Did you check for shorts? Take a volt meter set to (continuity or ohm meter) to the center conductor and chrome outside of the bnc. Should be a full open.
No BNC center to Outside continuity...
center pin on BNC to antenna element is 0 on multimeter meening no breaks in center conductor
checked continuity from outside of bnc to antenna ground plane and still turns out good
no shorts in coax....
ground from antenna to Ground Pole is good
I Just dont know 3 scanners and all the same... even when running off batteries
think my pro-106 needs alignment and adjustments but the 396xt works on another antenna and my pro-107 also works on another antenna...
Is it possible the groundplane or uhf elements couldt pick up this interference? and would it be worth trying to take the 3 lower groundplane poles off the antenna?
just a thought...
other antenna i use is a CB steel whip about 40 inches long with no ground plane but mounted on addition to trailer which is not aluminum sided and shingled roof.. and works great... kinda sucks cause i dont wanna rerun the antenna and coax unless i absolutely have too... aluminum siding on trailer has been grounded as well