NOTE:  Not all models have the following controls.

SQUELCH - Squelch controls the audio of the radio, turning it on or off.  If the squelch is turned down and you are not receiving a signal, you will hear background static.  This is normal, but can be annoying.  To avoid hearing the background static, slowly turn up the squelch just until the noise stops.  This is the normal operating position for the squelch.  If your radio receives a transmission, the squelch will "open up" and you will hear the transmission.  When the transmission goes away, the squelch will "close" and you will not hear the background static.  Do not turn the squelch any higher than necessary, otherwise your receive range will be reduced.

RF GAIN - RF Gain controls the receiver sensitivity.  Normally you would have the RF Gain turned up all the way for maximum sensitivity (and maximum range).  If the other person is nearby and you are receiving a strong signal, you can turn the RF Gain down.  This will provide very quiet reception.

DYNAMIKE - This control amplifies your voice to make you sound louder.  It is like a built-in power mike.  Normally you would have this control turned all the way up.  If you are using a power mike and you experience squealing or distortion, try turning down the Dynamike.

DELTA TUNE - If the other person's CB is a little off-frequency, their signal may sound a little distorted.  If so, you can adjust the Delta Tune to clarify their voice.  Delta Tune only affects received signals, it has no effect on transmit.  Normally you would leave the Delta Tune at the 12:00 position.

S/RF, SWR, CAL SWITCH - The normal operating position is the S/RF position.  In the S/RF position the meter will show transmit power and receive signal strength.  The CAL and SWR positions are only for check the SWR of the antenna.

SWR - This is a measure of antenna performance.  Some radios have a built-in SWR meter to measure the SWR.  It tells you how well the antenna system is tuned to the CB band.

AUTOMATIC NOISE LIMITER (ANL) - This is a noise filter, to help eliminate engine noise.  All mobile CBs have an ANL.  Most mobile CB radios have a full-time ANL, while others have a switch to turn it on and off.  In almost all vehicles it will be necessary to have it turned on.

NOISE BLANKER (NB) - This is an additional noise filter, to provide more filtering.  If there is no NB switch, then the CB does not have a noise blanker.  Don't use the noise blanker unless you need to, because it slightly lowers the receiver sensitivity.

ST SWITCH - Soundtracker (ST) is a Cobra exclusive noise reduction circuit, to provide quieter reception and stronger transmission.  If there is a lot of noise, however, the Soundtracker circuit can become overwhelmed and will not provide any noise reduction.  Soundtracker works best with moderate to low noise levels.  Additionally, maximum benefit is obtained if both radios have Soundtracker.  Using Soundtracker is optional.  Try it on and off, and choose which way you like best.

PA SWITCH - To use PA (Public Address), you need to connect a loudspeaker to the PA jack on the rear of the CB. When you talk into the microphone, you will be heard over the loudspeaker.  Typically you would install a weather-proof speaker under the hood.  On models with a Dynamike control, the Dynamike will control PA volume.  On models without a Dynamike, PA volume is not adjustable.  Please note that on some models you will hear CB reception through the PA speaker.  This is a feature to allow you to monitor CB traffic while out of your vehicle.  If you do not want to hear the CB reception, just turn the volume control down.

CH9, CH19 SWITCH - Channel 9 is reserved for emergency use only.  Channel 19 is the most popular channel, where you can get traffic reports, etc.  This switch provides instant access to channel 9 or channel 19.  In order to select other channels, this switch must be in the NORMAL position.

USB/AM/LSB SWITCH - This switch is used on radios equipped with Single Sideband (SSB), which is a special mode of transmission.  Use the AM position to communicate to regular CBs.  Use the USB and LSB positions to communicate to other Single Sideband radios.

VOICELOCK - This control is only used on Single Sideband radios.  When you are switched to USB or LSB, received signals may sound distorted.  Adjust the Voicelock control to clarify the signal.  Voicelock only affects received signals, it has no effect on transmit.

TALK-BACK - This control lets you monitor your voice when you transmit.  You might be wondering, “why would I want to do that?”.  Some people like to install sound effects in the CB, such as echo, reverb, etc.  If you are using an echo control, the talkback feature lets you monitor the echo level.  You will hear exactly how your voice sounds to other people.