Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1] 2 Next   Go Down
  Print  
Author Topic: Solid core 20 gage copper boundry wire antenna $32 for 500 feet  (Read 4125 times)
KF7ITG
Member

Posts: 82




Ignore
« on: November 09, 2010, 03:19:09 PM »

Looking for some inexpensive wire to string in the trees while camping? This solid core 20 gage copper boundry wire would work well as a full wave Loop Skywire antenna or maybe a Dipole or use some for radials. The stuff is cheap enough to play with. $32 for 500 feet.

http://www.amazon.com/PetSafe-500-foot-Spool-20-Gauge-Boundary/dp/B0017DGFSA
« Last Edit: November 11, 2010, 07:19:07 PM by James Angleton » Logged
W6USC
Member

Posts: 5




Ignore
« Reply #1 on: November 10, 2010, 08:13:53 PM »

thanks great info just bought some
Logged
K0BG
Member

Posts: 9863


WWW

Ignore
« Reply #2 on: November 11, 2010, 02:40:37 PM »

Wrong forum, but...

It will work about as good as steel fence wire, and unless you have some reference to judge it by, you might assume it's just great for the job at hand. It isn't!
Logged

KF7ITG
Member

Posts: 82




Ignore
« Reply #3 on: November 12, 2010, 12:48:21 AM »

I know Alan is an authority in the field of ham radio and I respect his thoughts on the matter. I have spent hours gleaning 411 from his web site. If Alan of someone else could expand on this explanation of why this wire won't work for antennas I would be greatfull. I'm still new to the Ham Radio game so any help will be appreciated. My original thought was everyone seems to be looking for reasonably prices parts so when I saw this Hard drawn solid copper 20 gage wire, about 1/32 of an inch, I thought this may be something others could use for Mobil camping antennas.It's cheap enough to through away. I had read in one of my ARRL wire antenna books that thin wire worked well except it had a tenancy to break. This stuff is strong. I was going to order several more spools of this wire but if there is a reason that it won't work for antennas then ............... Thanks for your help.   
James

It will work about as good as steel fence wire, and unless you have some reference to judge it by, you might assume it's just great for the job at hand. It isn't!
Logged
K0BG
Member

Posts: 9863


WWW

Ignore
« Reply #4 on: November 12, 2010, 06:22:22 AM »

Almost anything will work to some extent.

Steel wire, especially some types of stainless steel wire, don't work well because of their permeability. For example, a standard old CB whip, mounted atop an 80 meter mobile antenna will exhibit about 2 dB of loss when compared to a similar one made of aluminum. As the frequency goes up, the losses go down, but there is always some conductor loss. Even if the wire in question is copper, the fact it has insulation over it has an effect. How much depends on unknown factors.
Logged

K5LXP
Member

Posts: 4482


WWW

Ignore
« Reply #5 on: November 12, 2010, 06:33:47 AM »

Well, the thread title says it's copper, but I can't find any specification online other than links to a thousand vet supplies that sell it.

The primary question will be whether or not it's really copper or copper plated, and the secondary question is how durable it would be as antenna wire.  Solid copper wire that thin will stretch over modest spans, and will fatique from motion sooner than stranded or thicker solid wire.

Lastly, there's expectation.  If the goal is a temporary antenna that can make a contact, just about any wire will work.  If the goal is longevity and performance, then it's probably best left to keeping K9DOG in the yard.


Mark K5LXP
Albuquerque, NM
Logged
KF7ITG
Member

Posts: 82




Ignore
« Reply #6 on: November 12, 2010, 12:49:31 PM »

I believe the wire is copper. My point was not longevity or tremendous performance. It was about $32 for 500 feet of copper wire that may work well as an antenna. Unlike Home Depots 500 foot spool of 18 gage copper wire for $156. I am not saying the pet safe 20 gage is good for anything. Well thats not exactly true it will get a dogs attention if he goes near it. All I can say is it is what it is.

Alan, K0BG and Mark, K5LXP have much more knowledge than I have in the field of antennas and radios. I sent you both a 10 foot sample by way of snail mail today. Please let me know what you think. I continually read that people are looking for ways to put up economical antennas. I thought possibly I had run into something good and affordable that other Hams might be able to use. I could be wrong.

Simple test on the Pet Safe 20 gage boundary wire.

First I carefully filed the end of the wire. After inspection with 10X lenses I found no indication of any steel.
Next I took a 10 foot section and attached insulators in typical fashion to each end. I hung the wire from the 12 foot ceiling of my shop. I hung a plastic bucket on the end which gave me an 11 inch clearance to the floor. I loaded the bucket with five lbs of lead to take any slack out of my wire wrap connections. The bucket at this point was 10 ½ inches above the floor. I added weight until it reached 34 lbs and the bucket was at 9 7/8 inches. I continued to add weight. At 36 lbs the wire started to stretch with each ½ lb weight added. At 38 lbs the wire failed. It didn’t break it just suddenly stretched and the bucket sank to the floor. I am sure if the bucket would have been higher it would have parted the wire.

So this is where my math takes me. I’m no mathematician but here it is.

First the wire is insulated. Does this make any real difference you can decide.
The wire weighs one oz. per 15 feet or 240 feet per lb.
The wire starts to stretch at about 32 lbs.
32 lbs of wire equals 7680 feet.
For a fail safe antenna use only 25% of the 32 lbs of wire in any one antenna or 8 lbs.
8 lbs of wire equals 1920 feet of wire.
Add wind, snow, tree movement and kids swinging from it take away another 75%.
25% remaining of 1920 feet still leaves you with around 500 feet of wire with a good safety margin.

I don’t know if any of this 411 helps. Clear as mud so they say. Alan and Mark thanks for the input.

James

Logged
KE3WD
Member

Posts: 5689




Ignore
« Reply #7 on: November 12, 2010, 07:24:51 PM »

Magnifing glass may not be as good an indicator as a common permanent magnet would...
Logged
KF7ITG
Member

Posts: 82




Ignore
« Reply #8 on: November 12, 2010, 07:37:36 PM »

Good idea. I took a good strong magnet from my tool box and I mean strong. I removed the insulation from a one inch piece of wire ... Nothing it just lays there.

James
Logged
WB6BYU
Member

Posts: 13244




Ignore
« Reply #9 on: November 12, 2010, 09:54:39 PM »

Well, it is probably better wire than my first antennas were made of - I used scraps of telephone wire and
spliced all the individual strands together.

And I applaud you for carrying out tests!

There is nothing in the ad that says it is copper, though it may well be.  Certainly the stretch test would
argue for solid copper.  Steel wire, unless it has a thick copper coating (not just the flash copper coating
found on welding wire) is more lossy, both due to a higher DC resistance and due to hysteresis losses in
the magnetic steel as the RF waveform cycles back and forth.  Not that you can't use steel wire for an
antenna, it just isn't as efficient:  with some antennas the difference is small, others it can be huge.

So, yes, I'd say it should work for antennas, but here are some additional points to keep in mind.

The stress on a wire strung between two trees is not merely due to the weight of the wire involved. 
Here's a question:  if you string the wire between two trees and add a coax feedline weighing 2 pounds
in the center of it, how much tension do you have to pull on the wire so it doesn't sag?  The answer,
of course, is that you need infinite tension to eliminate the sag.  Let's say that you have the same
100' span between supports and 2# weight in the the middle and the sag is 5'.  Each end wire, then,
is 50 feet horizontal and 5 feet vertical.  Since the weight divides between the two wires (and we'll
ignore the weight of the wire for the moment) we can say that each wire has 1 pound of downward
force.  Given the 10 : 1 slope of the wire that translates into 10 pounds of horizontal pull to counteract
that 1 pound downwards.  Given the breaking strength that you demonstrated, that is about the
maximum stress you would want to put on it, and it assumes that neither tree moves in the wind and
stretches the wire even more.

That's not to say you can't put up a 100' wire antenna, just that the forces involved are more than
the static weight of the wire itself, and such a wire  probably can't support a very long length of coax
cable if it is fairly flat.  The simple solution would be to put a counterweight of no more than 10 pounds
on the rope holding each end, which limits the stress that can be put on it.

I use a lot of thin wire myself for portable antennas, some of it #24 or smaller.  From an electrical
perspective there is no problem, though it has some mechanical considerations to take into account.
But I find that stranded wire is much better for portable antennas (presuming it is available) because
it doesn't kink as easily and I can tie knots in it, etc.  Again, this is because I tend to roll up the wires
and stick them in my backpack, so they take a lot of flexing.  When I find surplus wire for 1 cent/ft or
so I consider it a good deal and stock up, but it may be every few years that I come across something
like that locally.  However, you work with what you have available, and I used several antennas in
Alaska made from the solid copper wire used in blasting rock pits (which was never reused due to
the risk of a bad connection if a rock fell on it during a blast.)  Yes, it stretches somewhat, but that
means that if your antenna resonates too high in the band you can just pull on it a bit until you get
it where you want it.


So go ahead and use it to experiment with antennas, if that is the best price you can find for suitable
wire.  I think Steve WB2WIK has posted a source for wire that he uses in southern California, but I don't
know what the shipping costs would be.  Personally, for an antenna that will see a lot of putting up and
taking down in the field, I think you will find that stranded wire is much more convenient.  But, hey, get
started experimenting - part of that process is finding what materials work for your needs.

Have fun!
Logged
KF7ITG
Member

Posts: 82




Ignore
« Reply #10 on: November 13, 2010, 12:25:53 PM »

My original thought was and still is an inexpensive mobile, possibly a one time use, wad it up and throw it away when done antenna. What got me interested in the use of this wire was an article on the all-band full wave HF Loop Skywire antenna in a ARRL publication by Dave Fisher, W0MHS. It looked like a likely option for temporary antenna on top of a mountain in Arizona with the right wire. I didn't want an weekend antenna that took hours to put up and if I could just pull it down when finished even better.

James
Logged
WB6BYU
Member

Posts: 13244




Ignore
« Reply #11 on: November 13, 2010, 01:50:09 PM »

Get busy and build some antennas from it, then go try them out.  Don't let our quibbling about minor details
keep you from having fun!  As you do it you'll discover better ways to do it and make it easier.


I've had good luck with loops - I put up a horizontal 80m loop for Field Day and that one antenna made
more contacts than the rest of the antennas combined.  Granted, it did take more time to set up than
many of the others, but the terrain was challenging:   the feedpoint was at the corner of my tent and
the loop went out over the edge of a cliff and across to some trees on the other side of a road below.
For monoband use a vertical delta loop hanging from one (or preferably two) trees and fed at the bottom
keeps the feedline short and gives an excellent signal, especially for 40m.  The horizontal type work better
for multiband use require more supports to string up - this might or might not be a limitation in the place
where you plan to operate.  If trees are sparse I just string the wire around on the ground in the desired
shape, then toss a rope over a tree in each corner, tie it around the wire (electric fence insulators are
quite convenient for this, or you can just tie a loop in the rope and let it slip along the wire) and pull it up
in the air.  If the trees are denser you may have to thread the wire through them, in which case I'd toss
a rope with a throwing weight over each branch and use it to pull the wire through.  (This requires that
one end of the antenna be disconnected at the feedpoint.)

You can cut your wires to length before you go to speed up your time in the field.  I cut a set of wire
dipoles for my backpacking kit and tuned them up in a local park 30 years ago and still use them without
the bother of an antenna tuner.  You can also clip a 1/4 wave wire to the feedpoint of a mobile whip
antenna to get much improved performance while parked.  (This came in very handy once when I cracked
the transmission housing on my car some distance from civilization.)  So you can cut wires for 40m and
80m and keep them in the car.

On occasion the wires get so tangled in the trees and you just have to abandon them.  Oh, well.  Don't
risk injury trying to retrieve them (been there, done that, was fortunate to survive.)  Find some way to
roll the wires up conveniently and you should be able to reuse them many times.  And take some extra
wires in case you need to put up something else:  if you only have one tree you might need an inverted
vee, delta loop or vertical.  I carry individual wires for each band and attach the desired set to my center
insulator and coax each time I set it up - this gives me the flexibility to use the wires in other ways as
well.  (For example, a 40m dipole leg makes a full wave loop on 10m with the addition of one clip lead for
SSB and two for CW.)


As Nike used to say, "Just Do It."  And have fun.
Logged
KB1GMX
Member

Posts: 772




Ignore
« Reply #12 on: November 15, 2010, 08:09:14 AM »

Like others said just do it.

I've used 22ga stranded hookup wire for quickie experimental wires and found it good enough for short
term use.

If you want tougher wire that same stuff in 16ga copper with PE insulation is about the similar price
and certainly heavier.


Allison
Logged
K5LXP
Member

Posts: 4482


WWW

Ignore
« Reply #13 on: November 16, 2010, 03:35:05 PM »

I received the sample of the wire from KF7ITG and since he was willing to go through the trouble and two stamps to do that, I figured it was worth at least two stamps' worth of my time to check it out.

My micrometer says it's 32 mils in diameter, which matches the size of 20ga wire in my copper wire table.  I measured its length, then ran some current through it using my bench supply and measured the voltage drop across it.  Using ohms law I came up with 10.83 milliohms/ft, which very closely matches the table-specified resistance of 20 ga copper wire within my capabilities to measure it.

By all accounts, this is plain ol' soft copper wire and will work fine for most any antenna electrically, albeit a bit fragile for long suspended spans.  The insulation appears to be PVC which means it won't last terribly long in the sun, provided it's up long enough for that to be a problem.  Being intended for direct bury anyway it could also be used as radial wire for verticals, with the same caviat about its fragile nature in mind.

Just for giggles I contacted my company's wire supplier and for a solid 20ga PVC wire, a 1000ft spool goes for about $93, or 9.3 cents a foot.  This pet fence wire at $35 for 500 feet is a bit less at 7 cents a foot, so that's even cheaper than what I could get it for with the benefit of a commercial supplier relationship.  Being available retail and at a relatively small quantity definitely places this wire in the "good value for what it is" category.  It's definitely not the steel-core or some other unknown alloy wire we initially assumed it would be for the price.


Mark K5LXP
Albuquerque, NM
Logged
WD4AOG
Member

Posts: 21




Ignore
« Reply #14 on: November 20, 2010, 08:43:46 AM »

James,

There are some so-called "experts" on here whose real hobby seems to be pouring cold water on the posts of others in an apparent effort to elevate themselves in their own mind.  Regardless of what they do or do not know, I get nothing from their posts beyond that.

I, for one, want to thank you for your patience with that garbage as well as your helpful post.  I would also like to thank Mark for taking the time to test your sample and his positive contribution of the results.

Instead of jumping to fault-finding mode, what do say we all encourage posts like these?  Perhaps then we'd see more of them.

Sincerely,
Michael
WD4AOG
Logged
Pages: [1] 2 Next   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!