Numb-nuts 1 Posted April 5, 2014 Have you ever wonderd why some BNC connectors are more prone to issues than others? I recently suffered a horrendous batch of BNCs, the worst I have EVER experienced, almost dropping off the cable simply handling the connectors. Thge BNC Bayonette Niel Concelman design was for a fast and very efficient connector that could be engaged in difficult military field conditions i.e. while the lead is flying around you. Take a look at these two BNCs, notice any difference? The one on the left is missing the locating guide bush, an essential component of the design, was the connector would efficiently engage in difficult conditions. The one on the right has the guide bush which located the pin and receptacle centrally 100%, however where the outer guide bush is omitted, there is potential for misalignment. We all know that BNC jacks are not always easily accessible and often face away from us when installed, without the guide bush, any slight pulling on the cable, the pin could mis-align going into the jack's dielectric or worse still being bent. Take a look at the BNC with guide bush and then look at the 90 degree convertor and you can view the mating guide bushes. I have just been offered plugs at a very good price, an excellent nickel finish but NO GUIDE bush. From my perspective too much potential for failure or misalignment. To me this rather defeats the object of having a tried and tested connection system so as good as these are I must pass on them. Share this post Link to post Share on other sites
aibudo 0 Posted April 5, 2014 I've had several that produce intermittent video, just because the "ground/shield" portion is just so loose when you connect it to the back of a DVR. Just never know what you're getting. Share this post Link to post Share on other sites
Numb-nuts 1 Posted April 6, 2014 I've had several that produce intermittent video, just because the "ground/shield" portion is just so loose when you connect it to the back of a DVR. Just never know what you're getting. That of course leads to the two or more other factors that affect BNC performance. The crimp ferrule must be a good tight fit and merely exposing 'enough braid to cover the length of the body contact is not enough. I always expose far more and before crimping twist it around the knurled contact to make it ALL fit under the ferrule before crimping. Then of course the worst offender fault that it's possible to encounter, non-mating center contacts. When inserting a center contact we should be listening for a distinct click when it is engaged into the nylon dielectric of the plug. So many of the cheap plugs fail this simple feature and fail for this reason alone. When crimping center pins, it is ESSENTIAL that the center conductor is no longer than in needs to be, to seat the contact fully onto the cable's dielectric, but no shorter than it needs to be to make a good electrical transfer. Part of the strain between the cable and the plug is taken by the center pin and part by the braid of the cable. To further reduce and strain a cable boot can reduce further the potential strain on the center and braid making a very acceptable and durable connection very much suited for military and industrial use, which engages quickly and efficiently, it's original purpose, When selecting BNC connectors and when installing them, you should be aware of these issues and be vigilant, but don't let these things spoil what is a simple operation for you. Crimping any type of connector has always held a fascinating satisfaction for me, from red, blue and yellow insulated connectors to PL259s, BNC and TNC connectors and even RJ45s and even cord end ferrules the feel of the crimping tool the strength and appearance of the finished connector all I find a satisfaction and fascination. I even like the feel of swaging wire rope, is this weird or what? Share this post Link to post Share on other sites
Numb-nuts 1 Posted April 7, 2014 One supplier of BNC connectors has sent me this article from Wikipedia. It makes VERY interesting reading and contradicts many of my assumptions. Go to the article here if interested. Share this post Link to post Share on other sites
Numb-nuts 1 Posted April 13, 2014 I've had several that produce intermittent video, just because the "ground/shield" portion is just so loose when you connect it to the back of a DVR. Just never know what you're getting. There is a self fix technique you caan aply in this case, the braid must be stripped back doule what is reuired and then bunched together, the remainder of the stripping is done but keep the braid extra length intact and twist it around the knurled part of the BNC twisting the ferrule onto it before crimping. You should find this cures that particular issue but frankly its a self fix for emergency, better to have a known good product and if one or two fail , well thats life. Share this post Link to post Share on other sites
aibudo 0 Posted April 13, 2014 What I was referring to, wasn't where the shield goes on to the connector, but the female part of the cable connector that connects to the male connector on the equipment. Share this post Link to post Share on other sites
Numb-nuts 1 Posted April 30, 2014 What I was referring to, wasn't where the shield goes on to the connector, but the female part of the cable connector that connects to the male connector on the equipment. Oh you mean the bulkhead BNC jack on the DVR itself ? Yes I think we've all experienced that at some time. If you put too much stredd on those they can short out and cause intermittent video during connection. One reason I bought myself a BNC insertion/extraction tool which allows you to do te job in a tight space and without risk of breaking or shorting anything Share this post Link to post Share on other sites
