H2O molecules are pretty small. I'm told that copper oxide eventually turns
from green to black. I use Coax Seal, but it can be nasty to remove-- at least
it seems to do its intended job.
George W1EBI
From George's iPhone
> On Oct 31, 2016, at 6:51 AM, Franki ON5ZO <on5zo@telenet.be> wrote:
>
> Probably not the appropriate forum but there ought to be a technically
> skilled ham here? Sorry that this post isn’t about cheating and what defines
> ‘assistance’. Some contesters have real issues though.
>
> A few weeks ago I was doing some relocating and rerouting of the coaxes
> outside. One RG-213 is used for my active RX loop. It needed a different plug
> on the antenna switching side so I cut the existing one off and prepared the
> cable for a new one. Much to my surprise I found the inner conductor black
> from corrosion. I cut off a few centimeters at a time, but after having cut
> off two meters, it still was black. I have been working with these things for
> ages and I can tell you: it is NOT water ingress. Everything is sealed
> properly. I was a pain to solder the new plug to the center conductor. I had
> to sand the black film off and even then the tin wouldn’t flow.
>
> Last week I took the loop down and cut away the layers of tape that kept the
> feed point coax dry. And dry it was. However I noticed the N male-female
> junction had a green mush developed around the mating pins of the inner
> conductors.
>
> I didn’t pay attention in chemistry class, but I’d label this as corrosion.
> Right?
> Since I have never seen this before, and this is the only coax that ever
> carried DC around here, I assume the DC voltage is the culprit here?
>
> * Can I avoid this?
> * Does it hurt? I seem to remember something about DC and polarity that can
> eat your copper away?
> * My coax shields are tied to a dedicated earth system. Does this relate to
> the corrosion in a good or bad way?
>
> I’m thinking of ways to improve my 80/160 RX situation, and several scenarios
> involve DC over the coax. So I better know what I’m up against.
> Thanks and 73
> Franki ON5ZO / OQ5M
> _______________________________________________
> CQ-Contest mailing list
> CQ-Contest@contesting.com
> http://lists.contesting.com/mailman/listinfo/cq-contest
_______________________________________________
CQ-Contest mailing list
CQ-Contest@contesting.com
http://lists.contesting.com/mailman/listinfo/cq-contest
|