Notes on the purchase and installation of a 2 meter antenna on your boat


(courtesy of Bill Call, KJ4W)

 

Shakespeare appears to be the largest manufacturer of marine antennas.  They seem to have recently produced a suitable broadband antenna, but they seem to be orienting it to the military market, so it's expensive and very few dealers have it listed.  Its model number is HS-2774-1.  See http://www.shakespeare-marine.com/antennas/galaxy/hs-2774-1.htm .   One dealer list it for a bit over $200.

There are some other products.  AC Marine/Celwave makes a model CX4 (see http://www.acmarine.dk/VHF.htm, and stocked by Tessco http://www.tessco.com/products/inv_display.jsp?selsku=74479); also, http://boatantenna.com/vhf/553-V.html shows a possibly suitable product.  I don't know who makes theirs.

Larsen's  model NMOWB150B is a 1/2 wave broadband mobile antenna, claiming 23% bandwidth at 2:1 SWR.  They have some other 1/2 wave models that are similar, with different mounts.  With different specs, too, which doesn't make sense.  But they don't make a marine model of any of them.  A marine model would have an elevated feedpoint to get the RF above head level and provide a ground counterpoise.  That's what is built inside those large fiberglass radomes of Shakespeare antennas.  I've given some thought to building my own base section to accomplish just this.  Larsen has a description of the NMOWB150B at http://www.radialllarsen.com/docfiles/MobileVHF136-174MHz.pdf page 16, but this is a slow download.

Homebrewing something completely or buying a product and adapting it, would be other options.  But the homebrew j-pole doesn't have the elevated feed/ground sleeve and is rated at only 7 watts max, and the eBay item isn't clear about its feed and would still need a mount rigged.  Guess I'll study the thing for a while longer. 

The boating industry has some neat mounts.  Shakespeare makes a whole line of them:  See http://www.shakespeare-marine.com/antennas/mounts.htm  The "ratchet mount" is probably the best style for my boat.  The "lift 'n lay" would work fine if I had a level flat fender or deck area.  Either will allow the antenna to be laid on its side for stowage.  If I go with a homebrew or auto mobile type antenna, the hard thing will be to adapt one of these mounts to the antenna.  Or to build something comparable.

Of course, if the radio club someday installs a repeater to cover the Lake area
well, my handheld might just do fine!  :>)

73

Bill

 

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Murray State University
Amateur Radio Club

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Murray, Kentucky 42071

http://campus.murraystate.edu/org/msuarc/

President: Mark Garland, K4SDI
Vice President: Randall Winchester, WD4HVA
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