How to Connect CCTV Cameras
Even in a largely digital age, there are plenty of uses for coax video cables and the relevant connectors. One popular choice is BNC, often due to its security and ease of use.
What is the BNC Connector?
Originally designed for military use, the Bayonet Neill-Concelman connector, or BNC connector is a twist-on locking connector used for coaxial cable in both 75 and 50-Ohm variations. As with many other connectors, it comes in two flavors, male and female with the male plug normally being found on cables while the female jack is mounted on the hardware to which it's attached:
- BNC Male: This connector features a center pin as well as a knurled outer knob that's designed to slide over the female and then lock home with a quarter twist.
- BNC Female: The BNC female connector has a center jack that accepts the male pin as well as two bayonet lugs on the outside that help hold the male connector in place.
What Should You Use a BNC Connector For?
There are a number of different uses for BNC male connector cables, including security systems and networking. It has a number of advantages over other coaxial connectors such as the F-Type because it allows for a rapid and positive connection and can function in place of many other connectors with a simple adapter. Often all you need to do to attach a BNC male connector is simply crimp it onto the cable. When using these cables there are a few points to remember:
- Ohm Rating: While a 50-Ohm BNC and 75-Ohm BNC cable can physically connect to each other they are not interchangeable. In general, the higher resistance cable is better suited for video while the lower resistance cable is more useful for radio.
- Frequency: Due to the nature of the connector, most cables start leaking at the BNC when used with frequencies of 4 GHz or higher. You can reach 11 GHz with the TNC connector, but not BNC.
Using Connectors
In most cases you can simply twist the BNC male onto the jack and be done with it. However sometimes you may need a BNC tool to get into close quarters. It's an effective choice for coax both because of the robust physical connection and also because you can disconnect much more rapidly than with threaded adapters. Do keep an eye out for reverse polarity connectors which flip the location of the center conductor from the plug to the jack. They still retain the male and female terminology, but the reversed polarity version has the sleeve on the plug rather than the jack, making it impossible to accidentally connect the two.