A+: Connector Types

Most coaxial cables, including RG-58, RG-59, and RG-6 use a BNC (Bayonet Neill-Concelman) connector. RG-58 uses a T-adapter to connect to a 10BASE2 Ethernet adapter. RG-11 (Thicknet) cable is connected to an Ethernet card by means of an external transceiver, which attaches to the AUI port on the rear of older Ethernet network cards. The transceiver attaches to the cable with a so-called “vampire tap.”

10BASE-T, 100BASE-T, and 1000BASE-T Ethernet cards using copper wire all use the RJ45 connector, as do newer token-ring, some ISDN and most cable Internet devices. DSL devices often use the RJ11 connector, as do dial-up modems.

To attach a cable using RJ11 or RJ45 connectors to a network card or other device, plug it into the connector so that the plastic locking clip snaps into place; the cable and connector will fit together only one way. To remove the cable, squeeze the locking clip toward the connector and pull the connector out of the jack. Some cables use a snagless connector; squeeze the guard over the locking clip to open the clip to remove the cable.

Fiber-optic devices and cables use one of several connector types. The most common include

    • SC— Uses square connectors
    • ST— Uses round connectors
    • FC— Uses a round connector

If you need to interconnect devices which use two different connector types, use adapter cables which are designed to match the connector types and other characteristics of the cable and device. Making these cables is generally a waste of time, and the quality is generally lower than factory-built cable.

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