SWR to high, cant get it down

i have a cobra 25, 5' antenna, on a f250 4x4.
the antenna worked fine on my cobra 19 ultra, but i broke the thing trying to put a power swing on it, so i went out and got a realy radio. but when i hooked it up the swr was at like 3.5:1. i tried ground out everything on my truck and only got little change. the only thing i can think it might be is i have a cheap coax from radio shack. but i dont know if that could be it cuz it worked fine for my other radio. whats wrong, anyone know??

 

i hooked up my swr meter and it gives me a diffrent reading than the swr meter in my radio.. witch one should i go by?

 

sorry thats a typo, i have the cobra 29 ltd Classic

 

well now im down to 1.3:1 on all chanels on my meter in the radio and the external. why? i have no idea. but it only does that when the jumper cable and external meter are hooked up. as soon as i disconect the external meter, the radios meter jumps back to 3.5:1. so im just going to leave it all hooked up, and im golden.

thank you all for your respons

 

i did, but i red that it chokes it so i fixed that....
my swr is low now, but when i key up, as soon as i start to talk my ant light comes on. why is that????