECEIVER.--(1) A telephone receiver. (2) An apparatus for receiving signals, speech or music. (3) Better called a receptor to distinguish it from a telephone receiver.
RECTIFIER.--(1) An apparatus for changing alternating current into pulsating direct current. (2) Specifically in wireless (a) a crystal or vacuum tube detector, and (b) a two-electrode vacuum tube used for changing commercial alternating current into direct current for wireless telephony.
REGENERATIVE AMPLIFICATION.--See Amplification, Regenerative.
RECEPTOR.--A receiving set.
RECEPTOR, AUTODYNE.--A receptor that has a regenerative circuit and the same tube is used as a detector and as a generator of local oscillations.
RECEPTOR, BEAT.--A heterodyne receptor.
RECEPTOR, HETERODYNE.--A receiving set that uses a separate vacuum tube to set up the second series of waves for beat reception.
REGENERATIVE ACTION.--See Feed-Back Action.
REGENERATIVE AMPLIFICATION.--See Amplification, Regenerative.
RELAY, ELECTRON.--A vacuum tube when used as a detector or an amplifier.
REPEATING COIL.--A transformer used in connecting up a wireless receiver with a wire transmitter.
RESISTANCE.--The opposition offered by a wire or other conductor to the passage of a current.
RESISTANCE, AERIAL.--The resistance of the aerial wire to oscillating currents. This is greater than its ordinary ohmic resistance due to the skin effect. See Resistance, High Frequency.
RESISTANCE BOX.--See Resistor.
RESISTANCE COUPLING.--See Coupling, Resistance.
RESISTANCE, HIGH FREQUENCY.--When a high frequency current oscillates on a wire two things take place that are different than when a direct or alternating current flows through it, and these are (1) the current inside of the wire lags behind that of the current on the surface, and (2) the amplitude of the current is largest on the surface and grows smaller as the center of the wire is reached. This uneven distribution of the current is known as the skin effect and it amounts to the same thing as reducing the size of the wire, hence the resistance is increased.
RESISTIVITY.--The resistance of a given length of wire of uniform cross section. The reciprocal of conductivity.
RESISTOR.--A fixed or variable resistance unit or a group of such units. Variable resistors are also called resistance boxes and more often rheostats.
RESONANCE.--(1) Simple resonance of sound is its increase set up by one body by the sympathetic vibration of a second body. (2) By extension the increase in the amplitude of electric oscillations when the circuit in which they surge has a natural period that is the same, or nearly the same, as the period of the first oscillation circuit.
RHEOSTAT.--A variable resistance unit. See Resistor.
RHEOSTAT, CARBON.--A carbon rod, or carbon plates or blocks, when used as variable resistances.
RHEOSTAT, FILAMENT.--A variable resistance used for keeping the current of the storage battery which heats the filament of a vacuum tube at a constant voltage.
ROTATING COIL.--See Coil.
ROTARY GAP.--See Gap.
ROTOR.--The rotating coil of a variometer or a variocoupler.
RUHMKORFF COIL.--See Coil, Induction.
SATURATION.--The maximum plate current that a vacuum tube will take.
SENSITIVE SPOTS.--Spots on detector crystals that are sensitive to the action of electric oscillations.
SHORT WAVES.--See Waves.
SIDE WAVES.--See Wave Length Band.
SIGNALS, CONVENTIONAL.--(1) The International Morse alphabet and numeral code, punctuation marks, and a few important abbreviations used in wireless telegraphy. (2) Dot and dash signals for distress call, invitation to transmit, etc. Now used for all general public service wireless communication.
SKIN EFFECT.--See Resistance, High Frequency.
SOFT TUBE.--A vacuum tube in which the vacuum is low, that is, it is not highly exhausted.
SPACE CHARGE EFFECT.--The electric field intensity due to the pressure of the negative electrons in the space between the filament and plate which at last equals and neutralizes that due to the positive potential of the plate so that there is no force acting on the electrons near the filament.
SPARK.--See Discharge.
SPARK COIL.--See Coil, Induction.
SPARK DISCHARGE.--See Spark, Electric.
SPARK FREQUENCY.--See Frequency, Spark.
SPARK GAP.--(1) A spark gap, without the hyphen, means the apparatus in which sparks take place; it is also called a spark discharger. (2) Spark-gap, with the hyphen, means the air-gap between the opposed faces of the electrodes in which sparks are produced.
SPIDER WEB INDUCTANCE COIL.--See Coil, Spider Web Inductance.
SPREADER.--A stick of wood, or spar, that holds the wires of the aerial apart.
STAGGER WOUND COILS.--See Coils, Inductance.
STAND-BY CIRCUITS.--See Circuits, Stand-By.
STATIC.--Also called atmospherics, grinders, strays, X's, and, when bad enough, by other names. It is an electrical disturbance in the atmosphere which makes noises in the telephone receiver.
STATOR.--The fixed or stationary coil of a variometer or a variocoupler.
STORAGE BATTERY.--See Battery, Storage.
STRAY ELIMINATION.--A method for increasing the strength of the signals as against the strength of the strays. See Static.
STRAYS.--See Static.
STRANDED WIRE.--See Wire, Stranded.
SUPER-HETERODYNE RECEPTOR.--See Heterodyne, Super.
SWINGING.--See Fading.
SWITCH, AERIAL.--A switch used to change over from the sending to the receiving set, and the other way about, and connect them with the aerial.
SWITCH, LIGHTNING.--The switch that connects the aerial with the outside ground when the apparatus is not in use.
SYMBOLS, APPARATUS.--Also called conventional symbols. These are diagrammatic lines representing various parts of apparatus so that when a wiring diagram of a transmitter or a receptor is to be made it is only necessary to connect them together. They are easy to make and easy to read. See Page 307 [Appendix: Symbols Used for Apparatus].
SYNCHRONOUS GAP.--See Gap, Synchronous.
TELEPHONY, LINE RADIO.--See Wired Wireless.
THERMAL AMMETER.--See Ammeter, Hot Wire.
THREE ELECTRODE VACUUM TUBE.--See Vacuum Tube, Three Electrode.
TIKKER.--A slipping contact device that breaks up the sustained oscillations at the receiving end into groups so that the signals can be heard in the head phones. The device usually consists of a fine steel or gold wire slipping in the smooth groove of a rotating brass wheel.
TRANSFORMER.--A primary and a secondary coil for stepping up or down a primary alternating or oscillating current.
TRANSMITTER, MICROPHONE.--A telephone transmitter of the kind that is used in the Bell telephone system.
TRANSMITTING TUNING COILS.--See Coils, Inductance.
TUNING.--When the open and closed oscillation circuits of a transmitter or a receptor are adjusted so that both of the former will permit electric oscillations to surge through them with the same frequency, they are said to be tuned. Likewise, when the sending and receiving stations are adjusted to the same wave length they are said to be tuned.
TUNING COILS.--See Coils, Inductance.
TWO ELECTRODE VACUUM TUBE.--See Vacuum Tube, Two Electrode.
VACUUM TUBE.--A tube with two or three electrodes from which the air has been exhausted, or which is filled with an inert gas, and used as a detector, an amplifier, an oscillator or a modulator in wireless telegraphy and telephony.
VALVE.--See Vacuum Tube.
VALVE, FLEMING.--See Fleming Valve.
VARIABLE CONDENSER.--See Condenser, Variable.
VARIABLE INDUCTANCE.--See Inductance, Variable.
VARIABLE RESISTANCE.--See Resistance, Variable.
VARIOCOUPLER.--A tuning device for varying the inductance of the receiving oscillation circuits. It consists of a fixed and a rotatable coil whose windings are not connected with each other.
VARIOMETER.--A tuning device for varying the inductance of the receiving oscillation currents. It consists of a fixed and a rotatable coil with the coils connected in series.
VERNIER CONDENSER.--See Condenser, Vernier.
VOLT.--The electromotive force which produces a current of 1 ampere when steadily applied to a conductor the resistance of which is one ohm.
VOLTAGE DIVIDER.--See Potentiometer.
VOLTAGE, PLATE.--The voltage of the current that is used to energize the plate of a vacuum tube.
VOLTMETER.--An instrument for measuring the voltage of an electric current.
WATCH CASE RECEIVER.--See Receiver, Watch Case.
WATER-PIPE GROUND.--See Ground, Water-Pipe.
WATT.--The power spent by a current of 1 ampere in a resistance of 1 ohm.
WAVE, BROAD.--A wave having a high decrement, when the strength of the signals is nearly the same over a wide range of wave lengths.
WAVE LENGTH.--Every wave of whatever kind has a length. The wave length is usually taken to mean the distance between the crests of two successive waves.
WAVE LENGTH BAND.--In wireless reception when continuous waves are being sent out and these are modulated by a microphone transmitter the different audio frequencies set up corresponding radio frequencies and the energy of these are emitted by the aerial; this results in waves of different lengths, or a band of waves as it is called.
WAVE METER.--An apparatus for measuring the lengths of electric waves set up in the oscillation circuits of sending and receiving sets.
WAVE MOTION.--Disturbances set up in the surrounding medium as water waves in and on the water, sound waves in the air and electric waves in the ether.
WAVES.--See Wave Motion.
WAVES, ELECTRIC.--Electromagnetic waves set up in and transmitted by and through the ether.
WIRELESS TELEGRAPH CODE.--See Code, International.
WIRE, ENAMELLED.--Wire that is given a thin coat of enamel which insulates it.
WIRE, PHOSPHOR BRONZE.--A very strong wire made of an alloy of copper and containing a trace of phosphorus.
WIRED WIRELESS.--Continuous waves of high frequency that are sent over telephone wires instead of through space. Also called line radio communication; carrier frequency telephony, carrier current telephony; guided wave telephony and wired wireless.
X'S.--See Static.
ZINCITE.--See Detector.
Don't use iron wire for your aerial.
Don't fail to insulate it well at both ends.
Don't have it longer than 75 feet for sending out a 200-meter wave.
Don't fail to use a lightning arrester, or better, a lightning switch, for your receiving set.
Don't fail to use a lightning switch with your transmitting set.
Don't forget you must have an outside ground.
Don't fail to have the resistance of your aerial as small as possible. Use stranded wire.
Don't fail to solder the leading-in wire to the aerial.
Don't fail to properly insulate the leading-in wire where it goes through the window or wall.
Don't let your aerial or leading-in wire touch trees or other objects.
Don't let your aerial come too close to overhead wires of any kind.
Don't run your aerial directly under, or over, or parallel with electric light or other wires.
Don't fail to make a good ground connection with the water pipe inside.
Don't attempt to send until you get your license.
Don't fail to live up to every rule and regulation.
Don't use an input of more than 1/2 a kilowatt if you live within 5 nautical miles of a naval station.
Don't send on more than a 200-meter wave if you have a restricted or general amateur license.
Don't use spark gap electrodes that are too small or they will get hot.
Don't use too long or too short a spark gap. The right length can be found by trying it out.
Don't fail to use a safety spark gap between the grid and the filament terminals where the plate potential is above 2,000 volts.
Don't buy a motor-generator set if you have commercial alternating current in your home.
Don't overload an oscillation vacuum tube as it will greatly shorten its life. Use two in parallel.
Don't operate a transmitting set without a hot-wire ammeter in the aerial.
Don't use solid wire for connecting up the parts of transmitters. Use stranded or braided wire.
Don't fail to solder each connection.
Don't use soldering fluid, use rosin.
Don't think that all of the energy of an oscillation tube cannot be used for wave lengths of 200 meters and under. It can be if the transmitting set and aerial are properly designed.
Don't run the wires of oscillation circuits too close together.
Don't cross the wires of oscillation circuits except at right angles.
Don't set the transformer of a transmitting set nearer than 3 feet to the condenser and tuning coil.
Don't use a rotary gap in which the wheel runs out of true.
Don't expect to get as good results with a crystal detector as with a vacuum tube detector.
Don't be discouraged if you fail to hit the sensitive spot of a crystal detector the first time--or several times thereafter.
Don't use a wire larger than No. 80 for the wire electrode of a crystal detector.
Don't try to use a loud speaker with a crystal detector receiving set.
Don't expect a loop aerial to give worthwhile results with a crystal detector.
Don't handle crystals with your fingers as this destroys their sensitivity. Use tweezers or a cloth.
Don't imbed the crystal in solder as the heat destroys its sensitivity. Use Wood's metal, or some other alloy which melts at or near the temperature of boiling water.
Don't forget that strong static and strong signals sometimes destroy the sensitivity of crystals.
Don't heat the filament of a vacuum tube to greater brilliancy than is necessary to secure the sensitiveness required.
Don't use a plate voltage that is less or more than it is rated for.
Don't connect the filament to a lighting circuit.
Don't use dry cells for heating the filament except in a pinch.
Don't use a constant current to heat the filament, use a constant voltage.
Don't use a vacuum tube in a horizontal position unless it is made to be so used.
Don't fail to properly insulate the grid and plate leads.
Don't use more than 1/3 of the rated voltage on the filament and on the plate when trying it out for the first time.
Don't fail to use alternating current for heating the filament where this is possible.
Don't fail to use a voltmeter to find the proper temperature of the filament.
Don't expect to get results with a loud speaker when using a single vacuum tube.
Don't fail to protect your vacuum tubes from mechanical shocks and vibration.
Don't fail to cut off the A battery entirely from the filament when you are through receiving.
Don't switch on the A battery current all at once through the filament when you start to receive.
Don't expect to get the best results with a gas-content detector tube without using a potentiometer.
Don't connect a potentiometer across the B battery or it will speedily run down.
Don't expect to get as good results with a single coil tuner as you would with a loose coupler.
Don't expect to get as good results with a two-coil tuner as with one having a third, or tickler, coil.
Don't think you have to use a regenerative circuit, that is, one with a tickler coil, to receive with a vacuum tube detector.
Don't think you are the only amateur who is troubled with static.
Don't expect to eliminate interference if the amateurs around you are sending with spark sets.
Don't lay out or assemble your set on a panel first. Connect it up on a board and find out if everything is right.
Don't try to connect up your set without a wiring diagram in front of you.
Don't fail to shield radio frequency amplifiers.
Don't set the axes of the cores of radio frequency transformers in a line. Set them at right angles to each other.
Don't use wire smaller than No. 14 for connecting up the various parts.
Don't fail to adjust the B battery after putting in a fresh vacuum tube, as its sensitivity depends largely on the voltage.
Don't fail to properly space the parts where you use variometers.
Don't fail to put a copper shield between the variometer and the variocoupler.
Don't fail to keep the leads to the vacuum tube as short as possible.
Don't throw your receiving set out of the window if it howls. Try placing the audio-frequency transformers farther apart and the cores of them at right angles to each other.
Don't use condensers with paper dielectrics for an amplifier receiving set or it will be noisy.
Don't expect as good results with a loop aerial, or when? using the bed springs, as an out-door aerial will give you.
Don't use an amplifier having a plate potential of less than 100 volts for the last step where a loud speaker is to be used.
Don't try to assemble a set if you don't know the difference between a binding post and a blue print. Buy a set ready to use.
Don't expect to get Arlington time signals and the big cableless stations if your receiver is made for short wave lengths.
Don't take your headphones apart. You are just as apt to spoil them as you would a watch.
Don't expect to get results with a Bell telephone receiver.
Don't forget that there are other operators using the ether besides yourself.
Don't let your B battery get damp and don't let it freeze.
Don't try to recharge your B battery unless it is constructed for the purpose.
Don't connect a source of alternating current direct to your storage battery. You have to use a rectifier.
Don't connect the positive lead of the charging circuit with the negative terminal of your storage battery.
Don't let the electrolyte get lower than the tops of the plates of your storage battery.
Don't fail to look after the condition of your storage battery once in a while.
Don't buy a storage battery that gives less than 6 volts for heating the filament.
Don't fail to keep the specific gravity of the electrolyte of your storage battery between 1.225 and 1.300 Baume. This you can do with a hydrometer.
Don't fail to recharge your storage battery when the hydrometer shows that the specific gravity of the electrolyte is close to 1.225.
Don't keep charging the battery after the hydrometer shows that the specific gravity is 1.285.
Don't let the storage battery freeze.
Don't let it stand for longer than a month without using unless you charge it.
Don't monkey with the storage battery except to add a little sulphuric acid to the electrolyte from time to time. If anything goes wrong with it better take it to a service station and let the expert do it.
Don't think you have an up-to-date transmitting station unless you are using C.W.
Don't use a wire from your lightning switch down to the outside ground that is smaller than No. 4.
Don't try to operate your spark coil with 110-volt direct lighting current without connecting in a rheostat.
Don't try to operate your spark coil with 110-volt alternating lighting current without connecting in an electrolytic interrupter.
Don't try to operate an alternating current power transformer with 110-volt direct current without connecting in an electrolytic interruptor.
Don't--no never--connect one side of the spark gap to the aerial wire and the other side of the spark gap to the ground. The Government won't have it--that's all.
Don't try to tune your transmitter to send out waves of given length by guesswork. Use a wavemeter.
Don't use hard fiber for panels. It is a very poor insulator where high frequency currents are used.
Don't think you are the only one who doesn't know all about wireless. Wireless is a very complex art and there are many things that those experienced have still to learn.