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Author Topic: Quality & Price of various 14 AWG Stranded Wire  (Read 6992 times)
W5WSS
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Posts: 1597




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« Reply #15 on: October 04, 2012, 10:38:26 AM »

There are two phases worthy of equivalent design considerations. Performance and longevity.
marketplace prices fluctuate The radial system need not.

The longevity of wire in the environment it is installed depends on many factors.

It is prudent to include techniques known to help slow down decomposition of yes insulated Copper wire. Especially if one is going to bury it. Purchasing a Copper conductor insulated wire designed for burial helps maximize longevity and returns dividends from the start.

It is equally prudent to design and build a counterpoise system that maximizes performance.

A word about radial system contribution to overall vertical antenna performance: We can maintenance service the radial wire to radial plate junctions.
We can also visually evaluate the condition of the radial along it's entire length when the system is above ground lying atop and kept that way.

Convenience of buried radials being out of the way costs some performance at higher frequencies.
resting the system on top the ground and maintainable  is a user choice worthy of consideration.

I see KK5J response prior to mine and fully agree.

73




 
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WX7G
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« Reply #16 on: October 04, 2012, 11:11:55 AM »

For very good performance from the 5BTV 20' radials will do the job. 30 to 60 radials and you will be well into the point of diminishing returns.
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WB2QIG
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Posts: 25




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« Reply #17 on: October 04, 2012, 12:51:55 PM »

Thanks all for the additional info. I can get my radials out to 65 feet on one side, 45 on the opposite. The remaining two sides are going to be just 20 feet each. I hope that is clear! The garage on one side and the property line on the other side comprise the 20 foot sides. As for the number of radials, I have time on my hands so I'll put down the 60 radials. What the heck.

Maxwell
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KK5J
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Posts: 76




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« Reply #18 on: October 04, 2012, 01:54:03 PM »

Maxwell

When I decided to put out radials, I did so in 20 radial sets. 20, 40, then 60. As WX7G has said, 30 to 60 does the job. I will say 40 did it for me. I saw no performance enhancement from 40 to 60, but I did see noticeable improvement from 20 to 40. FWIW

Bob
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WB2QIG
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Posts: 25




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« Reply #19 on: October 04, 2012, 04:05:45 PM »

Bob, interesting idea. I did locate single strand 14 AWG single conductor uv resistant wire. It was listed in of all places dog fence wire. I'll use your idea of putting radials down in sets of 20.

Appreciate your help.

Maxwell
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N4CR
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Posts: 1650




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« Reply #20 on: October 04, 2012, 07:44:54 PM »

6. Insulation protects the radials from corrosion. Copper does indeed corrode. When it does-and bare copper on/in the ground WILL ALWAYS CORRODE, the RF resistance of copper rises significantly and that rise is frequency dependent(skin effect). Two orders of magnitude increases in resistance have been measured due to corrosion. This can be found at various places on the internet. Do your own search. Resistance of copper has been used for many years in instruments that quantify corrosion- resistance increases as corrosion increases.

The lifespan of copper in most soils can be measured in the hundreds of years. Test the pH of your soil. If it's not acidic, it's not going to eat your copper. If it's acidic then you can still use bare copper if you build a sacrificial anode into the system. Similar to the sacrificial anode on a boat except the radial field sacrificial anode is buried in the soil. You can use zinc or magnesium. If you use zinc, you'll have to supply the sacrificial voltage but it costs less. Magnesium provides it's own anode voltage. Any old magnesium rim that got bent would be perfect.

Greenish brown patina on copper is a pretty good conductor and protects copper from further chemical changes. It is a stabilizing influence.

For every AM radio station where you say their radials corroded away, I can find 100 that didn't.
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73 de N4CR, Phil

We are Coulomb of Borg. Resistance is futile. Voltage, on the other hand, has potential.
KK5J
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Posts: 76




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« Reply #21 on: October 05, 2012, 07:28:36 AM »

Lifespan isn't the issue and never was. The issue is surface roughness and how it relates to resistance at RF.  It really doesn't do any good to have a radial with a high RF resistance (say greater than the 37 ohm resistance of a vertical) whether its too small a diameter or due to increased surface roughness. I agree that the green patina/brown discoloration of copper oxide provide a protective coat to prevent complete deterioration. It is, however, a corrosion product that increases the surface area/surface roughness significantly. While your comments on soil are noted, "eating" copper isn't the issue, its whether you have copper losses that will disturb the surface roughness of the original wire and/or reduce its effective diameter. This can occur due to inherent soil conditions-such as acidic soil, the presence of a corrosion cell, or repeated washing/drainage action and movement of soil.

AM broadcast radials, as you mentioned, have been replaced due to corrosion. So much for lifespan in hundreds of years. Those radials are larger (10 ga), longer, and much more numerous than what amateurs typically use. They are utilized in a lower frequency system where RF resistance versus wire diameter/roughness is much less critical. As a result, I would not expect their rate of replacement to be any indicator of the suitability of bare copper radials for a multiband vertical.

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N4CR
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Posts: 1650




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« Reply #22 on: October 05, 2012, 12:15:27 PM »

I agree that the green patina/brown discoloration of copper oxide provide a protective coat to prevent complete deterioration. It is, however, a corrosion product that increases the surface area/surface roughness significantly.

I'd like to see your cite on that. I can't find any reference to it and I've been searching for hours.

If you're at all concerned that you might add a few percentage points of RF conductivity, lay 4 more radials and forget about it.
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73 de N4CR, Phil

We are Coulomb of Borg. Resistance is futile. Voltage, on the other hand, has potential.
KK5J
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Posts: 76




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« Reply #23 on: October 05, 2012, 12:46:47 PM »

Actually Im not concerned about it. I just use insulated wire. Thats all it takes and its not much effort-or expense. Might try scanning electron microscopy/copper corrosion.
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KF7NUA
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Posts: 153




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« Reply #24 on: October 05, 2012, 03:14:50 PM »

Talking about copper in the ground has me asking a question.
What if you live right next too the largest Copper mine's you would ever see, they go for miles and miles around where I live? Would the antenna still need a radial field?
« Last Edit: October 05, 2012, 03:23:30 PM by KF7NUA » Logged
K0ZN
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Posts: 1525




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« Reply #25 on: October 05, 2012, 04:06:03 PM »

Yes. You still need radials even if you live near a copper mine. Lots of them!  There is little relationship between the small amount of copper in copper ore and the conductivity of your ground system.  The copper in the ore is locked in various kinds of rock.

Other than sea water, almost no earth ground is anywhere near the conductivity of copper or other metal at RF. Even "good" ground is not all that great in terms or conductivity for RF. I lived in your area so I am quite familiar with your ground/soil.   Basically, most of Arizona is an INSULATOR !!  .....Chuckle......

The critical area around a ground mounted vertical is the near field, typically extending out about 1/4 wavelength. With most typical 1/4 wave verticals the current is highest
near the base of the antenna, so that is where the radials are most important.

Bottomline:  dirt, dry dirt, and especially dry desert rocky soil are very poor conductors of Radio Frequency current compared to copper wire.

If I lived in the desert and wanted a vertical, I would consider either a true Ground Plane antenna or something with elevated radials.

73,  K0ZN
« Last Edit: October 05, 2012, 04:09:36 PM by K0ZN » Logged
AE5JU
Member

Posts: 223




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« Reply #26 on: October 10, 2012, 09:03:42 PM »

This is what I use, MTW.  After about 6 years it is still soft and flexible.

http://www.wireandsupply.com/product_p/mtw-14g.htm

http://www.wireandsupply.com/product_p/mtw-12g.htm

Paul - AE5JU
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W9DEC
Member

Posts: 47




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« Reply #27 on: October 20, 2012, 07:38:19 PM »

I,m just finishing the installation of my ground radials and  I must say it was a very hard task for an old  man. I am putting up a 6BTV and using dx engineering wire. My original plan was to lay the wire on the grass, staple it, and let Mother  Nature do her thing. I have St. Augistine grass that is very thick and the wire would just lay on top. The tech at dx said I shoud slice it to allow the wire to get to the ground. Slicing is not easy to do!  I elected  to buy a small edger with a metal blade which allowed me to  make a slice for my radials. It was a hard job but  I  did put down 40. Hope it works well to pay me back for all my manual labor.

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