The Radio Amateurs Hand Book | Page 3

Preachers reach the stay-at-homes.
Great singers thrill thousands instead of hundreds. Soon it will be
possible to hear the finest musical programs, entertainers, and orators,
without budging from one's easy chair.

In the World War wireless proved of inestimable value. Airplanes,
instead of flying aimlessly, kept in constant touch with headquarters.
Bodies of troops moved alertly and intelligently. Ships at sea talked
freely, over hundreds of miles. Scouts reported. Everywhere its
invisible aid was invoked.
In time of peace, however, it has proved and will prove the greatest
servant of mankind. Wireless messages now go daily from continent to
continent, and soon will go around the world with the same facility.
Ships in distress at sea can summon aid. Vessels everywhere get the
day's news, even to baseball scores. Daily new tasks are being assigned
this tireless, wireless messenger.
Messages have been sent and received by moving trains, the
Lackawanna and the Rock Island railroads being pioneers in this field.
Messages have also been received by automobiles, and one inventor
has successfully demonstrated a motor car controlled entirely by
wireless. This method of communication is being employed more and
more by newspapers. It is also of great service in reporting forest fires.
Colleges are beginning to take up the subject, some of the first being
Tufts College, Hunter College, Princeton, Yale, Harvard, and Columbia,
which have regularly organized departments for students in wireless.
Instead of the unwieldy and formidable looking apparatus of a short
time ago, experimenters are now vying with each other in making small
or novel equipment. Portable sets of all sorts are being fashioned, from
one which will go into an ordinary suitcase, to one so small it will
easily slip into a Brownie camera. One receiver depicted in a
newspaper was one inch square! Another was a ring for the finger, with
a setting one inch by five-eighths of an inch, and an umbrella as a
"ground." Walking sets with receivers fastened to one's belt are also
common. Daily new novelties and marvels are announced.
Meanwhile, the radio amateur to whom this book is addressed may
have his share in the joys of wireless. To get all of these good things
out of the ether one does not need a rod or a gun--only a copper wire
made fast at either end and a receiving set of some kind. If you are a

sheer beginner, then you must be very careful in buying your apparatus,
for since the great wave of popularity has washed wireless into the
hearts of the people, numerous companies have sprung up and some of
these are selling the veriest kinds of junk.
And how, you may ask, are you going to be able to know the good
from the indifferent and bad sets? By buying a make of a firm with an
established reputation. I have given a few offhand at the end of this
book. Obviously there are many others of merit--so many, indeed, that
it would be quite impossible to get them all in such a list, but these will
serve as a guide until you can choose intelligently for yourself.
A. F. C.

CONTENTS


CHAPTER
I.
HOW TO BEGIN WIRELESS
Kinds of Wireless Systems--Parts of a Wireless System--The Easiest
Way to Start--About Aerial Wire Systems--About the Receiving
Apparatus--About Transmitting Stations--Kinds of Transmitters--The
Spark Gap Wireless Telegraph Transmitter--The Vacuum Table
Telegraph Transmitter--The Wireless Telephone Transmitter.
II. PUTTING UP YOUR AERIAL
Kinds of Aerial Wire Systems--How to Put Up a Cheap Receiving
Aerial--A Two-wire Aerial--Connecting in the Ground--How to Put up
a Good Aerial--An Inexpensive Good Aerial--The Best Aerial That Can

be Made--Assembling the Aerial--Making a Good Ground.
III. SIMPLE TELEGRAPH AND TELEPHONE RECEIVING SETS
Assembled Wireless Receiving Sets--Assembling Your Own Receiving
Set--The Crystal Detector--The Tuning Coil--The Loose Coupled
Tuning Coil--Fixed and Variable Condensers--About Telephone
Receivers-- Connecting Up the Parts--Receiving Set No. 2--Adjusting
the No. 1 Set--The Tuning Coil--Adjusting the No. 2 Set.
IV. SIMPLE TELEGRAPH SENDING SETS
A Cheap Transmitting Set (No. 1)--The Spark Coil--The Battery--The
Telegraph Key--The Spark Gap--The Tuning Coil--The High-tension
Condenser--A Better Transmitting Set (No. 2)--The Alternating Current
Transformer--The Wireless Key--The Spark Gap--The High-tension
Condenser--The Oscillation Transformer--Connecting Up the
Apparatus--For Direct Current--How to Adjust Your Transmitter.
Turning With a Hot Wire Ammeter--To Send Out a 200-meter Wave
Length--The Use of the Aerial Switch--Aerial Switch for a Complete
Sending and Receiving Set--Connecting in the Lightning Switch.
V. ELECTRICITY SIMPLY EXPLAINED
Electricity at Rest and in Motion--The Electric Current and its
Circuit--Current and the Ampere--Resistance and the Ohm--What
Ohm's Law Is--What the Watt and Kilowatt Are--Electromagnetic
Induction--Mutual Induction--High-frequency Currents--Constants of
an Oscillation Circuit--What Capacitance Is--What Inductance
Is--What Resistance Is--The Effect of Capacitance.
VI. HOW THE TRANSMITTING AND RECEIVING SETS WORK
How Transmitting Set No. 1 Works--The Battery and Spark Coil
Circuit--Changing the Primary Spark Coil Current Into Secondary