Whatever the old coax terminates with & whatever the new coax uses... I strongly recommend that you either use the existing as is or, if it will not work, you replace it with new coax. The deal is, every time you add an adapter or otherwise introduce something into your line - you cut down the effectiveness of that line. Example, a single piece of coax, 30 ft long, will out perform 3 pieces of 10ft coax joined together by adapters.