Tuning your Cobra CB, or any other CB, will increase the accuracy with which it delivers and receives signals. A correctly tuned CB radio will have clear reception and the most powerful possible output to other CB radios. The tuning process works with any type of antenna, but a regular steel whip antenna is easiest.
- Skill level:
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Things you need
- CB Radio
- SWR meter
- Cutting dykes
- Adjustable antenna (optional)
Park the vehicle as far away from buildings and power lines as possible, and keep the doors, hood, and boot closed tight. Instruct those around the car to step back at least 10 nyards, but the further the better for accurate results.
Connect an SWR (standing wave ratio) meter to the CB, and place the CB on channel 1. Press the button on the microphone, known as "keying up," and adjust the knob labelled SET until the needle reaches its highest point. Then set the meter on REF, and key up again. Write this number down so it can be referenced later.
Turn the CB to channel 40, and key up again while in the REF mode. The needle level while on channel 1 should match or nearly match the level recorded on channel 40. If the needle reading on channel 40 is higher than while on channel 1, the antenna is too long. If the needle is lower on channel 40, the antenna is too short.
Adjust the antenna by either cutting off a quarter inch with a good pair of dykes and retesting, or raising it up a quarter inch if possible. Repeat these steps until the signal strength on both channels 1 and 40 are exact, or very close.
Tips and warnings
- Adjustable antennas allow you to raise or lower the height without cutting.
- Do not cut too much off the antenna at one time; this may be irreversible.