Helpful Links

A higher SWR (Standing Wave Ratio) on channel 40 compared to channel 1 means your physical antenna is acting as if it is too long for the frequency being used.

To fix an antenna that is too long, you need to shorten its electrical length: For Tunable Tip Antennas: Simply screw the adjustment screw on the top of the antenna "in" (counter-clockwise) to shorten it.

For Standard Whips: Loosen the set screws and push the metal whip down slightly into the mount. Do not cut the whip until you have exhausted all other tuning methods.

Always adjust in tiny increments (about 1/4 to 1/2 inch at a time), then re-test the SWR on both channels 1 and 40 until the readings are balanced. You are aiming for an SWR below 2.0 across the entire band.