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THE RADIO AMATEUR'S HAND BOOK
[Illustration: A. Frederick Collins, Inventor of the Wireless
Telephone, 1899. Awarded Gold Medal for same, Alaska Yukon Pacific
Exposition, 1909.]
THE RADIO AMATEUR'S HAND BOOK
A Complete, Authentic and Informative Work on Wireless Telegraphy and
Telephony
BY
A. FREDERICK COLLINS
Inventor of the Wireless Telephone 1899; Historian of Wireless
1901-1910; Author of "Wireless Telegraphy" 1905
TO
WILLIAM MARCONI
INVENTOR OF THE WIRELESS TELEGRAPH
INTRODUCTION
Before delving into the mysteries of receiving and sending messages
without wires, a word as to the history of the art and its present day
applications may be of service. While popular interest in the subject
has gone forward by leaps and bounds within the last two or three
years, it has been a matter of scientific experiment for more than a
quarter of a century.
The wireless telegraph was invented by William Marconi, at Bologna,
Italy, in 1896, and in his first experiments he sent dot and dash
signals to a distance of 200 or 300 feet. The wireless telephone was
invented by the author of this book at Narberth, Penn., in 1899, and
in his first experiments the human voice was transmitted to a distance
of three blocks.
The first vital experiments that led up to the invention of the
wireless telegraph were made by Heinrich Hertz, of Germany, in 1888
when he showed that the spark of an induction coil set up electric
oscillations in an open circuit, and that the energy of these waves
was, in turn, sent out in the form of electric waves. He also showed
how they could be received at a distance by means of a ring detector,
which he called a _resonator_
In 1890, Edward Branly, of France, showed that metal filings in a tube
cohered when electric waves acted on them, and this device he termed a
_radio conductor_; this was improved upon by Sir Oliver Lodge, who
called it a coherer. In 1895, Alexander Popoff, of Russia, constructed
a receiving set for the study of atmospheric electricity, and this
arrangement was the earliest on record of the use of a detector
connected with an aerial and the earth.
Marconi was the first to connect an aerial to one side of a spark gap
and a ground to the other side of it. He used an induction coil to
energize the spark gap, and a telegraph key in the primary circuit to
break up the current into signals. Adding a Morse register, which
printed the dot and dash messages on a tape, to the Popoff receptor he
produced the first system for sending and receiving wireless telegraph
messages.
[Illustration: Collins' Wireless Telephone Exhibited at the Madison
Square Garden, October 1908.]
After Marconi had shown the world how to telegraph without connecting
wires it would seem, on first thought, to be an easy matter to
telephone without wires, but not so, for the electric spark sets up
damped and periodic oscillations and these cannot be used for
transmitting speech. Instead, the oscillations must be of constant
amplitude and continuous. That a direct current arc light transforms a
part of its energy into electric oscillations was shown by Firth and
Rogers, of England, in 1893.
The author was the first to connect an arc lamp with an aerial and a
ground, and to use a microphone transmitter to modulate the sustained
oscillations so set up. The receiving apparatus consisted of a
variable contact, known as a _pill-box_ detector, which Sir Oliver
Lodge had devised, and to this was connected an Ericsson telephone
receiver, then the most sensitive made. A later improvement for
setting up sustained oscillations was the author's _rotating
oscillation arc_.
Since those memorable days of more than two decades ago, wonderful
advances have been made in both of these methods of transmitting
intelligence, and the end is as yet nowhere in sight. Twelve or
fifteen years ago the boys began to get fun out of listening-in to
what the ship and shore stations were sending and, further, they began
to do a little sending on their own account. These youngsters, who
caused the professional operators many a pang, were the first wireless
amateurs, and among them experts were developed who are foremost in
the practice of the art today.
Away back there, the spark coil and the arc lamp were the only known
means for setting up oscillations at the sending end, while the
electrolytic and crystal detectors were the only available means for
the amateur to receive them. As it was next to impossible for a boy to
get a current having a high enough voltage for operating an
oscillation arc lamp, wireless telephony was out of the question for
him, so he had to stick to the spark coil transmitter which needed
only a battery current to energize it, and this, of course, limited
him to sending Morse signals. As the electrolytic detector was
cumbersome and required a liquid, the crystal detector which came into
being shortly after was just as sensitive and soon displaced the
former, even as this had displaced the coherer.
A few years ahead of these amateurs, that is to say in 1905, J. A.
Fleming, of England, invented the vacuum tube detector, but ten more
years elapsed before it was perfected to a point where it could
compete with the crystal detector. Then its use became general and
workers everywhere sought to, and did improve it. Further, they found
that the vacuum tube would not only act as a detector, but that if
energized by a direct current of high voltage it would set up
sustained oscillations like the arc lamp, and the value of sustained
oscillations for wireless telegraphy as well as wireless telephony had
already been discovered.
The fact that the vacuum tube oscillator requires no adjustment of its
elements, that its initial cost is much less than the oscillation arc,
besides other considerations, is the reason that it popularized
wireless telephony; and because continuous waves have many advantages
over periodic oscillations is the reason the vacuum tube oscillator is
replacing the spark coil as a wireless telegraph transmitter.
Moreover, by using a number of large tubes in parallel, powerful
oscillations can be set up and, hence, the waves sent out are radiated
to enormous distances.
While oscillator tubes were being experimented with in the research
laboratories of the General Electric, the Westinghouse, the Radio
Corporation of America, and other big companies, all the youthful
amateurs in the country had learned that by using a vacuum tube as a
detector they could easily get messages 500 miles away. The use of
these tubes as amplifiers also made it possible to employ a loud
speaker, so that a room, a hall, or an out-of-door audience could hear
clearly and distinctly everything that was being sent out.
The boy amateur had only to let father or mother listen-in, and they
were duly impressed when he told them they were getting it from KDKA
(the Pittsburgh station of the Westinghouse Co.), for was not
Pittsburgh 500 miles away! And so they, too, became enthusiastic
wireless amateurs. This new interest of the grown-ups was at once met
not only by the manufacturers of apparatus with complete receiving and
sending sets, but also by the big companies which began broadcasting
regular programs consisting of music and talks on all sorts of
interesting subjects.
This is the wireless, or radio, as the average amateur knows it today.
But it is by no means the limit of its possibilities. On the contrary,
we are just beginning to realize what it may mean to the human race.
The Government is now utilizing it to send out weather, crop and
market reports. Foreign trade conditions are being reported. The Naval
Observatory at Arlington is wirelessing time signals.
Department stores are beginning to issue programs and advertise by
radio! Cities are also taking up such programs, and they will
doubtless be included soon among the regular privileges of the
tax-payers. Politicians address their constituents. 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. Tuning
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
Currents--What Ratio of Transformation Means--The Secondary Spark Coil
Circuit--The Closed Oscillation Circuit--How Transmitting Set No. 2
Works--With Alternating Current--With Direct Current--The Rotary Spark
Gap--The Quenched Spark Gap--The Oscillation Transformer--How
Receiving Set No. 1 Works--How Receiving Set No. 2 Works.
VII. MECHANICAL AND ELECTRICAL TUNING
Damped and Sustained Mechanical Vibrations--Damped and Sustained
Oscillations--About Mechanical Tuning--About Electric Tuning.
VIII. A SIMPLE VACUUM TUBE DETECTOR RECEIVING SET
Assembled Vacuum Tube Receiving Set--A Simple Vacuum Tube Receiving
Set--The Vacuum Tube Detector--Three Electrode Vacuum Tube
Detector--The Dry Cell and Storage Batteries--The Filament
Rheostat--Assembling the Parts--Connecting Up the Parts--Adjusting the
Vacuum Tube Detector Receiving Set.
IX. VACUUM TUBE AMPLIFIER RECEIVING SETS
A Grid Leak Amplifier Receiving Set. With Crystal Detector--The Fixed
Resistance Unit, or Grid Leak--Assembling the Parts for a Crystal
Detector Set--Connecting up the Parts for a Crystal Detector--A Grid
Leak Amplifying Receiving Set With Vacuum Tube Detector--A Radio
Frequency Transformer Amplifying Receiving Set--An Audio Frequency
Transformer Amplifying Receiving Set--A Six Step Amplifier Receiving
Set with a Loop Aerial--How to Prevent Howling.
X. REGENERATIVE AMPLIFICATION RECEIVING SETS
The Simplest Type of Regenerative Receiving Set--With Loose Coupled
Tuning Coil--Connecting Up the Parts--An Efficient Regenerative
Receiving Set. With Three Coil Loose Coupler--The A Battery
Potentiometer--The Parts and How to Connect Them Up--A Regenerative
Audio Frequency Amplifier--The Parts and How to Connect Them Up.
XI. SHORT WAVE REGENERATIVE RECEIVING SETS
A Short Wave Regenerative Receiver, with One Variometer and Three
Variable Condensers--The Variocoupler--The Variometer--Connecting Up
the Parts--Short Wave Regenerative Receiver with Two Variometers and
Two Variable Condensers--The Parts and How to Connect Them Up.
XII. INTERMEDIATE AND LONG WAVE REGENERATIVE RECEIVING SETS
Intermediate Wave Receiving Sets--Intermediate Wave Set With Loading
Coils--The Parts and How to Connect Them Up--An Intermediate Wave Set
with Variocoupler Inductance Coils--The Parts and How to Connect Them
Up--A Long Wave Receiving Set--The Parts and How to Connect Them Up.
XIII. HETERODYNE OR BEAT LONG WAVE TELEGRAPH RECEIVING SET
What the Heterodyne or Beat Method Is--The Autodyne or Self-heterodyne
Long Wave Receiving Set--The Parts and Connections of an Autodyne or
Self-heterodyne, Receiving Set--The Separate Heterodyne Long Wave
Receiving Set--The Parts and Connections of a Separate Heterodyne Long
Wave Receiving Set.
XIV. HEADPHONES AND LOUD SPEAKERS
Wireless Headphones--How a Bell Telephone Receiver is Made--How a
Wireless Headphone is Made--About Resistance, Turns of Wire and
Sensitivity of Headphones--The Impedance of Headphones--How the
Headphones Work--About Loud Speakers--The Simplest Type of Loud
Speaker--Another Simple Kind of Loud Speaker--A Third Kind of Simple
Loud Speaker--A Super Loud Speaker.
XV. OPERATION OF VACUUM TUBE RECEPTORS
What is Meant by Ionization--How Electrons are Separated from
Atoms--Action of the Two Electrode Vacuum Tube--How the Two Electrode
Tube Acts as a Detector--How the Three Electrode Tube Acts as a
Detector--How the Vacuum Tube Acts as an Amplifier--The Operation of a
Simple Vacuum Tube Receiving Set--Operation of a Regenerative Vacuum
Tube Receiving Set--Operation of Autodyne and Heterodyne Receiving
Sets--The Autodyne, or Self-Heterodyne Receiving Set--The Separate
Heterodyne Receiving Set.
XVI. CONTINUOUS WAVE TELEGRAPH TRANSMITTING SETS WITH DIRECT CURRENT
Sources of Current for Telegraph Transmitting Sets--An Experimental
Continuous Wave Telegraph Transmitter--The Apparatus You Need--The
Tuning Coil--The Condensers--The Aerial Ammeter--The Buzzer and Dry
Cell--The Telegraph Key--The Vacuum Tube Oscillator--The Storage
Battery--The Battery Rheostat--The Oscillation Choke Coil--Transmitter
Connectors--The Panel Cutout--Connecting Up the Transmitting
Apparatus--A 100-mile C. W. Telegraph Transmitter--The Apparatus You
Need--The Tuning Coil--The Aerial Condenser--The Aerial Ammeter--The
Grid and Blocking Condensers--The Key Circuit Apparatus--The 5 Watt
Oscillator Vacuum Tube--The Storage Battery and Rheostat--The Filament
Voltmeter--The Oscillation Choke Coil--The Motor-generator Set--The
Panel Cut-out--The Protective Condenser--Connecting Up the
Transmitting Apparatus--A 200-mile C. W. Telegraph Transmitter--A
500-mile C. W. Telegraph Transmitter--The Apparatus and Connections--
The 50-watt Vacuum Tube Oscillator--The Aerial Ammeter--The Grid Leak
Resistance--The Oscillation Choke Coil--The Filament Rheostat--The
Filament Storage Battery--The Protective Condenser--The
Motor-generator--A 1000-mile C. W. Telegraph Transmitter.
XVII. CONTINUOUS WAVE TELEGRAPH TRANSMITTING SETS WITH ALTERNATING
CURRENT
A 100-mile C. W. Telegraph Transmitting Set--The Apparatus
Required--The Choke Coils--The Milli-ammeter--The A. C. Power
Transformer--Connecting Up the Apparatus--A 200- to 500-mile C. W.
Telegraph Transmitting Set-A 500- to 1000-mile C. W. Telegraph
Transmitting Set--The Apparatus Required--The Alternating Current
Power Transformer-Connecting Up the Apparatus.
XVIII. WIRELESS TELEPHONE TRANSMITTING SETS WITH DIRECT AND
ALTERNATING CURRENTS
A Short Distance Wireless Telephone Transmitting Set--With 110-volt
Direct Lighting Current--The Apparatus You Need--The Microphone
Transmitter--Connecting Up the Apparatus--A 25- to 50-mile Wireless
Telephone Transmitter--With Direct Current Motor Generator--The
Apparatus You Need--The Telephone Induction Coil--The Microphone
Transformer--The Magnetic Modulator--How the Apparatus is Connected
Up--A 50- to 100-mile Wireless Telephone Transmitter--With Direct
Current Motor Generator--The Oscillation Choke Coil--The Plate and
Grid Circuit Reactance Coils--Connecting up the Apparatus--A 100- to
200-mile Wireless Telephone Transmitter--With Direct Current Motor
Generator--A 50- to 100-mile Wireless Telephone Transmitting Set--With
100-volt Alternating Current--The Apparatus You Need--The Vacuum Tube
Rectifier--The Filter Condensers--The Filter Reactance Coil--
Connecting Up the Apparatus--A 100- to 200-mile Wireless Telephone
Transmitting Set--With 110-volt Alternating Current--Apparatus
Required.
XIX. THE OPERATION OF VACUUM TUBE TRANSMITTERS
The Operation of the Vacuum Tube Oscillator--The Operation of C. W.
Telegraph Transmitters with Direct Current--Short Distance C. W.
Transmitter--The Operation of the Key Circuit--The Operation of C. W.
Telegraph Transmitting with Direct Current--The Operation of C. W.
Telegraph Transmitters with Alternating Current--With a Single
Oscillator Tube--Heating the Filament with Alternating Current--The
Operation of C. W. Telegraph Transmitters with Alternating Current--
With Two Oscillator Tubes--The Operation of Wireless Telephone
Transmitters with Direct Current--Short Distance Transmitter--The
Microphone Transmitter--The Operation of Wireless Telephone
Transmitters with Direct Current--Long Distance Transmitters--The
Operation of Microphone Modulators--The Induction Coil--The Microphone
Transformer--The Magnetic Modulator--Operation of the Vacuum Tube as a
Modulator--The Operation of Wireless Telephone Transmitters with
Alternating Current--The Operation of Rectifier Vacuum Tubes--The
Operation of Reactors and Condensers.
XX. HOW TO MAKE A RECEIVING SET FOR $5.00 OR LESS.
The Crystal Detector--The Tuning Coil--The Headphone--How to Mount the
Parts--The Condenser--How to Connect Up the Receptor.
APPENDIX
Useful Information--Glossary--Wireless Don'ts.
LIST OF FIGURES
Fig. 1.--Simple Receiving Set
Fig. 2.--Simple Transmitting Set
(A) Fig. 3.--Flat Top, or Horizontal Aerial
(B) Fig. 3.--Inclined Aerial
(A) Fig. 4.--Inverted L Aerial
(B) Fig. 4--T Aerial
Fig. 5.--Material for a Simple Aerial Wire System
(A) Fig. 6.--Single Wire Aerial for Receiving
(B) Fig. 6.--Receiving Aerial with Spark Gap Lightning Arrester
(C) Fig. 6.--Aerial with Lightning Switch
Fig. 7.--Two-wire Aerial
(A) Fig. 8.--Part of a Good Aerial
(B) Fig. 8.--The Spreaders
(A) Fig. 9.--The Middle Spreader
(B) Fig. 9.--One End of Aerial Complete
(C) Fig. 9.--The Leading in Spreader
(A) Fig. 10.--Cross Section of Crystal Detector
(B) Fig. 10.--The Crystal Detector Complete
(A) Fig. 11.--Schematic Diagram of a Double Slide Tuning Coil
(B) Fig. 11.--Double Slide Tuning Coil Complete
(A) Fig. 12.--Schematic Diagram of a Loose Coupler
(B) Fig. 12.--Loose Coupler Complete
(A) Fig. 13.--How a Fixed Receiving Condenser is Built up
(B) Fig. 13.--The Fixed Condenser Complete
(C) and (D) Fig. 13.--Variable Rotary Condenser
Fig. 14.--Pair of Wireless Headphones
(A) Fig. 15.--Top View of Apparatus Layout for Receiving Set No. 1
(B) Fig. 15.--Wiring Diagram for Receiving Set No. 1
(A) Fig. 16.--Top View of Apparatus Layout for Receiving Set No. 2
(B) Fig. 16.--Wiring Diagram for Receiving Set No. 2
Fig. 17.--Adjusting the Receiving Set
(A) and (B) Fig. 18.--Types of Spark Coils for Set No. 1
(C) Fig. 18.--Wiring Diagram of Spark Coil
Fig. 19.--Other Parts for Transmitting Set No. 1
(A) Fig. 20.--Top View of Apparatus Layout for Sending Set No. 1
(B) Fig. 20.--Wiring of Diagram for Sending Set No. 1
Fig. 21.--Parts for Transmitting Set No. 2
(A) Fig. 22.--Top View of Apparatus Layout for Sending Set No. 2
(B) Fig. 22.--Wiring Diagram for Sending Set No. 2
Fig. 23.--Using a 110-volt Direct Current with an Alternating current
Transformer
Fig. 24.--Principle of the Hot Wire Ammeter
Fig. 25.--Kinds of Aerial Switches
Fig. 26.--Wiring Diagram for a Complete Sending and Receiving Set No. 1
Fig. 27.--Wiring Diagram for Complete Sending and Receiving Set No. 2
Fig. 28.--Water Analogue for Electric Pressure
Fig. 29.--Water Analogues for Direct and Alternating Currents
Fig. 30.--How the Ammeter and Voltmeter are Used
Fig. 31.--Water Valve Analogue of Electric Resistance
(A) and (B) Fig. 32.--How an Electric Current is Changed into Magnetic
Lines of Force and These into an Electric Current
(C) and (D) Fig. 32.--How an Electric Current Sets up a Magnetic Field
Fig. 33.--The Effect of Resistance on the Discharge of an Electric
Current
Fig. 34.--Damped and Sustained Mechanical Vibrations
Fig. 35.--Damped and Sustained Electric Oscillations
Fig. 36.--Sound Wave and Electric Wave Tuned Senders and Receptors
Fig. 37.--Two Electrode Vacuum Tube Detectors
Fig. 38.--Three Electrode Vacuum Tube Detector and Battery Connections
Fig. 39.--A and B Batteries for Vacuum Tube Detectors
Fig. 40.--Rheostat for the A or Storage-battery Current
(A) Fig. 41.--Top View of Apparatus Layout for Vacuum Tube Detector
Receiving Set
(B) Fig. 41.--Wiring Diagram of a Simple Vacuum Tube Receiving Set
Fig. 42.--Grid Leaks and How to Connect them Up
Fig. 43.--Crystal Detector Receiving Set with Vacuum Tube Amplifier
(Resistance Coupled)
(A) Fig. 44.--Vacuum Tube Detector Receiving Set with One Step
Amplifier (Resistance Coupled)
(B) Fig. 44.--Wiring Diagram for Using One A or Storage Battery with
an Amplifier and a Detector Tube
(A) Fig. 45.--Wiring Diagram for Radio Frequency Transformer
Amplifying Receiving Set
(B) Fig. 45.--Radio Frequency Transformer
(A) Fig. 46.--Audio Frequency Transformer
(B) Fig. 46.--Wiring Diagram for Audio Frequency Transformer
Amplifying Receiving Set. (With Vacuum Tube Detector and Two Step
Amplifier Tubes)
(A) Fig. 47.--Six Step Amplifier with Loop Aerial
(B) Fig. 47.--Efficient Regenerative Receiving Set (With Three Coil
Loose Coupler Tuner)
Fig. 48.--Simple Regenerative Receiving Set (With Loose Coupler Tuner)
(A) Fig. 49.--Diagram of Three Coil Loose Coupler
(B) Fig. 49.--Three Coil Loose Coupler Tuner
Fig. 50.--Honeycomb Inductance Coil
Fig. 51.--The Use of the Potentiometer
Fig. 52.--Regenerative Audio Frequency Amplifier Receiving Set
Fig. 53.--How the Vario Coupler is Made and Works
Fig. 54.--How the Variometer is Made and Works
Fig. 55.--Short Wave Regenerative Receiving Set (One Variometer
and Three Variable Condensers)
Fig. 56.--Short Wave Regenerative Receiving Set (Two Variometer
and Two Variable Condensers)
Fig. 57.--Wiring Diagram Showing Fixed Loading Coils for Intermediate
Wave Set
Fig. 58.--Wiring Digram of Intermediate Wave Receptor with One Vario
Coupler and 12 Section Bank-wound Inductance Coil
Fig. 59.--Wiring Diagram Showing Long Wave Receptor with Vario
Couplers and 8 Bank-wound Inductance Coils
Fig. 60.--Wiring Diagram of Long Wave Autodyne, or Self-heterodyne
Receptor (Compare with Fig. 77)
Fig. 61.--Wiring Diagram of Long Wave Separate Heterodyne Receiving
Set
Fig. 62.--Cross Section of Bell Telephone Receiver
Fig. 63.--Cross Section of Wireless Headphone
Fig. 64.--The Wireless Headphone
Fig. 65.--Arkay Loud Speaker
Fig. 66.--Amplitone Loud Speaker
Fig. 67.--Amplitron Loud Speaker
Fig. 68.--Magnavox Loud Speaker
Fig. 69.--Schematic Diagram of an Atom
Fig. 70.--Action of Two-electrode Vacuum Tube
(A) and (B) Fig. 71.--How a Two-electrode Tube Acts as Relay or a
Detector
(C) Fig. 71--Only the Positive Part of Oscillations Goes through the
Tube
(A) and (B) Fig. 72.--How the Positive and Negative Voltages of the
Oscillations Act on the Electrons
(C) Fig. 72.--How the Three-electrode Tube Acts as Detector and
Amplifier
(D) Fig. 72.--How the Oscillations Control the Flow of the Battery
Current through the Tube
Fig. 73.--How the Heterodyne Receptor Works
Fig. 74.--Separate Heterodyne Oscillator
(A) Fig. 75.--Apparatus for Experimental C. W. Telegraph Transmitter.
(B) Fig. 75.--Apparatus for Experimental C. W. Telegraph Transmitter.
Fig. 76.--Experimental C. W. Telegraph Transmitter
Fig. 77--Apparatus of 100-mile C. W. Telegraph Transmitter
Fig. 78.--5- to 50-watt C. W. Telegraph Transmitter (with a Single
Oscillation Tube)
Fig. 79.--200-mile C. W. Telegraph Transmitter (with Two Tubes in
Parallel)
Fig. 80.--50-watt Oscillator Vacuum Tube
Fig. 81.--Alternating Current Power Transformer (for C. W. Telegraphy
and Wireless Telephony)
Fig. 82.--Wiring Diagram for 200- to 500-mile C. W. Telegraph
Transmitting Set. (With Alternating Current.)
Fig. 83--Wiring Diagram for 500- to 1000-mile C. W. Telegraph
Transmitter
Fig. 84.--Standard Microphone Transmitter
Fig. 85.--Wiring Diagram of Short Distance Wireless Telephone Set.
(Microphone in Aerial Wire.)
Fig. 86.--Telephone Induction Coil (used with Microphone Transmitter).
Fig. 87.--Microphone Transformer Used with Microphone Transmitter
Fig. 88.--Magnetic Modulator Used with Microphone Transmitter
(A) Fig. 89.--Wiring Diagram of 25--to 50-mile Wireless Telephone.
(Microphone Modulator Shunted Around Grid-leak Condenser)
(B) Fig. 89.--Microphone Modulator Connected in Aerial Wire
Fig. 90.--Wiring Diagram of 50- to 100-mile Wireless Telephone
Transmitting Set
Fig. 91.--Plate and Grid Circuit Reactor
Fig. 92.--Filter Reactor for Smoothing Out Rectified Currents
Fig. 93.--100- to 200-mile Wireless Telephone Transmitter
(A) and (B) Fig. 94.--Operation of Vacuum Tube Oscillators
(C) Fig. 94.--How a Direct Current Sets up Oscillations
Fig. 95.--Positive Voltage Only Sets up Oscillations
Fig. 96.--Rasco Baby Crystal Detector
Fig. 97.--How the Tuning Coil is Made
Fig. 98.--Mesco loop-ohm Head Set
Fig. 99.--Schematic Layout of the $5.00 Receiving Set
Fig. 100.--Wiring Diagram for the $5.00 Receiving Set
LIST OF ILLUSTRATIONS
A. Frederick Collins, Inventor of the Wireless Telephone, 1899.
Awarded Gold Medal for same, Alaska Yukon Pacific Exposition, 1909
Collins' Wireless Telephone Exhibited at the Madison Square Garden,
October, 1908
General Pershing "Listening-in"
The World's Largest Radio Receiving Station. Owned by the Radio
Corporation of America at Rocky Point near Port Jefferson, L. I.
First Wireless College in the World, at Tufts College, Mass
Alexander Graham Bell, Inventor of the Telephone, now an ardent
Radio Enthusiast
World's Largest Loud Speaker ever made. Installed in Lytle
Park, Cincinnati, Ohio, to permit President Harding's
Address at Point Pleasant, Ohio, during the Grant Centenary
Celebration to be heard within a radius of one square
United States Naval High Power Station, Arlington, Va. General
view of Power Room. At the left can be seen the Control
Switchboards, and overhead, the great 30 K.W. Arc Transmitter
with Accessories
The Transformer and Tuner of the World's Largest Radio Station.
Owned by the Radio Corporation of America at Rocky Point
near Port Jefferson, L. I.
Broadcasting Government Reports by Wireless from Washington.
This shows Mr. Gale at work with his set in the Post Office
Department
Wireless Receptor, the size of a Safety Match Box. A Youthful
Genius in the person of Kenneth R. Hinman, who is only
twelve years old, has made a Wireless Receiving Set that fits
neatly into a Safety Match Box. With this Instrument and
a Pair of Ordinary Receivers, he is able to catch not only
Code Messages but the regular Broadcasting Programs from
Stations Twenty and Thirty Miles Distant
Wireless Set made into a Ring, designed by Alfred G. Rinehart, of
Elizabeth, New Jersey. This little Receptor is a Practical Set;
it will receive Messages, Concerts, etc., measures 1" by 5/8" by
7/8". An ordinary Umbrella is used as an Aerial
CHAPTER I
HOW TO BEGIN WIRELESS
In writing this book it is taken for granted that you are: _first_,
one of the several hundred thousand persons in the United States who
are interested in wireless telegraphy and telephony; _second_, that
you would like to install an apparatus in your home, and _third_, that
it is all new to you.
Now if you live in a city or town large enough to support an
electrical supply store, there you will find the necessary apparatus
on sale, and someone who can tell you what you want to know about it
and how it works. If you live away from the marts and hives of
industry you can send to various makers of wireless apparatus
[Footnote: A list of makers of wireless apparatus will be found in the
_Appendix_.] for their catalogues and price-lists and these will give
you much useful information. But in either case it is the better plan
for you to know before you start in to buy an outfit exactly what
apparatus you need to produce the result you have in mind, and this
you can gain in easy steps by reading this book.
Kinds of Wireless Systems.--There are two distinct kinds of wireless
systems and these are: the _wireless telegraph_ system, and the
_wireless telephone_ system. The difference between the wireless
telegraph and the wireless telephone is that the former transmits
messages by means of a _telegraph key_, and the latter transmits
conversation and music by means of a _microphone transmitter_. In
other words, the same difference exists between them in this respect
as between the Morse telegraph and the Bell telephone.
Parts of a Wireless System.--Every complete wireless station, whether
telegraph or telephone, consists of three chief separate and distinct
parts and these are: (a) the _aerial wire system_, or _antenna_ as it
is often called, (b) the _transmitter_, or _sender_, and (c) the
_receiver_, or, more properly, the _receptor_. The aerial wire is
precisely the same for either wireless telegraphy or wireless
telephony. The transmitter of a wireless telegraph set generally uses
a _spark gap_ for setting up the electric oscillations, while usually
for wireless telephony a _vacuum tube_ is employed for this purpose.
The receptor for wireless telegraphy and telephony is the same and may
include either a _crystal detector_ or a _vacuum tube detector_, as
will be explained presently.
The Easiest Way to Start.--First of all you must obtain a government
license to operate a sending set, but you do not need a license to put
up and use a receiving set, though you are required by law to keep
secret any messages which you may overhear. Since no license is needed
for a receiving set the easiest way to break into the wireless game is
to put up an aerial and hook up a receiving set to it; you can then
listen-in and hear what is going on in the all-pervading ether around
you, and you will soon find enough to make things highly entertaining.
Nearly all the big wireless companies have great stations fitted with
powerful telephone transmitters and at given hours of the day and
night they send out songs by popular singers, dance music by jazz
orchestras, fashion talks by and for the ladies, agricultural reports,
government weather forecasts and other interesting features. Then by
simply shifting the slide on your tuning coil you can often tune-in
someone who is sending _Morse_, that is, messages in the dot and dash
code, or, perhaps a friend who has a wireless telephone transmitter
and is talking. Of course, if you want to _talk back_ you must have a
wireless transmitter, either telegraphic or telephonic, and this is a
much more expensive part of the apparatus than the receptor, both in
its initial cost and in its operation. A wireless telegraph
transmitter is less costly than a wireless telephone transmitter and
it is a very good scheme for you to learn to send and receive
telegraphic messages.
At the present time, however, there are fifteen amateur receiving
stations in the United States to every sending station, so you can see
that the majority of wireless folks care more for listening in to the
broadcasting of news and music than to sending out messages on their
own account. The easiest way to begin wireless, then, is to put up an
aerial and hook up a receiving set to it.
About Aerial Wire Systems.--To the beginner who wants to install a
wireless station the aerial wire system usually looms up as the
biggest obstacle of all, and especially is this true if his house is
without a flag pole, or other elevation from which the aerial wire can
be conveniently suspended.
If you live in the congested part of a big city where there are no
yards and, particularly, if you live in a flat building or an
apartment house, you will have to string your aerial wire on the roof,
and to do this you should get the owner's, or agent's, permission.
This is usually an easy thing to do where you only intend to receive
messages, for one or two thin wires supported at either end of the
building are all that are needed. If for any reason you cannot put
your aerial on the roof then run a wire along the building outside of
your apartment, and, finally, if this is not feasible, connect your
receiver to a wire strung up in your room, or even to an iron or a
brass bed, and you can still get the near-by stations.
An important part of the aerial wire system is the _ground_, that is,
your receiving set must not only be connected with the aerial wire,
but with a wire that leads to and makes good contact with the moist
earth of the ground. Where a house or a building is piped for gas,
water or steam, it is easy to make a ground connection, for all you
have to do is to fasten the wire to one of the pipes with a clamp.
[Footnote: Pipes are often insulated from the ground, which makes them
useless for this purpose.] Where the house is isolated then a lot of
wires or a sheet of copper or of zinc must be buried in the ground at
a sufficient depth to insure their being kept moist.
About the Receiving Apparatus.--You can either buy the parts of the
receiving apparatus separate and hook them up yourself, or you can buy
the apparatus already assembled in a set which is, in the beginning,
perhaps, the better way.
The simplest receiving set consists of (1) a _detector_, (2) a _tuning
coil_, and (3) a _telephone receiver_ and these three pieces of
apparatus are, of course, connected together and are also connected to
the aerial and ground as the diagram in Fig. 1 clearly shows. There
are two chief kinds of detectors used at the present time and these
are: (a) the _crystal detector_, and (b) the _vacuum tube detector_.
The crystal detector is the cheapest and simplest, but it is not as
sensitive as the vacuum tube detector and it requires frequent
adjustment. A crystal detector can be used with or without a battery
while the vacuum tube detector requires two small batteries.
[Illustration: Fig. 1.--Simple Receiving Set.]
A tuning coil of the simplest kind consists of a single layer of
copper wire wound on a cylinder with an adjustable, or sliding,
contact, but for sharp tuning you need a _loose coupled tuning coil_.
Where a single coil tuner is used a _fixed_ condenser should be
connected around the telephone receivers. Where a loose coupled tuner
is employed you should have a variable condenser connected across the
_closed oscillation circuit_ and a _fixed condenser_ across the
telephone receivers.
When listening-in to distant stations the energy of the received
wireless waves is often so very feeble that in order to hear
distinctly an _amplifier_ must be used. To amplify the incoming sounds
a vacuum tube made like a detector is used and sometimes as many as
half-a-dozen of these tubes are connected in the receiving circuit, or
in _cascade_, as it is called, when the sounds are _amplified_, that
is magnified, many hundreds of times.
The telephone receiver of a receiving set is equally as important as
the detector. A single receiver can be used but a pair of receivers
connected with a head-band gives far better results. Then again the
higher the resistance of the receivers the more sensitive they often
are and those wound to as high a resistance as 3,200 ohms are made for
use with the best sets. To make the incoming signals, conversation or
music, audible to a room full of people instead of to just yourself
you must use what is called a _loud speaker_. In its simplest form
this consists of a metal cone like a megaphone to which is fitted a
telephone receiver.
About Transmitting Stations--Getting Your License.--If you are going
to install a wireless sending apparatus, either telegraphic or
telephonic, you will have to secure a government license for which no
fee or charge of any kind is made. There are three classes of licenses
issued to amateurs who want to operate transmitting stations and these
are: (1) the _restricted amateur license_, (2) the _general amateur
license_, and (3) the _special amateur license_.
If you are going to set up a transmitter within five nautical miles of
any naval wireless station then you will have to get a _restricted
amateur license_ which limits the current you use to half a _kilowatt_
[Footnote: A _Kilowatt_ is 1,000 _watts_. There are 746 watts in a
horsepower.] and the wave length you send out to 200 _meters_. Should
you live outside of the five-mile range of a navy station then you can
get a general amateur license and this permits you to use a current of
1 kilowatt, but you are likewise limited to a wave length of 200
meters. But if you can show that you are doing some special kind of
wireless work and not using your sending station for the mere pleasure
you are getting out of it you may be able to get a _special amateur
license_ which gives you the right to send out wave lengths up to 375
meters.
When you are ready to apply for your license write to the _Radio
Inspector_ of whichever one of the following districts you live in:
First District..............Boston, Mass.
Second " ..............New York City
Third " ..............Baltimore, Md.
Fourth " ..............Norfolk, Va.
Fifth " ..............New Orleans, La.
Sixth " ............. San Francisco, Cal.
Seventh " ............. Seattle, Wash.
Eighth " ............. Detroit, Mich.
Ninth " ..............Chicago, Ill.
Kinds of Transmitters.--There are two general types of transmitters
used for sending out wireless messages and these are: (1) _wireless
telegraph_ transmitters, and (2) _wireless telephone_ transmitters.
Telegraph transmitters may use either: (a) a _jump-spark_, (b) an
_electric arc_, or (c) a _vacuum tube_ apparatus for sending out dot
and dash messages, while telephone transmitters may use either, (a) an
_electric arc_, or (b) a _vacuum tube_ for sending out vocal and
musical sounds. Amateurs generally use a _jump-spark_ for sending
wireless telegraph messages and the _vacuum tube_ for sending wireless
telephone messages.
The Spark Gap Wireless Telegraph Transmitter.--The simplest kind of a
wireless telegraph transmitter consists of: (1) a _source of direct or
alternating current_, (2) a _telegraph key_, (3) a _spark-coil_ or a
_transformer_, (4) a _spark gap_, (5) an _adjustable condenser_ and
(6) an _oscillation transformer_. Where _dry cells_ or a _storage
battery_ must be used to supply the current for energizing the
transmitter a spark-coil can be employed and these may be had in
various sizes from a little fellow which gives 1/4-inch spark up to a
larger one which gives a 6-inch spark. Where more energy is needed it
is better practice to use a transformer and this can be worked on an
alternating current of 110 volts, or if only a 110 volt direct current
is available then an _electrolytic interrupter_ must be used to make
and break the current. A simple transmitting set with an induction
coil is shown in Fig. 2.
[Illustration: Fig 2.--Simple Transmitting Set.]
A wireless key is made like an ordinary telegraph key except that
where large currents are to be used it is somewhat heavier and is
provided with large silver contact points. Spark gaps for amateur work
are usually of: (1) the _plain_ or _stationary type_, (2) the
_rotating type_, and (3) the _quenched gap_ type. The plain spark-gap
is more suitable for small spark-coil sets, and it is not so apt to
break down the transformer and condenser of the larger sets as the
rotary gap. The rotary gap on the other hand tends to prevent _arcing_
and so the break is quicker and there is less dragging of the spark.
The quenched gap is more efficient than either the plain or rotary gap
and moreover it is noiseless.
Condensers for spark telegraph transmitters can be ordinary Leyden
jars or glass plates coated with tin or copper foil and set into a
frame, or they can be built up of mica and sheet metal embedded in an
insulating composition. The glass plate condensers are the cheapest
and will serve your purpose well, especially if they are immersed in
oil. Tuning coils, sometimes called _transmitting inductances_ and
_oscillation transformers_, are of various types. The simplest kind is
a transmitting inductance which consists of 25 or 30 turns of copper
wire wound on an insulating tube or frame. An oscillation transformer
is a loose coupled tuning coil and it consists of a primary coil
formed of a number of turns of copper wire wound on a fixed insulating
support, and a secondary coil of about twice the number of turns of
copper wire which is likewise fixed in an insulating support, but the
coils are relatively movable. An _oscillation transformer_ (instead of
a _tuning coil_), is required by government regulations unless
_inductively coupled_.
The Vacuum Tube Telegraph Transmitter.--This consists of: (1) a
_source of direct or alternating current_, (2) a _telegraph key_, (3) a
_vacuum tube oscillator_, (4) a _tuning coil_, and (5) a _condenser_.
This kind of a transmitter sets up _sustained_ oscillations instead of
_periodic_ oscillations which are produced by a spark gap set. The
advantages of this kind of a system will be found explained in Chapter
XVI.
The Wireless Telephone Transmitter.--Because a jump-spark sets up
_periodic oscillations_, that is, the oscillations are discontinuous,
it cannot be used for wireless telephony. An electric arc or a vacuum
tube sets up _sustained_ oscillations, that is, oscillations which are
continuous. As it is far easier to keep the oscillations going with a
vacuum tube than it is with an arc the former means has all but
supplanted the latter for wireless telephone transmitters. The
apparatus required and the connections used for wireless telephone
sets will be described in later chapters.
Useful Information.--It would be wise for the reader to turn to the
Appendix, beginning with page 301 of this book, and familiarize
himself with the information there set down in tabular and graphic
form. For example, the first table gives abbreviations of electrical
terms which are in general use in all works dealing with the subject.
You will also find there brief definitions of electric and magnetic
units, which it would be well to commit to memory; or, at least, to
make so thoroughly your own that when any of these terms is mentioned,
you will know instantly what is being talked about.