■ FIGURE 1. Cobra Electronics Corporation
( www.cobra.com) was one of the earlier suppliers
of CB radios, and they are still in the business.
Some of their popular products are the
HH38WXST handheld which includes a weather
radio and their 29 NW LTC Classic mobile unit.
Check your local retailers to buy.
connection. Usually, those
who link up switch to
another clear channel.
CB radio really
became popular in the
1970s. It was initially
adopted by long distance
truckers who wanted to
know about gasoline
sources, speed traps,
heavy traffic, accidents,
and the like. Back then,
there was a gasoline
shortage and a 55 MPH
highway speed limit that
drove the truckers nuts.
CB radio really made it
easier for all of them.
Many other people put
CBs in their cars and
connected with the
truckers on long highway
CB radio became a
major hobby. It was for
those who wanted to be
amateur radio operators but didn’t want to learn the code
or electronics to pass the FCC exams. The FCC issued
licenses and call signs back then, but dropped both after it
could not keep pace with the millions that wanted them.
The license requirement and call signs were dropped. That
led CB operators to adopt a name or “handle” that could
identify them and present a radio personality.
CB was also popularized by many movies and songs
back in the 1970s. Movies like Smokey and the Bandit, TV
shows like Dukes of Hazzard, and songs like Convoy made
CB a real phenomenon. And don’t forget all the colorful
expressions like “good buddy,” “breaker, breaker,” plus the
10 codes like 10-4 (received clearly) and 10-20 (location)
were extremely popular.
The CB frenzy eventually faded, but it still continued
to be popular. Over the years as new technology has
come along, CB has now become a secondary
communication choice, if it is known at all. There are so
many other communications options today, CB has
become an anachronism.
The basic transmission mode is plain old amplitude
modulation (AM). A more sophisticated version uses single
sideband (SSB) — a form of AM that uses only one
sideband to conserve spectrum space. Maximum output
power to the antenna is limited to four watts for AM and
12 watts peak envelope power (PEP) for SSB. The
receivers are superheterodynes and all 40 channels are
frequency synthesized. Prices run from about $50 to $150
for a typical unit, making CB one of the most affordable
forms of two-way radio for personal or business use.
As for radio wave propagation, the 11 meter band has
some unusual characteristics. It is only good for a one to
five mile range in local coverage. However, frequencies in
the 27 MHz range use sky waves to communicate over
huge distances. Such waves go up to the ionosphere — an
ionized region miles above the earth, where they are
refracted or bent back to earth many miles away. Such
propagation permits worldwide communications even
with low power. This makes coast to coast
communications possible, not to mention contacts with
CB operators in other countries that use those
frequencies. However, be forewarned. The FCC Part 95
rules do not permit contacts beyond 155 miles.
CB radios come in two basic form factors: mobile
units for under-dash mounting and handheld units. Figure
1 shows some typical units. The mobile units take their
power from the car battery, while the handhelds have an
internal rechargeable battery. The mobile units rely on a
rather large (six to 10 feet) whip antenna, whereas the
handhelds have their own telescoping whip or “rubber
ducky” antenna. Some companies still make a basestation
unit with a built-in AC power supply.
THE FRS ALTERNATIVE TO CB
FRS means Family Radio Service — another personal
communications service created by the FCC. It uses the
460 MHz UHF spectrum and (like CB) specific channel
frequencies are assigned (see Table 2).
Channels 8 through 14 are strictly for FRS use, but
Channels 1 through 7 are shared with the General Mobile
October 2011 65