The way the OP reads I think he might well be trying to find a break in the cable and if so, that's means finding the middle of a coax in hope that he could find the break. However, a tone generator would likely not find the location of the break but it could identify which coax is which somewhere between the 2 ends if you can't just move the coax around from one end and see which one moves. The problem I have seen with the tone generators is that they can send the tone down multiple cables if they are bundled together making it easy to misidentify the right cable.