high SWR with K40 trucker

[Darwin666]

Hello everyone,
I've been experiencing some problems with high SWR, 3 - 3.5 I'm mounted in a 94 Sierra middle of the roof, a K40 trucker on a Wilson hole mount. K40 coax and with a Radio Shack SWR Meter. I'm running a Uniden PC78 Elite mounted on my floor board by the T Case shifter. I had moved from mid tool box with slightly higher SWR, same as a few other locations on the truck. Is there anything I can so with the antenna at this point? I'm out of ideas.

Thanks

[Buzzweiser]

The K-40 Trucker is a decent antenna once it's matched. Did you buy it new or is it used? On the back of the package there is a measurement guide that gives you the length of the whip for a specific frequency. The whip is usually way too long right out of the package and you have to trim it off. It is only a reference point however so always leave it a bit long to start with and trim down gradually. I have the guide somewhere if you don't have one. I would also check your mount and make sure it's not grounding the center out. Use an Ohm meter to check.

[MDYoungblood]

After you get the antenna at the location you want it, sounds like that is already done, check the SWR at 3 different channels, 1, 19 or 20, and 40. This will give you a indication of if the antenna is too long or too short. Most antennas on the market today are made long so they can be trimmed like Buzzweiser said. Try to get the best SWR at channel 19 or 20 then balance out the ends of the band, 1 and 40. If the SWR reads that the antenna is too short (if previously used) then you can space it up using a stud nut, I don't recommend springs.

3's

Greg

[Darwin666]

Thanks for the help, antenna just needed to be trimmed. Decided to then add spring and quick detach then trimmed more. Mounted in center of the toolbox now swr at 1.5.