If you have access to both ends, you can just use capacitance measurement if the center conductor is open - not shorted. Just disconnect both ends so there's no load shunting it, check for DC open-ness with a DMM. Assuming your cable is about 75 ohm type, the C should be around 25 pF/foot - I don't recall the exact figure, but you can it look up, and maybe get the exact spec for your cable type if you can identify it. If you can measure at both ends, you can get a better estimate of the location. Chances are that the problem is at a splice/connector, unless the cable is actually cut or burned open somewhere.
If you don't have a C-meter, trust me, it's a lot easier and cheaper to just get one, than to set up a TDR rig, especially for this kind of one-time use.
Ed
