Every installer has his or her own tips and tricks for installing a BNC connector on coax cable. But when bad habits lead to having to re-terminate connectors, labor time and scrap costs increase – and so does frustration.
Even in cases where the connection technically works, it may still negatively affect system performance. Read on to discover the 13 most common BNC connector installation pitfalls and how avoid them – improving reliability as a result.
Never force a plenum connector onto a non-plenum cable or an RG-6 connector onto an RG-59 cable. Use Belden’s cable-to-connector cross-reference guide to make sure you have the right BNC connector size, or check the manufacturer’s recommendations and dimensions.
If you are installing 4.5 GHz coax, make sure the BNC connectors you select are also guaranteed to that same level of performance. Other BNC connectors may only work to 1.5 GHz or 3 GHz. If you are installing a 4K coax cable, double check to make sure the BNC connector you select is also rated appropriately (If it’s a Belden 4K coax cable, the connector should be rated to 6 GHz or 12 GHz.)
Choosing a BNC connector with the correct impedance is an important step in maintaining system performance; however, if you follow the belief that 50 Ohm connectors look a certain way, and 75 Ohm connectors look a certain way, you may be mistaken. Can you tell what type of connector is shown below?
This is a 75 Ohm connector – but does it look like one? Don’t judge a connector only by its looks. Refer to the technical data sheet to choose the right impedance.
While industry veterans often prefer to stick with three-piece compression connectors, thiswhite paper proves that one-piece connectors can meet or exceed the performance of the traditional three-piece connector option.
Crimp connectors leave the coax crimped in a hexagon shape. Physical changes like these affect the electrical performance of the cable. Compression connectors use a 360-degree compression to maintain concentricity of the coax. Download the whitepaper to see the connector’s effect on actual return loss. For the best performance, locking BNC connectors limit movement in the connector body and deliver return loss performance that exceeds -20 dB at 4.5 GHz.
Electrical dykes are not designed to cut coax. They will flatten the cable’s dielectric, which changes the cable’s physical structure and results in performance issues. We recommend cutting coax with cable cutters that have curved jaws that don’t flatten the dielectric.
Belden compression connectors require a ¼” x ¼” strip, which results in a ¼” center conductor and ¼” dielectric and braid. If you’re using the wrong strip dimensions, the cable won’t fit in the connector the way it was designed. For three-piece crimp connectors, always prep the cable according to the installation instructions.
Dull tools can cause the braid to wrap around the center conductor, causing a short; long braids hanging out the back of the connector can create a moisture path.
Three rotations forward and three rotations back is the proper way to use a strip tool. Installers who use more rotations, or use a razor to strip the coax, run the risk of nicking the center conductor and impacting performance.
Flattening the foil prevents bunching. When foil bunches up inside the cable, the center pin won’t fully extend and lock in the front of the cable.
Failure to keep all the strands from touching the center conductor will cause a short. Use a tool with a braid flare feature, or put a strip of Velcro on the side of your strip tool to help “brush” the braid away from the conductor.
Before you pull on the BNC connector, keep in mind that there is a maximum pull tension on the cable. If you pull too hard to test the connector, you may exceed the pulling tension of the cable, resulting in poor performance.
When the wrong crimp die is used, the crimp isn’t shaped correctly and can negatively impact performance.
With some compression connectors, it is not possible to over-insert or push the cable too far into the connector; however, when not pushed in far enough, the connector’s center pin will not be fully extended to the edge of the connector.
Can you think of other mistakes that can easily be made when installing BNC connectors?
Let us know in the comments section below!