The World of CB Radio

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The

World

of

CB Radio

The origi nal Big Dummy's Guide to C.B. Radio has received international acclaim as lite halldbook on CB radio . Due to popular demand , this new global edition-The \Vorld of C.B. Radi~ was expressly produced to keep up wi lh the latest de­ velopments in today's CB World. The Authors

,

1:

The

World

of

CB Radio

by

Mark Long

Bonnie Crystal

&

Jeffrey Keating

The Book Publishing Company

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Summertown, TN USA .oS

C) 1987 Mark Long Ent erprises Inc.

99989695

6543

All rights res.:rv~d. No part of this book shall be reprod uced , st or~d in a retrieva l system. or tr.msmi ttcd by any m~ans. electronic, mechanical , pho­ tocopying, recording . o(otherwise, without written permission from the pub. lisher. No patent liability is assumed with respect to the use of the information contained herein. While ~\'ery precaution has been taken in t.he preparation of this book, the publisher and authors assume no responsibility for erro~ or o missions. Neith er is any liability assu med for damages re5uJting from the use of the information contained herein. Educational and factu al information o n the worldwide Slate uf the art is presented . It is up 10 the reader to d etermine th~ suitability ofinrormation for his or her intended usc. It is not the intention of this book to encourage in any way actions which are conlrary to existing or fut ure regu lat ions. rules. laws or local ordinances . Libra ry or Congress Cataloging.in-Publication Data

Long. Mark The world of CB radio Rev. ed. of: Big dummy's guide to C.B. radio. 1st ed. 198 1 Includes index 1. Citizens band radio I. Crystal, Bonnie. II Keating. Jeffrey. III. Long. Ma rk. Big dummy's guide to CB radio. IV. Title. TK6570.C5L66 1987 621.38454 87-70878 ISBN : 0-9 13990-53-1

Portions of this book originally a ppeared as: The Big Dummy's Guide to C B Radio and The Big Dummy's Guide to Brltlsh CB Radio

Executive Editor: Mark Long Cover Artist: Peter Hoy t Printed in the United States of America by R.R. Donnelley & Sons

Table of Contents

•

Introduction

XIV

Chapter One

16

Getting on the Air or Basic Modulating Getting a Handle - Breaking the Channel- Radio Check - Frequencies:

The 27 MegaHertz Citizen's Band - AMlSSB vs FM CB Radios ­ Channels - Ten Calls - Squelching The Noise - Skiplcnd - CB In America: Paying Your Dues to the FCC - CB In The United Kingdom : Paying Your Dues to the Home Office - British 934 Megahertz CB Rigs

34

Chapter Two

Buying a New Rig Knobs and Dials - Making Something Out of the Advertising - Warran ­ ty - Mobile or Bose??? - Buying a Used Rig

48

Chapter Three

Mobiles Installing Your CB - Negotive Ground Installations - Positive Ground

Installations -Mobile Antennas - Whips - loading Coils - Bose-loaded Steel Whips - Center or Top-loaded Steel \\!hips - Fiberglass Whips­ Twin Antennas - Mobile Antennas for UHF CB Operation - Mounts­ _ Quickie Installations - Quickie Mounts - Hooking Up The Coox ­ Connecting the Coax to the Antenna - SWR -Is your Antenna Work­ ing Right? - Checking SWR - Adiusting Your Antenna

Chapter Four

66

Base Stations Installing a Bose Station - Using a Mobile Rig as a Bose - Hooking Up the Battery and Charger - Home Twenty Aerials - Gain - Effective Radiated Power - Ground, Space, and Sky Waves - Polarization - The V'" Wave Vertical Ground Plane Antenna - The 5/8 Wavelength Vertical Antenna - Beams - Vertical Beams - Stocked Beams - Switchable HorizontalNertical (Criss-Cross) Beams - Quads - Coax - Cutting the Coax - Lightning - Towers and Masts - Rotators vi

Contents

vii

Chapter Five 86 Journey to the Bottom of Your CB Rig Inside the CB Receiver - North American CB Receiver Circuitry ­ European CB Receiver Circuitry - Peeling Off the Incoming CB Signal­ Inside the CB Tronsmitter - Generating Good Vibrations - Exploring the Phose Lock Loop - Inside a North American CB Transmitter -Inside a European CB Transmitter - Departure from Radio City

Chapter Six

100

AM, SSB and FM Amplitude Modulation - Overmodulation - AM Noise Elimination ­ AM Receiving - Single Side Bond - Frequency Modulation - Deviation - The Capture Effed - Kicking Out The Noise

Chapter Seven OX Guide for CBers

108

Sunspots - The Sunspot Cycle - The Seasonal Skip Cycle - The Daily Skip Cycle - Solar Storms and Radio Blackouts - Fading - Long Path ­ North/ South Skip - Sporodic E ond Other Exo~c Skip - Burne" - The Eleven Meter Bond - QSL Cords - SSB lingo - Readability and Signal Strength Reports - Amateur Radio - International Morse Code

Chapter Eight Gizmos

128

Power Mikes and Speech Compressors - Short Wave Receivers ­ Scanners - Wolkie~Talkies - Power and Modulation Meters - Combi­ nation FM and CB Receivers - External Speakers - Antenna Switches­ Antenna Matchers - VFO - Phone Patches - Frequency Counters ­ Receiver Preamps or Booster - Bilateral Amplifiers - Radar Detectors­ PA Hom - Power Reducers or Attenuators - TV Interference Filters (How to stay at Peace with the Neighbors) - Dummy Loads - Tone Squelch - Phaser Losers, Gooney Birds, Roger Bleeps, and Pings

viii

Contents

Chapter Nine

144

Emergency Procedures Chapter Ten

146

Fixing Your Rig or What Went Wrong Troubleshooting Guide - Repairing M icrophone & Antenna Connec­ tions - Tips on Soldering - Antenna Connedions - Coax Splices ­ Soldering Coax Connectors - Microphone Connections - Using a Continuity Tester - Replacing Crystals - How to Get Rid of Noise

Chapter Eleven

166

Do-It-Yourself Antennas 1/4 Wove Ground Plane Antenna - Coax Cable Vertical Antenna ­ Using a Mobile Antenna for a Base Station - Building a Gain Vertical­ Fishing Pole Ear-A Homemade Mobile Antenna - Tuning the Fishing Pole Ear - Building a Fishing Pole Antenna Mount - The long John Antenna-Build a 10 dB Gain Beam! - Buying the Aluminum -Assembly of the Beam Antenna - Feeding the Antenna - The Gamma Match ­ The Quad-Build This 12 dB Gain Beam l - Assembly of Our Home­ brew Quad Antenna

Chapter Twelve

188

How Far Can My CB Radio Talk?

(The CB Fanatic's Guide to GeHing Out)

Appendix A:

192

CB Citizen's Band Radia Service Rules 95.401

Appendix B:

204

U.K. Home Office Radio Regulatory Department CB Performance Specifications

, Contents

Appendix C:

ix

220

TEN CODE Used by CBers

Appendix 0:

222

SSB Codes

Appendix E:

223

Channel Jive (CBers Lingo) British and American CB Channel Frequencies British 934 MegaHertz CB Band

Appendix F:

232

American & British CB Frequency Chart

Appendix G:

234

Time and Metric Conversions

Index

235

Acknowledgments We \\,..ould Like to thank the following indi viduals for their con­ tribution~ to the original Big Dummy's Guide to CB Radio : William Brady, William He rshfield . Peter Hoy t, David Long,

Paul Mandels lein, Matthew McClure, Bruce Moore, and Mark Schlicting. We would al so like to thank the foll owing individu­ als for their contributions to the original Big Dummy's Guide to British CB Radio: Disco One, James Hartman, Gordon Hender­ son, Gregory Lowry, and Arthur Saarinen . All contributed their expertise and time in one way or another. The following companies also contribu ted photos and informa­ tion on their respective radio products for this edition : learn America, Midland International Corporation, Opta-electronics Inc., Tandy Corporation, and the Vniden Corporation . Final1y, but certainly not last, the following indiv idua ls were ins trumental in producing this global edition of the World oCCB Radio. Peter Hoyt d eSigned the cover and redrew some of his original technical drawings from the earli er edi tions. Kathleen Lon g proof-read the manuscript , computerized a mountain of information and assisted in the contac t of contributors to this work. Our thanks to Peter, Kathleen and all the other Big Dummies whose help made this book possible- all form er m embers of the KHT 1296 group.

Mark Long Bonn!e Crystal Jeffrey Keating Aprl11987

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Introduction There's all kinds of folks getting in to CB radio nowadays. CB radio has really become the people's radio service. It offers free communications for anyone who wants it, and you don't have to know a lot of fancy radio theory to gel on the air. You can even get CBs factory equipped in some new automobiles. So you might have ended up with a rig and not know much about how to use it or how it works. Or maybe you're interested in getting a CB but don't know where to start. In the first few chapters we discuss buying a rig. getting it set up to work , and talking on it. Also we'll give you some simple explanations about how they work. If you're an old time CBer and have had a rig for awhile, there are sume interesting ideas a littl e la ter in the book. CB communication is not only fun- it's a lso smart. On the super highways, back home or in the office, CB is a useful tool for a lmosl everyon e. Truck drivers. motori sts. a nd the highway patrol a ll use CB radios to keep things together on the road. It gives them an extra sense that stretches them on out miles ahead on the interstates and highways. so that they can perceive changi ng road conditions. weather, accidents and other driving hazards. Truck drivers use CB as a means of staying intelligent behind the fast -paced. hammer-down lifelines of North America and Europe. Owninga CB radio wi ll also let you talk to your home from your mobile via the radio airways . It's convenient for saving time at

Introduction

xv

stops, sending instructions, and relaying important phone calls and messages, as well as fo r helpin g you stay connected to your famil y. A CB radio a lso can offer a means of staying connected 'With your business. For many people, the added commun ica­ tions means added gai n as we ll . CB communications add an extra means of being in the right p lace at the right time. In an emergency, CB radio may be the only means of getting help. There are emergency groups (HELP and REACT in the US; THAMES and HARP in the UK and Ireland) that monitor the radio and can offer help and assistance. These folks also help in times of natura l disaster. Many police ve hicl es are now equipped with CB's too, making them more readily available to motorists when needed. CB clubs around the world have been inslrumenta[in gelting CB recognized as an excellent radio service for the public. Legaliza­ tion in Europe, for example, has come about because of dedi­ cated efforts by groups such as these. They offer you the opportunity to get to know your fellow breakers off the air as well as on it. CB clubs have also joined together to offer as­ sistance to fo lks in need of help, often giving aid to the elderly and the disabled. You can check around and find out where the local CB club meets in your area. We discovered that there are a lot of good folks out there to meet !

Getting on the Air

or

Basic Modulating

A CB radio is technically called a transceiver, which is a combi­ nation of a transmitt er and receiver. Your car radio is a receiver that you can listen to-but you can't ta lk back to the DI. CB radio can be more fun than a regular radio, because you get to communicate with the folks that you hear. Throughout the book we u se CH, CB radio. rig, tra n smitter, hunk of junk, chicken box, squawk box, and the like, interchangeably with the words "Cit­ izens Band rddio," 16

Getti'lg on the Air or Basic Modlilating

17

Well, you can't actually hear the radio waves themselves. Your voice is hooked onto the radio waves by a process called modula­ tion. Modulating a lso means talking on your CB. We use modu­ late, modjitate, and ratchet jawing to mean the same thing. When you first get a rig you could give a listen for a whil e to get the feel for what's going on. If you want to jump righ t in there, though, don 't worry- the other folks on the channel will let you know how you 're doing. CB is a down-home mode of commu ni­ cation and folks will love modulating with you. If you don't understand a ll the lingo, check out our international directory of Channel Jive at the end of the book.

Breaking the Channel There are forty channels for use, and each one may have as many as hundreds of users in certain areas. With so many folks using CB, you need to make sure that the channel is not in use before bulldozing your way in. The most common way to do that is to "break the channel". Always listen to see if someone is ta lking. Then you can say, " Break one-four," (if you 're o n channel 14), and usually if the channel is free, someone will come back and say, "Go breaker," oryou might be asked to "Stand by " or"Hold on ." If you don't hear anything, you can assume that the channel is clear and make your cal l. Other things you might hear for breaking the channel are "break, break," "breakity-break,"or "breaker broke break," etc. Asking for and giving a break keeps the channels from drifting into total madness. Tum that radio on. Take aspin around the dial. Listen to someof the people talking. Keep in mind that you are entering another dimens ion, and it would be wise to learn th e ways of the people that you will be talking to. A few minutes oftuming the channel selector should inform you which channels are in local use.

If a channel is a lready in use, and you would li ke to join the conversation, wait for one of the stations to finish a transmission and then quickly press your mike and say,"stati o n on the side!" One of the breakers on the channel might let you in by saying, "station on the side, go ahead ."

TJu Wurld o(CB Radio

18

Getting a Handle Your handle is your CB alter­ nate personality code name. You might only get to know the fo lks that you meet on the CB by their hand les.

YOU GOT THE AHH ... . . . . .

YZU ~O\~~~.. / ;HE. . .

......

Q

.

"..= One way to ge t a handle is to have your friends think one up for you , or you might think up one on your O\VO. You may go through a few, but eventually one will stick.

Getting olllhe Air or Basic Modulating

19

Radio Check One of the first things you'll want to do with your rig is to get a "radio check." This is when you call out on the channel for the purpose of finding out how well your radio is performing. A typical radio check might go like this:

Break (or a radio check. Go ahead, radio cJ'N.'k.

10-4. You got the BIc Dummy. Who we JOt there?

You got lire Fox. You'recomin' in good hent-pulling tJbol,r niue pounds

my meier. And good modulatioH, C'nIOH.

011

10-4. guy. We appnciate the "'-1­ mOUTH

BOOTLEGGER..

FRom Solfnol E'RN I'll DOLE NOR"TII OA~~

;RYIN' FOR Yf>.. ,,"""All.

rz-:;~ BREAK!

Getting 01'1 the Air or Basic Modulating

29

So get a load of the following FCC rules and regulations:

Remember that Channel 9 is reserved for emergency traffic. At all times you must give priority to emergency communications. You must use an FCC Type Approved CB transmitter as your CB station. The use of a linear amplifier (kicker) on the CB bands is not legal, and having a linear amplifier present (i.e. under your seat) can be consid· ered "de facto" evidence of its use. If you are causing television interference, you are required to install a "low pass filter" on your rig. Don't use obscene or profane language on the air. You should not in any way intentionally interfere with the communica· tions of other stations . Nor can you deliberately transmit off frequency (a feat which requires tampering with your rig). The use of CB for broadcasting or the reproduction of music is prohibited. Your communication with another station should be limited to the min imum amount of time practical. In other words don 't hog the chan nel. Never transmit the word May-Day or any other international distress signal unless there's is a confirmed grave and imminent danger to life or property.

If we remember how many fellow CBers there are, and that we're all in th is together, everything will be all right! 1O-4!

30

Tll~

World of CB Radio

CB in the United Kingdom:

Paying Your Dues to the Home Office

In the United Kingdom, the Home Office-Radio Regulatory Department, is in charge of administering the ainvaves. In Great Britain, portions of the 27 MHz a nd 934 MHz bands have been allocated foJ:' the Citizen's Band Radio Service. A copy of the Home Office Radio Regulatory Department perfonnance specificat ions for CB radio is included in an appendix in the back of this book. The most important points are summarized below: / - The operation, importation and installation of unapproved CB radio equipment is illegal under the Wireless Telegraphy Act of 1949 and 1968. Violators of t his act are liable for possible jail sentences, fines and confiscation of illegal equipment! The British government issues licenses. Each owner is given a call sign after filling out an applicat ion and paying a license fee_ The Post Office Radio Interference Service (a division of the GPO), has set certain technical standards to ensure both the effectiveness of CB and the minimum amount of interference to other radio services. All stations are required by law to use only type approved radios that are manufactured for 27 or 934 MHz FM. All previously imported AM/SSB radios remain illegal for use in the UK. It is the responsibility of the owner to ensure that only type approved radios are used . All type approved equip­ ment will have a 2?!SI circle stamped or engraved on the radio's front panel. The new license makes you responsible for whatever happens on your rig . Not everyone in your family will need to get a license­ one license covers it all . If you have a business, one license can cover your employees as well. No exam is required . The Home Office wants to keep Citizen's Band a good reliable means of local communications; it is t heir position that ifpeople want to communicate over long distance and make interna­ tional contacts, they should become licensed radio amateurs by taking the amateur radio exam. DX contacts on CB are consid­ ered an illegal offense. All British 27 MHz CB antennas are limited to a single element rod or wire antenna with a length of 1.5 meters (59") or less. This

Getling un the Air or Basic Modulating

31

effectively li mi ts the range of local as well as OX communica­ tions. All ot her a ntennas used by CBers on the continent and in the US are illegal for use on British CB channels. Antenna height is also restricted to below 7 meters (23 feet) unless a power reducer or attenuator is used to li m it the transmitted signal to less than one-tenth of its unallenualed amount. This would take your 4 watt signal down to toy power levels of less than '12 watt. All type approved CB radios are required to have a switch or other m eans of easily accomplishing this. The Home Office deci ded to put its 27 MHz CB service on frequencies located above the regular American AM/SSB chan­ nels. They felt that by doing this. a more reliable service would be possible. eliminating much of the interference caused by skip and the illegal local operation of AM/SSB equipmen t. It is just about the only legal 27 MHz CB service in the world operating on those frequencies!

32

The World of CB Radio A license from the Home Office, Radio Regulatory Division, is re­ quired for any CB radio equipment capable of transmiHing. This license will need to be renewed periodically. All CBers are required by law to purchase and use only CB transmit­ ting equipment that has been type approved for use within the UK. You are expected to say your assigned identification numbers at the beginning and end of each transmission. Handles are not a bona fide substitute tozyour call numbers. Never transmit the word May-Day or any other international distress signal unless there is a confirmed grave and imminent danger to life or property. You should not in any way intentionally interfere with the communica­ tion of other stations. Keep transmissions brief and to the paint. The use of CB radio for anti-social purposes is prohibited. Do not use obscene or profane language on the air. The use of CB for broadcasting or the reproduction of music is prohibited.

British 934 MegaHertz CB Rigs The UK Home Office has also licensed CB communications by means of a second, hi gher-frequency portion of the radio spec­ trum around 934 MHz. Whil e 27 MHz is considered a High Frequency (HF) Band, 934 MHz is called an Ultra High Fn:quen­ cy (UHF) Band. On UHF frequencies , al l skip interlerence is eliminated . Radio waves on 934 MHz are too short to skip off the ionosphere (they just kind of slip through it). 934 MHz radios have twenty chan­ nels for use, and eight watts of input power is the maximum

Gettirlg on the Air or Basic Modulating

33

allowed. The higher power helps to offset some of the disadvan­ tages of UHF. Unlike HF radio waves, which can travel along the ground , around buildings and over hills, UHF communications are strictly limited to line sight. All UHF antennas must be located at high and clear elevations for good results. UHF radios are the product of a new and sophisticated com­ munications technology and their cost is several times that of the more common 27 MHz radio. The higher cost of this equip­ ment means less crowded channels and is suited to certain business applications, where more private means of communi­ cation is desired. Because the 27 MHz FM equipment is alot cheaper than the 934 MHz gear, most of Britain's new eBers are now using the lower frequency band. Consequently, it is a lot easier to get a comeback when using the breaking, road or emergency channels on 27 MHz.

Fig. 1-4 Un idn! UHF CB (COUTIU1 Unidzn)

UHF radios operate on frequencies similar to those used by microwave ovens. There is still some question as to the long tenn health effects from the user's exposure to microwave radia­ tion. The Nation al Radiological Protection Board advises against placing your hand closer than 10 centimeters to a trans­ mitting 934 MHz antenna or damage to your eyes may result. All 934 MHz walkie-talkies are limited to 3 watts or less as a precau­ tionary measure.

Chapter Two

Buying a New Rig CB radios ca n be constructed in many different ways and come with lots of "extras." These extras, most of which are used for listening, make the djfference in the price of most radios. The many combinat ions of these features makes for a lot of dif[eren t CB radios on the market. Now it doesn't matter if you are driving a Yuga ora Porsche, YOllcan still get around. And with a moderate expense you can get into the CB action. In fact, the reason that we call these features ..extras" is because they are extra and not necessary to get out welL

Bilying a New Rig

3S

Legally, you aren't supposed to improve the transmitting quali­ ty by boosting the power. So manufacturers try to improve the performance of their units in other ways, by adding extra cir­ cuits (hat let you pull in weak stations or cut down on noise and interference. While some of these features do help, they are not critical. Don't get sno,\"ed into thinking you need a crystallal­ tice filter or a range expander in order to get out, because it isn't {rue. A tra,rsmitter is the generator of your radio signal, but it's the antenna that both catapults your signal outward on transmit, and captures the signals on receive. So keep in mind that you are going to need a good antenna and coaxial cable. This is one of the most important factors in how well your radio is going to get out. The power that your radio will pul out affects its petformance and its price. The power used by your CB is expressed in two ways: as power input and power output . The power input is the amount of power used by the transmitter to produce what goes out. The power output is the amount of power which actually gets out of the radio. Power is measured in watts . Both the U.s. Federal Communications Commission and the British Home Office have limited the output power of CB radios to 4 watts, which is what most new American and British CB rigs deli ver. So that 's the best you can legally do. The amount of power you

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36

Th e World of eB Radio

put out affects your range of communication::;:. Four watts out· put power to the antenna can provide relatively good communi· cat ion in a rad ius of to to 20 miles or more. Limi ting communi cations to low power was designed to improve q uality of local CB communication bv cuttins; down in terference from the traffic of ne ighboring cummunities~lso a llows there to be m any folks on the air at once. Now m aybe you aren't too concerned about ge tting out the maximum distance possible. There are cheaper rigs with fewer watts. The m ost common kind is the walkie· tal ki e. Some walkie· talkie models p ut o ut less tha n one watt of power. The lower power of these units combines with the smaller antenna size and lower anten na height to keep them from getting out as \vell as other ri gs. A stronger rig will help talk around hills and build­ ings , and will cut through the interference better, so it never hurts to have m ore walls. It is usua lly wurth the added expensr ised b y a big display of CB radios. You try to stret ch your ima g ination and compre· hend all the a d ver t ising boasting of the quality of their inner workings, b u t it leaves you a t a loss. We ll , don 't let that bog you down . Here arc som e common feat ures you m ay run into: Dual Conversion IF. A li tt le fan cier recei ve circuit th at gives som e added clarity of reception over a sin gle con version . Filters. Cera mic , crystal lattice a nd mechanical; these a re dif· ferent ways of filt ering your receiver in order to preven t bleed · iog over of a conversation o n channels nex t to the one that you are using. Automatic modulation compresser circuit (an d limiter ). This gizmo mainta ins a hi gh level o f modula ti on over a wide ra nge of voice loud ness. It a lso preven ts over· mooulat ion . A requirem en t on all new radios. Type Accepted. Only radios ma rked FCC Type Accepted are legal to use in the United Slates. Definite ly a consideration when buyin g one. Type APln-oved. Only radios m arked Type App roved by the Home Offi ce a;e l egal to use wi thin the UK . This is indicated by an authorized stam p that is e ngraved onto t he face o f the radio. Specifications. These a l'e usua ll y talked a bout w ith a lo t of fancy figures th rown in that add to the confusion. When bu ying a new rig. you shoul d try to ge l the:: best ratings you ca n .

Fig. Z·S Rnduric TR(.'-4 7. mob/k CB rc.div (Coul'til'.n' RtJdio SIHlCk Div.of TQJldy)

42

The World orCB R adio

us T.:ype Accepted a nd UK Type Approved rigs should have a mple selectivity for m os t a p pl ications and have equally good sen­ sitivity. Selectivity is the receiver's ability to d ifferen tiate be­ tween an a djacen t cha nnel signal an d the desired one, so folks aren 't bleeding over on your cha nnel. Adjacent Channel Rejec­ tion a lso has to do w ith t hi s. Sensi tivity is the m easurement of how wel l your radio can hear. Good sensitivi ty ca n really m ake a d ifference for a base s tat ion a nd give you a longer r~ n ge of reception. For m obile stations it is less cri tical since the ignition and static no ise of the vchicle w ill someti mes drown out the weak stations that would have been picked up by a sensiti ve ra dio . Here's a typical se t of sp ecs fo r a good q~lity r ig and what t hey m ean . Once again, keep in mind that American CB radIos will not have the FM functions, and British type-approved CB rigs will not offer the AM/SSB functions.

THUNDERBOLT 3000 SPECIFICATIONS Sensitivity - 0.5uV for 10 dB S + N/N; Selectivity - 6 kHz at - 6dB; Adjacent Channel Rejection - 50 dB at ± 10 kHz ; Squelch Sensitivity • .2 uV; Audio Power Output - 2 watts at 10% THO; FM Deviation ­ ± 2.5 kHz ; RF Power Output - 4 watts ; AM Modulation - 90%; Spu· rious Output - - 50 dB max.

AM Sensitivity (Nor th Ameri ca) - 0.5 u V for 10 dB S + N /N Sensitivity gives you an idea how good it is p ulling in a weak signal. The sensiti vity. "uV" m eans microvolts-th e lower the number, the be tter. The conditions a re indicated by "dB S + N J N". It 's the "signa l plus no ise·to-no ise ratio. " The larger the number of dBs, the be tter. FM Sensitivity (Europe) - 0.3 u V for 20 d B noise q uieting A specificatio n for European CB rigs, the FM sensitiv ity rating tells you the a mount of signal at the a n tenna input necessary to be 20 dB stronger tha n th e rece ived noise level. Th is is the m inimum signal that woul d fully Quiet the backgrou nd noise and make for a readable copy. Again the sensitivity is measu red in microvolts and the lower the num ber here , the better.

Buying a New Rig

43

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BOOT _ MOUNT MOBILE ANTENNA

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This is an easy antenna to build and find the parts for. If you follow these ins truc ti ons and have it come ou t looki ng like these pictures, it shoul d have a very low SWR and appreciable gain.

EARTH WIRE

COAX f'liI'.ELECT.

TAPE

Fig. 11-4 Us inCI.l mobile unttnn« Q.S 1.1 bl.lu 3Iatio"

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You can use any number of pieces of aluminum pipe so long as they are ridged and fairl y thick-walled so as not to get bent and broken in a strong w ind. The pieces should be gradually smaller, one being able to fit inside the next. Cut two 2" grooves with a hacksaw down the outer pieces of aluminum and put a hose damp around them. Now adjust the antenna to 22 1/2 fee t (6.85 me ters) a nd tighten the hose clamps down to hold it all together. This 22 1/2-foot vertical ele­ ment can now be mounted wi th two V-bolts on to the 2" x 6" board . This board shoul d be treated or painted to protect it from the weather. Put a bolt through the piece of wood a few inches below the vertical element. Here you should fasten one end of the 6 foot (183 centemeters) piece of copper wire or tubing, the ou tside

170

The World orCB Radio

braid of the coax and each of the 104' (264 cm)[J02" (259 em)] long, stranded wires. These are called the ground radials a nd should be tied off with string (not w ire) at a 45" angle away from the bolt. The ground radials and the braid from the coax can be soldered together or can be crimped together with a crimp connector which fi ts t he bolt . The other end of the 6' copper wire is bent and faste ned to the vertical e lement as the picture illus­ trates. The end of the center wire of the coax is then twisted onto thi s in such a way that it can be slid up or down a long the copper wire a nd soldered after adjustment . The SWR of this antenna is adjusted by sliding this connection. You do this by keying your rig up on channel 20 and sliding this connection up or down until you have the lowest SWR. In our experience, an SWR of 1.1 or 1 was easily reached on channel 20 with a low SWR throughout the 27 MHz band . Be sure to cover the end of th e coax real well with a moisture­ proofing sealing compound so no moisture can get in it.

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COAX

Do-It-Yourself AIHennas

17 J

Fishing Pole Ear-A Homemade Mobile Antenna Whi le the next project won't necessarily save you any money, you might want to give it a try if you are interested in under­ standing more about how fiberg lass whip antennas do their thing. We have talked 30 m i les mobile-to-base on one of these homebrew fishing pole a ntennas using a $20 barefoot rig. Antenna Parts One 7-foot fiberglass fishing pule with hollow base One piece of steel rod 4 to 6 inches long-right diameter to slip into base of pole One I/~· x I · machine bolt (threads to match mount) 12 feet of enamel 18 gauge wire

Some good epoxy glue

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Antenna Mount Parts One 'l? x 2lh- bolt and nut (same thn.'ads as boh on base of pole) One longer-than-usual y~. nut Two plastic insulating washers Three metal !fl. diameter washers One large lerrni nallug

First you've got to get yourself a fishing pole, 6 La 9 feet long. If you already have an old one lying around , you can clip off the line loops and cut the handle off. We did some shopping and found that a finis hed fishi ng pole as long as we wanted was at least as expensive as a newly-manufac­ tured CB antenna. But then we discovered a sporting goods store that so ld unfinished fiberg lass poles 7-fcet long for $6. The kind we found was a black hollow tapered pole with about a 'Va" inside diameter at the - ~base.

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