Hi Justin,

A few questions:

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)?
2) Have you tried any kind of "boot" on the outside of the mated
connection to prevent moisture entry?
3) Is there any material applied around the area where the cable
enters the connector?
4) Are those temperatures C or F?
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.
6) Do these connections need to be mated/unmated during normal
operation? If so, how often does that happen?
7) When mating the connectors, are they always carefully tightened
(neither too tight or too loose)?
8) Do these experience any kind of vibration or stress on the cables
after mating?
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?

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
<justin.richards@gmail.com> 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