A CB Radio is a two-way communications system that lets you broadcast messages to other CB users. It allows you to communicate from your truck, car, home, business, or boat to any other CB operator on the same channel. Technically, it is a transceiver - it functions both as a radio transmitter (when sending messages) and a receiver (when receiving messages).
Citizens Band Radio was created by the Federal Communication Commission (FCC) IN 1958. In that year, the FCC authorized 23 channels for private citizen use. The CB's popularity soon congested these channels, so the FCC added 17 more channels for a total of 40, effective January 1, 1977.
Recently, the FCC approved FM modulation for CB radios, adding access to much better sound quality. This is one of the biggest advancements in CB technology in modern times!
A CB requires a power source and antenna to operate. Commonly, the CB is wired into a vehicle or home base power supply and one of a variety of antenna types is installed. Antenna height will impact range, with a general rule of "the higher, the better".
TABLE OF CONTENTS
- CB Radio Controls and Functions
- Essential Connectors on a CB Radio
- Step-Up Controls and Features
Basic CB Radio Controls and Functions
The minimum controls required on a CB radio are:
This multi-function control is used to turn the radio on or off and adjust the volume level.
Channel Up/Down Control
This control can be a rotary switch or UP/DOWN buttons that are used to navigate thru all 40 channels.
This control allows the operator to control the strength of the incoming signal. In weak signal areas, the squelch should be set to fully open (counter-clock-wise. In strong signal areas, it should be set clock-wise to the quieting level or beyond to receive on strong signals.
The radios receiver will receive all signals including white noise (SSSSHHH) you hear when the squelch control is counter-clock-wise. The user can adjust the squelch control clock-wise to the threshold level to only receive intelligible signals that are strong enough to break the squelch setting.
Instant Channel 9/Normal Control
This control allows the user to quickly access emergency channel 9. The FCC designated channel 9 for emergencies only. Users should not use this channel for non-emergency communications.
This control allows the operator to switch from CB to PA and back to CB.
Essential Connectors on a CB Radio
Most radios in the marketplace are equipped with a 4-pin connector.
All CB radios are equipped with an antenna connector on the rear of the cabinet. The connector type is a UHF SO-239 (socket/female).
External Speaker Connector
All CB radios are equipped with a 3.5mm mono jack that will accommodate an external speaker. An external speaker is very useful when the radio is installed in-dash or used in a noisy environment.
Most CB radios are equipped with a 3.5mm mono jack the will accommodate a PA (public address) speaker that allows the user to broadcast voice outside of the vehicle.
Step-Up Controls and Features
This control adjusts the receiver sensitivity to match the incoming signal. Allows you to decrease the sensitivity for strong signals and increase sensitivity for weak signals.
Called DYNAMIKE on Cobra CB radios. Allows the user to deliver 100% modulation (voice) at all speaking levels.
CB accessories are after-market equipment that can be used on mobile CB’s base stations. There are many categories of CB accessories, including:
Replacement Coax Cable
What Exactly are Accessories for a CB?
External SWR/Power Meters
External Frequency Counter
HOW MANY TYPES OF CB ANTENNAS ARE THERE?
There are several types, the most common being:
Mobile Whips – For use in commercial truck (where the antenna usually mounts on a bracket on the truck’s mirror).
Magnet Mounts – For use in passenger vehicles (where the antenna usually mounts on a magnet mount) placed on the vehicle’s roof or trunk.
No-Ground – Designed to not use the vehicle as a ground plane.
Base Antenna – For use with a base station CB in homes or business.
Portables – (Rubber Duckie) for portable CB Radios.
DO I NEED TO TUNE A NEW ANTENNA?
Yes. You must calibrate your antenna to your vehicle. The antenna is pre-tuned out of the package to make certain that is within the general CB frequency specifications. It will be somewhat different on your vehicle because of the difference in the ground plane and surroundings. Always check the antenna…even if it is moved from one location on the vehicle to another.
WHAT DO I USE TO TUNE MY ANTENNA?
A SWR meter is needed. High-end CB’s have built-in SWR meters. For other CB’s you will need an external SWR meter.
HOW IMPORTANT IS IT TO HAVE THE ANTENNA MOUNT GROUNDED TO THE VEHICLE?
Extremely important, unless a no-ground plane antenna is used. Ungrounded mounts will usually cause SWR to be high across all channels.
WHAT ARE THE MOST COMMON ERRORS YOU FIND ON INSTALLATIONS?
1. Antenna not tuned to vehicle.
2. Mounting location chosen for convenience or appearance versus effectiveness. In passenger vehicles, the ideal location for a magnet mount antenna should be on the center of the roof. In commercial vehicles, it should be mounted on the mirror making sure mirror bracket is grounded to chassis of vehicle.
3. Coax Cable…low quality, worn out, wrong length, or severely pinched.
4. Antenna not grounded or poor ground.
WHAT IS A LOADING COIL ON A CB ANTENNA?
A CB antenna ideally should be 108 inches in length, but is important in most installations due to height restrictions. The loading coil is a wound wire that gives the antenna the correct length electrically.
WHAT ARE CENTER, BASE, AND TAP LOADED ANTENNAS?
A center load antenna is one where the loading coil is at the center of the whip. Recommended for Weather reception.
A base loaded antenna is one where the load is at the base of the whip, i.e. a magnet mount antenna.
A top loaded antenna is one where the load is at the top of the whip. Most top loaded antennas are fiberglass whips for trucks.
IS THE LENGTH OF THE COAX CABLE IMPORTANT?
Yes, it’s very important…especially with high performance antennas. Eighteen feet of coax is typical.
WHAT ARE THE DIFFERENT TYPES OF ACCESSORY MICS?
There are several:
Noise Canceling – A microphone that is capable of removing background noise from the voice signal being transmitted over the air waves.
Power – A pre-amplified microphone which the user can control the level of the voice signal. Its benefit is that the user can speak in a normal voice level and sound louder at the receiving end.
Echo – This type of microphone has a delay circuit that the user can control the echo effect of the outgoing voice, giving the outgoing signal an echo sound.
There are also combination microphones that incorporate power/noise canceling, and power/echo. All power and echo microphones use a 9-volt battery to operate.
HOW DO I KNOW WHAT TYPE OF REPLACEMENT MICROPHONE BY CB USES?
In the radio’s owners manual there is a specifications page where all the models specifications are listed. Under “microphone” you will see Dynamic or Electret element, that is the type of replacement mic you will need.
A Dynamic microphone is one that uses a voice coil diaphragm/no power. All Cobra professional series CB’s use a dynamic microphone.
An Electret microphone is one that uses an amplified microphone element, power comes from the CB. Most Cobra recreational CB’s use Electret mics.
CAN THE MICROPHONE CAUSE THE CB NOT TO TRANSMIT OR RECEIVE?
Yes, especially if the mic is old and abused. The mic is wired to the transmit and audio circuits; if any wires become loose, the radio will not receive or transmit.
ARE ALL EXTERNAL SPEAKERS EQUAL?
No, they are not. Construction and power handling capability are a big factor in the sound of the speaker. The more rugged the construction and the higher power handling, the better the sound.
ARE THERE DIFFERENT TYPES OF SPEAKERS?
Yes, there are several, the most popular being:
Dynamic – Features a full range voice coil for clarity.
Noise Canceling – Features a circuit that removes unwanted background noise from incoming transmissions.
Talkback/Noise Canceling – Feature a talkback circuit with a volume control that allows your transmission to be heard through the external speaker. This type of speaker is the top of the line.
IS THE POWER RATING OF A SPEAKER IMPORTANT?
Yes, a speaker should have a high power rating to avoid damage to the voice coil. The rating should be at least 10 watts.
GLOSSARY OF CB RELATED TERMS
ANL (Automatic Noise Limiter) acts as a filter, chopping holes in the received signal and substituting a period of silence, thereby reducing the static that the receiver picks up from man-made sources such as car ignition, machinery, etc.
BASE STATION Intended for use in one place, generally in a home on a desk or table.
BEAM Type of highly directional antenna (radiating in one general direction), but capable of providing high power gains.
CB Citizens Band.
CHANNEL Common name for a CB frequency.
COAX Coaxial cable used to connect the antenna with the transceiver (CB).
DECIBEL Unit of measure for the boundaries of sound. A numerical expression of the relative loudness of sound.
DELTA TUNE Compensates for a signal that is slightly off frequency.
DYNAMIKE Adjusts the microphone output the user’s voice level to achieve 100% modulation without distortion. Allows user to speak at normal level without having to shout to be heard.
DX Long Range.
FCC Federal Communications Commission.
FREQUENCY The pitch of a radio signal that distinguishes it from another.
HZ Hertz (cycles per second).
KHz Kilohertz (kilocycles) or thousand cycles per second.
MHz Megahertz (megacycles) or million cycles per second.
MICROVOLT (Uv) One millionth of a volt.
MOBILE Any set intended for use while in motion, as in any vehicle.
NOISE BLANKER See Noise Limiter.
NOISE LIMITER A circuit that reduces noise from man-made devices.
PA Public Address.
PEP Peak Envelope Power, applies only to SSB transceivers.
RF Radio frequency above 15 KHz.
RF GAIN Adjusts the receiver sensitivity to match the incoming signal.
SELECTIVITY Ability of the CB receiver to reject transmission on adjacent channels.
SENSITIVITY Ability of the CB receiver to pick up weak signals.
S/RF Signal strength of radio frequency.
SKIP A radio frequency, reflected by the ionosphere which is bounced back to earth at a far distant point.
SWR Standing Wave Ratio (matching of antenna system).
VSWR Voltage Standing Wave Ratio. A rating of the efficiency of an antenna. VSWR of 1:1 is deal, but rarely achieved. The lower the VSWR the better.
SSB Single Side Band. It involves dividing each channel into a carrier and two side bands, upper and lower. Single Side Band offers the advantage of greater range, les interference and generally better performance.
SQUELCH Circuit controls noise level at speaker until signal is received.
SUPERHET Superheterodyne circuit commonly used for its higher sensitivity and selectivity.
TVI Television interference.
UHF Ultra High Frequency.
VHF Very High Frequency.
USB Upper Side Band.
LSB Lower Side Band
GLOSSARY OF ACCESSORY RELATED TERMS
HIGHGEARTM Cobra’s new line of high-end accessories.
SWR Standing Wave Radio, a rating of the efficiency of an antenna.
TUNING Setting or tuning the antenna system to the vehicle where used.
WHIP The mast of the antenna system.
RUBBER DUCKIE A flexible rubber antenna used in handheld radios.
PTT The Push-To-Talk key on a microphone.
DIN CONNECTOR A plug-in type of connector of a microphone.
SCREW-ON A threaded connector of a microphone.
SUPER-CORONATM Cobra’s antenna tip, the largest tip available…for unsurpassed
TIP range and clarity.
LEXAN® Heat and fade resistant plastic used in HighGear by Cobra center-load antenna.
24/8 POWER Cobra’s 24 carat, 8 gauge loading coil on HighGear A6000 and
COILTM A200 antennas.
HIGH-FLEXTM 9’ Cobra’s 9-foot mic cord in the High Gear line.
NOISE TOYS After-market circuit installed in CB radios.
LIPGUARD Rubber lip guard on noise canceling mics.
COAX The type of cable used to connect CB antennas to CB radios.
GROUND PLANE Metal where a CB antenna is mounted.
FEED-BACK The noise heard when an active mic is very near a speaker.