Classic AquaSport
General Aquasport Forums => Electronics => Topic started by: Glock Diver on February 27, 2011, 11:44:24 AM
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Just curious what kind of ranges you guys are getting out of your VHF's.
Last weekend, I took the Aquasport as far offshore as I ever have- about 15nm off the tip of Sanibel. It was the first time I couldn't see land from my boat! :cheers: Had a great afternoon diving the ARC Tower reef.
I could hear VHF chatter pretty clearly (and we weren't the only boat out there), and I could receive transmissions from land, but none of my radio checks to land were returned. I tried SeaTow and BoatUS. Would my transmit signal be stronger while the motor is running?
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Increased voltage can help a little. First thing I would do is double check and grease all coax cable connections from the radio to the antenna. Then find someone with a SWR meter. If it shows 2 or higher you have serious signal loss either in the antenna or cable. It will also measure your watts output.
(http://www.walcottcb.com/images/ART3.jpg)
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Here's a line of sight calculator... http://www.calculatoredge.com/electroni ... fsight.htm (http://www.calculatoredge.com/electronics/lineofsight.htm)
I think to calculate line of sight you take the square root of your antenna's height and multiply that by 1.3. (?Antenna Ht X 1.3) and that's how far your antenna should be able to talk. That's assuming the receiving antenna is on the ground. Depending on the power output of your unit, you may be able to increase your transmission range.
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There is a 12ft change in height (curvature of the Earth) every 18 miles - so you might have been on the edge of being able to transmit/receive from shore.
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My 8' antenna is mounted about 8' above the water line, so with 16' total, I would think I'd get enough to reach land. The radio and antenna are about a year old.
I'll try one of those meters, hopefully I can find somebody that's got one!
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Given two good systems and no interference, if you can hear them you should be able to talk to them. What can happen and you never know it is that someone on the other side of them but out of your range is chattering and drowning out your signal. If it's a busy day on the water there are a lot of conversations going on that are not in your range but are in the range of the station you are trying to hit. A lot of the tow boats and other operations also monitor 11. I would try that. Sometimes a quieter channel will get you through.
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My 8' antenna is mounted about 8' above the water line, so with 16' total, I would think I'd get enough to reach land. The radio and antenna are about a year old.
I'll try one of those meters, hopefully I can find somebody that's got one!
Mike
If you have a local west marine, someone in there may have the VH/SWR meter, mine does, and they dont mind using it if you pull your boat to the store.
Marc