Wire for Random Wire Antenna

[JerryX]

I'm in the process of putting up a random wire receive-only antenna for the LW/MW/HF bands and am trying to choose what wire to use. The antenna will be roughly 150-200 feet in length, terminated at a 9:1 unun with a short coax run to the shack.

In the past, when I made wire 1/2-wave dipoles, about the only wire commonly available was bare, stranded copper and copperweld sold at places like HRO. I never liked either--the stranded copper has heavy and quickly turned green and the copperweld was like dealing with a tightly wound spring (and easy to kink).

Looking at site like Universal Radio and The Wireman, there is much more choice now. Some of the newer options are Poly-Stealth and FlexWeave. For this installation I plan to go with 18-gauge black-jacketed wire.

Anyone used any of these newfangled wires for antenna work?

 

[jwt873]

I put together t a 120 foot inverted vee antenna for 80 meters about seven years ago. I just used 12 gauge stranded bare copper. It's gone black over time, not green. Other than that, it hasn't suffered any real physical degradation.

I once had a Buxcomm Off center fed dipole. The wire they supplied for the antenna had a light blue jacket. I guess to better match the sky and supposedly to make it more stealthy. I didn't really make much difference

 

[phask]

WAAAAY back when I was a teenager we would tear down old auto starters and use the field wire. It was 14-16 gage magnet wire, lacquer coated. We had to twist and solder to get enough length but ended up with 300+ feet.

I've since made them with anything I could find I had some surplus flat braided tin coated stuff that was really great, around 1/4 wide and really strong.

 

[ka3jjz]

The well known PAR SWL antenna uses flex weave, I believe...Mike

 

[ridgescan]

I run #12 solid bare from good old Home Depot. It's been up there many years now in the sea-salty, foggy San Francisco air and it develops a green patina n its surface but the wire never degrades.

 

[prcguy]

The National Electrical Code calls out minimum wire sizes for both receiving and transmitting antennas. Yes, its true, the NEC has its fingers in that too.

According to NEC Article 810, Table 810.16(A), for wire receiving antennas less than 35ft long you must use at least 19 AWG copper or aluminum alloy or use 20 AWG copper-clad steel, bronze, or other high-strength material. More than 35 feet long but less than 150 feet long use 14 AWG copper (or 14 AWG aluminum alloy) or use 17 AWG copper-clad steel, bronze, or other high-strength material. Longer than 150 feet use 12 AWG copper (or 14 AWG aluminum alloy) or use 14 AWG copper-clad steel, bronze, or other high-strength material.

For transmitting its different and it must comply with 810, Part III (810.51 through 810.58). If the conductors are longer than 150 feet, use either 10 AWG hard-drawn copper or 12 AWG copper-clad steel, bronze, or other high-strength material. If the length is under 150 feet, you can use 14 AWG in any of the aforementioned materials (Table 810.52).

 

[Boombox]

I just use the old copper stranded wire I had in the 80's and 90's. It still works. It's just a receiving antenna. If it darkens, no big deal.

 

[WA8ZTZ]

Have had good luck with the 18 polystealth on a couple of 50' receive antennas…
have survived a number of ice and wind events.

The bare stranded copper is not the best choice for a receive antenna. Over time it will oxidize
and get noisy and become a potential source of external mixing products... copper oxide is
an excellent rectifier. Solid bare copper does not have the same problem as long as the joints
are made up tight and weatherproofed or soldered.

 

[prcguy]

I have never heard of this or experienced it with my stranded copper wire antennas near the ocean. Do you have any source of info you can point us too?

Have had good luck with the 18 polystealth on a couple of 50' receive antennas…
have survived a number of ice and wind events.

The bare stranded copper is not the best choice for a receive antenna. Over time it will oxidize
and get noisy and become a potential source of external mixing products... copper oxide is
an excellent rectifier. Solid bare copper does not have the same problem as long as the joints
are made up tight and weatherproofed or soldered.

 

[majoco]

I was a ship's Radio Officer back in the 60's. Every ship I joined I made a point of lowering the wire antennas for inspection and repair as required. At that time the antennas were made of 7 strand hard drawn copper with glass or rubber insulators for the top and the lead-in. Joints were wrapped and NOT soldered. Every time the wire was green with copper oxide but worked perfectly well for transmitting too, sometimes with a kilowatt up the lead-in.

 

[WA8ZTZ]

I have never heard of this or experienced it with my stranded copper wire antennas near the ocean. Do you have any source of info you can point us too?

Have had at least 2 stranded copper wire receive antennas that over time (several years) got heavily oxidized. Their performance on moderate
and strong signals was fine, no noticeable degradation. However, when trying to copy weak signals during good band conditions there seemed to be a lot of noise and mixing involving strong local AM broadcast stations. Eventually decided to replace the antennas after determining there was nothing wrong with the receivers, baluns or lead-ins. The problems went away with the old antennas.
IMHO, the copper oxide acts as a rectifier and causes the unwanted external mixing. Early rectifiers were actually made with copper oxide.
Also, if the terminations of insulated stranded copper wire are not weatherproofed, water will manage to get under the insulation.
You would be amazed at how far water will wick along the wire strands under the insulation... the wire will oxidize but, of course, you
won't see it.