There is no "knife edge" against the braid,it is a clamping type connector that the braid folds over a stepped insert. I will relate my experience with crimp connectors when we decided to try them for the first time. We had put 22 antennas up on a 500' Rohn 65 tower with crimped on connectors on all the pigtails and 11 of them failed within a month. They had pulled out or had broken the shield braid at the crimp. We did a little non-scientific stress test on crimp vs. clamp pigtails by suspending a weight from the cable ,adding more until they failed. The clamp type took THREE TIMES as much weight before it let go.We also did a flex test and the crimp braid failed long before the clamp one did. That was all I needed to see to change my mind! All were replaced with mil-spec clamp style connectors and are all still in service 20 years after the fact. Company policy was implemented that required all outdoor connectors be mil-spec clamp type Amphenols at all 303 company tower sites. Now maybe you can get away with crimps on some sites,but not up north on the Great Lakes where winds are tough and ice is common. You quickly learn what works and what doesnt and you will NEVER convice me to use crimp on connectors again! I guess I'm old and set in my ways,for good reason.... 73,Lee
Eric Lemmon wrote: >Lee, > >I appreciate your comments, but I can rebut them easily. I have seen too >many clamp-type connectors pull apart, usually because they were >over-tightened during assembly. Take a close look at a MIL-spec clamp-type >N connector, and you can see that the knife-edge component can slice right >through the braid if the nut is over-tightened, allowing the cable and the >center conductor to pull right out of the connector. That seldom, if ever, >happens with a properly-applied crimp connector. Moreover, how often do you >see a technician use a torque wrench to tighten the nut, per instructions? >Most cable techs just wrench the nut until it doesn't move any more- and >that's exactly where the faulty installation occurs. When the proper >crimper is used, that cannot occur with a crimp connector. > >One of the first requirements of a jumper or cable installation is that >there should not be any tension on the connector or the cable. I daresay >that any connector, whether crimp or clamp, that pulls apart did so because >of tension. DUH! A proper cable or jumper installation does *not* subject >its connectors to tension, so there should be no case of connectors pulling >apart! > >As far as consistent results, I think it's a wash. I recognize that an >experienced craftsman can assemble and attach any connector consistently, >time after time. But, time is money. I can install a crimp-type male N >connector on a given type of cable in perhaps 1/2 or 1/3 the time it takes >to install a MIL-spec clamp connector. On a complex job, this disparity may >amount to several hours. If the project engineer knows that a high-quality >crimp connector is just as reliable as a high-quality clamp connector, he or >she will make the right choice. Since the N connector is a >constant-impedance design, there should not be any impedance "bump" seen on >a VNA, regardless of whether it is attached by crimp or by clamp means. > >I will admit that a crimp N connector is not waterproof to the degree that a >MIL-clamp N connector is, but I don't install crimp N connectors outdoors >without a multiple overwrap of bi-seal tape. The final installation is >absolutely waterproof and reliable, as evidenced by several decades of >performance. I happen to prefer silver/gold connectors made by RF >Industries, but equally reliable crimp connectors are made by Amphenol, >Delta, Huber+Suhner, and others. > >73, Eric Lemmon WB6FLY > > >-----Original Message----- >From: Repeater-Builder@yahoogroups.com >[mailto:[EMAIL PROTECTED] On Behalf Of Q >Sent: Tuesday, January 31, 2006 4:53 AM >To: Repeater-Builder@yahoogroups.com >Subject: Re: [Repeater-Builder] Re: Loss through adaptors: > >I have issues with crimp-on connectors. I have seen too many of them >pull apart when used as pigtails to tower mounted antennas.I have also >seen the braid break right at the crimp. Blame it on improper crimping >or the human element or whatever,but I will use the clamp style >connectors. I seem to be able to get more consistent results and better >mechanical strength. I agree with all the other points and will add >proper weatherproofing to outside connections with vapor wrap and Scotch >tape topped off with Scotchkote. 28 years with a large RCC taught me >what works and what doesnt,lessons learned the hard way are not soon >forgotten! 73,Lee,N3APP > > > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
