[Antennas] Wire mainenance

[JK]

To: "Dave Sublette" <k4to at arrl.net>
It seems moisture got under the wire insulation and caused corrosion. I 
found that same problem years ago when I tried using insulated wire 
outdoors. I've been using bare wire for antennas for years and have not 
encountered those corrosion problems that were common with insulated 
wire.

With stranded wire especially, water can 'wick' through it quite easily. 
If the strands are covered with plastic insulation, the water cannot 
easily evaporate and corrosion will start. One can see similar corrosion 
on the braided copper shields of coaxial cables. 


Two or three coats of Liquid Tape covering the ends of your wires as 
they emerge from the insulation will help keep water out but you must 
also use the Liquid Tape on all of the exposed wires. Coax Seal is also 
very good at keeping out water and air, the components needed for 
corrosion to start.


Cover the connections with white electrical tape to prevent UV breakdown 
of the surfaces of the Liquid Tape or the Coax Seal .


U can probably re-use those wires that measured 0.3 - 0.7 ohms but I 
would discard the other two that read higher. Use solid bare wire for 
the replacement radials.


Before sealing up the wires that you will reuse, I suggest placing them 
in an oven for about 2-3 hours at about 125 degrees to try evaporating 
out any moisture that may be trapped between the wire and insulation. 
Seal the wires when it is a dry day and humidity is low. Cold air holds 
less water than warm air.


Good luck with it and many more years of hamming to you!


Jay...NE2Q

On Mon, Mar 27, 2017 at 08:14 AM, Dave Sublette wrote:
> I tried to post this last night, but I think it went to the wrong 
> address, so here goes again:
>
> Good evening,
>
> I have had almost 2000 feet of #14 polyethylene black jacketed 
> Flexweave in the air for over ten years.  The wire is used to form 8, 
> 130 foot radials for my elevated 160 meter vertical and four dipoles 
> for 3230 KHz. I recently had to take the dipoles down for maintenance. 
> The outer jacket looked as if it were new. The center insulator 
> section is the “Acrobat”, which uses stainless steel screws to secure 
> the connections between the coax and the dipole wires. These 
> connections were corroded to the point that electrical contact was 
> lost.   In addition, the flexweave, under the polyethylene coating, 
> was corroded on both ends when I stripped back about a half inch of 
> the coating.  The resistance of each of the eight wires was measured 
> to be between  0.3 and 5.3 ohms.  6 of the wires measured between 0.3 
> and 0.7 ohms.  The remaining two measured 2.1 and 5.3 ohms.  This was 
> after I cleaned and tinned the ends.  However, I didn’t use the acid 
> flux bath recommended in the technical paper on the website.  I will 
> do that soon.
>
>
> I have one overriding question.  How do I prevent the corrosion from 
> reoccurring?  Do I  1) coat the stainless steel to copper connections 
> with Pentrox, No-alox,  or some similar electrical joint compound?  2) 
> Seal the connection with some sort of epoxy, or caulking?  And 3)  If 
> I can restore the end to end low resistance of  0.3 ohms or better, 
> using the acid bath treatment on each end,  Is the wire still useable 
> for antennas and ground radials, even though I know there is corrosion 
> on the individual wires under the polyethylene coating?  Do I need to 
> take down the radials and treat them?
>
>
> I am 75 years old, a graduate BSEE, and an extra class amateur for 60 
> years.  This will probably be the last time I put this array up.  I 
> want to do it the best way possible.  At least there isn’t salt in the 
> air in Kentucky as there would be on a beach somewhere….
>
>
> 73,
>
>
>
> K4TO
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