Ham Radio FAQ : the ARRL Lab and "The doctor" answer your frequently asked questions

164 Pages·2001·47.418 MB·English

by  Alvareztorrez, Al, Ford, Steve

The ARRL Lab and
"The Doctor" answer your
Frequently
Asked
Questions
Compiled by
Al Alvareztorrez, AA 1 DO
With assistance from:
Steve Ford, WB81MY
Ed Hare, W1 RFI
Zack Lau, W1 VT
Michael Tracy, KC1 SX
Joe Carcia, NJ 1Q
Composition and layout:
Michelle Bloom, WB1 ENT
Paul Lappen
Graphics:
Cover-Sue Fagan
Drawings-Mike Daniels
Digital photography-Joe Bottiglieri
Copyright © 2001 by
The American Radio Relay League, Inc.
Copyright secured under the Pan-American
Convention
International Copyright secured
This work is publication No. 267 of the Radio
Amateur's Library, published by the ARAL.
All rights reserved. No part of this work may
be reproduced in any form except by written
permission of the publisher. All rights of
translation are reserved.
Printed in USA
Quedan reservados todos los derechos
First Edition
First Printing
ISBN: 0-87259-826-8
Contents
1 Antennas, Transmission Lines and Propagation
Getting your signal from here to there isn't all that difficult-if you've got a
decent antenna system and a rudimentary knowledge of how radio signals
travel.
2 The Station-Installation and Operation
If your station layout and operating skills are still a work in progress (and
whose aren't!), you'll find the answers here.
3 Mobile, Portable, Repeaters
Whether it's on the road or on a mountaintop, you'll enhance your enjoyment
of ham radio away from home with the answers you'll find in this chapter.
4 Batteries
When you can't be on ac, you'll be on battery power. You'll find powerful
answers to your mobile and portable power questions in this chapter.
5 Grounding and Lightning
Why do hams ground their stations? Why do some of us ignore the threat that
lightning can cause to sensitive electronic equipment-until it's too late?
6 References
All kinds of useful reference material you can put to good use right away:
Addresses, telephone numbers, Web sites, lists of tools every ham should
have- and much, much more.
Foreword
If you 're like most Amateur Radio operators, you have questions. Your questions may
be relatively straightforward, or complex. Regardless, now that you've identified a ques
tion or two (or 20), you'll need a source that will provide the information. Where should
you turn?
You could start with your Elmer, if you're fortunate enough to have one. Or you could
search for the information you need on the Web-but this might leave you sifting through
contradictory information from unknown sources. One Web site we heartily recommend
is www. arrl.org/tis/. TIS stands for the ARRL Technical Information Service, an ARRL
membership service that has been assisting hams with ham-related questions since the
early days of Amateur Radio. This Web search could well tum out to be fruitful, assuming
you have a computer handy. What if you don't, or you don't quite know what to ask?
That's where Ham Radio FAQ (for Frequently Asked Questions) comes in.
Ham Radio FAQ has been compiled to help Amateur Radio operators do what they enjoy
doing best -operate Amateur Radio - efficiently, comfortably and safely. If you've
ever had a question relating to:
+ your station- setting it up and operating it,
+ your antenna system,
+ operating mobile or portable,
+ getting the most from your batteries, or
+ installing a proper ground and efficient lightning protection,
you'll find this book will have the answers you've been looking for.
Just in case, we've included a comprehensive References chapter that provides sources
you can tap for answers to any remaining questions you may have.
Need still more help? Contact our Technical Information Service at [email protected] or by
mail c/o ARRL Headquarters, 225 Main St, Newington, CT 06111-1494.
I hope you'll let us know how you liked this book. There's a handy Feedback form at
the back, or you can send an e-mail message to [email protected].
David Sumner, KlZZ
Executive Vice President
May 2001
Prefa ce
The working title for this book started out as 101 Frequently Asked Questions about Amateur
Radio. It soon became apparent that 101 questions were not enough, so the title was changed.
This is intended as a technical book for the beginning to intermediate ham. The questions are,
for the most part, actual questions, virtually unedited, as received by the ARRL Technical
Information Service and The Doctor through the years. I've found that, except for minor
details, hams tend to ask questions on the same subjects again and again.
Hams are concerned about their antennas: how well they work, and how to fit them on their
property or inside their homes. They want to know about their grounding system and how to install
a radio or antenna on a vehicle. They want to know how to take care of their batteries and how to
best use their equipment. .. and of course, "How do I figure UTC?"
Although this is a technical book, I would be remiss if along with, "What is the best antenna?"
and "Which radio should I buy?" which, by the way, are answered inside, I were not to answer the
most frequently asked question: "Where did the name HAM come from?"
There is an urban legend that simply will not die about three fellows at the Harvard Radio
Club named Albert S. Hyman, Bob Almy and Poogie Murray. At first they called their station
"HYMAN-ALMY-MURRAY." Tapping out such a long name in code soon became tiresome
and called for a revision. They changed it to "HYALMU," using the first two letters of each
of their names. Early in 1910 some confusion resulted between signals from the amateur
wireless station "HY ALMU" and a Mexican ship named "HYALMO." They decided to use
only the first letter of each name, and the station call became HAM.
There are several variations on the theme, including one that involves the Congressional Record.
This story, however, has never been proven and the alleged Congressional Record, although
searched for, has never been found. I think a more plausible story is the simplest- like most words
in a language, "ham" just evolved and acquired new meaning over the years.
Before television, radio and the movies, almost all dramatic entertainment was via the live
performance of a theater group. Along with the logistical problems of the constantly traveling
troupes of actors there was the inevitable need to press into service local talent- amateurs.
Some of these inexperienced actors had a tendency to "over act" and I'm sure that in many cases
their antics were very annoying to the seasoned veteran actors. These "actors" were called
hams-to this day, improvising to the extent of being almost absurd is called "hamming it up."
Enter radio at the turn of the Twentieth Century. In the early days of Spark, everyone was
operating on virtually the same frequency-or more accurately everyone was operating on all
frequencies! On more than one occasion when a ship-to-shore operator was trying to pass
traffic, his receiver would be swamped by a local Amateur Radio operator's powerful signal
(there were no regulations on power level in those days). The professional operator, borrowing
a term with which he would have been very familiar at the time, would complain to his ship
mate, "THOSE @#&! HAMS ARE BLOCKING YOUR SIGNAL!" Amateurs, in a typical
Yankee response, took the name as a badge of honor.
But now let's get to the good stuff. What is the best antenna? What radio should I buy? . ..
Al Alvareztorres, AAlDO
Technical Information Services Coordinator
About the ARRL
The seed for Amateur Radio was planted in the 1890s, when Guglielmo Marconi began his experiments in
wireless telegraphy. Soon.he was joined by dozens, then hundreds, of others who were enthusiastic about
sending and receiving messages through the air-some with a commercial interest, but others solely out of a
love for this new communications medium. The United States government began licensing Amateur Radio
operators in 1912.
By 1914, there were thousands of Amateur Radio operators-hams- in the United States. Hiram Percy
Maxim, a leading Hartford, Connecticut, inventor and industrialist saw the need for an organization to band
together this fledgling group of radio experimenters. In May 1914 he founded the American Radio Relay
League (ARRL) to meet that need.
Today ARRL, with approximately I 70,000 members, is the largest organization of radio amateurs in the
United States. The ARRL is a not-for-profit organization that:
• promotes interest in Amateur Radio communications and experimentation
• represents US radio amateurs in legislative matters, and
• maintains fraternal ism and a high standard of conduct among Amateur Radio operators.
At ARRL headquarters in the Hartford suburb of Newington, the staff helps serve the needs of members.
ARRL is also International Secretariat for the International Amateur Radio Union, which is made up of similar
societies in 150 countries around the world.
ARRL pub Ii s hes the monthly journal QST, as well as newsletters and many publications covering al I aspects
of Amateur Radio. Its headquarters station, WI AW, transmits bulletins of interest to radio amateurs and Morse
code practice sessions. The ARRL also coordinates an extensive field organization, which includes volunteers
who provide technical information for radio amateurs and public-service activities. In addition, ARRL rep
resents US amateurs with the Federal Communications Commission and other government agencies in the US
and abroad.
Membership in ARRL means much more than receiving QSTeach month. In addition to the services already
described, ARRL offers membership services on a personal level, such as the ARRL Volunteer Examiner
Coordinator Program and a QSL bureau.
Full ARRL membership (available only to licensed radio amateurs) gives you a voice in how the affairs of
the organization are governed. ARRL policy is set by a Board of Directors (one from each of 15 Divisions).
Each year, one-third of the ARRL Board of Directors stands for election by the full members they represent.
The day-to-day operation of ARRL HQ is managed by an Executive Vice President and his staff.
No matter what aspect of Amateur Radio attracts you, ARRL membership is relevant and important. There
would be no Amateur Radio as we know it today were it not for the ARRL. We would be happy to welcome
you as a member! (An Amateur Radio license is not required for Associate Membership.) For more information
about ARRL and answers to any questions you may have about Amateur Radio, write or call:
ARRL-The national association for Amateur Radio
225 Main Street
Newington CT 06111-1494
Voice: 860-594-0200
Fax: [phone]
E-mail: [email protected]
Tnternet: www .arrl.org/
Prospective new amateurs call (toll-free):
800-32-NEW HAM (800-326-3942)
You can also contact us via e-mail at [email protected] or check out ARRLWeb at http://www.arrl.org/
1
Antennas, Transmission
Lines and Propagation
Most amateurs are searching for that "death-ray" an
tenna that will make their signal heard around the world.
While this chapter doesn't tell you exactly what that an
tenna must be, it should help you choose from among the
many antenna types available to hams today.
Let's start off with a question relating to safety.
Q Could someone be injured by touching the ground
side of a coaxial-fed dipole antenna when I am
transmitting at 100 W?
A Most definitely! There really is no such thing as a
"ground" side to a dipole. Although one side of your
dipole is connected to the shield that goes to ground at the
shack end, this is a "ground" fordc only. There is plenty of RF
voltage present on that side of the dipole-enough to get your
attention with a painful burn. Always be safe in everything This list is just a start. The rest of this chapter answers the
you do. Make sure your antennas are installed so that nobody question of what antenna is best for different applications
can come in contact with them inadve1tently. and needs. Much like choosing a husband or wife, you will
have to weigh the pros and cons-and live with the result.
ANTENNAS
Unlike choosing a mate, though, you probably don't expect
QI want to put up an antenna. What is the best
that you are choosing your last antenna. You are choosing
antenna I can make or buy?
your next antenna. Building and experimenting with anten
AA!though this is possibly the number one question nas is a life-long endeavor for most hams.
received by the ARRL Technical Information Service, The ultimate answer to your question is that the best HF
it is probably the hardest to answer. Choosing an antenna is antenna is probably separate monoband Yagi antennas
much like choosing whom to marry. They all have their mounted high and in the clear. For VHF and UHF use either
good points; they all have their bad points and the best stacked Yagis or a large parabolic dish. But few hams can
choice is often dictated by external factors. The major fac do that, so most hams select a compromise antenna based
tors that you may need to consider are: on the above criteria.
• What frequency band or bands you intend to operate?
QI am not sure what kind of operating I want to do.
• How much room do you have available?
What is a good first antenna for me to try on HF?
• Can you put up a tower?
• Do you have tall trees? AThe rest of this book will talk about many of the dif
• How much money do you want to spend? ferent antennas you can try over your decades of ham
• Will you have any zoning problems to deal with? ming, but first antennas should be easy to build and use.
• Will there be any neighborhood (or family) aesthetics The easiest first antenna is a half-wave dipole, mounted up
to deal with? as high as you can reasonably get it. Generally, if the dipole
• What are .the local weather conditions (high wind, ic is up at least 30 feet, it will work out pretty well. If you
ing, etc)? can't put it up high and straight, it is okay to put it in the
• Do you want an antenna that works in all directions, or form of a V, an inverted V, an L or even bend the ends
an antenna that has gain in one or more directions? around a bit. All you need are three insulators (one is used
Antennas, Transmission Lines and Propagation 1-1
as your center connector) and some wire. Strong, multi So, what type of coaxial cable should you use? At up to
stranded copper wire will withstand the elements best, but a few hundred watts, if the distance from your transceiver
nearly any wire, from speaker wire to ac-line cords, can be to your dipole is less than 50 feet or so, RG-58 is fine. For
used with great success! longer runs or higher power, you should use a low-loss
The only trick to making a dipole is cutting it to the right cable such as RG-8, RG-213 or Belden 8214. If you own an
length. A conventional dipole antenna is made of two equal antenna tuner, you can try feeding your dipole with 450-Q
lengths of wire with the total length adding up to a half ladder line. This type of open-wire feed line exhibits very
wavelength at the desired frequency. The length of a half low loss at HF. The only disadvantage of using ladder line
wave dipole is a bit less than a half-wave in free space. End is that you must keep it away from metal objects.
effects, conductor diameter and wire insulation tend to Choose your antenna supports: trees, flagpoles, chim
lower the resonant frequency a bit. Eq 1 can be used as a neys or whatever stirs your imagination. You can even in
real close starting point, although you may need to do a bit stall your dipole in an attic. If you decide to mount it out
of trimming. Adding a little bit to the end of each wire will doors, invest in enough high-strength rope or cord to do the
give you a bit of trimming room-it is easier to trim wire job. You want to be sure your antenna will survive storms,
off than to add it back. ice loading and so on. Mount your dipole as high off the
ground as possible. How high is "high"? Conventional wis
Length (feet) = 468 I f (MHz) Eq 1 dom states that your dipole should be mounted at least a
quarter wavelength above the earth at the frequency you
where f (MHz) is the frequency in MHz.
choose to operate. Getting an 80-meter dipole 60 feet off
the ground could present a challenge! If you can't raise
Here are the required di pole lengths for each of the Nov
your dipole to this altitude, don't worry about it! Your per
ice/Technician HF subbands:
formance may suffer a bit, but the antenna will work. Watch
80 meters: 126' 6"
out for nearby gutters, pipes, aluminum siding, window
40 meters: 65' 7"
screens and other large pieces of metal. They' II detune your
15 meters: 22' l"
dipole and increase the SWR if they're too close. And, of
10 meters: 16' 6"
course, never place your antenna near power lines!
For example, if you're making a dipole for the 10-meter
If you've cut your dipole to the proper length, your SWR
band, you'll need two lengths of wire 8' 3" long (8' 3" x 2
should be reasonably low (less than 2: 1). Don't worry if the
=
16' 6") plus enough extra so the wire can be looped
SWR seems to rise as you move in frequency toward the
through the insulator and secured tightly. Attach the wires
band edges-this is normal.
to the insulators and center connector as shown in Fig 1-1.
Attach your coax feed line at the center connector. Solder QThat sounds easy enough. Now, what can I use for
the shield braid of the coax to one side of your dipole. my first 2-meter antenna?
Solder the center conductor of the coax to the other side. Be AThe simplest antenna to make is a 2-meter ground
careful not to melt the coax while you' re soldering it to the plane. Most VHF FM operation is vertically polar
antenna. You can also purchase center connectors that fea ized, so you want to use a vertically polarized antenna. The
ture built-in S0-239 jacks. With a matching PL-259 plug
rubber ducky antennas common on handheld VHF and UHF
on your feed line, you can easily disconnect your feed line
transceivers work fine in many situations. That's no sur
from your antenna whenever necessary for portable opera
prise, considering that repeaters generally reside high and
tion, for example. Whatever way you connect the coax to
in the clear so you and your handheld don't have to meet
the antenna, be sure to waterproof the connection if it will
that requirement.
be outdoors. If water gets inside the cable its loss will in
Sometimes, though, you need a more efficient antenna
crease in a hurry!
that's just as portable as a handheld. Here's one: A simple
groundplane antenna you can build for 146, 223 or 440
MHz in no time flat. It features wire end loops for safety
(sharp, straight wires are hazardous) and convenience (its
top loop lets you hang it from high objects for better perfor
mance).
What You Need to Build One
All you'll need are wire (single conductor, #12 THHN),
solder and a female coax jack (S0-239) for the connector
Insulator 50 or 72-0 series of your choice. Many hardware stores sell THHN
Coax wire, which is thermal-insulation, solid-copper house wire,
and they sell it by the foot. You' II need 7 feet of wire for a
Pole
to Station 146-MHz antenna, 5 feet of wire for a 223-MHz antenna,
or 3 feet of wire for a 440-MHz antenna.
Fig 1-1-Dipole antennas for the HF bands are easy to
The only tools you need are a 100-W soldering iron or
make. .. and they perform well, tool
1-2 Ham Radio FAQ