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 Post subject: Copper Wire Antenna
PostPosted: Jan Tue 14, 2020 7:04 pm 
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Joined: May Fri 06, 2016 3:41 am
Posts: 386
Location: Johnstown, Ohio
For listening to shortwave I have a single copper strand antenna of about 50'. This has been up about 3 years now and I am noticing a black coating on the length of the antenna which I assume is copper oxide. Will this layer diminish the function of the antenna? It has been a very good antenna for my listening needs but I wonder if it is going to be not so good in the future.
Regards,
Don


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 Post subject: Re: Copper Wire Antenna
PostPosted: Jan Tue 14, 2020 9:15 pm 
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 Post subject: Re: Copper Wire Antenna
PostPosted: Jan Tue 14, 2020 11:25 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 992
Location: St. Louis, MO, USA
Back in the1920s they thought corrosion greatly affected the received signal. There were people who reserved Saturdays as “areal cleaning day”. They ran steel wool or sandpaper over the copper wire to shine it up. This was shown to not have much effect.

Dennis


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 Post subject: Re: Copper Wire Antenna
PostPosted: Jan Tue 14, 2020 11:38 pm 
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Posts: 7977
Location: Gretna, Nebraska
Not an issue for normal reception. Only exception is if your antenna wire has any connections or splices outside that may have been compromised.

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 Post subject: Re: Copper Wire Antenna
PostPosted: Jan Wed 15, 2020 1:09 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 14446
Location: S. Dartmouth MA 02748-1225 USA
Soldering the downlead to the copper antenna wire will anneal it, a heavy ice load (whatever) the antenna will part where the soldering was done.

Joining with corrosion proof bronze clamps will keep the hardness, if sufficiently tighten the gas tight seal will keep out corrosion...Cover the joint if need be in a marine environment with pitch.

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 Post subject: Re: Copper Wire Antenna
PostPosted: Jan Wed 15, 2020 4:12 pm 
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Joined: Nov Sun 15, 2015 8:32 pm
Posts: 196
Location: Poteau, OK
Old Tube wrote:
For listening to shortwave I have a single copper strand antenna of about 50'. This has been up about 3 years now and I am noticing a black coating on the length of the antenna which I assume is copper oxide. Will this layer diminish the function of the antenna? It has been a very good antenna for my listening needs but I wonder if it is going to be not so good in the future.
Regards,
Don


Don,

I'm going to assume the overall length of your 50-foot wire antenna is one long run of copper wire, not 2 lengths of copper wires
twisted together to form the 50-foot antenna. If that's true then the answer to your question is "No", the black coating will
not diminish the antenna's efficiency in receiving signals.

If there are individual lengths of copper wire spliced together to form the 50-foot antenna then you will need to clean the spliced
ends using a wire brush or a knife to scrape clean the copper wire. Twist the wire ends tightly together then solder the spliced
ends. Apply some rubber coating, you can use the "Flex Seal" rubber to coat the spliced area. Do NOT use Acid Core solder!!!
Use 60/40 solder which is designed for electrical connections.

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 Post subject: Re: Copper Wire Antenna
PostPosted: Jan Wed 15, 2020 11:50 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3549
Location: Seattle WA US
Soldering copper wire should not anneal it, if you keep the temperature down to soldering iron temperature.
If you use a torch, and heat the joint until you see the copper blue-green color in the flame, you may indeed anneal the copper.
-Chuck K7MCG


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 Post subject: Re: Copper Wire Antenna
PostPosted: Jan Thu 16, 2020 1:00 am 
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Joined: May Fri 06, 2016 3:41 am
Posts: 386
Location: Johnstown, Ohio
Thanks for the posts. I used some sandpaper on the end section of the copper wire and then redid the connection to the drop wire. I think the original problem was me in that I tied into the long wire with a new drop wire whose end i just wrapped on top of the copper oxide/copper wire. I am not listening to short wave with much better reception than before.
Thanks again,
Regards,
Don


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 Post subject: Re: Copper Wire Antenna
PostPosted: Jan Thu 16, 2020 2:18 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3549
Location: Seattle WA US
Don-
Suggest you try a small antenna tuner between your antenna and SWL receiver. I found it made a big difference with some radios, very little with others.
-Chuck K7MCG


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 Post subject: Re: Copper Wire Antenna
PostPosted: Jan Thu 16, 2020 3:02 am 
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Joined: May Fri 06, 2016 3:41 am
Posts: 386
Location: Johnstown, Ohio
Thanks Chuck,
Could you recommend one?
Don


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 Post subject: Re: Copper Wire Antenna
PostPosted: Jan Thu 16, 2020 3:15 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3549
Location: Seattle WA US
I used a MFJ-901. There are many similar devices on the market. Should be $10-15 at a Spring hamfest, only a few weeks away.
-Chuck


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 Post subject: Re: Copper Wire Antenna
PostPosted: Jan Thu 16, 2020 6:38 am 
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Joined: Oct Sun 18, 2009 5:38 am
Posts: 3397
Location: Tyler, Texas 75707-4212
Copper is annealed by heating and then quenching, usually in water. Heating to soldering temperatures and air cooling will not typically anneal it. It might quench fast enough in some of your northern winter winds :D Annealing temperature ranges from 700 to 1200° F. Copper is hardened by cold working. It does not respond the same as typical ferrous materials.

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 Post subject: Re: Copper Wire Antenna
PostPosted: Jan Thu 16, 2020 2:39 pm 
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Joined: Aug Mon 09, 2010 2:57 am
Posts: 695
Location: York PA.
Don --

If you're going to splice the wires together, I suggest you use a dog-bone (or similar) insulator at the splice point. Wrap the wire ends once or twice through the holes for structural strength, then solder the wires. Made sure you clean the wires first. Covering the soldered joint afterwards is optional (I don't). The one or two loops in the antenna will not matter at HF.

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 Post subject: Re: Copper Wire Antenna
PostPosted: Jan Fri 17, 2020 11:17 pm 
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Joined: May Sat 12, 2012 1:33 pm
Posts: 1730
Location: Rochester, NY.
I have read books about long-wire antenna installation from the 1920's. 7-strand, 16 gauge was a favorite,
Most homes were heated by coal which would spread a layer of acidic ash overnight. Mixed with dew, this would corrode longwires and gutters.
With many regenerative receivers in an urban setting, there were heterodynes from the feedback circuit of regens tuned on or around your listening frequency. They would act as little transmitters unless isolated by an added RF stage between the antenna and regen circuit.
They had to suffer with both environmental and interference issues back then as we have now. :|


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