Marine VHF antenna?

[mattttt25]

Re: Marine VHF antenna?

"I don't need to "argue" the issue with ICOM. I have more authority than they do."<br /><br />now that's funny.<br /><br />i'm sure icom has a few experts somewhere in their company. i'm also sure their statement has been rewritten several times by their lawyers.

 

[Boatist]

Re: Marine VHF antenna?

18 Rabbit<br />San Francisco Groups antenna is on top of Mount Diablo???? I don't know why but I always thought it was on top of Mt Tamalpais. I know it has great range as have talk to them from between the levees on the Sacramento River in Sacramento and also from 30 miles north of Bodega in the ocean at Salt Point.<br /><br />Do you think the FCC has more Authority? Ha Ha Ha.<br /><br />I have read two studies on VHF radiation and both reached the same conclusion. The radiation does some damage and the human body tries to repair it. Also both said need much longer study to find long term affects. These study are why VHF handhelds and Cell phone are limited in watts output. Everyone in studies think cell phone use will some day show the long term affects.

 

[Boatist]

Re: Marine VHF antenna?

The 3 foot 3DB gain antennas are really best for sailboat mast head antennas. Main reason is the radition pattern is wide enough that signal will get out even when a sail boat is heeled over. <br /><br />A 8 foot 6DB antenna with it narrower horizontal radiation angle would be transmitting into the sky on one side and into the sea on the other side of a Sailboat heeled over. These antennas work good for most power boats. <br /><br />The 9DB 15 foot antenna have such a small horizontal radiation angle that going thru swells radio would be cutting out. They are designed for Larger boats not affected as much by swells.<br /><br />Still there is a big difference from one 6 DB antenna to another. The biggest difference may be in how long they last but also a big difference in what signal you can receive. We camp in a public campground when we take our boat to the ocean. Over time we have maid a lot of friends and many have noticed my radio receives many more signals than their radio. Since I carry a SWR bridge I have checked a lot of radios. Some turn out to be bad connections at the PL259 connector but most are the antenna itself. In fact I have seen so many I now carry 25 feet of coax cable to make it easy to hook their radio to my Shakespeare 5225 antenna. After hooking up they are shocked at the difference. Check their antenna on the meter and it looks fine but their is a clear difference. There may be better antennas out there but the 5225 is a good place to start.

 

[rwidman]

Re: Marine VHF antenna?

...... In the Army, the antennas were quite close to personnel when mounted on the turret, they pushed a LOT more power than a marine VHF, and there was never an issue.

The army is not real concerned about your safety, if they were they wouldn't send you to places where people shoot at you!

 

[18rabbit]

Re: Marine VHF antenna?

Originally posted by Boatist:<br />San Francisco Groups antenna is on top of Mount Diablo???? I don't know why but I always thought it was on top of Mt Tamalpais. I know it has great range as have talk to them from between the levees on the Sacramento River in Sacramento and also from 30 miles north of Bodega in the ocean at Salt Point.

USCG Pacific Area command is on Coast Guard Is. Vessel traffic control is on Yerba Buena Is. The primary antenna for the SF bay is on top of Mt. Diablo. Makes sense for shooting out into the Pacific and coving most of the bay and a parts of the delta, but there is no way one antenna can cover the whole SF bay. You know how this thing is shaped … and it’s surrounded by mountains. The other antennas that I know of are on top of Mt. Tam, Mt. Jenner, Yerba Buena Is., and somewhere in Vallejo for lower delta coverage. The CG can simulcast as needed for area specific or total bay/delta coverage. There must be more antennas for the SF bay and especially the delta because there are 12 antennas for just the Bodega bay USCG station.<br /><br />I’m sitting half way up the west side of the Oakland Hills. From here I can see some of the southern bay, Coast Guard Is, the Alameda estuary, western span of the bay bridge, SF, Sausalito area. If I want to sneak over and cut down the neighbor’s tree, I could see YBI, Alcatraz, Angel Is., and most of the bay bridge. I monitor vessel traffic (ch 14), tugs (ch 7), calling (ch 16), and idiots (also on ch 16). I think I receive Mt. Tam but I know I don’t get Mt Diablo because it’s up and over the hill behind me. I can hear boat-to-boat and boat-to-traffic but not always the traffic-to-boat if from Mt. Diablo. I think what I hear from Mt. Tam is CG-to-boat but never boat-to-CG ... possibly because the boats are in Drake’s Bay or Tomales Bay or Bodega Bay? Sometimes I can also pick up boats and CG out of Monterey bay (serious diving accident last Saturday on one of the dive boats). I use a little 4-1/2 foot Morad 156 HD bungee corded to my display monitor. I also get similar reception on a little handheld Standard Horizon with its wimpy 6” antenna.

 

[18rabbit]

Re: Marine VHF antenna?

Originally posted by Boatist:<br /> ... There may be better antennas out there but the 5225 is a good place to start.

The Shakespeare 5225 XT is the antenna against which all other VHF antennas are judged. Anything else is either better than a 5225 or worse than a 5225. The Morad is a 4-1/2 ft, 6db antenna compared to the 8ft, 9db 5225 XT. Thom has posted his recommendation for antennas from Digital Antenna. They’re good stuff, too, and worth looking at. The DA 529 is an 8-ft, 6db antenna. Powerboat Reports likes the Shakespeare 5225 XT as the best 8-ft antenna (9db), per their July 2000 evaluation.<br /><br /> http://www.digitalantenna.com/vhf.html

 

[Boatist]

Re: Marine VHF antenna?

18 Rabbit<br />I did not know they had that many antennas around the bay but that extpains the great coverage they have.<br />I fish out of Bodega Bay all the time and did not know they had that many antennas. I knew they have the standard VHF direction finding antenna. Also two VHF and a HF antenna. Also on highest part of Bodega Head they have a main antenna at 1,200 feet per the chart. Every year or two we take one of the tours of the station and Boats. Usually on that day it is just too windy and rough to enjoy the ocean. <br /><br />The Shakespeare 5225 or 5225-XT are actually only 6 DB gain but solid antennas. If mine should ever have problems I will check what out there but will start by comparing to the 5225.<br /><br />I also monitor 16 as required and 21, 22,for Coast Guard, 12 for offshore Vessel Traffic when offshore and at least one fishing channel. I can hear 16 and 22 here in Sacramento inside with a hand held. Can't here Reo Vista with out useing the outdoor antenna or my 2 Meter antenna up 30 from the roof.<br /><br />Thank for the good info.

 

[rwidman]

Re: Marine VHF antenna?

Originally posted by 18rabbit:<br />

Originally posted by Boatist:<br /> ... There may be better antennas out there but the 5225 is a good place to start.

The Shakespeare 5225 XT is the antenna against which all other VHF antennas are judged. Anything else is either better than a 5225 or worse than a 5225. The Morad is a 4-1/2 ft, 6db antenna compared to the 8ft, 9db 5225 XT. Thom has posted his recommendation for antennas from Digital Antenna. They’re good stuff, too, and worth looking at. The DA 529 is an 8-ft, 6db antenna. Powerboat Reports likes the Shakespeare 5225 XT as the best 8-ft antenna (9db), per their July 2000 evaluation.<br /><br /> http://www.digitalantenna.com/vhf.html

The wise boater balances the quality and cost of the antenna against the likelyhood that it will be damaged by unseen overhead objects while boating or trailering.