SSB - Backstay antennae length/placement?

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1 year 3 weeks ago #3001 by Mike Aubie
SSB - Backstay antennae length/placement? was created by Mike Aubie
Hi, looking to use the main mast backstay as the SSB antennae, what length and how far off the deck should the first insulator be to avoid the mizzen rigging interfering with the transmit signal? Or does that even matter as the GTO cable that will feed the wire conducts as well? I believe that the top insulator should be a minimum of 4' from the top to avoid interference with the VHF antennae that is mounted at the top of the main mast.
Lots of general info out there on antennae lengths insulator to insulator, however looking for what works well on our boats as far as 'placement' of the radiating part of the wire. Thx!

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1 year 3 weeks ago #3002 by Peter Hughes
Replied by Peter Hughes on topic SSB - Backstay antennae length/placement?
Hi,

That depends!

What antenna tuner are you using and which bands will you be utilizing? (the antenna will need to be optimized for them, unless you are using a good antenna tuner...)
For example, my AT (the Icom AT-120) will match a 7 m (23 ft), or longer wire antenna across 2~24 MHz.

It's worth reading up on this, as certain lengths of antenna element should be avoided, to make the AT's job easier.

Peter ZF1HP
SV AMARAI
WB42

Peter C Hughes
SV AMARAI
W42 #061

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1 year 3 weeks ago #3004 by Debi Shaimas
Replied by Debi Shaimas on topic SSB - Backstay antennae length/placement?
Total length of isolated cable plus GTO wire should be no shorter than 7 meters (22.96 feet) and no longer than 15 meters (49.212 feet). Install lower isolater at good working level as you will need over time to change the GTO wire (recommend every 5 years or so) and, at times, check the joint for corrosion.
Many people slather the joint between GTO wire and isolator with “waterproofing” but this actually leads to corrosion because you can never prevent water traveling between the rigging wire strands. Use just a hose clamp and put an inverted “U” at top of GTO wire to prevent water leaking down the wire.
It makes no difference how high the upper isolator is as long as you do not exceed the total overall length. Optimal is 9.5 meters.
I have 21 feet isolated cable with 12 feet GTO wire for a total of 33 feet (10 meters).

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1 year 3 weeks ago #3005 by William Weigel
Replied by William Weigel on topic SSB - Backstay antennae length/placement?
On my W42 I am using my starboard backstay. The lower insulator is about 6' off the deck. It is easy to access the connection point of the feed wire when standing on the aft cabin top. For what it is worth, the feed wire is held away from the lower part of the stay using 4" pieces of PVC tube and wire ties to create an insulated spacer. This is the way it was setup when I bought the boat and I have never thought to eliminate the spacers and wire tie the insulated feed wire directly to the rigging wire.

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1 year 3 weeks ago #3006 by Debi Shaimas
Replied by Debi Shaimas on topic SSB - Backstay antennae length/placement?
Did someone advise to eliminate the separation of the GTO wire from the stay? I also have spacers and have never heard of not using them. PITA so can you cite where you saw it wasn’t needed? I would like to research this. Thanks!

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1 year 3 weeks ago #3008 by Robert Strickland
Replied by Robert Strickland on topic SSB - Backstay antennae length/placement?
Keeping them separated is a good idea to avoid signal attenuation. If they are close together you will lose power in your transmissions.

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1 year 3 weeks ago #3011 by William Weigel
Replied by William Weigel on topic SSB - Backstay antennae length/placement?
I have not read that they can be eliminated. I have seen many boats that do not use spacers which lead me to question whether they are important. My radio works well as configured so I have not made any changes. I agree that the spacers are a pain but I am keeping mine installed for now.

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1 year 1 week ago #3026 by Mike Aubie
Replied by Mike Aubie on topic SSB - Backstay antennae length/placement?
Hi, sorry for the delayed response.
Thinking all of the West Coast/Mexico cruising nets. At some point in the future the Pacific Seafarers net as well if we make it out that way.
So generally 3 - 4 - 7 - 8 - 14- 21 mhz off the top of my head. I know these are broad frequencies and not specific at this point.
We currently have an older Icom AH-2 tuner and I am not opposed to an upgrade....

Mike VA7 WBY

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1 year 1 week ago #3027 by Mike Aubie
Replied by Mike Aubie on topic SSB - Backstay antennae length/placement?
Thx, that makes sense. Still thinking of keeping the top at least 4' away from the VHF/AIS antennae though.

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1 year 4 days ago #3029 by Mike Aubie
Replied by Mike Aubie on topic SSB - Backstay antennae length/placement?
I found an online calculator for length and it looks like a total length of 30.5 feet should not cause any tuning problems. Only the 10M band will be compromised if the calculator is accurate. Can't see how to upload it in this forum.
Thx

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1 year 3 days ago #3030 by Edward Watson
Replied by Edward Watson on topic SSB - Backstay antennae length/placement?
Check out the bad lengths, to NOT use.

www.hamuniverse.com/randomwireantennalengths.html


And,

udel.edu/~mm/ham/randomWire/

Marine Bands are close to the HAM bands and if in trouble you can us any freq. that you need to.
There are ALWAYS Hams listening and the the best chance of help is often on the Ham Bands.
Only good Marine tuners should be used, ones that can tune your wire to the 2 mhz band

New Hope
W4SZZ
The following user(s) said Thank You: Mike Aubie

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