Using an antenna for HDTV
I don't know exactly how old your TVs are, or how many inputs they usually have, so several of the thing I'm planning to state is conjecture.
The "RF in" / "To RF in" harbors are for actually old TVs that have only one coax feedback. Put differently, TVs having neither S-Video, Component Video, Composite Video, nor HDMI inputs. The past resort is it coax connection. You almost certainly don't want to use this coax connection unless you haven't any other means of linking your TVs. It delivers the lowest high quality video clip and sound signal of choices. The most effective audio quality you could get by using this choice is stereo (unless you also link an audio cable making use of an alternative input interface).
The reason why routing both your cable sign and your Over-The-Air [OTA] sign together did not work is as the the OTA sign is ATSC together with cable sign is QAM - they have been different. They have been both digital but they never combine.
If you have contemporary TVs after that your TVs need numerous inputs. You need to be in a position to connect _both_ a cable from your cable field plus one antenna cable straight to back of each and every of your TVs. You'll then alter video clip sources by selecting a button on your TV remote. One hit associated with video origin switch would choose cable, the second push would choose OTA, as well as perhaps the third would pick DVD, based on the method that you have actually create your activity center. Naturally there are many methods for setting your equipment up, particularly if you own A/V receivers.
BTW, i am presuming your TVs all have High-Def tuners being capable of decoding OTA [ATSC] indicators. All late-model HD TVs do, and from that which you've said i do believe this is certainly your situation.