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Jlaj£ Director of Thesis -.5 Radio for high school students Item Type text; Thesis-Reproduction (electronic) Authors Ashe, John Lawrence, 1910- Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 04/10/2021 02:43:21 Link to Item http://hdl.handle.net/10150/553513 RADIO FOR HIGH SCHOOL STUDENTS by John L. Ash® ******* A Thosis submitted to ths faeulty of the Department of Education In partial fulfillment of the requirements' for the degree of Master of Arts in the Graduate College University of Arizona 1 9 4 0 Approved: JLAj£ Director of Thesis -.5 J t. r p .a B.A > ^ 9 7 9 / /99<3 6 * 2L. TABLE OF CONTENTS Chapter Page I. INTRODUCTION.................................. 1 General Importance of Radio..... oa c\j r-i Problem of this Study........... Limitations of the Study......... c m Plan of Procedure............... ^if II. THE PAST,PRESENT AND FUTURE OF RADIO Purpose of this Chapter Brief History of Radio. Opportunities in Radio................... • 10 Broadcasting.............................. 10 Communication...................... 11 Factories.................. 13 Servicing........ 14 Distribution................. 14 Electronics.............. 15 Television................................ 15 Facsimile........ 15 Therapy.... .............................. 15 As a Hobby................................ 16 Probable Future of Radio........... 10 III. TOOLS.......................................... 31 Selection and Use of Tools................. 21 General................................... 21 Soldering Iron............................ 22 Pliers.................................... 24 Screwdrivers.............................. 25 Hand Drill and Bits...................... 25 Miscellaneous Tools...................... 26 Summary................................... 27 IV. CONSTRUCTION OF A RADIO RECEIVING SET......... 28 General Discussion......................... 28 Schematic Circuit Diagrams.................. 29 i 1 3 2 U i. 1 Chapter Pag© Construetion of a Crystal Set.............. 31 // Circuit Diagram................ ........ 32 Antenna Construction.... U . i Coil Construction....... //./ir-vv The Variable Condenser.. The Crystal.......... The Fixed Condenser.... The Phones..... ........ Other Parts............. --- Arrangement of the Parts V. HOW A BROADCAST STATION WORKS Wave Propagation...... ................... .. f Water Waves............................... } ' Mechanical Waves......... ................ Picturing Alternating Current............. Relation of Radio Waves to Other Waves.... The Broadcast station....................... Modulation................................ Parts of the Station................... VI. HOW THE RECEIVING SET WORKS ? Crystal set................. Antenna Circuit........... How the Coils Work..... The Tuned Circuit......... Transformer Action........ How the Crystal Works...... How the Bar Phones Work.... Summary........... ........ Vacuum Tube Receiver........ Comparison with Crystal sot VII. ELECTRON THEORY AND ELECTRICITY Need for Theory.......... ....... Electron Theory............. .. Molecules.............. Atoms...................... Protons and Electrons.......... Electricity in Terms of Electrons Electric Current........... Conductors and Insulators..... Current vs. Electron Flow..... ii Chapter Page T i l l . ELBCTROiacafBTISM.......... ............................ 62 Permanent Magnets................ 68 Lines of Force. Electromagnetic Fields......... Field surrounding a Wire........ Field Surrounding a Coil...... Inductance............... Inductive Couplings............. Effect of Coils on D. C. and A. C Impedance.... ............. Summary................ ......... IX. CONSTRUCTING A VACUUM TUBS RECEIVER......... Selecting the Type of set to be Constructed. Purpose for Which the Set is Designed.... Cost..................... ............ Frequency.................... .......... Volume of Output.......................... Construction....... ....................... The Chassis......... .................... The Circuit............ .........-........ How to Operate....................... X. ELECTRICAL UNITS, LAWS, Definition of Terms. Amperes........ .. Ohm#.......... Volts........ Laws....... ........ OhmTs Law....... Heat Loss........ ........................ Length of Wire as Related to Resistance... Diameter of Wire as Related to Resistance. Magnetic Attraction and Repulsion...... .. XI. TWO ELEMENT VACUUM TUBES Importance of Vacuum Tubes......... How a Two Element Vacuum Tube Works Filament Emission... Action of the Plate. Detector Action.... Half-Wave Rectifiers 883822 2 3 SSSSSiSgSS 8 83SS82888 Full-Wave Rectifiers..................... 91 Advantages of Each Type.................. 92 ill Chapter Page XII. THREE ELEMENT VACUUM TUBES.................... 93 Importance of the Discovery.............. 93 How the Triode Worka... .................. 95 Amplification*.*........... ............* * 95 Amplification Factor**........ 95 Characteristics Curves and Amplification.. 96 The Triode as a Detector........... 97 XIII. HOW THE ONE-TUBE RECEIVER WORKS.............. 99 Circuits..................... ........ 99 Relationship of Tubes to Circuits... 99 Operation of the First.One-Tube Set... 99 How the Tube is Used. .............. 99 Purpose of the Various Parts of the Circuit......................... 100 The Grid Leak..................... 100 The R. F. Choke....... ............ 102 Batteries...................... 103 _____ Summary................. .......... 103 Operation of the Second One-Tube Set. 104 Regeneration....................... 104 XIV. CONDENSERS................................ 106 Theory of Condensers....................... 106 Definition of Terms....................... 106 Capacity or Capacitance..... 106 Voltage and Battery..... .................. 108 The Effect of the Size of the Plates..... 106 Effect of spacing on Capacity..............108 Dlelectric Constants............... 109 Alternating Current and Condensers.........110 Blocking and Coupling Condensers...........Ill Voltage Rating............... 112 Breakdown Voltage........................ 112 Working Voltage........... 113 XV. THE NAMING, CONSTRUCTION, AMD USES OF CONDENSERS............. 114 Classification............... 114 As Fixed and Variable..... 114 By Nature of the Insulation 115 By Construction........... 116 By Use.................... 116 It * Chapter Page Construction of Condensers.............. 117 Air-Dieleetrlo Condensers.... ............. 117 Paper Condensers.......... ............. 117 Fixed Mica Condeneera. ................... 118 Electrolytic Condensers.. ............. 118 Dry Electrolytic Condensers......... 119 Uses of Condensers.......... 120 Importance of Condensers............... 121 XVI. POWER SUPPLIES................... ......... 122 Purpose................. ............... .... 122 Theory...... ......................... 122 Schematic Diagram....................... 122 Four Parts of a Power Supply...............183 The Filter........................... 124 The Bleeder-Voltage Divider............ 186 Construction.... .......... 128 Selection of Chassis....................... 188 Laying Out and Construction of Chassis.... 128 Mounting the Parts.......... .......... .. 129 Wiring........ 129 ADDING AUDIO AMPLIFIERS TO THE ONE-TUBE SET--- 131 Types of Coupling.............. ............. 131 Transformer Coupling..................... 131 Theory of Transformer Coupling............ 133 Choke or Impedance Coupling..... ......... 134 Resistance Coupling........ .............. 13# XVIII. VACUUM TUBES 137 Triodes.... ......... 137 Filament Structure..... 137 Cathodes........ .... .. 138 . Multi-Grid Tubes..... ... 139 Tetrodes...... ......... 139 Pentodes............... 141 Beam Power Tubes...... 141 Multi-Purpose Tubes....... 142 Gas Filled Tubes......... 143 Mercury Vapor Rectifiers 143 XIX. RADIO FREQUENCY AMPLIFIERS 145 Reason for Radio Frequency Amplifiers in Receivers....... ....................... 145 v Chapter Page Sensitivity....................... 145 L Selectivity...............................146 <* Types of Radio Frequency Amplifiers......... 147 Untuned Radio Frequency Amplifiers........ 147 Tuned Radio Frequency Amplifiers....... 147 Begenerative Pre-Selection....... 148 XX. OSCILLATION; RESONANCE... ............. 149 Oscillating Circuits.... ................... 149 Definition................................ 149 Coil and Condenser...................... .. 149 The Vacuum Tube in an Oscillating Circuit. 150 Audio Oscillators.......................... 151 Test Oscillators........ 152 --- £j3eat Note Oscillators........................ 153 Use of Oscillators in Transmitters........ 154 Resonance............. 156 Tuned Circuits....... 156 XXI. SUPERHETERODYNE RECEIVERS... ... ...... ..... 157 Theory of the Superheterodyne................157 Block Diagram........................ 157 Preselector........... 157 The Frequency Converter..... 158 The Intermediate Amplifier.............. 169 The Second Detector.... .................. 159 The Audio Amplifier.... .................. 16# Necessity for the Preselector........ ISO Advantages of the Superheterodyne........... 161 • Sensitivity................................ 161 Selectivity................................ 161 -All-Wave Receivers..... .................. 162 XXII. SELECTING
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