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Old 23-11-2013, 10:24   #1
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SSB split backstay advice

I know there are a few of you out there that now your stuff when it comes to HF radio. I've decided that I want to add a SSB to my smaller cruising boat. I will purchase a new backstay with insulators no problem but, but my backstay splits at the bottom and has a mechanical purchase for adjustment. Each side of the split has a cable about six feet long going to the outboard corners of the transom. There is a a wire block on each cable connected to a triangular plate that is pulled down by a purchase to tighten the backstay. I wish I had a picture to post, but it's a common setup on smaller boats.

When running antenna wire from tuner located just below deck up to backstay I have seen posts saying to keep the wire away from other wires and metal objects. What would be the best way to route and secure the feed up the bridle to my backstay antenna?
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Old 23-11-2013, 10:29   #2
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Re: SSB split backstay advice

I wouldn't bother cutting the backstay. Run a wire up with a spare halyard. Anchor the antenna near where your feed line comes through the deck. Use lifeline wire.
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Old 23-11-2013, 10:53   #3
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Re: SSB split backstay advice

Well I have replaced all my rigging except the backstay. It's time to do the backstay anyway. I really don't want to run the antenna up when ever I use the radio. I would like it to be more permanent. Aren't you describing an emergency antenna. Thanks for your response. I've seen your post before and know you know quite a bit about the subject.
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Old 23-11-2013, 11:09   #4
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Re: SSB split backstay advice

HF antenna needs to be a specific length to give the best transmission. The typical length for marine usage is about 32'. Our split backstay with mechanical adjusters was designed so the single wire from the masthead to the insulator / HF antenna connector is 32' and the two split sections from the insulator to the transom make up the rest of the difference.

Antenna length is important if you want to optimize the use of your HF radio.
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Old 23-11-2013, 21:54   #5
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Re: SSB split backstay advice

The typical approach (and it's a good one) is to put the insulator above the split, and of course another near the top of the backstay. You then run insulated "GTO-15" feed wire, or something similar, from the tuner to the backstay.

As you've heard, you will want to stand the feed wire off from the grounded portion of the backstay. One common method is to cut several 2" lengths of small-diameter PVC pipe. Run a heavy-duty ty-wrap around the backstay, through the pipe, and around the feed wire. Cinch it tight and there are your standoffs.

The length of the standoffs is not critical, but an inch or two is good. Since you have an adjustable backstay, make sure that the feed wire has enough slack, but not so much that it gets snagged on something.

The overall antenna length includes both the backstay and the feed wire length. A total length of around 15 meters has been suggested by Icom.
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Old 23-11-2013, 22:02   #6
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Re: SSB split backstay advice

Insulator above the split or consider a GAM antenna. http://www.gamelectronicsinc.com/pro...t-lead-antenna
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Old 23-11-2013, 22:16   #7
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Re: SSB split backstay advice

Quote:
I would like it to be more permanent. Aren't you describing an emergency antenna.
Not at all. btrayfors uses this on his boat and he has recommended it several times in this forum. He is certainly one of the most knowledgeable radio/electronic contributors on the forum. I'm sure he has added a light halyard with pulley to his mast (just guessing here).

Bill's Marine Pix

He calls it an "Alternate Backstay" antenna.
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Old 23-11-2013, 23:00   #8
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Re: SSB split backstay advice

I elected to install a stand alone HF whip antenna...quite tall but not out of proportion to the boat.
I found the benefit of not buying insulators, new wire & not employing riggers to be the way to go!
Chances are Ill still have an antenna if the rig was lost too!
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Old 25-11-2013, 04:11   #9
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Re: SSB split backstay advice

Toddedger,

Installing the insulators is a cost (probably not a risk...).

The big disadvantage of cutting up the backstay to install 2 isolators (a single stay or a split one like in your case) is - as stated above - that you have no possibility left to change the length if the auto tuner encounters tuning problems on some frequencies. OK you might lengthen or shorten the GTO-15 or similar wire that runs from the lower insulator untill the antenna tuner but that will have its limits.

I am also using a permanently installed "alternate backstay antenna" - the Bill B.Trayfors design. Total length (sloping wire + the wire connecting it to the antenna tuner) is 9.2metres. This favours frequencies from 7 Mhz untill 21 mhz but my SGC-230 atu tunes every frequency between 2.2 Mhz and 30 mhz.

One might argument that in your case the lower part of this alternate backstay wire would run close to SB or port lower part of your split backstay hence coupling into it, distorting the radiation pattern etc. This even goes for the alternate stay versus a single wire central backstay. Bear in mind that on HF frequencies every sloping wire antenna or even SSB whip (backstay or other) is close to the rest of the rigging, coupling into it, distorting the radiation pattern.

Summing up, I can advise you the alternate backstay antenna:
- cheap (2 cheap insulators, ss wire or HD insulated copper litze, one isolated through-hull connector)
- can be built for sturdy permanent installation
- length can be trimmed easily before deciding on definitive length
- needs no or few standoffs to lead the GTO-15 (or alike) wire to the antenna tuner

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Old 28-11-2013, 08:55   #10
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Re: SSB split backstay advice

We have not a split backstay, but rerigged with Dynex Dux, so using the backstay for SSB antenna was not feasible. During the rerig, I added to the masthead an attachment point for a 3/16 dyneema line. Bottom anchor point at the port side bimini frame at the stern. Reeved a correct length wire into the dyneema for the SSB antenna. The location is well aft of the mainsail so no interference there. Later added stretchy bit at the bottom to maintain minimal tension on the dyneema when using backstay adjuster. Voila.
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Old 28-11-2013, 09:20   #11
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Re: SSB split backstay advice

we have a GAM electronic antenna and it works great -- we have a icom 802 with a 140 turner - our ground plate is copper stripping down the bottom of the hull and attached to our keel bolts -
i am not a techie or know much about electronics but we have been comlimented many times on the reach and clarity of our ssb --
all i know is that is really works for us
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Old 28-11-2013, 09:42   #12
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A rope antenna on a spare halyard works perfectly and saves a lot of time and money, KISS counter poise is also perfect and works just as well as a $800 sintered bronze bolted through the hull. Listening to the " experts " will not help you, talk to the hams and SSB users.
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