bought a shakespeare PL-259-G connector for my antenna. i don't have a radio yet but getting ready. my cable looks to be just under 1/4" thick but this connector looks like it has closer to about a 3/8" opening that is threaded. the instructions on the back say to thread it onto the cable. i don't see how this can thread onto it. am i wrong or did i buy the wrong part? i didn't open the package yet so maybe there is a piece inside i'm not seeing?