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NORO LIM



Joined: 24 Apr 2008
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PostPosted: Wed Jan 09, 2019 11:09 am    Post subject: Reply with quote

Foggy wrote:
. . .

This could bother those garrulous at night on the VHF.
. . .


Only a problem if they become querulous.

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colbysmith



Joined: 02 Oct 2011
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PostPosted: Wed Jan 09, 2019 2:17 pm    Post subject: Reply with quote

Quote:
I had to look it up. It's a good word, and apropos for that usage. Thanks for expanding my vocabulary this morning.


I had a supervising senior officer in the USCG use that word on one of my OPRS (officer performance reports) one time. I wasn't impressed with his big words. I'm still not. Mr. Green Colby
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Gene Morris



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PostPosted: Wed Jan 09, 2019 2:56 pm    Post subject: Reply with quote

This is an excellent article from our friends at SLOWBOAT.

http://slowboat.com/2018/05/vhf-ais-performance-upgrade-morad-antennas/[/list]

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AstoriaDave



Joined: 31 Oct 2005
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PostPosted: Wed Jan 09, 2019 3:17 pm    Post subject: Reply with quote

Great article. The URL needs to have the last 7 chacters removed, however:

[/list]

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thataway



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PostPosted: Wed Jan 09, 2019 4:59 pm    Post subject: Reply with quote

Agree that the Slowboat article is excellent--On Morad antennas.

As suggested they used separate specialized antennas on the VHF voice and AIS frequencies. Also avoided the perils of soldering.

As far as the LED lights and interference. There was a Third "alert" by the USCG August 2018. The Second was reported in 2016 and a write up in Practical Sailor that year. The first was brought up by the EU technical commission on emissions from light bulb sources. They found that only 17% were technically properly built.

Superbright and Moonbeam are interference free. Look for the C E symbol, USCG Approval 33 CFR 183.810 or Meets ABYC A-16 or equivalent on running lights (steaming/anchor, and red and green side lights), as well as spreader or spot/flood lights mounted near the antenna. If you have other LED bulbs which cause the interference, you can twist the feed power wires closely together and place a small capacitor (100 pF or less) between the power leads. It is not the LED, but the type of voltage controller which is responsible for the VHF range RF interference.

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Thataway
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hardee



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PostPosted: Wed Jan 09, 2019 5:09 pm    Post subject: Reply with quote

Great article, and info. I have seen some of the Morad antennas around. They will be what I replace my Shakeys with if/when that happens. My 8ft glass is a Commrod and it has tested and performed well. I am a firm believer in having good antennas to get out (and in) good radio performance.

Harvey
SleepyC Moon


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colbysmith



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PostPosted: Wed Jan 09, 2019 6:48 pm    Post subject: Reply with quote

Regarding the LED light issue with AIS and VHF, I've checked mine and found no problem. I suspect most of us on our C-Dory's are not going to experience any issues... Colby
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hardee



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PostPosted: Wed Jan 09, 2019 7:10 pm    Post subject: Reply with quote

colbysmith wrote:
Regarding the LED light issue with AIS and VHF, I've checked mine and found no problem. I suspect most of us on our C-Dory's are not going to experience any issues... Colby


Colby, it depends on the LED lights, (Brand) that are installed, and if they are on or off when the VHF is being used.

One issue that has not been mentioned is the proximity of the antennas one to another. That was my biggest concern when starting to add antennas. Optimally they would be 8 feet apart, and as we know, the C-Dory is not a boat with that kind of acreage readily available. I was able to scrape almost 4 feet between each, (I have 3, forward port and stbd and aft on the port side,) and that covers 3 VHF's and the AIS.

Harvey
SleepyC Moon

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thataway



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PostPosted: Wed Jan 09, 2019 9:47 pm    Post subject: Reply with quote

hardee wrote:


One issue that has not been mentioned is the proximity of the antennas one to another. That was my biggest concern when starting to add antennas. Optimally they would be 8 feet apart, and as we know, the C-Dory is not a boat with that kind of acreage readily available. I was able to scrape almost 4 feet between each, (I have 3, forward port and stbd and aft on the port side,) and that covers 3 VHF's and the AIS.

Harvey


NMEA publication on interference of various antennas, other metal objects, including horizontal as well as vertical spacing.

The NMEA gives 4 foot separation--I have found that on both sides of the cabin or radar arch is adequate. One must also avoid putting many other antennas in the radar beam. (Probably less with the new digital antennas, but some early GPS antennas were damaged by radar frequency waves.)
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colbysmith



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PostPosted: Sat Jan 26, 2019 12:29 pm    Post subject: Reply with quote

Well, In changing out antenna's I managed to damage the good one I was keeping on the boat, so the new 5225XT went to replace that one. (Which was the same model.) SO, I still have the cheaper antenna on the boat and once things warm up again and we dig out from all the snow coming (Polar vortex. Minus 50-60 degree windchills next week, with 8-12" of snow forecast for Monday. It may be a while before things warm up again.) I'm now looking at Shakespears new Quick Connect 8' antenna and wondering if anyone has experience with it.

Colby
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tsturm



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PostPosted: Sat Jan 26, 2019 12:47 pm    Post subject: Reply with quote

colbysmith wrote:
Well, In changing out antenna's I managed to damage the good one I was keeping on the boat, so the new 5225XT went to replace that one. (Which was the same model.) SO, I still have the cheaper antenna on the boat and once things warm up again and we dig out from all the snow coming (Polar vortex. Minus 50-60 degree windchills next week, with 8-12" of snow forecast for Monday. It may be a while before things warm up again.) I'm now looking at Shakespears new Quick Connect 8' antenna and wondering if anyone has experience with it.

Colby


Gotta love that global warming Wink Mr. Green

good luck on your project.
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colbysmith



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PostPosted: Sat Jan 26, 2019 1:06 pm    Post subject: Reply with quote

Also, is anybody using the Morad 9120 "hot rod" antenna? Is that the one you have Bob? How tall is that antenna.. I'm seeing some descriptions that say 86.75", but others that say 4 ft. Thanks. Colby
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jkidd



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PostPosted: Sat Jan 26, 2019 2:03 pm    Post subject: Reply with quote

Mine is a Morad 156 hotrod it is 46 tall. The 9120 is the manufactures part number.
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journey on



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PostPosted: Sat Jan 26, 2019 3:11 pm    Post subject: Reply with quote

Well, I'd like to point out that both Shakespeare and Moorad build 6 dB antennas. And 6 dB is 6 dB whether the antenna is cheap or expensive, good or bad. It's measured performance.

The Moorad discussed in Slowboat is 6 dB and 4 1/2 feet tall, replacing a Shakespeare which has 3 dB and is 4 feet tall. Then Slowboat added a 2 foot extension so the installed length of the Moorad is 6 1/2 feet. So the final cost is $190 for a durable good 6 dB antenna.

Shakespeare has several VHF 6 dB antennas, all 8 foot tall. The prices at WM range from $80 to $95 thru $130 and $230 up to $300. I don't know what you get for $300, but it better be good.

I bought the cheap Shakespeare, which quickly broke and then found out the more expensive antennas are built better. Since I remove the antenna for trailering, I poped for the good one but I don't expect better VHF performance.

Also the co-ax lead in should be low loss, but for a C-Dory (any size) the run isn't very long. So, don't count on any performance increase on that account. The connectors need to be good and Bob has several posts on how to solder them.

My conclusion is that even the cheap 6 dB antennas deliver full performance; they just don't last as long if you beat them up.

Boris
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thataway



Joined: 02 Nov 2003
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PostPosted: Sat Jan 26, 2019 5:09 pm    Post subject: Reply with quote

Quote:
Morad 9120 "hot rod" antenna? Is that the one you have Bob? How tall is that antenna..


Yes Colby that is the antenna I am using on one of my radios. I probably will eventually replace the other, which is a 4'--not sure of the brand--it was on the boat.

The antennas are on top of the radar arch, so the base is over about 18" above the cabin top to start with. I did not add a base extension--but have in some other boats. The antenna its self is about 54 1/2" long. (including SS whip). Just making a guess but about 13 feet off the water at the tip.

The difference between the "quality" and "cheap" is a multitude of factors, from the materials of the casing, the quality of wire used, if crimped or soldered, plated fittings, quality of coax, if mini fittings are used, even the finish on the outside (Gel coat, two part urethane paint, or powder coating. Generally the more costly antennas will perform slightly better after a year of use; less corrosion, etc. A lot of the information is anecdotal. For example when I was cruising offshore and using a number of different antennas on 15 meter to 80 meter ham bands, I would rely on "signal strength" and intelligibility or quality of signal received by another ham operator thousands of miles away. There were lots of variables. But certain antennas performed better consistently on my particular boat. These antennas were much different physically than the VHF which is in the 156 +/- MHz frequency range. Propagation was entirely different. But the quality antennas performed better.
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