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Author Topic: Antenna radial material??  (Read 2466 times)
AJ4RW
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« on: October 25, 2012, 08:11:31 PM »

I'm in the process of building a fairly large radial field for a shunt fed tower antenna.  I've pretty much depleted my copper wire that I was going to use.  The price for copper wire is substantial and I'm looking at alternatives.  One very promising idea was to use 14 ga aluminum electric fence.  The price isn't bad and I know it has good electrical conductive properties and  17 ga aluminum electric fence is even cheaper but will it work as well?  Is there anything I'm forgetting to consider about using aluminum electric fence that might affect my decision?  Is there any other alternatives I might look at.  I will need over 8000 feet still so buying aluminum electric fence is cost effective for the quantity.   Any advice or suggestions.
Thanks 73 Randy AJ4RW
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K3VAT
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« Reply #1 on: October 26, 2012, 04:38:58 AM »

Hi Randy,

Thanks, but this topic has been thoroughly covered in a number of past posts --- did you try using the search engines?  73, Rich, K3VAT
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K3GM
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« Reply #2 on: October 26, 2012, 05:00:48 AM »

You suspect you will get two responses:
1) Aluminum wire will disintegrate shortly after installing it.
2) Aluminum wire works great for me.

I have a radial field with approximately 5000' of copper wire in it.  In 2008, I placed and additional dozen or so very long surface radials (as they all are) made from high tensil 17 ga. aluminum electric fence wire.  Much of the wire has been covered with thatch and leaves, but where they are still visible, the wire is still very shiny, and shows no sign of corrosion.  Wire under the thatch is somewhat dull, but is neither pockmarked or corroded in any way.  Would I bury aluminum radials under the soil? No.  But from my experience, aluminum electric fence wire works fine for surface use in the 4 years that I've used it.
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W5DXP
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« Reply #3 on: October 26, 2012, 05:15:23 AM »

Any advice or suggestions.

I use 75 ohm coax shorted at both ends, obtained free from my local TV cable company, for my radials. A lot of their coax can be buried and I haven't found a better price anywhere else.
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AJ4RW
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« Reply #4 on: October 26, 2012, 06:57:09 AM »

Rich, I used the search engine on eham but I didn't find the answers I was looking for.  The one thing about aluminum I had never considered was it's decomposition when buried.  I made several inquiries this am and was told by a knowledgeable electrical person that aluminum will corrode over time unless it's insulated.  Since I don't feel like digging the wire out of my mower, I have to bury slightly because I mow this part of the field.  Cable is a possibility but it looks like I'm going to spend some time considering these alternatives but I still like copper.  Thanks for the wonderful replies and thought provoking ideas.
Randy
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W8GP
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« Reply #5 on: October 26, 2012, 10:05:28 AM »

Surplus Center has 5000' spools of 22ga copper wire for $40, it's a little thin but I've had my radials  down for 5 years with no signs of deterioration. Cut your field as short as you can where the radials will go and stake them down with "U" clips made of stiff wire, a cut up clothes hanger will work fine.After a year or so you won't even see them.I mow over mine with no problems.Good luck...
                                 Greg
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W8JI
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« Reply #6 on: October 26, 2012, 11:43:02 AM »

How fast aluminum goes away depends on the soil, how thick the wire is, and what else is in the ground system.

Aluminum certainly is not a first choice for soil contact.

I buy bare #16 copper buss wire. It lasts until something cuts through it, plus I can solder it. Smiley
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AJ4RW
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« Reply #7 on: October 26, 2012, 03:14:49 PM »

Aluminum wasn't my first choice either but the price was right and easy to get.  I've always used copper but it's hard to find any used spools around here.  I'm planning to solder to a copper framework I'm putting at the base of the tower.  I found some surplus 18 ga copper insulated at a very reasonable price from a surplus center so that's what I'll go with.  You're right about burying it but I was afraid of hitting it with mower but I think I'll just let the weeds grow until it covers it, the burying is time consuming and I'm no spring chicken.  The coat hanger was a good idea that I plan to use, a lot cheaper than using landscape fabric pins.
Thanks Randy
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N8CMQ
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« Reply #8 on: October 26, 2012, 10:15:33 PM »

I used coper clad steel wire for my 4BTV radial field, but I am going to use 17 gage aluminum for my next project.
I mow down to the surface, stretch the radials out and pin the end with a 16P nail and a crimp terminal.
I did not use any lawn staples, as the grass was allowed to grow two years before I started mowing the area again.
I also mow high over the radial field.
Insulated wire will outlast bare wire of any type, but adds expense. An alternative is insulated magnet wire.
30 gage copper radials are OK, as long as you have LOTS of radials. I have 125 radials under the 4BTV.
A one pound spool is 3200 feet, and you can get it relatively inexpensive, $18 on amazon.com.
However, 30 gage wire is easily broken, and I have many deer with sharp hooves roaming the area.
17 gage aluminum is $22 for 1/4 mile or 1320 feet. It should hold up well.
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W5DXP
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« Reply #9 on: October 27, 2012, 07:07:58 AM »

17 gage aluminum is $22 for 1/4 mile or 1320 feet. It should hold up well.

It depends on the actual earth ground chemistry. After two years at one QTH, my #16 solid aluminum ground radials were dotted lines under the ground.
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W8JI
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« Reply #10 on: October 27, 2012, 09:12:11 AM »

I used coper clad steel wire for my 4BTV radial field, but I am going to use 17 gage aluminum for my next project.
I mow down to the surface, stretch the radials out and pin the end with a 16P nail and a crimp terminal.
I did not use any lawn staples, as the grass was allowed to grow two years before I started mowing the area again.
I also mow high over the radial field.
Insulated wire will outlast bare wire of any type, but adds expense. An alternative is insulated magnet wire.
30 gage copper radials are OK, as long as you have LOTS of radials. I have 125 radials under the 4BTV.
A one pound spool is 3200 feet, and you can get it relatively inexpensive, $18 on amazon.com.
However, 30 gage wire is easily broken, and I have many deer with sharp hooves roaming the area.
17 gage aluminum is $22 for 1/4 mile or 1320 feet. It should hold up well.

Copperweld is terrible for direct burial. It rots. So can aluminum.

The best wire is reasonably thick solid copper, at least #18 ga.
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N8CMQ
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« Reply #11 on: October 27, 2012, 01:10:45 PM »


Copperweld is terrible for direct burial. It rots. So can aluminum.

The best wire is reasonably thick solid copper, at least #18 ga.


I agree, many materials will decompose in direct contact with soil.
Copper-clad or copper-weld wire will even rot in the air.
At the time I used the copper-clad steel, I was not worried about duration, but cheap.

I am looking at insulation properties and durability of various materials, but I am
also worried about the animal traffic on the area. Size of the wire may help in that regard,
but the hooves of the deer are small and sharp.

I have been looking at stainless wire for the radials, and using aluminum wire for the above
ground portion of the antenna. But I also have been looking at PVC insulated copper for radials.
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