New Radio, quick question about best settings for distance

Not really, and not even close depending on the type of coax. Many here will argue that down at 27mhz the length doesn't matter. I personally run the electrically correct length figured up with the accepted formula. Since no coax has a velocity factor of 1.00, 18' is never correct for CB, and depending on the type of coax, there can be almost a foot of difference between channel 1 and channel 40.

For instance if you are running the better type of RG-58 (poly foam dielectric, .66 VF) the correct length is 12 feet. If you're running the worse type of coax (solid poly dielectric, .53 VF) it is just over 9 feet.

 

By the sounds of it, without cutting or spending on some custom length, 18 ft was a good length due to the cable routing.

 

Squelch knob left. Rf gain right. Noise blanker on. That's as good as it gets for receive. You can turn the RF gain knob slightly to the left to filter out some of the noise. If you want to reduce the distance that you can hear, you could turn the squelch knob to the right.