[Elecraft] Antenna Wire

[Jim Wiley]

Time for just a short note -

I have used nothing but copperweld for antenna wire for 40 years, never 
had a span fail due to corrosion, or for that matter, for any other 
reason.  And, I have always lived in coastal communities.   I normally 
use #12 AWG wire for antennas, #16 AWG for things like open wire feeders 
(I make my own lines).   I agree that there are different quality levels 
for this wire.  The brand I use is Crown Metals, and it has never let me 
down.  As a side note, when I worked for the phone company up this way, 
we had some open wire spans for telephone service (both direct and 
carrier).  These spans survived harsh Alaskan winters for more than 50 
years.  They normally used #10 AWG for "regular" spans of up to 250 feet 
between poles, and #8 AWG for long spans, up to 500 feet. Crown metals 
brand products are available from AES, the last time I looked, and 
probably from most of the other vendors of antenna parts you see in QST. 


Yes, copper clad wire gets an outer layer of copper oxide, but there 
seems to be no degradation of performance.  I dislike insulated wire 
because water can creep inside the insulation, and that can be bad news 
for any antenna.   Using house wire is not a good idea, as it is not 
very strong for its weight, and it is carrying the added load of plastic 
insulation.  Stretching regular wire about 10% will harden it 
considerably, but this only approximates "real" hard drawn wire - which 
does not stretch appreciably. 


Also, there is no rule that says you have to use copper.  Aluminum 
electric fence wire works well, but you have to remember to use an 
anti-corrosive coating at the joints.  A typical product is "Noalox".   
Fence wire is light weight, inexpensive, and quite strong per unit of 
length. 


Try to find 14 or even 12 gauge if you can, but smaller sized work for 
most uses.  Larger diameters are better both from a strength perspective 
and have less ohmic losses.  However, in a pinch, any size is better 
than none.  For low power work, I often use 24 gauge  magnet wire for 
temporary antennas, and it always performs well electrically, even if it 
has trouble surviving storms. 


Here's a hint for making your own open wire feeders:  For spreaders, I 
use a plastic material sometimes called "UHMW" (stands for Ultra High 
Molecular Weight, I am told).  This is a black UV stabilized material 
that is nearly indestructible.  I get it in 1/2" thickness, and use my 
standard wood bandsaw to cut it into strips about 1/2" square by 5" 
long.  Drill a couple of 1/8" holes about 1/2" in from each end, and 
attach the insulators to your feedline with tie wires,  spacing then no 
closer than 3 or 4 feet.  25 of these spreader insulator thus make a 100 
foot open wire feeder.  Use #16 AWG  copperweld for the feeders, #18 for 
the tie wires.  Solder each tie wire to the main feeder wire.  BTW - the 
tie wires go through the holes, not the feeders  I have had such a 
feeder up for 30 years, and it has never failed.  It will also take any 
(legal) level of power you care to use.  There is no significant heating 
or other  distress at  1500 watts CW, even when working with high VSWR 
(8:1 mismatch or more), and in rain or snow.  The plastic can often be 
obtained from your local vendor of plastic products as "cutoffs" for 
significantly reduced prices.  The material is commonly used for sled 
runners, boat fenders, dock fenders, and so on.   UHMW is also suitable 
for end insulators,  Cut a length about 8" to 10" long by 1" wide (from 
the same 1/2" thick material), drill a 1/4" hole about 1" in from each 
end, and you're good to go.  Such an insulator held a 700 lb test load 
without difficulty.  It might have held more, but the wire I was using 
to support the weights broke.


Good luck, and 73


Jim, KL7CC





N2EY at aol.com wrote:

>In a message dated 9/8/2004 5:40:06 AM Eastern Daylight Time, Charles Greene <W1CG at QSL.NET> writes:
>
>  
>
>>If you live near enough sea water to get an >occasional sea spray, the 
>>copperweld  copper clAdding will corrode green, >then the core will rust in 
>>several places.  After that the wire breaks if >flexed like.  
>>    
>>
>
>It doesn't require salt spray to do that, either. Just takes longer.
>
>What happens is that *any* break in the copper cladding can let in moisture, and set up an electrolytic corrosion situation. The steel core corrodes like mad because it's essentially the cathode in a copper-steel cell whose plates are shorted. Of course salt water makes a better electrolyte than rain water, but any sort of ions in the water help things along.
>
>Pretty soon you have a piece of copper tubing and the wire fails.
>
>There are different levels of copper cladding, too - some are much thicker than others. There are also versions with insulation, which tends to protect the wire everywhere except joints. Joints can be protected by Plumbers Goop or similar noncorrosive sealer. 
>
>Some folks swear by copperclad, others swear at it, but it *is* the strongest stuff for a given gauge.
>
>In the end, a lot depends on your replacement philosophy. Some folks replace before it falls down, others after...
>
>73 de Jim, N2EY
>
>I didn't used to believe all the stuff about acid rain and UV exposure until I saw what my wire antenna hardware looked like after 5 years aloft. Not pretty!
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