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Old 04-10-2015, 10:19 PM   #61
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Another thing that can affect a radio signal is the proximity of another antenna. When we added a second antenna for our flying bridge radio to replace the selector switch that had been there when we got the boat, the proprietor of the electronics shop we used cautioned us to make sure the new antenna was NOT a specific distance from the other VHF antenna or a multiple of that distance. It's been a long time since we did this so I don't remember the basic distance but seventeen inches comes to mind.

The reason given had to do with the wavelength and the partial signal blocking an antenna at these distances from the transmitting antenna could cause.

Of course if this is a new problem for the OP or for this particular boat, then antenna position would not be a factor since everything was working fine before.
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Old 04-10-2015, 10:49 PM   #62
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35 year Ham operator here. As you all know VHF is line of sight. If you have a 9 DB antenna then your ERP, effective radiated power is roughly +- nine times your radio output. That is a LOT of power.


VHF is line of sight. If your antenna is up high and in the clear your 9 DB stick should EASILY talk 50 miles if not more.


So you have coax loss, do you have RG58 or RG8? Or maybe you have some crappy 75 Ohm coax. What is it?


You need a good 50 Ohm Coax, RG213 come to mind, unsure of marine grade.


If you have a PL259 connector at the radio make sure it is soldered correctly. No short, continuity to the shield.


I have talked 100+ miles on VHF with a HH and a 3 DB antenna, line of sight, full quieting.


If you are unable to talk 5 miles with a gain antenna you have serious issues.


Look at connectors first, then feedline name and antenna connections.


With 25 watts and a 9DB stick you should be able to talk from Anacortes to any island.
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Old 04-10-2015, 11:33 PM   #63
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With 25 watts and a 9DB stick you should be able to talk from Anacortes to any island.
Yes, we have talked from our slip in Bellingham to boats in the lower half of the Gulf Islands no problem.
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Old 04-11-2015, 08:51 AM   #64
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We never bothered to switch the radio from 25 watts (it's normal setting) down to 5. We just left it on 25 watts and there were no problems, no complaints.
Somebody 20 + miles away having to listen to you might not complain directly because they can't reach you on their radio. But that doesn't mean they couldn't hear you and you were not annoying them. :-)

I'm with George. Someone not turning the transmit power down on their VHF when they're talking to some one they can see is one of my pet peeves. It's just lazy and rude. Sort of like having a loud personal conversation on a cell phone while in a public area.

Up where you are it may not happen often. But here, it's constant.

Now I may not always remember to drop the power down on my VHFs all the time but I try to.
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Old 04-11-2015, 12:33 PM   #65
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Corroded connection common cause of poor transmit. Especially if there are connections between radio and ant up in bridge or antenna masts. Usually still receive ok with corroded connections, but transmits poorly.
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Old 04-11-2015, 12:41 PM   #66
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Somebody 20 + miles away having to listen to you might not complain directly because they can't reach you on their radio. But that doesn't mean they couldn't hear you and you were not annoying them. :-)

Up where you are it may not happen often. But here, it's constant.

Now I may not always remember to drop the power down on my VHFs all the time but I try to.
I certainly agree with you when it comes to those folks who blather on and on and on about stuff on the radio. That's annoying at 5 watts or 25. But I and the people I communicate are all "minimalists" on the radio. If we say a partial sentence that's a lot.

I'm more interested in reaching the the person I'm trying to reach when I'm trying to reach them than who else might hear me. And up here, 25 watts does the job every time. Five would not most of the time.

And, as I say, outside of the two tourist months, the radio is silent 95 percent of the time other than the VTS and commercial shipping channels.
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Old 04-11-2015, 12:46 PM   #67
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5 watts?

Our handheld is 5w, or 1w on the low power setting.

Our main radios are 25w or 1w, no 5w choice. There are brands with a 5w choice?

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Old 04-11-2015, 12:48 PM   #68
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5 watts?

Our handheld is 5w, or 1w on the low power setting.

Our main radios are 25w or 1w, no 5w choice. There are brands with a 5w choice?

-Chris
You are correct, sorry. Since we never use low power I've confused it with our handheld's power. 25 and 1 is what it is (I'm pretty sure). They're all Icoms and it's been awhile since I installed them and frankly, I've totally forgotten what the low power rating is. Thanks for the correction.
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Old 04-11-2015, 01:02 PM   #69
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Ah. (Well, didn't mean it as a correction anyway, just a question.)

That said, the antenna on our handheld is so puny that 5w on that probably works approx. like 1w on our ICOMs with the 8' antennas mounted 16' off the water.

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Old 04-11-2015, 01:11 PM   #70
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When our radio at the lower helm developed a problem and was sent to Icom here in Bellevue for troubleshooting, the owner of the electronics shop we used made us up an adaptor cable that let us plug our VHF handheld (also an Icom) into our 24' antenna. This, he said, would at least extend the radio's range over the little rubber duck antenna it normally uses.
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Old 04-11-2015, 01:37 PM   #71
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While power and antenna height both affect signal propagation, antenna height has the greatest effect. Line of sight is the key in VHF comm. Extra power can help some transmissions with slight LOS issues, but you'll see better broadcast and reception performance with a raised antenna. Another significant factor in performance is antenna quality.
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Old 04-16-2015, 01:15 PM   #72
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One of the things that helps clutter up the airwaves is guys transmitting at 25 watts. Completely unnecessary for 99% of coastal cruising.

I typically run on the 1 watt setting and have no problem communicating with the locks and bridges. When I bought the boat on the 25 watt setting to test the VHF I could talk and receive from a lock 27 miles away. While in the slip with the antennas down I have no problem hearing conversation between lock #22 and tows up river 18 miles. I've been told by other boaters the lock guys don't appreciate someone calling from 2 or 3 miles away on hi-power setting, I've at times used my handheld because I can hear better on it using the head set that has the talk to transmit function.
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Old 04-16-2015, 03:57 PM   #73
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My new Standard Horizon 2200GX has a "safety feature" that I did not expect. When you manually switch to 1 watt on Ch 16 while cruising and then switch to another channel like 9 for a bridge, then go back to 16 using the 16/9 button, it reverts back to 25 watts on its own. I thought I was going crazy. So now I have to look at the power indicator every time I switch. Funny thing is that Ch 9 will stay on 1 watt.
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Old 04-17-2015, 06:41 AM   #74
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Folks that run inshore , the AICW or similar should remember that big antenna may have to be laid down for bridges .

At low power with a flat antenna even a great VHF has a hard time going very far.

Solution , second inshore antenna or a hand held VHF to talk to the lock & bridge folks.
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Old 04-17-2015, 05:11 PM   #75
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You could also buy Shakespeare's multi-function test device: it tests Receiver function; Power Output; and Antenna SWR. Available at Defender ( & elsewhere): here's the link to the product page for the ART-3 meter:http://shakespeare-marine.com/sites/...sets/art-3.pdf
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Old 04-26-2015, 01:43 PM   #76
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Assuming good co-ax connections and a properly working VHF radio, with your antenna height of 32' above the water and accounting for earth curvature with no obstructions, you should broadcast and receive to 6.9 miles.
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Old 04-26-2015, 01:55 PM   #77
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The characteristics and height of the other party's antennae affects the effective range of your radio too.
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Old 04-26-2015, 03:40 PM   #78
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Indeed. Height of 32 feet gives distance to the horizon of 6.12 nm (1.17 x the square root of the height in feet). Calculate for each of the two antennae, and add together. If the receiver's antenna is also at 32 feet, they could be able to converse at a distance of 12+ nm.

Same calculation will tell how far apart someone on a ship can see another ship starting to peek above the horizon.
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Old 04-27-2015, 10:39 AM   #79
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I know my experience is contrary to conventional wisdom that VHF is line of sight, but I routinely get 50nm loud and clear comms with other boats (not just ships and USCG) when offshore. Moreover, my AIS (also VHF) is usually receiving active signals from ships more than 100nm distant. -- I am sure the antennas on those ships are a few hundred feet high, but not high enough to explain that range.
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Old 04-27-2015, 12:26 PM   #80
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I know my experience is contrary to conventional wisdom that VHF is line of sight, but I routinely get 50nm loud and clear comms with other boats (not just ships and USCG) when offshore. Moreover, my AIS (also VHF) is usually receiving active signals from ships more than 100nm distant. -- I am sure the antennas on those ships are a few hundred feet high, but not high enough to explain that range.
I too often experience much better range from VHFs than what the theory says.
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