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Old 08-02-2007, 10:06   #1
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SSB Antenna - What we ended up with....

Thanks to all those who gave us pointers and good ideas around a month back when we asked Q's. We'd purchased an ICOM 802 SSB / DSC and knowing nix on installation, wanted feedback then on whats the best antennas to use.

Took some time to get to a firm outcome, but someone who came to our blog via Cruiserforum asked me to clarify why we got where we got, and to do so on this site.

So I'm apologising in advance if this comes over as nieve dribble to those more experienced. I know already we ended up with a solution that others may not have got to, but here's how it went in all its boring detail.

Its a choice that was finally influenced by safety and effectiveness rather than cosmetics or price - although those last two were uppermost when we started looking. We're not short of a quid - but hate wasting it! We do like the boat to retain its good looks.

We started off really not wanting whip antennas. We aft park most often in the Med and any more clutter on the pushpit / transom was really not needed.

So first off, we aimed to try and use the lower section of our backstay.
SSB HF/MF with DSC requires two antenna - one longer (say 5+ metres) for radio and one shorter (say under 2 metres) for the DSC. I was hopeful we could add in four insulators to the bottom inverted Y of the lower backstay they fit to our yacht. We've a Hanse 461 with a 26 metre fractional rig - and a hydraulic backstay tensioner set on the straboard side of the inverted Y.

That plan was to allow us to create the longer radio antenna on port side wire, and short length DSC anetenna on starboard. Sounded as if it would be neat and effective. Sadly not so. Apart from the strong risk the two antenna would have of disrupting transmission being so close to one another, both the lower backstay wires would also be easy for a crewmber to hang off (and fry hands when transmitting) - plus both wires ran milimetres away from our stainless framed bimini.

So stroke plan # 1 from the list.

The next plan was to do what many already do - simply use top wire of the backstay with just two insultators - to create the longer antenna away from the crew and bimini. Plus add a short DSC antenna transom mounted. But the more we checked out insulators and spaced cabling required down from the bottom insulator to the ATU - the more we went off the idea. Many reminded us if we did go with a backstay - we'd need to also carry a spare antenna just in case the rig came down - and as cutting and swaging a perfectly good backstay never did sound sensible - we put that aside and looked into plan # 3.

Several savvy cruisers had simply suggested running a rope covered wire from a spare halyard at mast head, with one insultator at the bottom of the wire, and take it to one side of the pushpit!! This would mean this antenna was separate from the backstay - and indeed cheaper to insall - but for for us that presented difficulties again due to our biminin size. We did consider running such from a deck point further forward - but the close it got to a verticle plane the closer it got to the mast - which other techies definately told us was a no-no. They advised that having such a wire running almost parallel with another metal line (either backstay or indeed mast) could lead to reception / transmission problems. And of course, even though is is not the backstay iteself - we'd still have issues trying ti use it if the rig ever came down.

So plan # 5 - which was to check out the US made GAM antenna innovations - where the antennas moulded into a plasticated strip which simply clips over the backstay (and avoids inserting insulators and maybe keeps this antenna away from biminin frame) and is easy to effect. At US$450 this was one of the cheapest options also - but after mocking up a profile fo the plasticated strip to the dimensions given in the spec - we finally binned plan #5 as in our opinion - it would look ugly as!!

So as you might gather by now, we've eventually come full circle and ended up back with two whip antenna.

Up side is all modern reports say the long radio whip is as good if not better than a longer backstay antenna anyway - plus whip antennae radiate in the vertical plain which is ideal for longer range HF communication. There is also less possibility of radiation getting back into the yacht, which reduces the effects of onboard interference.........

And of course - it is usually still there if the mast comes down.


Means we will have to live with the issues of more stern clutter - but of all options - suggest we'll adapt to these issues easier than all others identified above.

The other chap also asked what we'd decided to do about fixing our ground plane? As we've learnt - a good antenna system requires a good ground, and on a yacht this means simply having a good connection to salt water. On a GRP yacht like ours, this is best achieved by fitting something like the Dynaplates (USA made) which have the reputation of being the best.

So repeat apologies for this being so long winded but hopefully, might just help others who were as ignorant as I was (still am really) about setting up SSB antenna!!

Cheers
JOHN
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Old 08-02-2007, 11:23   #2
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Thanks John. I'm still thinking about it. Let us know how it performs. I like Bill's idea about using the toerail for ground plane?

Regards,

JohnL
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Old 08-02-2007, 13:19   #3
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Do you have any pictures of the installation? I would love to post them on my site... (assuming of course the installation works well for you )
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Old 09-02-2007, 04:11   #4
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HI Guys,
Will take pics once all installed. My head can't get round the toe rail acting as a ground plane but it clearly works for others. But as I don't have a metal toe rail - for me the sea via Dynaplate is best option.
JOHN
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Old 09-02-2007, 05:12   #5
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Thanks for the update Swagman. I was that poster on your blog. You invited readers to ask so I did. Let us know how well it all works. I am interested in the 802 myself. I have a bit of time before install so I'm going to be absorbing others' experience for now.
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