[TowerTalk] how to keep water out of fittings

[cqtestk4xs at aol.com]

Sealing coax doesn't have to be messy.  I wrap with a silicone tape.  Then I  wrap with black electrical tape.  I finish it off with a couple of coats of liquid tape.  Even on the rainy side of the Big Island of Hawaii never a problem.  Plus, it's pretty easy to remove.  Just cut with a utility knife and peel back.

Bill K4XS/KH7XS



-----Original Message-----
From: George Harlem <george.harlem at gmail.com>
To: Franki ON5ZO <on5zo at telenet.be>
Cc: cq-contest <cq-contest at contesting.com>
Sent: Tue, Nov 1, 2016 2:30 pm
Subject: Re: [CQ-Contest] oxidized inner conductor when coax carries DC power

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 W1EBIFrom George's iPhone> On Oct 31, 2016, at 6:51 AM, Franki ON5ZO <on5zo at 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 at contesting.com> http://lists.contesting.com/mailman/listinfo/cq-contest_______________________________________________CQ-Contest mailing listCQ-Contest at contesting.comhttp://lists.contesting.com/mailman/listinfo/cq-contest