What is the max distance a HDTV signal go on a coaxial cable and which is the best cable to use?

Outside commercial facilities, raw HDTV signals do not travel on co-ax. In a production studio, an HD signal will travel up to 500 feet as an uncompressed full bandwidth HD signal. This signal format is not seen outside the studio. Once the signal has been prepared for broadcast, it is in a compressed format and carried to a transmitter, satellite base station or put onto a cable for distribution to homes. In the case of cable operators, the main trunks are normally fiber optic with the drops to each house either on co-ax or fiber. Whatever solution is chosen by the cable company, it is engineered to provide reliable service to each home using specific cables and connectors.

Once the signal has been received by a cable, satellite or terrestrial receiver, it is output as an HDMI signal. There is virtually no equipment that will output HD in any other format.

HDMI is a multiple twisted pair cable rather than co-ax and has a maximum length approaching 100 feet. In terms of the best HDMI cable to use, it is important to use a cable that has been tested and approved by the HDMI organization. If the cable passes that quality test, it will work as well as any other cable, regardless of cost or any other claim by cable manufacturers. If an HDMI cable works, it will deliver the signal without any corruption, so claims by manufacturers that they offer the "best quality" image are without substance. In essence, the cable either works or it doesn't.