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#11
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On Tue, 9 Dec 2008 07:52:00 -0800 (PST), JIMMIE
wrote: I dont have a problem with crimp on terminals just that where I work someone has always borrowed the crimp tool just when I need it. I know the problem. Tools are expensive. However, there are a variety of cheap replacements that seem to work well for me: http://802.11junk.com/jeffl/antennas/Misc/slides/crimpers.html I have several sets of these that cover everything from RG-188 to LMR-400 size coax. There's also one for LMR-600 but it was being borrowed when I took the photo. (Yes, it came back eventually). I think I paid about $35/ea for the tools in the photo. At that price, spares are an option. I always have my trusty soldeing gun handy, no one wants to borrow it. When I was working on the bench, I had my soldering iron bolted to a large block of wood to discourage the borrowers. My biggest problem was someone trading or outright stealing my Weller solder tips. I kept my supply locked up and hidden. For me one is as easy and works as well as the other. I beg to differ. Many of my connector installs had to be done in the field, usually at a mountain top repeater site or up on a tower. The problem was that the wind would cool just about any soldering iron, gun, or even a propane torch, sufficiently to cause problems. Same with the USCG vessels, where the coax was snaked through the mast, and the connector had to be crimped at the top in the field. The only place where I would effectively solder a connector was inside a building. I do recall one day on a tower, when I draped my jacket over my head, and soldered some connector by flashlight, but I don't recommend doing that. The biggest problem I have with the non crimp type is the shield is eventually cut from the connector. Agreed. I have the problem with my test cables. A good strain relief is a big help at immobilizing the shield. Pomona jumper cables have molded plastic strain relief's. I use clear shrink tube (so I can see when things are starting to come apart). In general, it's nut much of a problem as I have far more UG-88/u BNC plugs fall apart than the crimped variety. The ones at work that are disconnected weekly for preventive maintenance have only lasted about 20 years before needing the connectors replaced, BUMMER. Weekly? 52 weeks per year times 20 years is over 1000 connector cycles. That's quite a few. I suspect the ears on the BNC jacks will also be worn. I'm not surprised that they're failing. I did some Googling and found specs for UG-88/u connectors ranging from 500-1000 mating cycles. Methinks you're at the upper limit of the lifetime. The crimp-on type are not without their problems. I was doing an inspection after some equipment installation and was able to pull the the ends off of 20 BNC connectors. The inspection stopped at that point and the decision was made to reaccomplish all of the connectors, about 200 of them. The installer was not happy. The problem turned out to be a bad crimp tool. Like the solder-ons if done properly they are both reliable connections. Bummer. At one employer, we had an Amp-o-lectric crimping machine. Someone found that it was possible to mis-adjust the tool to produce defective crimps and proceeded to explore the possibilities. I was blessed with dozens of field failures and a recall because nobody had thought to run a pull test on the crimped connections. Everyone assumed the machine could do no wrong. However, that's the big advantage of a crimped connection... it's consistent. I can't get that kind of consistency from soldered connectors, especially those done in the field. Incidentally, I've seen more damage done by the razor blade coax stripping tools, than by the crimping or soldering. One nick in a solid center conductor and the center pin connection falls apart inside the connector. I try to use a thermal wire stripper, but that also takes some skill. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#12
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In article .net,
SparkyGuy wrote: Halfway down this page (it's a PDF doc): http://www.cablesandconnectors.com/PIX/CC-040.pdf the TNC and BNC connectors are advertised as "dual-crimp". What does this mean? "Dual" as in center in crimp and outer shield ferrule crimp? yes As opposed to what? Single-crimp? That would be connectors that use the center, solid conductor as the center pin yes(solder or captivated and then crimp the shield ferrule? Or...? yes Newly (did you guess?) into small coax connectors and trying to get the terminology straight... you did good are you just trying to learn the terminology or do you really need to make some connectors and seek the best/easiest? way to do that?? if you did you got a bunch of good tips here from the others Thanks. i'll throw in a few other simular options to connectors there are strip tools that can cleanly and safely strip the coax they just spin around and do a great job i've seen cost between 50 to 100bucks depending on coax also you can get a fixed center pin whereby you don't have to solder or crimp, the captivated connectors the outer sheild part gets a crimp only typically a bit of glue on the inside heavy ga heat shrink shrink goes over all they are rated very good soare are the center pins /outer shield that gets crimped using the right tool of course no matter what you use skills at doing the job and inspection/testing of the work will always remain a constant |
#13
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One nick in a
solid center conductor and the center pin connection falls apart inside the connector. Can you say more about this? Or point to some web discussions / photos? Thanks. |
#14
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no matter what you use skills at doing the job and
inspection/testing of the work will always remain a constant Your spacing makes for difficult parsing and comprehension. |
#15
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SparkyGuy wrote:
One nick in a solid center conductor and the center pin connection falls apart inside the connector. Can you say more about this? Or point to some web discussions / photos? Thanks. Any time you nick a solid copper wire it will be severely weakened and will likely break. |
#16
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Any time you nick a solid copper wire it will be severely weakened and
will likely break. Dittos, can short internally too. If it is anything important, the cable should be swept or at least checked for return loss at a higher frequency. Just in case the parts were mismatched out of the bag. Quality control can be a batch problem even in the high end stuff. Good help is hard to find. |
#17
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On Dec 10, 9:58*am, "JB" wrote:
Any time you nick a solid copper wire it will be severely weakened and will likely break. Dittos, can short internally too. If it is anything important, the cable should be swept or at least checked for return loss at a higher frequency. *Just in case the parts were mismatched out of the bag. *Quality control can be a batch problem even in the high end stuff. *Good help is hard to find. I learned to make cables while assisting installation of a Doppler VOR facility . We were sweeping the pre-made cables that came with the system and finding a lot of them bad. We cut open a few of the bad cables and founnd the center conductor was not in the center of the cable. All of a couple of hundred cables had to be remade and cut for proper phase. The other grunt worker Dust Craig and I became very proficient at putting N connectors on RG-214 and using a vector voltmeter. Jimmie |
#18
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On Wed, 10 Dec 2008 01:44:29 -0800, SparkyGuy
wrote: One nick in a solid center conductor and the center pin connection falls apart inside the connector. Can you say more about this? Or point to some web discussions / photos? Thanks. There's not much to say or show. The usual example is the common RG-6/u cable TV coax, that uses the solid center wire as the center pin of the F connector. By necessity, the center wire is rather stiff. There's also no way to immobilize the center wire as there would be no room for the mating jack. If the rotary razor blade wire stripper or half asleep tech with the wire cutters manages to nick the center wire, chances are good that moving the cable around will eventually break the center wire at the nick. Crimp type BNC plugs are also susceptible in the same area. The difference is that the center pin is either crimped or soldered. The center pin is also supported by the Teflon insulator. However, if the coax is moved constantly, as is common with test cables, any nicks in the center wire will eventually turn into a break. This one is particularly insidious because it occurs inside the connector, where both ends of the break are supported in place, resulting in an intermittent, rather than a clean break. Big fat center wires are not immune. They just have a different problem. When one of the heavy stranded center wires from RG-8/u style coax breaks at a nick, it's usually perfectly positioned to short to ground. In the common PL-259 UHF connector, the coax end of the break is not supported, resulting in a difficult to find, and impossible to see, intermittent. In my limited experience, the tools that cause the most problems are the ones with the built in razor blades: http://www.mytoolstore.com/ideal/ide08-07.html http://www.mytoolstore.com/ideal/ide08-06.html#coax http://www.mytoolstore.com/ideal/ide08-08.html http://www.fab-corp.com/product.php?productid=1665&cat=281&page=1 http://www.hyperlinktech.com/item.aspx?id=879 (Note the huge variation in pricing) As long as the blades are sharp they work just fine. However, when the blades get dull, the user tends to bend the cable to assist in the cutting, which sometimes results in a nicked center wire. Cleaning up the stripping job with a pair of diagonal cutters also causes problems. Stripping is also difficult with Teflon insulated wire and non-wicking insulation (marine coax), where the dielectric materials are bonded to the conductors. The best way to strip these materials and to be sure not to nick the wires is with a thermal wire stripper. http://www.teledyneinterconnect.com/products/wire_strippers/wirestrip.asp I got lucky and ended up with pile of these from some aerospace surplus outlet. Very handy. Just take care not to breath the fumes. However, if you're working with LMR-400, LMR-600, or larger, the blades of the thermal stripper cannot expand wide enough to fit the coax cable. Therefore, I suggest getting the correct Times Microwave EZ-Strip coax stripper for these cables: http://www.hyperlinktech.com/item.aspx?id=881 http://www.hyperlinktech.com/item.aspx?id=882 -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#19
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A lot of this would seem to be trade secrets.
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