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Author Topic: Vertical over salt water canal.  (Read 292 times)
W4DL
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Posts: 182




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« on: February 23, 2007, 05:09:08 PM »

I'm plannning on putting up a quarter wave vertical for 40 meters on the dock which is on a salt water canal.  The vertical piece will be on a piling about 3 feet horizontally from a concrete seawall.  I am soliciting suggestions from you vertical gurus on the best method of counterpoise-ground coupling for the other half of this antenna.  I'm thinking some quarter wavelenght wire in the water with the feedpoint (vertically) about 3 ft off the water to account for tide changes.  Any input appreciated!

Good DX..Mike W4DL
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WB2WIK
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Posts: 20612




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« Reply #1 on: February 23, 2007, 06:07:15 PM »

I'd use regular wire radials, like for any other location.

Saltwater is better than fresh water, and better than earth, but isn't even close to wire conductivity.  

When I lived at the beach, I tried a vertical with a few #4 AWG stranded copper cables going directly into salt water as a counterpoise, and it was certainly better than nothing; but no comparison to running 32 1/4-wave #16 wire radials on the sand in the conventional manner.  Obvious difference, measurable by antenna radiation resistance.

WB2WIK/6
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N5LRZ
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« Reply #2 on: February 24, 2007, 07:39:39 AM »

Not having any intentions of belaboring the obvious...

Be sure to use couplings that have miminal reactance with a salt water environment.

Seal the antenna connections very well.

AND MOST OF ALL be sure that you put the antenna base/very bottom above high tides.

All the above postings also apply of course.

Good luck and good hunting.

N5LRZ
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N4UM
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Posts: 476




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« Reply #3 on: March 01, 2007, 06:03:40 PM »

Mike:

I've been using several verticals mounted on dock pilings in my salt water canal for a number of years.  I use sheets of copper flashing down in the canal for ground plates.  The sheets are about 2 by 10 feet.  The bases of my verticals are about 3 feet above the water level.  I don't use radials on these verticals and they work extremely well.  At one point I had individual verticals for 160, 80, 60, 40 and 30 meters but got sick of putting them up and down for hurricanes.  I've replaced the verticals for 80 and 60 with base fed, base loaded wire slopers running from the dock pilings towards the top of my tower.  I now use an inverted L (actually a bent Marconi) on 160 with a 40 foot vertical section and a 90 foot horizontal section. It'll come down well before hurricane season and won't go back up until next winter. I can't believe that the performance of my verticals would improve by the addition of radials.  I tried it once on my 40 meter vertical and nothing really changed.  I've done some QRP operating from my small sailboat and have not used radials.  I simply take along a piece of copper flashing about 6 inches wide and 8 feet long and drop it over the side when operating at anchor.  My insulated backstay works like gangbusters with this setup.

Tim, N4UM
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N9RLR
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« Reply #4 on: April 04, 2007, 07:45:19 AM »


n4um question to:

I live in Tampa and am researching doing the same you have done, using a vertical on a salt water canal.  

I have plenty of AL put up a 20M or 40M vertical.  Im experimenting with the design and setup.  Do you run the coax down to the seawall and have the matching system located there?  How do you weather protect the coax from the salt and water?  I would like to use PL-259 or N connector, I saw the current choke-DX engineering is selling with a connector on it which has a PL-259 connector on it.  I don’t like the idea of leaving coax exposed, especially when people strip back the coax to expose the center conductor and the braid to connect to the antenna and ground system.

I read that you have copper in the water.  You mentioned it didn’t enhance the quality that much.  Nice to know!  How did you connect the copper flashing in the water as a radial system?

Are the antenna true ¼ wave or loaded in some way?  

Do you have any photos of the antennas?  

I have a website with little radio info but a webcam with a photo of the canal… www.baycrestfl.com

W4DL-

Did you ever get the verticals installed along the canal?  Can you provide your experiences with the install or how its going?

Anyone out there that can provide information on this topic is much helpful!

Thanks
Noid Wilson
Tampa, FL
noid@baycrestfl dot com
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