The proper seal on such connectors includes the application of a piece of heavy heat shrink tubing that has a sealant on the inside. Industry standard is to supplement even that with a coating of tape and another layer of protection such as Scotchkote. There is even a certain way the tape is applied to resist contamination ingress. If these connectors are outdoors, then they were not properly sealed and that is why you have water ingress and the resulting corrosion. As for laying the cable in the elements unprotected, I suspect you are correct that it was contaminated, and I would not be surprised if your cable is experiencing corrosion as well. I would seriously consider contacting the company that installed these cables and force them to correct the underlying problem, although if you supplied the cable, they may say you supplied contaminated products. Regardless, they should replace the connectors and attach and seal them properly. At this point, it may not solve the problem, as you likely have water laying in your cable. I'm a relative newbie to PICS, but I have over 30 years in the radio communications industry which includes extensive use of this cable. When these connectors are installed and sealed properly, they should last decades with no issues, as I have many that are decades old and still perform to spec. I've also had many customers who have had problems, and each time it came down to improper installation or improper sealing (done by other companies - many of them "reputable") - with the occasional piece of Heliax that suffered from bullet holes or vandalism. Joe M. Justin Richards wrote: > As mentioned ... > > There is no boot but a Orange washer that seals the 2 sides of the connector > and a grey SPINNER Plast 2000 is sqeezed in thru a purpose made hole > in the side of the connector to fill the space around the cable and > the inner of the connector. > > The washer you speak of we think is a orange silicon washer and they > are in use and have been injected with Plast 2000. > > We suspect that as it took approx 18 months+ to build (this is a large > receive array) that at some stage cable would have been laid but > un-terminated. It is is easy to consider that at one point in time it > would have rained and contaminated the cable. > > This is only a guess. > > The cable can not really be replaced because concrete was poured on > top. I do not know why. But it was a large reputable company that > was tasked with building the array and laying the numerous cables. > > My main concern at the moment is that we are being told to apply this > grease and i need good arguments or evidence where we can clearly show > that this is a very bad idea. > > I have mentioned that I believe over time we will do more damage than > good using the grease but we are at at risk of being over ruled unless > I can clearly demonstrate it is bad. > > So we are interested in peoples experience using the silver conductive grease. > > Cheers Justin > > > On 21 February 2010 15:12, MCH wrote: >> This really sounds like you haven't weatherproofed the connectors >> properly. How are you sealing them? Did you use the rubber gaskets that >> come with them? >> >> Joe M. >> >> Justin Richards wrote: >>>> 1) What kind of plating is there on these connectors (both the male >>>> and the female, and both on the shield conductors and on the center >>>> conductors)? >>> The male side is the LDF450 rigid coax that has been trimmed back and >>> prepared to take the connector. The connector has a female side the >>> takes the LDF450 and male side that has a N type male connector. The >>> N-Type male connector interfaces to a female N Type connector >>> typically on a Balun or Combiner. The N-Type part of the connectors >>> always appear fine. It is the end of the LDF450 with a copper center >>> conductor that tarnishes (which we have to disassemble the connector >>> to get at). The female part of the connector also appears fine. >>> >>> LDF450 inner conductor is aluminium with a copper coating. So the >>> mating surface is copper. >>> LDF450 shield is copper >>> Connector female side appears to be aluminium (aluminum) whitish silver >>> Connector N type side appears to be aluminium (aluminum) whitish silver >>> >>> >>>> 2) Have you tried any kind of "boot" on the outside of the mated >>>> connection to prevent moisture entry? >>> There is no boot but a Orange washer that seals the 2 side of the connector >>> and a grey SPINNER Plast 2000 is sqeezed in thru a purpose made hole >>> in the side of the connector to fill the space around the cable and >>> the inner of the connector. >>> >>>> 3) Is there any material applied around the area where the cable >>>> enters the connector? >>> Yes, as above. >>> >>>> 4) Are those temperatures C or F? >>> C >>> >>>> 5) Is the connector part number you gave for the part on the cable or >>>> the part it mates to? It would be helpful to know both kinds. >>> That part number as far as I can tell identifies the connector as a >>> whole but is made up of 2 halves (6 separable parts:- N Type side, >>> Cable Side, washer, two cable collars that go around the outer >>> conductor, 1 collar that goes around the dielectric and 1 M9 grub >>> screw that fills the entry hole for the Plast 2000. >>> >>>> 6) Do these connections need to be mated/unmated during normal >>>> operation? If so, how often does that happen? >>> No, they should not need to be touched only when our tests fail. >>> >>>> 7) When mating the connectors, are they always carefully tightened >>>> (neither too tight or too loose)? >>> We have a specially made 20Nm torque wrench IAW the connector specs >>> that is used to tighted the two halves of the connector body. >>> >>>> 8) Do these experience any kind of vibration or stress on the cables >>>> after mating? >>> No stress or vibration. Except aileron noise (I think thats what it >>> is called, the noise generated by the wind blowing past the antenna) >>> and the stress of heating and cooling on the rigid LDF450. >>> >>>> 9) How much power is transmitted through these connections? What >>>> frequency range? How much variation in attenuation and phase are you >>>> seeing for failed connections? >>>> >>> HF, receive only power, a small dB variation (I am required to be >>> ambiguous here) between similar receive paths will flag a fault. >>> >>> >>>> It almost sounds to me like the connectors aren't making a proper >>>> gas-tight seal and you are getting normal silver sulfide tarnishing. >>>> Another possibility is that you are actually using incompatible >>>> connectors (like, for example, a gold-plated one on one side and a >>>> tin-plated one on the other) and you are getting incompatible metal >>>> effects, or you are getting fretting corrosion between connections >>>> which can move very slightly over time. >>>> >>>> You mention a copper center conductor - I have never seen an N >>>> connector which uses a copper, unplated center pin or any unplated >>>> parts. To what are you referring here? >>>> >>>> Sean >>>> >>>> >>>> On Sat, Feb 20, 2010 at 10:54 PM, Justin Richards >>>> wrote: >>>>> We have an application that involves over 1000 N type connectors >>>>> exposed to the elements and from time to time tests indicate that the >>>>> phase or attenuation values are outside limits. >>>>> >>>>> Often an investigation reveals that the inner copper conductor has >>>>> tarnished/turned black/blue and a clean with some fine sandpaper and a >>>>> re tighten returns the connector to a serviceable state. >>>>> >>>>> However, for some of these connectors we find a short time later that >>>>> they have once again tarnished and thus we suspect that there must be >>>>> moisture in the cable and it is a constant battle repairing these. >>>>> >>>>> Recently someone suggested we use Conductive Silver Grease on the >>>>> conductor inner. >>>>> >>>>> I have concerns that perhaps silver may react with the copper, or that >>>>> as these connectors withstand extremes in temperature and this may >>>>> cause the silver grease to slowly weep and find a way that results in >>>>> the dielectric becoming contaminated over time. >>>>> >>>>> The length of these cables are important so if the end was to be >>>>> contaminated cutting the cable would present a serious issue. >>>>> >>>>> Anyone had experience using conductive silver grease for this type of >>>>> application. >>>>> >>>>> The cable is LDF450 and the connectors are RFS-H15566001 and >>>>> temperature ranges from 0 - 50 deg. >>>>> >>>>> The technical data indicates that it is good for this range but mainly >>>>> concerned that over time the grease will move especially as the >>>>> connectors are unfavorably oriented and exposed to the elements. >>>>> >>>>> Cheers Justin >>>>> -- >>>>> http://www.piclist.com PIC/SX FAQ & list archive >>>>> View/change your membership options at >>>>> http://mailman.mit.edu/mailman/listinfo/piclist >>>>> >>>> -- >>>> http://www.piclist.com PIC/SX FAQ & list archive >>>> View/change your membership options at >>>> http://mailman.mit.edu/mailman/listinfo/piclist >>>> >>>> >>>> ------------------------------------------------------------------------ >>>> >>>> >>>> No virus found in this incoming message. >>>> Checked by AVG - www.avg.com >>>> Version: 9.0.733 / Virus Database: 271.1.1/2700 - Release Date: 02/20/10 14:34:00 >>>> >> -- >> http://www.piclist.com PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >> >> >> ------------------------------------------------------------------------ >> >> >> No virus found in this incoming message. >> Checked by AVG - www.avg.com >> Version: 9.0.733 / Virus Database: 271.1.1/2700 - Release Date: 02/20/10 14:34:00 >> -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist