RoadTrip America

Routes, Planning, & Inspiration for Your North American Road Trip

Road Tripping and CB Radios


by Mark Sedenquist with technical expertise provided by Bruce L. Clark


I credit Citizen Band (CB) radios with saving my life a couple of times on the road. Being able to access information like my vehicle's immediate proximity to a speeding eighteen-wheeler on a one-lane logging road or an approaching tornado enabled me to make decisions that without this timely information could easily have resulted in a fatal crash. Likewise, CBs can bring peace of mind when you're "trapped" on a highway in a traffic jam of unknown cause. On a lighter note, they can also provide conversation on long solo journeys. It's easy to think that cellular telephones have turned CB radios into dinosaurs, but in fact, nothing could be further from the truth.


These relatively low-tech devices are enjoying a resurgence of popularity among professional truck drivers and road trip enthusiasts for some very good reasons. They're relatively inexpensive to buy and free to use. They work well, and they provide communication under circumstances where other forms of technology still don't do a very reliable job.


Cobra 19DXIIV
What around $60 will get you: the Cobra 19DXIV

I have owned and used Cobra Electronics radio products for nearly thirty years, and since the company is very generous with the use of photographs, I have included examples of Cobra radios in this article. Keep in mind that there are many excellent CB manufacturers, and I'm not endorsing any one in particular.


Although CB radios have been available since 1959, the first time I used a CB was in 1976, when I worked as a fire lookout on a remote mountain peak in Arizona. During my off-hours I used the radio to alleviate the occasional boredom that such a job can engender. Since I was sitting on an 8000-foot peak with an unobstructed, several-hundred-mile view, I was able to reach and talk to other radio operators an amazing distance away from my location. That first radio featured 23 crystal-controlled channels and required a registration from the Federal Communications Commission (FCC). Today, neither registration nor license is required to operate a two-way "Citizen's Band" radio, and the basic radio has been expanded to 40 channels.

Motorola FRS radios
Short range, low power: FRS/GMRS radios
The world of CB radiotelephony has enough jargon to arouse self-doubt in any normal human. It is easy to start feeling a little lost when someone starts talking about "bird" watts, LSBs, 10-meter radios, Standing Wave Ratios, skip, swing, and slide. Fortunately you don't need to know most of this to own and use a CB perfectly competently.

Citizen's Band refers to a range of radio frequencies that lie between the short-wave broadcast signals and the 10-meter Amateur radio bands. These frequencies are divided into 40 channel starting from 26.965 MHz up to 27.405 MHz in 10KHz steps. "Meters" are just an arbitrary benchmark for measuring the wavelength at a given frequency. For example, the CB band is also known as the 11-Meter band (this is an arithmetic function where the number 300 is divided by the frequency: 300/27Mhz = 11).

Bruce L. Clark: "Frequency is measured in MHz, while wavelength is measured in meters. They are just two different ways to measure a radio signal. The length of an antenna is directly proportional to the radio wavelength used. The shorter the wavelength, the shorter the antenna. Convert 11-meters to feet and you end up with one wavelength being about 36-feet long at the CB frequencies. This is why a ½ wave CB base station is typically 18-feet long and a ¼ wave mobile whip antenna is 8-feet long. The measurements of frequency, wavelength, and antenna length are all inter-related.

CBs are part of what the FCC has designated 'Personal Radio Services.' They are characterized as being 'short-range, low power radios for personal communications.' The three most well known of these are CBs, Family Radio Service (FRS), and General Mobile Radio Service (GMRS). FRS radios are supposed to be limited to a one-mile range, have a maximum ½ watt effective radiated power and have non-detachable antennas. These radios are sold just about everywhere and are frequently seen being used by 'family members' at sporting events or even being used by spouses when backing large RVs into parking spots."

The Cobra 75WXST: Everything in the palm of your hand

GMRS radios, which look a lot like FRS radios, can transmit at higher power levels (up to five watts). They often have detachable antennas, and although they are often sold at the same sales counters as FRS radios -- which don't require licenses -- users of GMRS radios are supposed to obtain licenses from the FCC to operate them. Currently these cost about $80.00, but many retailers fail to mention this legal requirement.

Bruce L. Clark: "Both GMRS radios and FRS radios (which share some GMRS channels) have two big advantages: they use UHF frequencies and FM modulation. This eliminates the 'skip' phenomenon which plagues CB operations on the shortwave/High Frequency band. The FM mode of modulation eliminates the pops, whistles, and power line interference common with AM modulation. But in 1959, HF frequencies and AM modulation was what was commonly available when the FCC attempted to create an inexpensive 'business band' radio service for the average person. The use of higher frequencies and FM modulation would have added to the cost of a basic CB radio."

CB radios, on the other hand, are limited by FCC regulation to "4 watts of carrier power" and operate on the CB radio band. The CB band was originally part of the Ham band (amateur radio) but was opened up to the general public by the FCC. In recent years, there has been an on-going debate about what whether or not adjusting the potentiometer "pot" setting inside a CB radio would violate the statute limit of 4 watts. What we recommend is that you read the FCC statutes and make your own decision.

Bruce L. Clark: "You can check the current regulations at the FCC Web site. Go down the left side of the screen and select 'Rules and Regulations.' Select 'FCC Rules: CFR Title 47' which is short for 'Title 47-Telecommunications.' Select 'Part 95 - Personal Radio Services.' Follow the link and you will find that CB radio is covered in the regulations starting with paragraph 95.401. Paragraph 95.410 states that CB output power is limited to 4 watts (carrier power) when using Amplitude Modulation (AM) or 12 watts Peak Envelope Power (PEP) when using Single Sideband (SSB) modulation.

Midland likes to quote on many of its radio boxes '7 watts of power.' But when you read the fine print, it is actually 7-watts of audio power to the speaker. This has nothing to do with the RF output of the radio, which is still the same 4-watts as everyone else.
I recommend folks spend their time checking the SWR match on their antenna to ensure all of the 4-watts output is getting radiated from the antenna. Don't use ridiculously short antennas and don't mount them next to the car body! An antenna needs to be free and clear of obstructions in order to radiate a signal effectively.

A good source of information and advice on CB radio antennas is available from the 'Firestik' CB antenna company. This company has been around for many years, and offers great information on its Web site. Go to the web site and select 'Tech Help' for a huge listing of various CB related topics. My only disagreement with Firestik concerns their disapproval of CB radios with NOAA weather channel reception. I find the weather channels to be helpful and prefer a CB radio with that feature."

You may hear people referring to the use of Single Side Band (SSB) radios as if they were some form of a super-duper CB, but here is what is really going on:

Bruce L. Clark: "The selection of the Lower Side Band (LSB) or the Upper Side Band (USB) concerns the transmission mode. SSB is a derivative of AM. In an AM signal you are actually transmitting a carrier signal and two side bands (one just below the carrier signal and one just above it). In the early 1950's amateur radio operators experimenting with different modes of transmission observed that the 'intelligence' or 'voice' signal is actually contained in the side bands. The carrier is just a waste of power. Both side bands, the lower and the upper, are identical and contain the same 'intelligence' or 'voice.' So really, you only need a single side band to communicate. These hams found that if you suppressed the carrier, and selected either the upper or the lower side band, the result was a signal much narrower in bandwidth that also had all the power concentrated into one side band signal. That is why the FCC allows CB radios to have 4 watts of AM power, but up to 12 watts of SSB power.

If you want to talk farther with a more efficient signal, Single Side Band is the way to go! It also gives you a 'poor man's encryption' on the CB band, since an AM-only CB radio cannot decipher a SSB signal. It just sounds like Donald Duck talking. But to take advantage of the greater range and power of SSB, both stations must have a SSB CB radio. All SSB CB radios also have AM capability. You can still select 'AM' mode if you want to listen to the truckers on CB Channel 19."

Many truck stops still carry what is marketed as a 10meter/CB radio. This is actually an amateur band radio, which requires a full Ham radio license, but includes a toggle switch that operators can use to speak on the CB radio bands. As configured, these radios are illegal, and the FCC has begun to crack down on both the truck store chains and the radio operators who are using them. In 2006, the FCC fined the owners of the Pilot Travel Centers nearly $125,000 and levied a consent decree making the continued practice of selling these radios a costly proposition.


In recent months, the FCC working under the auspices of the DOT has been stopping trucks and searching for these illegal "10-meter" radios. If the vehicle owner is unable to produce a Amateur Radio license or prove that their 10-meter radio only operates in the Ham radio band, then they are reportedly being cited. If you are interested in learning more about becoming a licensed amateur radio operator, this site is the bible for Hams.


One curious thing about CB radios -- or for that matter any radio -- is the nature of "ground plane." Ground plane is the area under the reflective area of an antenna -- imagine that the antenna is the pole in an invisible patio umbrella. When installing a CB radio it is important to choose a location where this invisible umbrella will have the best coverage. Another issue is what's known as radio frequency "hash". Any vehicle has a host of electrical components and all of them create electrical interference which a CB radio can "hear" and reproduce for your listening pleasure. It is common to hear the sound of alternators and power window motors through CBs. This irritating "whine sound" can be reduced or eliminated by filtering the 12-volt DC power going into the CB radio. This can also be accomplished by using extra capacitors, creating a better ground for the radio, properly tuning the antenna with the vehicle, or a combination of all three.

Cobra HH38WXST
Handheld CB: Good option for rental cars


A good CB shop can tune your CB and antenna to your vehicle in about 30 minutes, and the cost should be around $35.00. A decent quality CB costs $100 to $150, and a reasonable antenna costs between $35 and $75. Although our primary road trip vehicle has a permanently mounted antenna, we also use a handheld radio (which looks like an oversized walkie-talkie) and a magnet-mounted short antenna in our other vehicles. We find that it works fine, although there is an extra level of wear and tear on the coax cable over time since the door closes around it. Another option is to install a hand-held CB where the controls are all built into the microphone. We have had mixed results with this radio setup, and generally I recommend getting a standard format (box-like) transceiver if it will fit in your vehicle.


Generally, a properly tuned CB has a range of 10-20 miles, but it is "line of sight" transmission, and mountainous terrain can reduce this range to less than a mile. One of the things you might notice when using a CB is a slight, squeal-like harmonic which is caused when several strong radio signals are mixing in the receiver section of the CB. Unfortunately, this is one of the drawbacks of the AM modulation used by CB radios. Another really cool thing that happens with CB radios is the phenomenon known as "skip." Basically, the radio signals are bouncing off the ionosphere, allowing you to hear conversations that are occurring hundreds, sometimes even thousands of miles away. Near my office in Las Vegas, Nevada, I can usually hear a CB shop that is transmitting from a location near Chicago, Illinois.


With the advent of better cellular phones, some folks rely on them when communicating with other cars on road trips, but we find that CBs actually work much better and often provide a much cleaner quality of sound. In addition, virtually all CB radios include weather channels which can be very helpful for obtaining quick and accurate weather conditions on unfamiliar roads. For examples of roadtrippers who use their CBs every day, check out the commentary on the Great American RoadTrip Forum. Also, read Andrew Youderian's article about CB radios, how to choose a CB Radio, How to choose and Mount a CB Radio Antenna, and How to Tune a CB Radio Antenna.

Photos courtesy of Cobra Electronics, Inc.

Bruce L. Clark is a radio technician who recently retired from the Air Force after 24 years of active duty. Now the Land Mobile Radio (LMR) manager and radio spectrum manager for Malmstrom Air Force Base in Montana, Bruce holds an Amateur Extra class radio license and has been actively involved in shortwave listening, CB radio, and Amateur Radio since before he enlisted in the military. Bruce has also served as a radio advisor to county emergency managers in North Dakota.


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