SSB wire Antenna - mast flex

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rvivian
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SSB wire Antenna - mast flex

Post by rvivian »

I'm ready to mount the antennas on my newly installed radar post and am planning a long wire ssb / HF antenna from the top of the post up to the masthead.

I searched the forum about wire antennas and it appears that some sort of bungee snubber on low end of the the antenna to allow for mast flex is required.

Anyone have advice on the best bungee / snubber size and configuration to accommodate the masthead movement?

(Going up the mast will be another story. I hope 210# is not too much weight.)

Thanks

rvivian
Heart's Desire
Freedom 30
Shelton, WA

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GeoffSchultz
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Re: SSB wire Antenna - mast flex

Post by GeoffSchultz »

Why not use a 24' whip antenna? I have a Shakespeare antenna that I use with my SEA235 SSB which great success. I used to me a network controller for the NW Caribbean SSB network and people always commented on what a good signal I had. Note that I also had 2 Dynaplates.

-- Geoff
BlueJacket
1997 Freedom 40/40
http://www.GeoffSchultz.org

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rvivian
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Re: SSB wire Antenna - mast flex

Post by rvivian »

Thanks for the reply Jeff.

I have thought about the Shakespeare whip antenna on the stern opposite the radar post. (Saw your boat pictures too.)

I can buy a new Shakespeare 28 foot ssb antenna whip for under $200 at the local consignment shop right now and adding the bracket for it will put it on the stern for another $150.

But I am having troubled thoughts about the 28 foot antenna (or even the 24) unsupported and more than 1/2 the height of the +/- 40 foot F-30 mast (and it's not carbon fiber).

If I don't break the mast hoisting my 210# body to attach a wire to the top I can put in a wire antenna for less than $100, and the bottom of it will still be almost 10 feet above the deck when attached to the radar post. (Will the aluminum post shield the feed line?)

I already have two Dynaplates to put on the sides of the bilge when I get around to it
.
Still in a quandary about what's best.

rvivian
Heart's Desire
Freedom 30
Shelton, WA

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Castaway
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Re: SSB wire Antenna - mast flex

Post by Castaway »

I have a mooring rope snubber at the bottom of the SSB antenna. It is about 40cm long and 2cm diameter, and I suspect it is grossly overspecified for the task, which is just to stop the wire flapping around whilst allowing normal mast flex. At the masthead, it is held by 3mm terylene cord lashing through an eyebolt, and its main use is to hold up the courtesy ensign halyard. It would probably make more sense to fix it at the base, and lash the top with thick bungee cord, although that would need to be checked in situ every year. I'm sure the mast won't even flex if you hoist 90kg on the halyard, although the winchperson might be a little stressed!

I would be surprised if conditions would be encountered rough enough to allow the Shakespeare antenna and mast to intersect, but if so, you will probably already have used it to send the Mayday message! :lol:
Gerald Freshwater,
s/y 'Castaway', (UK F35 cat ketch, centreboard, 1987)
Lerwick Boating Club
Shetland Isles, Scotland

marno
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Re: SSB wire Antenna - mast flex

Post by marno »

I have some normal 6 mm bungie cord that I bought from a hardware store. My antenna base comes through a gland on the staboard side deck just forward of the mizzen mast. For an antenna I have some 6 square mm wire after I was having problems with the stainless wire I was using. It is attached as described with a whipping to an eyebolt at the top of the mast. I don't have a dynabolt, I am using one of sea cocks and I have tapped a screw into the lead keel which the foil is also attached to. I could talk to Herb (weather router in Canada) from the Canary Islands.
Hope that helps.
Marno

F39 Express

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Michel
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Re: SSB wire Antenna - mast flex

Post by Michel »

Hi Marno,

Your solution for an SSB antenna on a freestanding mast sounds very simple and apparently works great. Can you tell a bit more about it, e.g.:

- is the 6mm2 cable supported along its length?
- how did you attach it at the top and bottom to the fixed points/bungie? e.g. do you have a loop in the top end of the cable with a kind of grip fastener to attach the lashing?
- how do you prevent water entering the top of the cable?

- does the bottom end of the antenna run straight through the deck gland and to the transceiver?

Perhaps you have a photo of the top and bottom end of the antenna wire?

About your earth connection: can you tell a bit more about that? Do you have a flat copper cable running into the bilge to the bolt in the keel? Your bilge must be bone dry then, or else the flat cable corrodes quickly, or not? Is the paint on the keel not preventing a good ground plane? Why do you use both a seacock and the connection to the keel?

Thanks for sharing your good solution!
Michel Capel, Freedom 44 #4 1981 'Alabama Queen', NED8188, cat ketch with wishbones, home port Enkhuizen, the Netherlands, 52*42.238'N 005*18.154'E.

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THATBOATGUY
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Re: SSB wire Antenna - mast flex

Post by THATBOATGUY »

Michel,

I can answer one of your questions. The ground plane doesn't have to be in direct contact with the water. In fact a nice grid fiberglassed into the hull below the waterline makes an excellent counterpoise.

Having said that, and the Icom manual aside, I've seen really great working radios that had plumbers copper strap full of holes run to one isolated through hull for a counterpoise. I searched and searched and talked with many old Hams before I finally settled on Gordon West's Kiss system of ground planes.

As for the airial portion of the antenna, I was recently on a Freedom 40 which had a dipole rig that could be hoisted aloft. It was coiled on the deck at the time, as well as a horizontal (beam?) that ran mast tip to mast tip. I did not observe the feed to that antenna.


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George
George and Kerri Huffman S/V Marquesa Freedom 40 CC CK Sail MarquesaImage

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THATBOATGUY
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Re: SSB wire Antenna - mast flex

Post by THATBOATGUY »

Here's a scan from a book about communications at sea. Frank, I can't help but wonder if the author of the book didn't see this on your Freedom?

George
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rvivian
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Re: SSB wire Antenna - mast flex

Post by rvivian »

Still mulling over the installation.

So far I've settled on a 14 ga vinyl covered copper random length wire antenna tied off th to mast head with some leftover 1/8" Spectra and extending downward to a bungee attached 7-foot fiberglass antenna extension mounted to the starboard side of the transom.

My antenna tuner will be mounted on the inside of the transom next to the antenna extension mount.

The remaining question --

Should the connection between the tuner and the antenna wire led through the fiberglass extension be the normally recommended high voltage "neon" wire or can I avoid the splice by just extending the random wire through the antenna extension and direct to the tuner?

Any Opinions??
Heart's Desire
Freedom 30
Shelton, WA

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