Help installing VHF antenna

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Retcoastie
Captain
Posts: 673
Joined: Sat Sep 16, 2006 7:00 am
Sailboat: MacGregor 26X
Location: Gray Hawk, Kentucky 2002 X "Last Flight"

Re: Help installing VHF antenna

Post by Retcoastie »

IIRC, the gain of the antenna is the important parameter. Omni-directional antennas, whips, have a pattern like a donut. As the gain is increased, the donut is flattened and expanded, going from a donut shape toward a flat washer shape. The high gain, flat washer shaped pattern is not desirable on sailboats due to the heeling. One side would be beaming to Mars and the other toward Atlantis, with good coverage only directly fore and aft. The rule of thumb is no more than a +3db gain on a sailboat. That gives the best coverage over the widest range of attitudes.

Ken
Kelly Hanson East
Admiral
Posts: 1786
Joined: Sat Apr 19, 2008 2:35 pm
Sailboat: MacGregor 26X
Location: Kelly Hanson Marine........Mac 26M Dealer......Freedom Boat Works

Re: Help installing VHF antenna

Post by Kelly Hanson East »

I recall the salesguy telling me "I do desire that we be better strangers" so that would make it a Shakespeare.... :D
Kelly Hanson East
Admiral
Posts: 1786
Joined: Sat Apr 19, 2008 2:35 pm
Sailboat: MacGregor 26X
Location: Kelly Hanson Marine........Mac 26M Dealer......Freedom Boat Works

Re: Help installing VHF antenna

Post by Kelly Hanson East »

deleted duplicate post
Last edited by Kelly Hanson East on Thu Sep 03, 2009 2:44 am, edited 1 time in total.
ausmike
Just Enlisted
Posts: 15
Joined: Fri May 30, 2008 2:00 pm
Sailboat: MacGregor 26M
Location: Sydney AUS

Re: Help installing VHF antenna

Post by ausmike »

I installed a 3' whip on top of my 2008 M. Ran the cable down the mast (inside). Cut through the foam in there by using some conduit with a holoe saw blabe screwed to the end ( a 2 man job but went down a treat, 10 minutes work). Used a waterproofed clam over the hole and filled it with 420 and placed a quick connect so it can be unscrewed when the mast is down. At the same time I installed a mast head light and ran the wires for that too with a quick connect on that. Ran the cables through the head liner and tunes and VHF all go great.

Installed a splitter from Shakespere so that I get crystal clear AM/FM and VHF from the one run and antenna 30' up. It was a fair amount of work (soldering the ends on to make the cables and feeding the wires), but well worth the effort.

See my mod "Antenna on Mast" for how I mounted both on the top of the mast so that the antenna does not shade the light...
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