That's pretty decent coax. As long as the cable itself hasn't been compromised, Just replace the connector and an inch or so of the coax and you should be good to go. You might want to carefully check your connection from the coax to the J-pole. It may have a problem at that point which would certainly cause the noise you describe. Did you mount a UHF connector to the antenna, and then connect to that with a PL259 on the end of the coax?