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Re: Topband: radial wire size

To: topband@contesting.com
Subject: Re: Topband: radial wire size
From: Herbert Schoenbohm <herbs@vitelcom.net>
Date: Wed, 15 Apr 2015 11:53:27 -0400
List-post: <topband@contesting.com">mailto:topband@contesting.com>
In AM broadcast installations the use of buried copper wire (bare) smaller than #10 is considered unacceptable. Here in the Caribbean cooper thieves have found radios stations a good source for black market copper wire and some stations replace thier systems with barbed wire which is harder to steal but very difficult to install. Depending upon the soil the ability to last more than a few years he use of such a solution is very questionable.


Herb Schoenbohm, KV4FZ

On 4/15/2015 11:43 AM, donovanf@starpower.net wrote:
Hi Jorge,


Bill is almost correct, in most soils mechanical durability is the only
consideration for long term durability of copper wire, but out of sight
out of mind can be a big problem for radial systems in at least two cases.


Galvanic corrosion will damage a buried radial system i f small (or large!)
electrical currents flow from the shield of your coaxial cable into your radial
system. Of course, small diameter wire will fail more quickly than heavier
wire. This is not a trivial consideration because in many installations the
buried radial system has significantly lower ground resistance than any
other ground in your home or in your station. You can determine if this is a
problem in your installation by using a milliammeter (or a common VOM)
to check for shield current.


Corrosive soils may damage a buried radial system. Fortunately most soils
are not corrosive for copper but there are important exceptions, some
examples are:
- soils with large quantities of organic matter,
- poorly drained soils such as wetlands,
- soils with a history of heavy agricultural use with farm animals or 
fertilizers
- soils containing materials such as cinders or cinder blocks.


73
Frank
W3LPL







----- Original Message -----

From: "Bill Wichers" <billw@waveform.net>
To: "Jorge Diez - CX6VM" <cx6vm.jorge@gmail.com>, "topband" 
<topband@contesting.com>
Sent: Wednesday, April 15, 2015 2:27:01 PM
Subject: Re: Topband: radial wire size

The only real difference when using reasonable-gauge sizes is in physical 
durability. Electrically it makes little difference since you effectively have 
a large number of radials in parallel so each one carries only a relatively 
small percentage of the overall current in the system.

I use 18 gauge bare solid copper on my radials. I use that size since I 
consider it a practical minimum in terms of physical durability and I can get 
it for around $50/thousand feet from my supplier (although they have a 5,000 
foot minimum order). I've had some 60+ radials in place for about 4-5 years 
without any problems. Once the copper turns a dull-brown color after the first 
season it's almost impossible to see on the ground.

A lot of people use 14 gauge since that's a commonly available size for building wire in 
the US. It's easy to get through "regular" (hardware store) channels and it's 
strong. There isn't really any electrical advantage to the heavier wire -- you won't 
notice any difference in performance.

I think you'll be fine with the #17 wire you have access to. Save the money on 
the smaller radial wire and spend it somewhere else where it will make more 
difference in your overall antenna system.

-Bill

Hello



Thinking in a 4 SQ, buried radials, 60 or more on each vertical



What is the difference in performance between installing radial wire size
#14 (2.08 mm2) or #17 (1.04 mm2) ?



#14 is the size that DXE sell, so I think is a good size for radials. But what 
about
#17?



In $$$ is the half J, so want to know what I am loosing in performance, if any



Thanks in advance



73,

Jorge

CX6VM/CW5W



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