Installing BNC Coaxial Cable Connectors
What’s the best way to terminate BNC connectors for analogue CCTV cameras?
A: The secret to successful connecting and termination of cables is working in a gentle and exacting manner. The best way to terminate coax cable is as follows:
* Make a 90-degree cut straight across the cable. If you get this wrong, try again a centimetre or so further up till the cut is straight.
* Pick up your 2-step coaxial cable wire stripper and set it to the RG-59 setting using your hex allen key. What you want to do here is expose about 1cm of the cable’s conductor and 1cm of its insulation. When your settings are right, insert the cable into the stripper and close it around the cable.
* Rotate the stripper so the blades strip the coax in the usual 2-stage manner. You need to rotate the stripper 3-5 times always in the same direction. We’ve seen some installers go back the other way using a 180-degree swing in each direction with most unappealing results. Vital here is not to go all the way through the jacket and into the shield – this is the most common error with coax installs. Go nearly all the way through and then pull the jacket to and fro till it separates along the line of the cut. Ripping with the stripper is fine for stripping AWG or zone cable but it’s guaranteed to make a mess of coax more often than not.
* Give the cable a careful inspection. Don’t be afraid to carry a magnifying glass for this purpose. Even if magnifying the cable tip isn’t essential it makes the inspection process easier and much faster because damage will be obvious. Once you’ve established the insulation is not nicked or scratched and there are no whiskers of braid sneaking out of the conductor then you’re ready to crimp the centre pin.
* Seat the centre pin of the BNC onto the stripped conductor. When you’re happy that you’ve got all the conductor into the centre pin for a good contact and that there are no whiskers peeking around the BNC pin’s hole, crimp the centre pin to the conductor with the pin crimp on your ratchet crimper – you’ll use the small pin die. Use firm but not too much pressure and turn the pin to get even crimping.
* Fit the sleeve ferrule over the pin and the still exposed insulation. What you want to do is slide the ferrule down over the pin and then put the BNC connector body onto the end of the cable. Doing this will force the braid to spread and you want to press the connector all the way down the braided shield without applying excessive force. All the time this process is going on make sure no stray whiskers are being bent back outside the connector body by its downward passage. Also vital is to ensure that the pin flange sits on the exposed insulation and that the pin top is flush with the top of the BNC body.
* Slip the crimp ferrule sleeve up till it covers the exposed shield braid all the way to shoulder of the connector body. You then need to get your ratchet crimper and set it to the right diameter using that Allen key. Put the crimper over the ferrule sleeve and put firm and even pressure on the crimper handles till the ferrule is perfectly crimped to the connector body.
* Next you should give the completed connector a careful inspection to make sure it’s a solid and sturdy unit. Flex the cable and give a firm but not destructive tug on the cable holding the connector body to ensure its properly held and won’t come apart at the slightest disturbance.
Now you’re done. BNC connectors built this way by studious technicians make excellent connections that, if environmental conditions aren’t extreme, should easily outlast the systems they are serving.