Chapter XXV: Appendix: Useful Information (2)

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.

Plain.--A spark gap with fixed electrodes.

Rotary.--A spark gap with a pair of fixed electrodes and a number of electrodes mounted on a rotating element.

Quenched.--A spark gap formed of a number of metal plates placed closely together and insulated from each other.

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.

A. C.--See _Power Transformer_.

Air Cooled.--A transformer in which the coils are exposed to the air.

Air Core.--With high frequency currents it is the general practice not to use iron cores as these tend to choke off the oscillations. Hence the core consists of the air inside of the coils.

Auto.--A single coil of wire in which one part forms the primary and the other part the secondary by bringing out an intermediate tap.

Audio Amplifying.--This is a transformer with an iron core and is used for frequencies up to say 3,000.

Closed Core.--A transformer in which the path of the magnetic flux is entirely through iron. Power transformers have closed cores.

Microphone.--A small transformer for modulating the oscillations set up by an arc or a vacuum tube oscillator.

Oil Cooled.--A transformer in which the coils are immersed in oil.

Open Core.--A transformer in which the path of the magnetic flux is partly through iron and partly through air. Induction coils have open cores.

Oscillation.--A coil or coils for transforming or stepping down or up oscillating currents. Oscillation transformers usually have no iron cores when they are also called _air core transformers._

Power.--A transformer for stepping down a commercial alternating current for lighting and heating the filament and for stepping up the commercial a.c., for charging the plate of a vacuum tube oscillator.

Radio Amplifying.--This is a transformer with an air core. It does not in itself amplify but is so called because it is used in connection with an amplifying tube.

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._

Coarse Tuning.--The first adjustment in the tuning oscillation circuits of a receptor is made with the inductance coil and this tunes them coarse, or roughly.

Fine Tuning.--After the oscillation circuits have been roughly tuned with the inductance coil the exact adjustment is obtained with the variable condenser and this is _fine tuning._

Sharp.--When a sending set will transmit or a receiving set will receive a wave of given length only it is said to be sharply tuned. The smaller the decrement the sharper the tuning.

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.

Amplifier.--See _Amplifier, Vacuum Tube._

Amplifying Modulator.--A vacuum tube used for modulating and amplifying the oscillations set up by the sending set.

Gas Content.--A tube made like a vacuum tube and used as a detector but which contains an inert gas instead of being exhausted.

Hard.--See _Hard Tube._

Rectifier.--(1) A vacuum tube detector. (2) a two-electrode vacuum tube used for changing commercial alternating current into direct current for wireless telephony.

Soft.--See _Soft Tube._

Three Electrode.--A vacuum tube with three electrodes, namely a filament, a grid and a plate.

Two Electrode.--A vacuum tube with two electrodes, namely the filament and the plate.

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.

Continuous. Abbreviated C.W.--Waves that are emitted without a break from the aerial. Also called _undamped waves_.

Discontinuous.--Waves that are emitted periodically from the aerial. Also called _damped waves_. Damped.--See _Discontinuous Waves_.

Intermediate.--Waves from 600 to 2,000 meters in length.

Long.--Waves over 2,000 meters in length.

Radio.--Electric waves used in wireless telegraphy and telephony.

Short.--Waves up to 600 meters in length.

Wireless.--Electric waves used in wireless telegraphy and telephony.

Undamped.--See _Continuous Waves_.

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._

WIRELESS DON'TS

AERIAL WIRE DON'TS

_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.

TRANSMITTING DON'TS

_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.

RECEIVING DON'TS

_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.

STORAGE BATTERY DON'TS

_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.

EXTRA DON'TS

_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.

THE END.