K30 roof mount help

If it's thinner, you need to make it longer.

 

Loaded antennas generally are designed to achieve resonance pretty near what the factory supplies them with.

The mag-mount K30 I have is a 35-inch antenna. On the sedan I tuned it on, I had to trim it down to about 32 inches to be resonant. An antenna this short usually won't achiever really low SWRs at both ends of the frequency; i.e., you might have to compromise one end or the other in order to achieve best results somewhere in the 27 mhz band. In my case, I quit cutting when I got SWRs of about 1.3 on Channel 1, 1.2 on 19 and maybe 1.9 on 40. Since I only used it on 19, that was good enough for me. Any more cutting and I probably would have had high SWRs on the whole band.

Once you've cut too much, the stinger is pretty well screwed. The best thing would be to get another stinger that is about factory length and try tuning it again, only cutting in quarter-length segments and not trying to achieve too much with a three-foot shorty.

Of course, with the too-short antenna you might find an acceptable SWR somewhere in the 27 mhz band that satisfies your needs and use it like it is. I'd say any SWR value less than maybe 2:1 is acceptable and won't damage anything except cutting your actual transmit power by maybe 10% or so.

 

You cut the whip too short. Now you need a new one. You might need 4 feet of shaft to compensate for the half inch of whip that's missing. Easier to replace the whip.

 

FWIW, I’ve a collection of stingers. Can’t say I know what to do with the short ones, but there they are at the bottom of the truck electrical tool bag.

Unlike bad studs. Mighty good they are for heaving at a/wipes who cut you off in traffic. Or would be if I learned to sidearm pitch with left hand.

 

Make curb-feelers out of them! Just drill a hole next to the right front tire and right back tire and stick'em in!