Hobbies And Interests
Antenna Tuning
Antenna length and tuning are important facets in achieving optimum performance of your Cobra CB radio. Achieving proper tuning requires temporarily connecting an SWR meter between the antenna and the radio, and then keying the microphone on and off on channels 1 and 40. The goal is to locate an SWR ratio of 1.5:1 or lower on each channel. The optimal antenna length can be determined by adjusting the antenna's height until the SWR reading on channels 1 and 40 are as close as possible.
Grounding
Proper grounding of the Cobra radio and the antenna will dramatically increase performance, as this decreases interference and strengthens the signal. Short wire runs are the key: ground both the antenna and the radio to exposed metal on your vehicle or radio base station, as close to each as possible. If the Cobra is installed in a vehicle, it's also a good idea to add grounding straps between the body and the vehicle frame.
Noise Switch
Most Cobra CB radios come with a noise reduction switch, which filters out interference without any necessary changes from the user. Turning on noise reduction will increase the clarity of reception, but it sometimes comes at the expense of not receiving distant or faint signals. Try turning the switch off if you're having difficulty receiving a specific signal.
Trim Dial
Some older (pre-digital) Cobra CB radios have a trim knob that allows the user to manually search for a signal on a specific bandwidth. If you're searching for a signal on channel 32, for instance, but are receiving only a faint or distorted transmission, try slowly turning the trim knob in either direction until the signal comes in more clearly.