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