I need suggestions on getting my SWR below where it is now. It sits at 3 or above. I know that this is not good. I am running a 102" ant. with 18' of rg-58 co-ax. on my Uniden PC76XL which has been fitted with an internal modulator. What do I need to shorten or lengthen? How would you recommend running my co-ax.? I am running a rear bumper mount, is this a problem? I can always move the ant. to the top. Thanks.