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Old 15-10-2010, 09:30   #16
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SSB whip antenna

If you are looking at a dynaplate or grounding system for your SSB antenna, take a look at KISS-SSB.com. Its a preloaded watertight 10' cable which couples to your tuner. Way simpler and cleaner than copper foil and other ground plane choices. Also, google up marine SSB whip antennae....many are less than $200 USD with fittings.
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Old 15-10-2010, 10:03   #17
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Yes there are quite a few whips out there that are cheap, but I would go for the best antenna you can afford. Everyone buys incredibly expensive transceivers and attach some crappy antennas on them. The key to good reception/transmission is having a good antenna as well.
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Old 15-10-2010, 10:14   #18
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For long-distance contacts, you want to radiate signals as close to the horizon as you can. Vertical antennas are pretty good in this regard so long as they're located down low. Raise them up and their vertical angle of radiation increases.
Bill,

I thought it was the exact opposite. Looks like you are correct. I found a pretty good site that describes it.

http://www.qsl.net/d/df3lp//projects/vertical/

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Conclusion: Do not mount groundplane antennas at heights between 0.25 and 1.25 wavelength. At those levels above ground most of the energy will be radiated at angles of 27 to 45 into the ionosphere.
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Old 15-10-2010, 10:21   #19
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Whips aren't as heavy and whippy as one would be led to believe in some of the posts. At least not all of them are. We have a 28' Shakespeare 5300 free standing whip that I can grab at one end and wave around like a light saber while making "vrrrm" "vrrrm" noises. When I am not playing Yoda and the whip is in its mount (in its mount, the whip is?), it moves about very little even when the boat is pitching hard. The whip we have is a thin wire network in a honeycomb construction surrounded by a light layer of thin glass. It is tapered, stiff and light.

Mark
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Old 15-10-2010, 11:07   #20
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Brad,

You were not alone in holding that (incorrect) belief. I suppose it comes from the fact that in the VHF realm higher is better and, also, in regards to beam and other antennas in the HF realm (yagis, log periodics, dipoles, etc.).

But with verticals at HF frequencies, lower is better.

One of the very best DX antennas you can put on a sailboat is a vertical dipole, i.e., a plain old horizontal dipole turned on its end, with the lower insulator mounted close to the deck. Puts out a whale of a signal at 5-10 degrees above the horizon...exactly where you want it for DX. Recently, DX-peditions have discovered the fantastic properties of vertical dipoles, and have used them very successfully.

Why is it important to have a low vertical angle of radiation for DX? Because, with a low takeoff angle you minimize the number of "hops" between the ionosphere and the earth, and as a result realize a significant "gain" as compared to antennas with a higher takeoff angle. Some DX-peditions have estimated this "gain" as high as 18-20db....all of which comes from the low angle of radiation (and fewer hops), and not from the dipole itself which as we know has no gain.

I've been using and writing about vertical dipoles on sailboats for upwards of 40 years. They work well over land, too; I have worked lots of DX with 5 watts QRP from my home QTH, using vertical dipoles on 20m and 15m.

For those interested in constructing a single-band marinized marine vertical dipole, see details on my website: http://wdsg.com/gallery/main.php?g2_itemId=125

Bill
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Old 15-10-2010, 11:38   #21
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Originally Posted by SaltyMonkey View Post
Having done my own research for my own journey, I'd add a vote for the whip antenna, although they can get quite expensive compared to the usual backstay options. I've heard mixed reviews regarding the GAM Split Lead SSB antenna for a backstay, but this is another option.
I just installed the Gam antenna one the backstay last month, and in testing have boomed out to Indiana, Fiji, Long Beach,Ca. from the slip at Kewalo Basin in Honolulu on the 25 meg band. Had no problems at 4 meg to reach a couple of other boats that were doing the Calif to Hawaii trip as I was on the Hawaii to Morro Bay route. It was easy to install, bosun's chair clipped to the back stay and a bunch of black wire ties. Simple,clean,(if you mind black backstays), and effective.
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Old 15-10-2010, 11:56   #22
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Good testimonial Loco Gato. Thats a very good range!
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Old 15-10-2010, 13:52   #23
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You really only need one insulator for your backstay. Put the insulator at the top of the stay and connect your radio output to the base of the stay or the chainplate for that stay. The stay must not be grounded with any other wires, like a bonding wire, connected to it. If you are worried about RF burns from someone hanging on the stay while you're transmitting, put a piece of PVC pipe over the bottom 5' or so.

As far as ground, it's not a ground per se but a ground plane. You don't need to connect to the ocean, in fact get a better signal if you don't. I ran two 30' strips of copper under the deck for my ground plane and it works perfectly. No extra pukas in the hull or expensive ground plates.
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Old 15-10-2010, 14:43   #24
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If you want economical, and your lower spreader is 25' or more above the deck then run a #10 insulated wire up a messenger line to the lower spreader. Cost of the wire is far less than a vertical or cutting the backstay. The downside is that you may have frequencies that your tuner doesn't work well with and range can be less than the much higher backstay antenna. But you can't beat the cost.
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Old 15-10-2010, 15:19   #25
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The OP is planning a two-year circumnavigation. I doubt he's interested in temporary or delicate low-cost alternatives.

Do it right the first time. The single insulator near the top of one backstay, fed from the chainplate is what I'd recommend (and did in my first post).

Whips may be fine for some...especially cats which don't have many options sometimes... but with your Bene I'd go for the backstay. Robust, trouble-free. I'm sure you have other things to worry about.

Bill
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Old 15-10-2010, 21:39   #26
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To me, it's more of a personal preference, I use a whip and have never seen a difference in RX or TX.
I use a whip antenna mounted on the mizzen spreader of my ketch. used the old trick of slipping a tennis ball down the whip and securing it to the shroud to give extra support to the whip...
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Old 16-10-2010, 03:21   #27
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Hi Bill,

You're right! This is not a matter of cost saving, but finding the solution that fits the need of best possible communication combined with keeping the orginaly constructions as unspoiled as possible. One matter regarding my backstays could be quite important. I have two completely individual backstays. Their length is around 25 metres, and the biggest distance between them at the stern is 2 metres. The one that will not be in use will most probably affect the insulated second stay in a bad way for a long distance down the stay. However, the SSB require no more than 10-12 metres of antenna and it is important to instal it as close to the water surface as possible. Di I have completely wrong in these assumptions?

Fair winds,
Gunnar

And thanks all for your valuable contribution!
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Old 16-10-2010, 05:55   #28
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Gunnar,

No, mostly right, except that I believe the second (unused for radio) backstay will have only a minimal effect.

You can choose the length of the antenna to fit your intended circumstances. Shorter will favor the higher (longer distance) bands, while longer will favor the lower (shorter distance bands). However, since you'll be doing a circumnavigation you'll often be sailing at night, when skip distance lengthens out on the lower bands. So, I'd recommend a length of about 40-45' for the backstay-antenna, i.e., install the insulator about 40-45' above the deck.

Locate the tuner directly belowdecks near the chainplate, and attach a short length of GTO-15 wire between the chainplate and the antenna lug on the tuner.

This should give you a very robust setup for your world cruise :-)

By the way, be sure to pay close attention to the power for the radio (use AWG6 up to a 20' one-way run to the house batteries). Also, I believe you can reduce the occurrence of troublesome radio frequency interference (RFI) by using RG-213 or, preferably, RG-214 double-shielded coax between the radio and the tuner.

Then, a good RF ground will complete the setup and you'll be good to go.

Bill
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Old 16-10-2010, 12:51   #29
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Quote:
Originally Posted by btrayfors View Post
The OP is planning a two-year circumnavigation. I doubt he's interested in temporary or delicate low-cost alternatives.

Do it right the first time. The single insulator near the top of one backstay, fed from the chainplate is what I'd recommend (and did in my first post).

Whips may be fine for some...especially cats which don't have many options sometimes... but with your Bene I'd go for the backstay. Robust, trouble-free. I'm sure you have other things to worry about.

Bill
I'm aware of his plans. In eight years of continuous cruising using that simple antenna scheme, I replaced the "antenna" twice. You don't need to cut backstays or install marine vertical antennas to get good coverage, reliability, and durability.
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Old 16-10-2010, 13:49   #30
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G'day, Mates. When we bought our Mason, we got an antenna system almost exactly what Bill has described. Our 2 to 3 year cruise is now beginning year 13. I work both the marine and amateur bands, help out with the various nets and consistently get good signal reports. When I have to replace the backstay at some point, I will continue with the insulator setup. I also have an Outbacker antenna on board that I could use, should we loose the rig. I have used the Outbacker (no tuner required) in a motorhome with a pactor modem to send/recieve email without any issues. Cheers.
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