DXE Technical Note: Importance of Correct Termination of Shielded Cat5 Networking Cables. By Scott MacDonald, KD8BDX. Parts list:

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1 DXE Technical Note: Importance of Correct Termination of Shielded Cat5 Networking Cables By Scott MacDonald, KD8BDX needing the flexibility of custom wiring length and being comfortable with terminating cat5, I researched cable, ends, and tools to determine what was the best to use to make my own shielded, twisted, bonded pair cat5. Below is a listing of the products used and an illustrated guide to working with them. A computer with an internet connection is an important tool in today s ham shack, used for a large variety of vital purposes. Not only that, but many other pieces of equipment are incorporating Ethernet ports, to allow easy interaction with each other, with computers, or for direct remote access. Conventional thinking is that network communication is an enclosed system, where the unshielded twisted pair (category 5 cable, or Cat5 for short) keeps the signaling voltages in and other RF out. In my own experience I have found this not to be the case and this tech note is intended to detail some of the reasons behind this and the construction of shielded Cat5 that I have found to be the solution. Twisted pair is used widely when it comes to balanced communication lines as a constant twist of the wire helps to merge the magnetic field around the pair and keep important voltages in and noise out. The problem is too many cat5 cables do not have a constant twist the pairs of conductors are not bonded and any time the cable is bent the integrity of that balanced pair can be compromised. Parts list: Belden 7921A DataTuff Cat 5e, 4pr 24 Belden 1797B - Cable Tool Sentinel 111S C34 Shielded RJ45 3M 1181 Copper Foil Tape Sentinel Crimp Tool Sentinel B0051 Black RJ45 Boot Xcelite 170M Side Cutters Though not shown in this guide, it is recommended that a wire tester be used to verify that your custom cables are terminated properly. This is also a useful tool to check existing wiring or the connection integrity of premade jumpers. Note that any substitute for the 3M Copper Tape needs to have conductive adhesive. If this is lacking, the continuity of the shield from RJ45 to RJ45 may be broken. The second and maybe larger issue is with the lack of adequate shielding on most cat5 cables. As with any current-carrying conductor, the magnetic field extends beyond the size of the wiring itself, so if you are using UTP (unshielded twisted pair) and it is running physically against other unshielded low voltage or line voltage wiring, there is the potential for network noise to get out or other noise to get into the network. The best way to ensure your network is not interfering with your reception is to replace the existing cat5 with better cabling, specifically Ethernet wiring that is well shielded, incorporating both shielded RJ45 connectors and bonded pairs. There are a variety of cables available online that meet these requirements and would be sufficient for many applications. With

2 Trim off outer jacket of 7921A cable with 1797B cable tool, using an old piece as a guide. If it is your first end, measure and cut about 1-3/4 1-7/8 from a clean cut, and save the piece of jacket for next time. A deep score and pop off of the insulation is better than a cut that is too deep and penetrates the shield. Cut a piece of copper tape about 1-1½. Wrap tape on shielding, leaving a small gap from the insulation. Remove braid, drain line, foil, and plastic to the top edge of the copper tape, exposing the twisted pairs.

3 Push the boot onto the jacket, far enough to be out of the way until it is needed. Using cable tool, untwist pairs down to the tape. Then separate the pairs with the hook at the other end of the tool. Be careful not to tear up the wires.

4 Arrange the conductors to your preferred layout I use T568 B. Straighten and cut off the very ends to get a clean edge. Bend the conductors with solid colors down and the others up slightly and then bunch all of it together. Install load bar on conductors and place it so with the very inner end of the crimp at the jacket it is just past the end of the connector.

5 Cut wires just past load bar. Bend up crimp and push wires and load bar into the connector. Wires should all bottom out in the connector and the copper tape should be just inside it. Verify the wires are still in the correct order. Bend the crimp back down. Grab the crimp in one hand and the rest of the connector in the other and twist to get them lined up as well as possible.

6 Insert into crimp tool carefully, crimp twice, and press button to release the end from the tool. This is what it should look like upon removing from the tool. Notice the crimp firmly on the copper tape, shielding intact all the way to the connector, and all wires to the very end of the connector. Pull the boot up and you have a complete end. On to the next one.