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Old 26-10-2016, 14:37   #1
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Rope cover on SSB wire antenna?

Hi Everyone,
What do you think of using a rope cover on an SSB wire antenna?

The top section of our fiberglass antenna broke off, and we are unable to replace it here in Fiji. I used stainless fishing wire to make a 12m wire antenna on our mizzen. Unfortunately it comes close (~5") to the spreaders and a mast step, and though it's super tight, in a lot of wind it may vibrate and touch. The lead wire through the deck is short, so I can't get it further away. I covered it with the outer core of rope, with the thought to insulate it if it vibrates in the wind and touches metal, but now wonder if this won't work if it rains. Maybe instead I should use bare wire and put heat shrink on it wherever it gets close to something metal? Or use thin hose instead of rope?

By the way, this simple wire works way better than the fiberglass antenna.
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Old 26-10-2016, 15:13   #2
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Re: Rope cover on SSB wire antenna?

Hmm. When its wet it wont provide the insulation needed. Cover it where it passes the spreader with some plastic waterpipe I reckon. But there are others here who understand SSB better than me....
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Old 26-10-2016, 15:20   #3
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Re: Rope cover on SSB wire antenna?

Frankly, I wouldn't worry about it. Even if it did touch a grounded bit of metal, the effects would only be a momentary increase in SWR and possibly reduced power output if the transmitter does an automatic power roll-back. The chances of this happening whilst you are transmitting are pretty slim in the first place.

Enjoy the increased performance of your new random length wire antenna!

Jim
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Old 26-10-2016, 15:26   #4
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Re: Rope cover on SSB wire antenna?

The proximity to nearby metal will affect the radiation pattern but probably not noticeablly. If it physically contacts nearby metal, especially when wet, , it will significantly affect what your tuner 'sees' although it's impossible to predict precisely how much effect. As you correctly assumed, find something non-conductive to act to insulate the wire (or spreader).
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Old 26-10-2016, 15:27   #5
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Re: Rope cover on SSB wire antenna?

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Originally Posted by Jim Cate View Post
Frankly, I wouldn't worry about it. Even if it did touch a grounded bit of metal, the effects would only be a momentary increase in SWR and possibly reduced power output if the transmitter does an automatic power roll-back. The chances of this happening whilst you are transmitting are pretty slim in the first place.

Enjoy the increased performance of your new random length wire antenna!

Jim
Cool, thank you. Hurting the radio is my main concern. It's good to hear it won't hurt it if the antenna momentarily touches the mast.
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Old 27-10-2016, 15:22   #6
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Re: Rope cover on SSB wire antenna?

I was reading an article about a different way to do the backstay for SSB. I quote, "You can replace an insulated backstay with a single unbroken length of Dux, we use 11mm on Isbjoon-and bury a 14 AWG coated copper wire inside the open strand braid for about 3/4 of its length." They declare the copper set up is a much better conducter than the stainless wire. Thought I would share the thoughts. I know almost nothing about SSB
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Old 27-10-2016, 22:19   #7
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Rope cover on SSB wire antenna?

Although copper is a much better conductor than stainless steel, replacing a ss antenna with copper will only result in a very small improvement in radiated power - you could not notice it. This is borne out by analysis with antenna modeling software.
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Old 28-10-2016, 13:33   #8
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Re: Rope cover on SSB wire antenna?

Sooner, do you see any advantages to using Dux on the backstay versus the expense and weight of stainless?
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Old 28-10-2016, 15:24   #9
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Re: Rope cover on SSB wire antenna?

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Sooner, do you see any advantages to using Dux on the backstay versus the expense and weight of stainless?
I don't think I understand what you are asking. Is that a standing rigging question, or does it have to do with antennas? I have no personal experience with Dux rigging btw.

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