Randomwire: to insulate or not

[Michiganrailfan]

Folks:

I'm experimenting with a low-cost, Rube Goldberg randomwire in my backyard, and boy am I impressed. It receives great with my Softrock Ensemble SDR. I'm looking to modify the antenna...mainly it needs raising (now it's hung on fence posts). It's insulated isn't long enough to stretch between 2 trees in my backyard.....so I need more wire.

I'll use the standard "egg" insulators (one attached to each tree), with one insulator connected to a pulley that'll compensate for the trees swaying in the wind.

It turns out I have a large spool of non-insulated steel wire that was left over from an electric fence. It is single strand. I believe it is galvanized. Standard electric fence wire. There's at least 200 feet.

Cheap and crazy that I am, I'm thinking of using this as a randomwire, and stretching it as far as it'll go.

The articles I've read on randomwires, longwires, etc., all seem to focus on multistrand, insulated wire.

Do you guys see any problem with standard electric fence wire?

 

[n5ims]

Go for it. While the galvanized wire won't make quite as good of a connection (solder won't stick well, etc.) and it's a bit more resistance per foot than regular copper wire, it should work OK. Just make sure that since you don't have any insulation to protect it that it doesn't touch anything metal or otherwise conductive or you'll get noise when they rub together.

 

[ridgescan]

FWIW my 50' #10 copper randomwire is bare-been up there for a year so far.

 

[Token]

Galvanized electric fence wire works fine as antenna. While it is not my material of choice I have made many wire antennas with it, particularly to test a concept. The connections can be problematic so I tend to try and make firm mechanical connection, instead of soldering I might use looped wired and a small bolt/nut to make a connection.

Insulation is not required on any antenna wire, it simply does not matter. Just make sure it is isolated and does not touch anything or run close enough to touch when hit with high winds. In general touching things, even non-conductive things, will cause static and erratic behavior.

T!

 

[gcgrotz]

I once had a 600 ft Bevridge antenna made of fence wire. It worked great! Very convenient was the use of electric fence insulators nailed to trees. Check your local farm supply for electric fence stuff, I use a lot of it in my antenna experiments.

 

[Michiganrailfan]

Cutting corners

Thanks for your very helpful comments.

A bolted connection, eh? Makes sense, given how difficult it'd be to solder galvanized wire. I havent yet figured out how to connect the lead wire to the randomwire. I'm thinking of winding the randomwire through the egg insulator a couple of times and then using the end of that wire to connect to the balun. The end of the randomwire would end up being the feedline.

From the standpoint of better reception, is there any reason (impedance?) to select copper versus electric fence wire?

I went to Home Depot today and saw 500 feet of #14 copper wire (stranded, single lead) for 40 bucks.

Ouch. I need to find a junkyard. For me, working in a junkyard would be a good retirement job.

Cheers

 

[jackj]

Anything that will conduct electricity will work as an antenna, even your body. Insulated or bare makes no difference.

You CAN solder to galvanized wire but it is hard. You have to clean it very well and protect the surface from oxidation but once it is tinned, you are good to go. Copper is the material that most of us use for antennas because it is very easy to work with and it is a very good conductor. However most commercial beams are made out of aluminum and they work very well.

The type of material you use will NOT effect the impedance of the antenna but it will effect the radiation resistance. Good luck and Merry Christmas.

 

[n5ims]

From the standpoint of better reception, is there any reason (impedance?) to select copper versus electric fence wire?

Performance on either Copper or galvanized steel would pretty much be the same as far as the antenna goes. Copper is easier to attach to, but will stretch over time and will break more easily since copper is softer than steel. There is some wire designed for antenna use that's copper coated steel, called copperweld that has the strength of steel and ease of use of copper (except it's harder to cut, but also harder to break) Davis RF Co. - Copperweld Wire

I went to Home Depot today and saw 500 feet of #14 copper wire (stranded, single lead) for 40 bucks.

Fairly standard price nowdays. The cost of copper has really jumped, which is why you see folks doing all kinds of things to rip it out of air conditioning units, cell phone towers, businesses, schools, and even power lines Vandals Chop Down Tree, Steal Copper Wire From Power Lines - News Story - WJAC Johnstown

I need to find a junkyard. For me, working in a junkyard would be a good retirement job.

With the increased price of copper, the junkyards no longer have any of useful lengths. It's either sold quickly or folks that would normally dump it there now sell it to recyclers for $$$.

 

[kb2vxa]

If galvanized steel were so hard to solder I wouldn't have made all those mobile antenna to base station conversion mounts out of covers for 4" square electrical boxes. What you need are proper soldering equipment and rosin paste flux, it's easier than you think. I'd much rather solder than twist or bolt alone for the sake of a proper electrical contact and eliminating the risk of corroded joints which lead to a host of reception problems.

BTW, many give up after making a bunch of solder blobs without realizing they're not heating the work sufficiently. What helps a whole big bunch is one of those horse leg irons used in industry for soldering sheet metal.
Hexaon Electric has a wide variety of tools for anyone seeking the best in hand soldering equipment.

For outdoor work a gas soldering pencil works well. I have the PT-130 at the top of the page but it might be a bit tricky for some so the PT-230 and related models might be better for the flame shy.
Roburn Soldering Iron and Gas Torches

If these aren't to your liking Google is your friend. Oh and I just thought of the obvious, if you want to get a gas pencil locally just ask any crack head. Never mind the pipe, you can't solder with it. (;->)

 

[talkpair]

Do you guys see any problem with standard electric fence wire?

I've been using a folded dipole made of electric fence wire for over a year now for highway patrol low band with no problems.

It's smooth, strong, doesn't stretch, and cheap.......With talk of highway patrol moving away from low band, i didn't want to invest much in antennas, but wanted something that would perform well.

 

[Michiganrailfan]

braided electric fence wire ?

Today I went to Tractor Supply to look for electric fence supplies....insulators and stuff.

They have something I've never seen before: braided electric fence wire. It made me wonder how well it might work as a randomwire antenna.

Basically, it looks just like a braided nylon rope...about 1/8 inch in diameter. If you look closely, there are 4 or 5, ultra-thin aluminum wires braided alongside the nylon fibers. The salesman says the only other alternative for an electric fence is solid galvanized wire. Apparently the braided wire handles mechanical abuse better than galvanized solid wire.....like horses bumping up against it.

$16 for 600 feet.

But there's only 4 or 5, independent, tiny aluminum fibers braided loosely alongside the nylon fibers. Most of the volume of the "fence wire" is nylon...the fibers barely take up any room at all. I couldn't find a good closeup picture on the internet.

What do you guys think about this from an antenna performance standpoint?

Has anyone tried this?

 

[Michiganrailfan]

Electrobraid

The company, Electrobraid, makes a similar product, but with 2 copper wires, forming a double helix intertwined among polyester fibers making up the bulk of the rope. It's attached to fenceposts using the same electric insulators for single strand galvanized steel.

Electric Horse Farm Fence Enlarged View of Electrobraid Fence

Apparently horses can see the rope better than a single strand of galvanized steel.

 

[k9rzz]

If it conducts, it can be an antenna. I think this thread is going the route of "what can I get away with?" and I say get away from that thinking. If you want the best performance, then stick with "how big can I get away with?" W6AM used rhombics that were 800 to 1500 ft long, as high as 150ft, and made of #8 copperweld. He had the loudest signal of anyone around the world during his time. Finnish MW Dxers in Lapland use beverages 1km long and they hear stations from all over the world. I worked a friend 4 miles away on 80 meters using just 6 inches of wire attached to a soda can, but who cares? Sure the antenna was small, but it only reached 4 miles.

As far as insulated house wire from your local building supply house, after a few years, that outer plastic cover starts peeling off. Looks like heck. By then, it's probably time to pull down the antenna and check the connections anyway. I use #12 or #14 insulated copper wire all the time. Works great. So what if your 200 ft span of copper wire stretches a few inches? Just snug it back up again. My .02

 

[a29zuk]

Also, if you don't want to solder, ring terminals can be used to connect your feed line to your antenna. They come in various sizes for both the wire and the screw hole and are available at auto parts stores and hardwares. You will also need a crimp tool to secure the terminals to the wires. Make sure to tape your connection very well with electrical tape to prevent moisture and oxidation.

Jim