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Arc over in F fittings on satelite dishes

C

CaptBob92

I just ran into something again today that I've noticed several times when I repair a satelite dish and I'm wondering if anyone else has seen this.

When I open the F fittings at a barrel connector ( aka butt splice ) I frequently find a trace of copper running from the center conductor to the shield across the dielectric of the f fitting but never on the barrel connector. It looks like rust. It doesn't happen on all f fittings but only one per installation. Do you think this is the result of lightening? moisture? Any ideas?

I'm in South Florida where the humidity is usually very high. maybe that has something to do with it although I always tape the fittings to keep water out.
 
Howdy,

Had the same problem here in indiana. I had the worst time with the xds. I found the one connection outside (which was taped) had been apparently rusting. Exactly what you are explaining. I have 4 dishes and this is the only problem. Faces SW. Heavy humidity just like FL.

I have opened the sealed connector 5 times in the last 2 months. Recently added a silicone material to the innards to further isolate the connection. We are on day 7.
 
I wonder what direction it is in?
Maybe gravity helps to move a very small trace of moisture across the insulation. If there are dissimilar metals there, it could cause some small migration of the copper atoms, especially since there is a DC voltage on the line too.

Are you sure it's not just corrosion, which could be somewhat conductive (especially at RF frequencies)?
 
It's not corrosion but you make a good point about dissimilar metals. I've always been concerned about barrel connectors withan aluminum conductor inside being used with coax with copper as the center conductor. Doesn't this always create problems? Since just about all the RG6 coax I've seen uses copper for the center why can't you find barells with copper in them in most shops?
 
Capt. Bob-

If you suspect a moisture problem, satellite supply houses sell a teflon-based waterproofing compound that is supposed to seal moisture out of the F-connectors. This is not a fix, but may help.

What is more permanent is to really seal out the moisture. Scotch makes what they call "electrical splicing tape", a rubber tape that can be tightly stretched and wrapped around the connector, coax, and connection. This tape, stretched tightly, bonds to itself and becomes a solid piece of rubber. If used at a butt splice - wrap it tightly around the last 1 or 1 1/2 inches of coax, over the F-connector, barrel, second F-connector, and onto the first 1 or 1 1/2 inches of your second coax line.

This splicing tape has to then be covered with a spiral wrapping of vinyl electrical tape, and I strongly reconmmend Scotch because of the superior adhesive that will be needed in the winter-to-summer temperature changes. Get both at your local electrical supply house.

In 15 years of repairing satellite systems, this is the ONLY method successful to seal out moisture
from spliced RG-6 or RG-6 connections. Even the splicing kits... where you seal a spliced line in silicone rubber or epoxy... don't work. WNRR forever!!!
 
You should be sealing the f connector with amalgamating tape only.
This is special rubber type tape that chemically bonds to itself within 24hrs.
The upshot is that after wrapping one continuous spiral from lnb/f connector/cable it forms one sleeve,also tension somewhat whilst spiralling,but don't overstretch it !
Also do this when dry not raining.
 
One layer of Scotch amalgamating tape. One coat of Scotchkote<tm>one more layer of sticky. One layer of regular Scotch 33. Haven't had one leak yet.
 
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