Not all coaxial cables are made alike. For example, various types of coaxial cables are made from different conductor and insulation materials; they may have different impedance values and different connector types. Time Warner calls for the use of a specific type of coaxial cable for its TV cable and modem connections.
According to the specifications listed in Time Warner's cable box manual, for "basic cable connections, use 75-ohm coaxial cables equipped with F-type connectors." This type of coaxial cable is also required to connect a Time Warner cable modem to a cable outlet.
"Seventy-five ohm" refers to the impedance characteristic of the cable. The "impedance" characteristic of a coaxial cable is a measure of the resistance encountered by a signal as its conducted through the cable wire. The resistance is calculated based on a formula of Ohm's law. Voltage (volts) divided by current (amps) equals resistance (ohm).
A connector is the interface used to connect two units to each other. With an "F-type" connector, the center wire of the coaxial cable serves as the conductor, which is secured to the RF port of a device (such as a TV) via a screw-on cap.