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Author Topic: VHF Antenna Suggestions?  (Read 4156 times)

January 29, 2011, 11:47:03 AM
Reply #45

DOCREED

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Re: VHF Antenna Suggestions?
« Reply #45 on: January 29, 2011, 11:47:03 AM »
Quote from: "RickK"
Beamwidth - the higher the db the narrower the beamwidth
----------------------------------------------------------
Range: http://reviews.ebay.com/VHF-Marine-Radio-Antenna-Buying-Guide_W0QQugidZ10000000000015940
Square Root of Height Above Water (in feet) times 1.42 equals Range in Miles

Example: Highest point of your boat is 6 feet above water. You attach your 3-foot antenna at that point. The antenna is now 9 feet above water. The square root of 9 (which is 3) times 1.42 equals 4.26 miles


You must also take the height of the other antenna into consideration.  If you are calling a land station with a tall antenna, your range will be much better.
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January 29, 2011, 12:19:09 PM
Reply #46

John Jones

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Re: VHF Antenna Suggestions?
« Reply #46 on: January 29, 2011, 12:19:09 PM »
Quote from: "DOCREED"
Quote from: "RickK"
Beamwidth - the higher the db the narrower the beamwidth
----------------------------------------------------------
Range: http://reviews.ebay.com/VHF-Marine-Radio-Antenna-Buying-Guide_W0QQugidZ10000000000015940
Square Root of Height Above Water (in feet) times 1.42 equals Range in Miles

Example: Highest point of your boat is 6 feet above water. You attach your 3-foot antenna at that point. The antenna is now 9 feet above water. The square root of 9 (which is 3) times 1.42 equals 4.26 miles


You must also take the height of the other antenna into consideration.  If you are calling a land station with a tall antenna, your range will be much better.

yep.  You calculate for both stations, then add the results, just like the website I posted pages back does for you so you don't have to do the calculations.
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January 29, 2011, 07:40:42 PM
Reply #47

MarshMarlowe196

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Re: VHF Antenna Suggestions?
« Reply #47 on: January 29, 2011, 07:40:42 PM »
Don't buy a Cobra.  :roll:  

SeaBob already told me this once... but I guess since I already had it, I was gonna use it.

Lately, when I've gone to prep my boat, the starting battery (which everything excluding the troll motor, courtesy lights, and spotlight/cigarette lighter plug is hooked up to) has been less than 12Volts.  I put a charge on it at least once a month.  I figured I had a slow draw somewhere  :scratch: .  Didn't feel like investigating.  2 weeks ago, charged the battery, ran the motor for 20 minutes, and dialed everything in.  Went to go pick up the boat tonight to take it out tomorrow, and the battery was stone dead  :x  :x

The slow to increasingly fast draw on the battery:  the positive lead to my busted Cobra VHF.  When it went out (which took less than a year), it tried to take the battery with it.

Perfect excuse to try out my new radio and antenna.  When I install it  :tongue:
Key West 1720 / Yam C90

Sold: 1973 Aquasport 19-6

 


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