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What do I buy?
Spending too little
Spending too much
Installation
Antenna Tuning
In the simplest and cheapest of installations, you're
going to have to go out and buy 2 things: a CB radio, and an antenna.
If all you ever plan to do is talk more or less line-of-sight, from your
car to the friend's car that you're traveling with, that's pretty much all
you need to know. Other than wondering where you'll mount the radio
and antenna, and possibly worrying about "tuning" your antenna, that is.
BUT keep reading, 'cause I might change your mind about buying the absolute
cheapest, no-name stuff you can find, or reinforce your reasons to do just
that.
Assuming you buy a decent CB radio, the most significant
issues for you are what antenna to buy, and where to put it. Also important
is tuning the antenna if you want good performance out of the setup.
Some antennas aren't designed to be tuned, and are assumed to already be
tuned when you buy them. Sometimes, when you buy a radio, the store
will be willing to tune it for free, or may charge a small fee to do it.
You may know a friend who can do it. Or, since it's not really a big
deal to tune an antenna to a reasonable level, you may want to tune it yourself
by buying an SWR meter. See Antenna Tuning
below. If you're not really concerned about total performance, you
might feel like skipping the antenna tuning step. Keep reading before
you do.
First of all, you may feel that you don't need good equipment
because you'll only use it in the situation mentioned above. Okay -
what happens when you, driving behind your buddy, need to stop for a red
light that he (or she) managed to squeak through. There's a good chance
that, if you have a really bad setup, your buddy will be out of range
before you can brake, get your hand off the shifter, and get your hand on
the mike to tell them "Wait for me!" In the worst radio setup I've
used, the reliable transmission distance was measured in car
lengths, not miles. If a car passed one of us, and ended up
between us, the bulk of the car presented problems for transmitting.
If you stick to the name-brand companies like Uniden,
Cobra, Midland, GE, and heck, even Radio Shack and Maxon, for both your radio
and antenna, you'll pretty much avoid this rather drastic example.
No matter what others say about the quality of a given company's radio, they
do have to make stuff that at least works, otherwise they'd
be out of business. The danger area is if you choose to buy a walkie
talkie instead of a real radio, or even one of those "emergency" radios that
you keep in a plastic case under your seat until you need it. If you're
considering one of those, (and, yes, there are valid reasons to buy them)
you better read the section I wrote about the special considerations for
them.
Okay - so you're still not interested in spending any
more than you absolutely have to for your setup, and you want to get the
littlest, least visible antenna because you don't want it to affect the styling
of your truck? That's fine. There's nothing wrong with this
philosophy. For some, that's all they want. Just be aware of
the limitations. Don't expect to see a friend drive by in the opposite
lane on the interstate, and then try to page them for a conversation of any
length.
Also, be aware that the cheaper the setup, the more likely
you're going to run into problems with interference (RFI,EMI, ignition noise,
whatever you want to call it.)
At this level of spending, I would advise you to worry
more about your antenna than your radio. The best radio in the world
wont make up for a rotten antenna.
The other extreme to spending too little is spending too
much. This is what a lot of people do. Like getting talked into
buying a $2000 kevlar kayak when a $300 canoe would suit someone just
fine. Not everyone needs DSP noise elimination, or the ability to transmit
single sideband, or other fancy options. Some people, whether they
want to believe it or not, only really use their CB's for a total of a couple
hours a month, and never really get to use all the fancy features to their
full potential. Just like some people buy a $300 stereo, and others
spend $3000, you may be quite happy spending no more than $50-$70 total on
your CB and antenna.
You might be considering certain specialty features, like
one that has the weather bands built in, or is weather resistant, or a remote
mount CB that puts all the controls on the mike, and hides the radio itself
under the dash. These kind of options are going to drive up the price
of the radio, but if you want one of these, go ahead, knock yourself out,
'cause these options aren't dependent on someone saying "oh, this is worth
it! You'll get MUCH better reception if you buy this one that's $80
more."
In the world of under $100 spending, I can't see going
into long arguements on how X brand radio has better selectivity and
sensitivity than Y brand, or is better at eliminating noise. If you
really think you need some of the fancy features, or think you might be concerned
about the relative performance of one radio over another, go read the more
in depth areas of this site, and find out if it's really neccessary.
So, you've bought a Kmart blue light special, and now you want to know how
to go about installing it. Well, I can't really help you when it comes to
where to put the radio. Basically, wherever it's convenient to reach
the controls, and not in the way of your legs, or head. I mention your
head, because many people like to mount the CB on the roof, somewhere around
the rear view mirror or sun visors. Think twice before doing this.
Admittedly, this is a convenient spot, but a friend of mine who's a volunteer
firefighter pointed out the extreme danger of mounting a large, heavy object
with sharp edges in the general path that of your skull will take during
a collision. If you're short, and drive a full-size pickup, this is
obviously not as much of a consideration as if, like me, you're 6'2" and
driving a (relatively) compact Jeep Cherokee XJ. In this case, I'd
be mounting the beast right in my face. Not very smart.
Check to see how the channel display on your radio looks
in direct sunlight. Some aren't very readable, and you may want to
find a spot that is relatively shaded to make it more readable. The
biggest suggestion I could make is try something temporarily, by securing
the radio with duct tape in a place you might like for a few days before
cutting up your dash.
Wiring the power to the radio is pretty straightforward,
especially if you've ever added anything electrical to your vehicle
before. Most radios have a ground wire (duh..) and two power leads.
One hooks to an unswitched battery circuit, and the other to your accessory
circuit. The first provides power at all times for electronic tuning
to remember your channel selection when you pull out the keys, and the other
powers the radio when you turn the ignition on. Some only have one
wire - especially the older non electronically tuned radios. These
get hooked up to just the accessory circuit. A convenient way to hook
up a radio is to buy the little spade fuse adapters sold at Radio Shack,
the kind that slip over one blade of a fuse, and then get inserted into the
fuse block. They work great. Just make sure you put the adapter
on the downstream side of the fuse. Alternately, just buy an
adapter and plug it into the cigarette lighter. That's the best
solution if you plan on using the radio in more than one car.
Now we're up to the coax cable and the antenna.
This is where things get interesting, and where lots of arguments start.
I'll save all the technical talk for the Radio 101 theory pages for those
who wish to know all the geeky stuff. If you really don't care about
getting the best performance out of what you just bought, skip this stuff,
and mount the antenna wherever you darn well please, with as much coax run
around the truck as you can. You'll still be able to talk car to car,
but not much else. Otherwise, keep reading.
First, try to keep the amount of coax cable between your
radio and the antenna as short as possible. There is a certain amount
of loss in any cable, and the longer the run, the more of your signal is
lost before it even reaches the antenna. If you don't feel comfortable
cutting the wire that came on your antenna, don't bother. It may void
any warranty. But on the other hand, don't go crazy adding extension
patches to your antenna so you can mount it 30 feet away from your radio.
Keep the path as short as possible. I'll be writing more on this.
Where does the antenna go? Ideally, on the highest point
of your vehicle, and even more ideally, permanently (this means drilling
holes) mounted in the middle of a large horizontal piece of sheet metal -
your roof. Any other installation is a compromise from this ideal,
but sometimes awkward, location. The roof acts as a ground plane, a
sort of sounding board, that focuses the energy coming off the antenna in
a direction where it does the most good - straight out sideways. Most
antennas are designed to depend on a ground plane for good operation.
So why do truckers - folks who are supposed to be so concerned
with good CB installations - mount their antennas on their mirrors rather
than the roof of the truck? Simple - height restrictions. They'd
benefit just like anyone else from a roof mount, but then they'd hit every
bridge, traffic light, and power line on the road. They usually
mount two antennas, one on each mirror, because from any given angle other
than straight ahead or behind the truck, one of the antennas is blocked by
the bulk of their truck.
If you're concerned about whacking the antenna on low
branches, drivethru overhangs, or parking garages, that's a very valid concern
on tall vehicles. The most expensive, highest mounted antenna in the
world is useless if it's broken. There's other options. Some
antennas, such as the American Antenna K40 that I bought, have a bayonet
quick disconnect that will let you yank the antenna off the roof and stow
it for safekeeping. The only problem with this is remembering
to take it off before it's too late - a big issue if you drive a tall vehicle
and drive into parking garages often. Also you lose the ability to
transmit (Well, you can, but it wont be pretty...) I'm contemplating
making a spring loaded base for my antenna to keep it from breaking if I
forget to take it off, or just don't feel like it.
Okay - you say you don't want that big ugly antenna in
the middle of the roof. Other choices, in my order of preference, would
be the gutter or light bar, the trunk or hood, the rear of the bed
rail of a pickup, the mirrors, or a bracket halfway up the side of the body
(similar to the way Army vehicles mount them on the side) Just remember,
altitude is everything. As an extreme example, CBers have reported
that my signal as being "5 by 9" from 50 miles away when I transmitted with
a 1 1/2 watt walkie talkie from the top of a mountain. Altitude is
everything, and having a good ground plane is a close second.
About the worst place you can mount an antenna is on your
back bumper. The only worse place is under your vehicle.
Just like with the truckers mentioned above, nearly half of the circle around
the antenna is blocked by a large chunk of sheet metal called a tailgate.
On cars, pickups, and jeep CJ/YJ/TJ's this is slightly less of a problem
than sport utilities and minivans, since the rear of the vehicle isn't as
tall. It's still not a good use of an antenna. If you really
want to mount one on the bumper, mount one up front, too. That way,
you'll have two antennas, just like the big dogs.
So, once again, I say antenna placement is vital - put it in the middle
of the rooftop if you possibly can! (Just don't do what I did, and end
up nearly drilling the hole to permanently mount it right through my dome
light and wiring - check for that before drilling...)
Great - you're still with me. This area might be
a bit confusing, but it's still something you should know about.
Whenever you talk about CB radio for any length of time,
the term "SWR" will come up. SWR refers to Standing Wave
Ratio. It's the ratio of standing waves (duh).
The two standing waves in the equation are your transmitted wave (or foward,
or output, or whatever you want to call it) and your reflected wave.
Just like you have to tune a hi-fi speaker cabinet for best sound, you have
to tune an antenna - find its sweet spot, in other words. Just for
reference, if an SWR reading is 1 to 1, that's perfect, and also practically
impossible to achieve. You're going to get SOME reflection no matter
how good your equipment is. Maybe your meter just can't measure that
low. A signal of 1.1 to 1 is great. If your reading climbs
to 1.5, that's okay if you're not too concerned with the best signal.
Above that, and you're doing lousy. Things that can affect the SWR
of the antenna are mounting position of the antenna, parking the vehicle
right next to a building or other vehicle, open doors on the truck, etc.
Some affect it more than others. Try to eliminate the obvious stuff
before playing with the antenna.
Without getting too deep into antenna theory (read the
other areas if you want that), I'll describe whats goin on. The frequency
that a radio (any radio, not just CB) transmits and receives on can also
be referred to as a wavelength (the length of the radio wave). An antenna
has to be adjusted in its length to closely match the wavelength of the
transmitted signal. If an antenna is perfectly tuned, all the RF energy
being transmitted by the radio will be effectively radiated by the
antenna. If the antenna is out of tune, some of the energy is actually
reflected back to the radio, and is not transmitted. Too much
energy reflected back to the radio not only seriously hurts the effective
power output of your setup, but it can actually damage the radio over time.
The way you tune an antenna is to use a meter that measures
the SWR, and adjust the antenna until you get the lowest possible SWR reading
you can. Technically, you are only worried about eliminating or minimizing
the reflected power. The ratio of output to reflected power is kind
of a moot point. Maybe you're using a meter that can measure reflected
power separately. This is fine. Wherever I mention looking for
a smaller SWR reading, substitute smaller reflected reading, and press on.
I mentioned earlier that maybe the store where you bought
the radio will tune it for you, or maybe they'll loan you the meter so you
can tune it yourself. If you are going to set up and forget about your
radio, this is great. If you see a point in your future where you're
going to play with your CB setup, it's a good idea to get at least a cheap
SWR meter, or make friends with someone who owns one. Contrary to popular
belief, you don't have to spend $80 on a meter if you only spent $50 on the
radio and antenna. I picked up my first one for about $15 new, and
years later measured its accuracy against a $1100 meter (Bird digital model
4391M), and the readings were close enough for the average CBer. If
you want to spend lots on your meter, wait until you have a CB that's worthy
of the better meter. If you buy your own, you could maybe leave it
permanently installed, and then you get another useless gauge in your truck
to look at.
Okay - how do you tune your antenna with the meter?
First, hook it up to the back of the radio, then hook your antenna up to
the meter. Then, read the instructions that came with the meter on
how to calibrate the meter, and how to set it to read SWR. You got
instructions with the meter, didn't you? :-)
Tune your radio to a middle channel, like 19 or 20. Press transmit, and look at the meter. With any luck, your reading is 1.2 or less, and you can call it a day (remember, this is the section of the website that isn't dealing with getting really uptight over the smallest details...). If it's more, or you are obsessed with perfection, keep going. It is entirely possible that with the equipment you have, and the place you mounted your antenna, that you will not be able to get your SWR reading below 1.5 to 1. If so, you'll have to re-examine what exactly you've done, and how you set up your equipment, and probably read more than just this quick-start guide to get the most you can out of your setup.
What you do now is tune the radio to the last channel
(40, unless you have an ancient radio), and press transmit. Make a
note of the reading. Then tune to channel 1, and do the same.
If the SWR measured on channel 40 is greater than the
SWR on channel 1, that means that your antenna is too long.
Why, you ask? Because, I answer, the wavelength of channel 1 is longer
than that for channel 40, and the meter said your radio was happier transmitting
on the longer wavelength.
If the reading was greater on channel 1 than channel 40,
it's just the opposite. You'll need to shorten the antenna.
To lengthen or shorten the antenna, most antennas have
a small allen screw on the base that you loosen to move the antenna whip
up or down. Move the whip in the direction required just a little bit
(maybe 1/8" to start), and try all this over again. Keep doing it until
the readings for both channel 1 and 40 are almost identical.
Now, tune back to channel 19 or 20. You should see
a very good reading, lower than what you could get on either end channel.
What you did is tune the antenna so it's happiest transmitting in the exact
middle of its range. You could set it up to have the lowest
reading on, say channel 35, if you use it a lot, but then you're going to
get higher SWR readings on the lowest channels. It's all a
compromise. For the record, my CB and antenna combination gave me an
SWR of less than 1.1 to 1 on channel 19, and I could regularly get contacts
in hilly Vermont of more than 10 miles, although 7-10 miles were more the
norm. For practical, extended conversations while driving through the hills,
5-7 miles was normal. All this without lots of expense or illegal
equipment. Basically, if my radio could hear a signal reliably, I could
talk to the person. You can't ask for any more.
There - now you're done. Go out and enjoy the CB.
And on your way out, be sure to check out the section on radio discipline
& manners, because we're all trying to live, work, and play on the same
section of radio space, and we need to respect others using this very public
resource. Think of it as "Treading Lightly" on the CB wilderness.
Last update: 25 August 1998
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