Antenna for Marantz 10B

I recently installed a Marantz 10B into my system. It has an antenna "block" with a ground screw and two other screws net to the ground that are labeled for 300ohms. I have a 75 ohm cable coming in from the outside antenna or a 75 ohm cable from Charter. I have hooked up the Charter cable to the ground and one of the 300 ohm screws and it works but is it the best way? I live in an area with few FM options so the best approach will have to be good enough. Sure is fun to see the 10B sitting in the system. The tubes have all been checked with a few marginal that I will have replaced soon. Who serves as "the oracle" for this "holy grail" of tuners? Probably worth having it gone through by an expert so I can listen to the few available stations with confidence. Thanks...