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Old 11-03-2018, 05:30   #1
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Using standing rigging as a short wave antenna

I have installed the R-75 Icom using the same backstay antenna as the vessels SSB. As hoped it has simplified picking up transmissions and appears to be more sensitive than the transceiver. The Icom has the ability to utilize two different antennas. I am considering attempting to use the vessels cap shroud as a different type of antenna with the idea of better reception on different frequencies. So the answers to a couple of questions would be appreciated. The cap stay is connected to to external chain plates and the mast is 50' tall, the stays are connected at the top with tangs that are through bolted to the opposite side stay. Should I have fair expectation that there would be continuity to both stays and would this essentially create a 100' inverted dipole? If I connect feed wire to the 1/2" chain plate bolt on the inside of the boat would the bronze turnbuckle attached to the stay interfere with the performance of the stainless wire antenna and would I need to put a stainless bridge wire from the chain plate to the rigging wire to improve reception. Finally, is there any benefit to what I am thinking about doing ?
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Old 11-03-2018, 05:51   #2
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Re: Using standing rigging as a short wave antenna

Duplicate post?
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Old 11-03-2018, 06:02   #3
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Re: Using standing rigging as a short wave antenna

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Originally Posted by cburger View Post
...Should I have fair expectation that there would be continuity to both stays and would this essentially create a 100' inverted dipole?
There is really no antenna known as an inverted dipole. The term "dipole" refers to the radiation pattern of the antenna, not to a particular form of the antenna. The most common form of antenna with a dipole radiation pattern is a half-wavelength horizontally polarized linear antenna fed in the center. If the legs of the antenna droop, this is often called an inverted-vee half-wavelength antenna.

There is no expectation and no reasonable basis for a jumble of random length rigging wires, a mast, and other conductors all bonded together to exhibit a dipole radiation pattern across the 3 to 30-MHz spectrum.
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Old 11-03-2018, 06:14   #4
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Re: Using standing rigging as a short wave antenna

One question, I'm replacing standing spectra rigging.

Now would be a good moment to put a wire in the core to be used later for Short Wave Radio.

What kind if wire should I put in?
Coax? Tinned? Stranded?
What length should I put in?
What diameter?

As stated above its just to prepare a possible later marine short wave radio installation at a convenient point in time.
I am aware that later there will be more stuff to do, like a ground plate and the like...

Thanks for suggestions.
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Old 11-03-2018, 08:37   #5
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Re: Using standing rigging as a short wave antenna

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Originally Posted by continuouswave View Post
There is no expectation and no reasonable basis for a jumble of random length rigging wires, a mast, and other conductors all bonded together to exhibit a dipole radiation pattern across the 3 to 30-MHz spectrum.
Very true, but there's no reason we should necessarily desire a dipole pattern. The OP wants to use the rigging as a receive antenna, so optimum gain isn't usually an issue either. My guess is that it will work well enough, but will be no better than a proper backstay antenna.

My concern is that if the receiver will be damaged if connected to the rigging when the transmitter is keyed.
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Old 11-03-2018, 09:17   #6
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Re: Using standing rigging as a short wave antenna

Quote:
Originally Posted by Franziska View Post
One question, I'm replacing standing spectra rigging.

Now would be a good moment to put a wire in the core to be used later for Short Wave Radio.

What kind if wire should I put in?
Coax? Tinned? Stranded?
What length should I put in?
What diameter?

As stated above its just to prepare a possible later marine short wave radio installation at a convenient point in time.
I am aware that later there will be more stuff to do, like a ground plate and the like...

Thanks for suggestions.
I have found tinned copper 14g works well. Make sure the wire will not get pulled tight, even though spectra is low stretch all rigging will stretch a bit when first installed.
Have you thought about using a separate line? Means you can lower it for repairs or when not in use and with luck will still work if you ever loose the mast!
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Old 11-03-2018, 09:34   #7
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Re: Using standing rigging as a short wave antenna

I used the standing rigging on my Cabo Rico 38 many years ago for my ham transceiver. I attached to the chainplate just behind the unit, and the ground was a sintered copper plate connected by a wide copper strip. I used both the built-in antenna tuner and another one. I had great swr readings on all amateur high freq bands. Some standing rigging may have a wire or strap going to ground for lightning protection. It won't work with that connection.
There could be a concern for an unsafe condition if another crewmember was near the standing rigging due to the rf power on some bands.
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Old 11-03-2018, 09:38   #8
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Re: Using standing rigging as a short wave antenna

Hey Roland, thanks.

Is that just a one strand wire with plastic insulation around it?

Not coax? Not multi strand?

The wire will be pulled up inside the spectra. It will not get attached to the upper end and terminate about 300mm/1ft before the upper splice.
So apart from a but of friction there will be no load on it.

If the wire gets damaged it can be replaced by taking down the stay and replacing the core.
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Old 11-03-2018, 09:54   #9
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Re: Using standing rigging as a short wave antenna

I am using my Backstay presently. I have wondered tho if a regular sideband antenna mounted aft wouldn’t perform better.
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Old 11-03-2018, 09:54   #10
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Re: Using standing rigging as a short wave antenna

Quote:
Originally Posted by cburger View Post
I have installed the R-75 Icom using the same backstay antenna as the vessels SSB. As hoped it has simplified picking up transmissions and appears to be more sensitive than the transceiver. The Icom has the ability to utilize two different antennas. I am considering attempting to use the vessels cap shroud as a different type of antenna with the idea of better reception on different frequencies. So the answers to a couple of questions would be appreciated. The cap stay is connected to to external chain plates and the mast is 50' tall, the stays are connected at the top with tangs that are through bolted to the opposite side stay. Should I have fair expectation that there would be continuity to both stays and would this essentially create a 100' inverted dipole? If I connect feed wire to the 1/2" chain plate bolt on the inside of the boat would the bronze turnbuckle attached to the stay interfere with the performance of the stainless wire antenna and would I need to put a stainless bridge wire from the chain plate to the rigging wire to improve reception. Finally, is there any benefit to what I am thinking about doing ?
I have only ever seen SSB aerials fitted with ceramic isolators on backstays. Also have i been warned of high voltage when transmitting which can be dangerous. I would suggest further research and adopting proven methods.
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Old 11-03-2018, 10:03   #11
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Re: Using standing rigging as a short wave antenna

Just another side question from my end, sorry about high jacking this partially.

Would a single strand copper wire inside the hollow core of a spectra (=non conductive!) rope work as antenna?
There are no metal backstays or shrouds on my boat.

For safety I would remove the wires insulation only starting at a minimum of 2.6m/8ft above deck.

These antenna do not get hot during transmission, or do they?
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Old 11-03-2018, 11:50   #12
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Re: Using standing rigging as a short wave antenna

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Originally Posted by turtleofdart View Post
I have only ever seen SSB aerials fitted with ceramic isolators on backstays.
While the insulated backstay is probably the most common SSB antenna (that's what I have and it works well), there are many other options. Running a wire inside the hollow core of a spectra (or similar) backstay has been done many times and probably works just as well. People also haul up temporary rope/wire hybrid antennas with good results.

Quote:
Also have i been warned of high voltage when transmitting which can be dangerous. I would suggest further research and adopting proven methods.
Mardi
Yes, it is possible to see high voltages of several hundred volts near the base of a vertical antenna, depending on the length, frequency, and distance between the tuner and the exposed antenna. Feeding the non-insulated standing rigging could potentially (pun alert!) expose crew members to a shock hazard. But remember that the OP is considering using this for a *receive* antenna.
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Old 11-03-2018, 13:52   #13
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Re: Using standing rigging as a short wave antenna

Insulation does not prevent the rf power from radiating perhaps harmful energy. Only separation does that. The normal solution is to have an insulated backstay with the antenna portion high enough to keep crew members far enough away. My use of the standing rigging worked as I was either single handed or with a crew member that was very aware and then I only transmitted rarely.
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Old 11-03-2018, 14:09   #14
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Re: Using standing rigging as a short wave antenna

@ndavie

What about a metal sheathed wire in the lower 2.6m?
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Old 11-03-2018, 14:50   #15
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Re: Using standing rigging as a short wave antenna

Quote:
Originally Posted by ndavie View Post
Insulation does not prevent the rf power from radiating perhaps harmful energy. Only separation does that. The normal solution is to have an insulated backstay with the antenna portion high enough to keep crew members far enough away. My use of the standing rigging worked as I was either single handed or with a crew member that was very aware and then I only transmitted rarely.
Actually, the feed wire from the tuner to the insulated backstay radiates just as much as the "antenna" portion, so if you are worried about exposure to HF radiation, it makes no difference how high the insulator is.

But, as i have often posted in threads like this one (and they come up very frequently) we've used the entire rig... mast and all rigging... as an uninsulated antenna for many years. We have done it with the base of the mast grounded and with it isolated, and it works well either way. It may not be ideal, but it works as well as insulated backstays as far as signal reports from distant stations can determine.

As far as the type of wire to insert in Dyneema rigging... makes no difference as to insulation, and not much difference as to gauge. I'd worry more about its physical characteristics (strength and corrosion resistance, etc) than it's electrical characteristics.

It is very easy to overthink and over analyze these issues!

Jim
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