The first essential in order to manage a wireless station, after
learning the construction and handling of the instruments, is to acquire
a thorough knowledge of the telegraph codes.
The two codes in use in wireless service are the Morse and the
Continental. They are given below.
In some cases, the intending wireless operator has had some experience
with a Morse sounder and then it is merely a matter of transition and of
accustoming the ear to a new sound. However it is always best to learn
the Morse code first as Continental is merely an adaptation in which no
space characters appear.
A beginner may learn to receive most easily by communicating with
another person to whom it is also new. They should first memorize all
the letters of the code and practice transmitting before commencing any
communication.
It is a great mistake for a beginner to start by writing down the dots
and dashes as he receives them on paper. He should make an effort to
translate them and set the characters and words down directly. This at
first will sacrifice speed but will make a better operator and enable
one to become proficient sooner than if he begins otherwise.
In case two complete sets of wireless apparatus are not convenient, one
may learn to read from a buzzer connected to a key and a battery. The
signals may be read directly from the sound of the buzzer itself, but if
a pair of telephone receivers are connected across the terminals, a
sound will be produced in the phones similar to that of a wireless
receptor.
In sending, avoid a short, choppy or jerky style and handle the key with
a light but firm touch. Keep the dots and dashes firm and of the proper
relative length, as also the spaces between letters and words.
The following suggestions and instructions adapted from the Rules and
Regulations governing Naval Wireless Telegraph Stations may be of value
and service to many in operating their instruments.
"The operating room should be well lighted and free from vibration. The
room should have a well insulated entrance for the aerial and should be
fitted with an operating table about two and one-half feet wide, not
less than seven feet long and of a convenient height for working the
sending key.
The table should be of dry, well-seasoned wood and the instruments
should be mounted on the table at safe sparking distances from each
other.
"The connections should all be as direct as possible and well insulated.
High potential leads should be kept away from low potential leads and
where they cross it should be at nearly right angles.
"Sending key contacts must be kept clean and flat with surfaces parallel
to each other.
"All sliding contacts, especially in the receiving tuning coils, should
be kept clean and bright and free from foreign matter. A sending set
working at low power with all connections good, closed and open circuits
in resonance, no sparking from edge of condenser, jar or plates, no glow
from aerial and no sparking to rigging, is utilizing its power much more
efficiently than the same set pushed to the limit with high resistance
connections, sparking at all points and out of resonance."
[Illustration: Fig. 147. Marconi Station at Siasconset, Mass.]
It is a good plan for any amateur to keep a note book in which he can
record the various distances he has been able to receive and transmit.
He should try more than one circuit and jot down the results. It is then
possible to bring a station up to an efficiency which cannot be reached
in any other manner.
ELECTRICAL TERMS AND DEFINITIONS.
_Accumulator:_
A cell whose positive and negative electrodes are formed or
deposited by a current flowing from a separate source.
_Aerial:_
A network or a number of wires insulated from surrounding objects
and suspended in the air to emit or intercept electromagnetic
waves.
_Alternating Current:_
An electric current, of which the direction of flow reverses a
number of times per second.
_Ampere:_
The quantity of current which will flow through a resistance of
one ohm under a potential of one volt. The unit of current.
_Ampere Hour:_
The quantity of electricity passed when flowing at the rate of
one ampere for one hour.
_Anode:_
The positive terminal of a broken circuit or a source of
electricity. It is the carbon of a cell or the pole at which a
current enters a solution.
_Capacity:_
The relative ability of a conductor to receive and retain an
electric charge.
_Circuit:_
An unbroken conducting path for an electric current.
_Condenser:_
A device for receiving and storing up electrostatic energy.
_Cycle:_
The full period of reversal of an alternating current. A 60-cycle
current is one making 60 complete reversals per second.
_Detector, Wireless:_
An instrument for detecting oscillations in the aerial of a
receiving station. It either varies its own internal resistance
or generates a weak intermittent direct current similar in time
and duration with the signals emitted by the transmitting
station.
_Dielectric:_
A non-conductor or insulator. It usually refers to the material
interposed between the oppositely charged coatings of a
condenser.
_Direct Current:_
A current flowing in one direction only.
_Electrode:_
The terminal of an open electric circuit or a conductor carrying
a current and immersed in an electrolyte.
_Electrolysis:_
The separation of a chemical compound into its elements by the
action of an electric current.
_Electrolyte:_
A solution which will conduct a current of electricity.
_Electromagnet:_
A mass of iron which is magnetized by the passage of a current of
electricity through a coil of wire wound around the mass and
insulated therefrom.
_Farad:_
The unit of electrical capacity. A condenser having a capacity of
one farad would be raised to a potential of one volt by one
ampere flowing for one second.
_Field of Force:_
The space which is under magnetic stress in the neighborhood of a
magnet or a wire carrying a current.
_Helix, Transmitting:_
A coil of heavy wire which furnishes the inductance for the
closed oscillation circuit of a wireless transmitter and acts as
an auto-transformer to raise the voltage of the high frequency
currents.
_Henry:_
The unit of induction. It is the induction in a circuit when the
electromotive force induced in this circuit is one volt, while
the inducing current varies at the rate of one ampere per second.
_Inductance:_
The property of an electric circuit whereby lines of force are
developed around it.
_Induction Coil:_
An instrument or device consisting of two independent coils of
wire wound around an iron core, and which by magnetic induction
steps up an intermittent direct current from a low to a high
voltage.
_Insulator:_
A non-conductor or a substance impervious to the passage of
electricity.
_Key:_ A device for making and breaking a current into periods
corresponding to the dots and dashes of the telegraph code.
_Kilowatt:_
1,000 watts. See watt.
_Leyden Jar:_
A static condenser which will store up static electricity and is
cylindrical in form. So-called because it was originated in
Leyden, Holland.
_Multiple:_
The term expressing the connection of several pieces of
electrical apparatus in parallel with each other so that the
current is divided between them.
_Ohm:_ The unit of resistance. It is arbitrarily taken as the resistance
of a column of mercury, one square millimeter in cross sectional
area and 106 centimeters in height.
_Parallel:_
The same meaning as multiple. Parallel circuits are those which
start at a common point and end at a common point.
_Polarization:_
The collection of hydrogen upon the positive electrode of a
primary cell with a consequent loss of voltage.
_Potential:_
Voltage or electrical force.
_Resistance:_
The quality of an electrical conductor whereby it opposes the
passage of an electric current. The unit of resistance is the
ohm.
_Rheostat:_
A variable resistance to regulate the strength of an electric
current.
_Series:_
Opposed to parallel or multiple. Instruments in series are so
connected that the current passes from one to the other and does
not divide.
_Spark Gap:_
An air gap or open space between two electrodes for the passage
of a high voltage discharge.
_Storage Battery:_
See accumulator.
_Transformer:_
A device for stepping up or stepping down the voltage of an
alternating current by means of magnetic induction.
_Tuning Coil:_
A variable inductance for changing the period of the receptor
circuit.
_Volt:_
The unit of electrical force or potential. The electromotive
force which, if steadily applied to a conductor whose resistance
is one ohm, will produce a current of one ampere.
_Voltmeter:_
An instrument for measuring voltage.
_Watt:_
Unit of work. It is the rate of work of one ampere flowing under
a potential of one volt. Seven hundred and forty-six watts
represent one electrical horsepower.
[Illustration: *Plate VI. DeForest and Marconi Systems.*]