First, replace the factory coax. Most "stock" coax is junk...Next go to a cb shop and have them set your SWR's for you. That means tune the antenna to the vehicle its on. They usually do it for a few bucks..5$- 10$ at the most. Sometimes if you buy coax or antennas from the cb shop they discount your price on setting the swr's for you. As long as that cobra 25 your using hasn't been hacked, you should be in alot better shape after tuning the antenna and the new coax. If it's the same then it's prolly the radio..