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Picking up a VHF
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| dmrose |
Posted on 08/27/08 - 7:08 PM
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I have just planned a last minute trip to Tofino on the West of Vancouver Island and need a radio for my 17 Montauk. I only fish the inshore waters of Puget Sound and the west coast of Vancouver Island. I know absolutely nothing about VHF differences but am thinking about getting this before I go. I'm planning on mounting it to the top of the console.
http://www.rivermarinesupply.com/xcart/catalog/product_12452_Standard_Horizon_Eclipse_DSC_GX1000S_VHF_Radio.html
Does anyone see a huge problem here with this option and is it more powerful than most handhelds? I'm also looking for a shorter metal antennae (maybe two feet) that I saw somewhere on this site that I can simply mount to the console grab rail and pivet up or down. Any ideas?
I'm leaving in a week and a half and have to put this together last minute. Ultimate procrastinator....
D
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| MW |
Posted on 08/28/08 - 12:52 AM
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Fixed mount VHF has 25 watt's of power, most Hand Held's have 5 watts max. The Antenna is a VERY important part of how far a VHF radio can transmit, they work on what is called "Line of site" (one antenna must see the other one to communicate). The higher up in the air that you can get the antenna, the further you can transmit, Example: My Antenna is 8' tall, a sail boat with the same antenna mounted up on the mast will have a much greater range than I will. You want a "GOOD" antenna, my antenna cost much more than my radio. A smart move would be to also throw an inexpensive Hand held VHF in a waterproof "floatable" bag, as well as a cell phone as a last resort. An external speaker is practically a "Must" on fixed mount VHF radio's, as hearing the radio over engine noise with the little "Built in" speaker is nearly impossible.
mw
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| CapnJs |
Posted on 08/28/08 - 4:49 AM
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I bought that same radio this summer and am very happy with it. I use it only in the rivers and near shore. I agree with all MW said, especially the need for a tall antenna; and an external speaker if you want to hear the radio when you are travelling above an idle.
I have an antenna mounted to the rail at the stern. It folds down out of the way when I'm not using it and is not in the way when it's up. Pay more for the antenna!
If you hurry before the personal pages go away you can see the antenna on the last picture on my photo album page; you can just see the antenna aft on the starboard side. I also carry a waterproof handheld.
http://www.whalercentral.com/infusion...er_id=4293
Jack
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| dmrose |
Posted on 08/28/08 - 5:47 AM
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Okay, sounds good. My only problem with buying a tall antennae is that ALL of my fishing is Fly Fishing and generally I have one angler casting in front and one in back. I need to find a way to mount it on the console???
D
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| Phil T |
Posted on 08/28/08 - 6:20 AM
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The mounting of a VHF antenna on a center console style boat has always been a challenge.
As stated above, there are two obvious locations. Center console or stern corner. As for height, a 3' whip tends to be the standard length on the top console rail. An 8' fiberglass antenna for the stern corner.
Recently, I have read of a hybrid option for the console. Basically, it is a ratcheted bracket on the side of the console holding a 3-4' extension mast with a 3' whip on top. One could mount this option on the top of the console rail with a rail mounted ratchet mount.
Parts:
The console ratchet mount is a Shakespeare 4188-S
[img]http://www.starmarinedepot.com/smd/images/prodimages/shakespeare/SS1115_L.jpg[/img]
The extension mast looks like
[img]http://www.jmsonline.net/ppp/images/10677.gif[/img]
The whip looks like this:
[img]http://a1672.g.akamai.net/7/1672/116/20080801/www.ritzcamera.com/graphics/products/3-04/316032804.jpg[/img]
All of these can be found on the Shakespeare Website
Edited by Phil T on 08/28/08 - 6:21 AM
1992 Outrage 17 I
2019 E-TEC 90, Viper 17 2+
2018 Load Rite Elite 18280096VT |
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| Blue_Northern |
Posted on 08/28/08 - 6:53 AM
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Just a little note about mounting your radio. Be sure to mount the mic on a vertical surface. A friend of mine just replaced his radio and blames the mic malfunction on water left in it after washing. He had it mounted flat on top of the console and it would not drain. May be good advice or may not but why take the chance.
Rob
1973 Outrage/Lo-Pro Conversion |
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| MW |
Posted on 08/28/08 - 9:18 AM
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good point, and don't forget that you should have no less than 3' of antenna coaxial cable between the antenna, and the radio.
mw
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| CES |
Posted on 08/28/08 - 9:53 AM
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The antenna has to be a certain length in order to get the proper Signal to Noise Ratio (SNR) which should optimally be 1:1. If you put a shorter antenna with your system, you will have a much higher SNR as the antenna is not matched propery with the radio. You should go with the exact radio manufacturers recomended antenna as that is the antenna that particular radio is matched up with for optimum performance. Also, DO NOT cut your coaxial cable to length. It is factory cut to be the proper wavelength for that radio frequency range and antenna. I've known guys to modify their antennas and coax cables only to short change themselves in radio performance. Also, with a higher SNR, you could burn out your radio if you have a mis-matched antenna attached to it. If you can, buy the radio and antenna as a set.
Cliff
1966 13' Sport with a 1993 40hp Yamaha 2 Smoker |
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| Blue_Northern |
Posted on 08/28/08 - 10:21 AM
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Cliff - can you go larger antenna for better results or does that create an issue as well?
Rob
1973 Outrage/Lo-Pro Conversion |
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| CES |
Posted on 08/28/08 - 11:23 AM
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Rob, going larger creates the same issue as well as the SNR is off. Typically what the antenna manufacturers do is center tune the antennas. The FCC VHF frequency band is 30MHz-300MHz. The marine portion of that range is 156 to 174 MHz. An antenna mfgr will typically center tune their antennas to the mid range of the spectrum they're using. In this case, about 165MHz is the center tuned frequency (Channel 16 emergency frequency is 156.8 MHz). So a marine antenna is cut to the optimal wavelength of about 165MHz. If you go to a larger antenna, you effectivly increase the wavelength size of the antenna causing a higher SNR which make the antenna less efficient meaning less power out. Yes, you can use a larger antenna however it won't give you the effect you're looking for, which is more range. Now if you mount your antenna higher on your boat, you may get a few extra feet or range with that method as VHF range is line of sight and you are restricted by the curvature of the earth (about 14 miles at the surface of the earth, or surface of the ocean).
Cliff
1966 13' Sport with a 1993 40hp Yamaha 2 Smoker |
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| Blue_Northern |
Posted on 08/28/08 - 11:26 AM
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That is very informative -- I always went under the assumption bigger is better. Of course we are in Texas  . I have a friend giving me a VHF radio with no antenna so this is going to be very helpful when I go to rig it up.
Thanks Cliff!
Rob
1973 Outrage/Lo-Pro Conversion |
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| CES |
Posted on 08/28/08 - 11:29 AM
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Blue_Northern wrote:
That is very informative -- I always went under the assumption bigger is better. Of course we are in Texas . I have a friend giving me a VHF radio with no antenna so this is going to be very helpful when I go to rig it up.
Thanks Cliff!
It's all about the technique Rob. lol. 
Cliff
1966 13' Sport with a 1993 40hp Yamaha 2 Smoker |
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| Blue_Northern |
Posted on 08/28/08 - 11:34 AM
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Thats just what women tell guys with small antennas! lol 
Rob
1973 Outrage/Lo-Pro Conversion |
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| CapnJs |
Posted on 08/28/08 - 4:33 PM
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Why not just lower it when you are fishing?
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| dburton |
Posted on 08/28/08 - 8:21 PM
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You really need a primary radio and a backup. Most of us can only afford to buy one at time. I would buy a handheld first. Take a look at HX850S.
http://www.manventureoutpost.com/mari...ts_id=6362
This radio will get help if you need it and is the state of the art in handhelds. It also floats.
Doug
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| Fishmore |
Posted on 08/28/08 - 9:06 PM
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Some things to remember on a VHF radio install are:
1. Do not leave the cable too long and then wrap the excess in to a tight bundle. It is better to cut/shorten and solder a new end on the cable than it is to have a lot of excess cable that you wrap it in to a tight bundle. A few loose service loops 1-2 foot in diameter is sufficent.
2. Do a professional job when connecting the connector on the cable. A bad job on soldering the pin or not getting a good connection on the sheathing will really screw with your ability to transmit and recieve.
3. Do NOT buy a cheap antenea. Get one with Brass and or copper elements and a stainless ferule, your mount should also be stainless. You can buy cheaper but if you looked inside the antenea you would know why. The cheaper anteneas use a plastic ferule as a mount and then they run a thin wire up through the fiberglass tube and it is held in place with soft foam and tape. After a while that wire tends to come loose and fall down inside the antenea decreasing your range dramatically. The more expensive units use brass and copper elements in side the fiberglass or polyurethane casing and they do not have this problem. However, any antenea if treated roughly or allowed to develop corrosion can fail.
4. A bad ground on the radio. Opens you up to all kinds of problems.
5. Do NOT run your power/ground/antenea wires in parallel other power wires. Do not run parallel for more than 2 feet or you will tend to introduce noise in to your system.
6. Antenea height is very important. the DB of the antenea is not as important as the height.
7. Buying a high gain antenea (larger number on the DB scale) on a boat that is not very stable. The more your boat rocks the lower gain you want otherwise your signal ends up pointing in to the water or up in to the sky. That is why Sailboats tend to use 3db anteneas so that they can still communicate when healing over. If you want to reach longer distances height is more inportant than gain on a boat antenea. A good general use antenea on small power boats is either a 8' 6db or a 4' 4.5db or a 3'3db depending on available mounting space.
One of my favorite anteneas is a Digital Antenea model 528-VW or 528-VB (vw is white vb is black) it puts out 4.5db and is 4' high and comes with 15' of cable and a small connector that is easy to route through existing wire chases/console holes. I have used this with and without antenea extensions depending on the boat and always had good results.
Hope this helps...
Edited by Fishmore on 08/28/08 - 9:09 PM |
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| CES |
Posted on 08/29/08 - 3:12 AM
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Fishmore,
You don't want to cut the coaxial cable at all as it's length is calculated into the antennas wavelength. Sure you can cut the cable a few feet, but that will reduce the efficiency of your antenna. I realize that with smaller boats you may have extra cable and not know what to do with it aside from cutting it off and re-soldering the connector. Yes, space on a small boat is an issue and when you coil the coax, you have a buildup of inductance as the coiled coax essentially becomes a "Coil" which creates issues with the antenna efficiency too. But if someone wants the most power out of their radio, cutting the coax hurts more than helps. Let's look at it this way. A typical marine VHF puts out 25 watts of power. Do you think that 25 watts is actually coming out of the antenna? In an optimal world and a 1:1 Signal to Noise Ratio (SNR), yes. However that's only if the antenna is matched perfectly with the radio i.e. coax is not cut and also at the optimum length for the equipments frequency. The more the SNR is away form a 1:1 ratio, the less efficiency one will get from their radio. So if you have a poor SNR, though you may have a 25 watts of output from the radio, the anntenna may eat up 5 or more watts as reflected energy and you may be essentially be sending out 20 watts or less of power (which also affects your range too). So if at all possible, do not cut the coaxial cable at all.
Hope this helps.
Edited by CES on 08/29/08 - 4:59 AM
Cliff
1966 13' Sport with a 1993 40hp Yamaha 2 Smoker |
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| Fishmore |
Posted on 08/29/08 - 8:47 AM
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CES, I beg to differ as VHF cables are used in many lengths and it is the quality of the cable and the connections and the antenea hieght that determine performance more than the length of the cable. I know that what you say is true for CB anteneas.
From the Shakespeare Antenea Website...
"Can I cut the cable on my VHF antenna?
A: Yes, if you need to. However, you should leave at least three feet of coax, measured from where the cable exits the antenna.
Note: This is NOT true for all antennas. CB antennas' coax generally should NOT be cut. See separate question regarding CB antennas' cable length.
Reasonable lengths of excess cable can be rolled in a coil of at least 8 inch diameter and stowed in an out-of-the-way place. "
View other FAQ's here http://www.shakespeare-marine.com/faq.asp
I can find other examples from other manufacturers stating the same or similiar and I have done quite a few installs myself where cable legnth was added or removed based on the installation needs. However if a person is going to cut thier cable they should make sure they know how to install a proper connector. I also always leave several service loops in an install just in case.
One item I did relearn from the ICOM website that I had forgotten was that safe operating limit for a transmitting high gain VHF antenea is 2 meters. That means you should mount an antenea at least 6' higher than your head. When you transmit at high power the RF (radiation) is produced at unsafe levels if you are in the beam. That is why handhelds are limited to 6 watts max due to radiated emissions during transmission. If your antenea is not that high I would reccomend staying at low power on your radio whenever possible and only switching to high power if you cannot be heard.
Another great source for VHF radio questions I found was here...
http://www.catfleet21.org/rigging/June.htm
Hope this helps...
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| CES |
Posted on 08/29/08 - 8:52 AM
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Great info!
Peace!
Cliff
1966 13' Sport with a 1993 40hp Yamaha 2 Smoker |
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| dmrose |
Posted on 08/29/08 - 8:58 AM
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Wow... Head is swimming! This is great info. I want to go with the Standard Horizon Guest GX1255S. I'm not sure how to find out what the recommendations are for the matching antenna, but a four foot version mounted high on the console rail makes sense to me.
D
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