VHF radio

wgr270

Cadet
Joined
Sep 23, 2003
Messages
26
I'm looking to purchase a mounted vhf radio. I never more than 20 miles from shore.<br />Any input on a make or model that will suit my needs? <br />Is a $100-150 radio good enough for me?<br /><br />Thanks!
 

kd6nem

Chief Petty Officer
Joined
Jul 25, 2003
Messages
576
Re: VHF radio

20 miles? The more important question is how much antenna is enough! 20 miles can be very difficult unless the antenna is way, way, way up in the air. Get a good antenna then worry about the radio.
 

wgr270

Cadet
Joined
Sep 23, 2003
Messages
26
Re: VHF radio

My bad...I'm not 20 from shore (I'm sometimes 20 miles from my port) I'm no more than 6 miles from shore.<br />Sorry about that!
 

Boatist

Rear Admiral
Joined
Apr 22, 2002
Messages
4,552
Re: VHF radio

Wgr270<br />I have to agree with Bearcat get a good antenna first then get a good radio. I like Shakespeare's 5225 antenna and Icom radios. Boat to boat with a 8 foot 5225 antenna you are looking at 10 miles or more. Boat to shore to a Coast Guard out here can be over 80 miles, because most Coast Guard antenna on top of a mountain up 3000 feet.<br /><br /> http://mastercatalog04.westmarine.com/0076.asp <br /> http://mastercatalog04.westmarine.com/0075.asp <br /> http://mastercatalog04.westmarine.com/0070.asp
 

BLU LUNCH

Lieutenant
Joined
Aug 8, 2003
Messages
1,316
Re: VHF radio

Don't worry about the size of the attenna. What you want to buy is the best attenna with a least a 1/2 to 5/8 of a wave lenth. Also you want the maxium db gain from the attenna the more gain the higher erp{effective radiated power}. Every 3 db's you double the radio's erp output. Ex{25 watts in to 3db anttena=50watts erp} And most important use quality co-ax and keep the swr under 1:5:1 a mismatch will send rf back in to your rig and it's has to go someware...back in to your trasmit finals they WILL heat them up quickly and burn them up
 

ThomWV

Senior Chief Petty Officer
Joined
Dec 19, 2003
Messages
701
Re: VHF radio

Whoa here for just a minute. First off worry very much about the size of the antenna. It is the single most important feature of any of the marine antennas on the market when it comes to your communications range. Also, virtually every one sold by any of the major marine antenna manufacturers is either 1/2 or 5/8 wave. Then on that gain - no, you do not of necessity want the highest gain antenna you can lay your hands on. The reason for that is that with each increase in gain of 3 decibels you not only effectively double your power but you also cut the width of the radiating pattern in half. That in itself wouldn't be a bad thing if it were not for the fact that boats rock. That means that the more focused beam of outgoing energy will tend to spend a lot of its time beaming either off into space as the boat rocks one way and then down into the depths as the boat rocks back the other way, with just a brief passing in the middle where your radiation pattern is pointed in anyting resembeling a useful direction. Then there is the coax question. Actually the coax you are going to get to use is the coax that came with the antenna on a small boat. None of the marine manufacturers are producing any antenna that doesn't come with its own attached coax so what you see is what you get. As luck would have it Shakespeare uses RG8X on all of their top of the line antennas (including the 5225 series, which are very nice antennas) and Digital Antennas (my own favorite of the manufacturers) for all of theirs, use this heavier cable. And yes, you should check your SWR if you have the ability throug a friend or maybe even have one of those inexpensive meters that Shakespeare markets. Its not that you are going to find that a correctly connected radio and antenna are going to have a problem and its not like you could do a thing about either the radio or the antenna even if they didn't have a good match, but really just to check the condition of your antenna connector (the PL-259 that is on the end of the antenna cable) from time to time. They do corrode and degrade over time and if you check the SWR now and then you can see it comming. I just cut mine off in the spring and put a new one on. I hook up the meter to make sure I got it right and if its OK I probably won't stick a meter on it again until about the 4th of July, and again in the fall.<br /><br />As for the original question. There are a pretty good number of suprisingly well made radios on the market these days for not too much money at all. For around a hundred and a half you can buy an ICOM 302 or one of the older ICOM model 45. Also, you could do a lot worse than to go take a look around E-Bay for a deal on a used radio. I saw an almost new ICOM M-127 sell there for less than $300 just last week. You should confine your search to radios by either ICOM or Standard Horizon, avoid all the rest. A good antenna is going to cost you about a hundred bucks. You can find the Shakespeares for a little less than that (their top of the line Gallaxy models) and you'll pay a little more for that if you buy one made by Digital Antennas. The Digitals are the better made antennas, but you pay for it.<br /><br />Thom
 

18rabbit

Captain
Joined
Nov 14, 2003
Messages
3,202
Re: VHF radio

None of the marine manufacturers are producing any antenna that doesn't come with its own attached coax so what you see is what you get.
Actually, only Morad’s low end, budget VHF antenna comes with attached RG-58U coax. All of their other VHF antennas have a PL-259 connector with supplied o-ring so you can choose the cable of your choice. Morad’s higher quality antennas without coax are priced similar to the Shakespeare antenna with coax, so in that respect they do cost more.<br /><br /> http://www.rell.com/pdfs/Moradcatalog.pdf <br /><br />What Thom mentioned about an antenna’s db gain relative to its radiating pattern cannot be over emphasized when the water moves. As a boat pitches and rolls the ability to broadcast to a target antenna becomes increasingly more difficult with the ‘motion of the ocean’. :) It is for this reason many ocean going boats are equipped with multiple antennas of different gain and will switch between them as needed.<br /><br />What Blu Lunch mentioned is important as well, quality coax!
 

Boatist

Rear Admiral
Joined
Apr 22, 2002
Messages
4,552
Re: VHF radio

A top quality antenna is most important. As Thom said a high DB antenna not a good idea for most boats. Sailboats work best with a 3 DB antenna mounted up on the mast. Most recreational power boats a 6 db antenna works well. Ships can use the 9 DB antenna or have lots of antennas. Coax I fell is not much of a factor. To start with all the good antennas come with good coax attached. On most even if you wanted to change the coax you really can't. Most power boats have coax less than 20 feet long and many less than 6 feet. Almost every year I check and fixed a couple of antenna durning our week stay at Bodega bay. I always take my Swr meter a dummy load and 35 feet of RG8X coax. Have always taken my SWR meter for the Marine gear and Ham gear used to talk home every day, but several year back started takeing the COAX and a PL258. I just made so many friends and seen so many people with antenna problems I decided would take enough gear to troubleshoot radio / antenna problems. It is really funny people will come to me at the dock and want to know what brand radio I have, then say when I was near you today your radio picked up twice as many boats as I could here. I usually respond it is not the radio but the antenna that makes the difference. Find lots of bad pl259 connections, either shorted where thay tried to solder or just very poor connection. I am supprised how many people don'tknow the braid needs to be connected. Also found lots of the small 3/8 inch flexible antenna with broken wires inside. Flex or shake the antenna and see the meter go crasy. I sure wish ICOM had just upgraded their M-127 as I think best marine radio I have seen.
 

BLU LUNCH

Lieutenant
Joined
Aug 8, 2003
Messages
1,316
Re: VHF radio

To ThomWV: By using a high gain antenna YOU WILL NOT cut your radiating pattern in half. Vertical antenna's ARE 360 degrees omni they radiate equally all directions. All so there was a comment that co-ax quality is not much of a factor....don't skimp on cheap co-ax so or later you will find out when you get water in the co-ax and your swr is sky high and you go spend couple hundred bucks for another antenna and come to find out it was water. Also cheap co-ax will have a problem called the skin effect where RF will radiate on the jacket and you tramsmit and all your electronics go BS. every time you key up.
 

18rabbit

Captain
Joined
Nov 14, 2003
Messages
3,202
Re: VHF radio

Originally posted by Boatist:<br /> To start with all the good antennas come with good coax attached.
This is not true for the Morad products. They are top quality marine antennas that do not have coax attached, fwiw.<br /><br />Blu Lunch – you are technically correct, marine antennas do radiate in all directions to a some degree. What Thom is talking about is the way a significant portion of signal flies out of the antenna. He is correct, the bigger the db gain, the narrower the horizontal pattern coming out of a vertical marine antenna. A 9 or 10db antenna is almost pancake like in the way it radiates, so even a small rolling of the boat with a high mounted antenna and you are broadcasting to the sky on one side on the fishes on the other. :)
 

Boatist

Rear Admiral
Joined
Apr 22, 2002
Messages
4,552
Re: VHF radio

Blu Lunch<br />See the link below, it has a good graph of what Thom and I are talking about. It is true the 9 DB antenna has a 360 degree radition pattern, also has a narrow horzional raditation pattern. When boat bow is high going over a swell you will be transmitting into the sky in front and into the sea aft. Either way boat you are talking to will loose your signal. Most power boats I see in the 18 to 24 foot range have coax runs between 2 and 10 feet so Coax loss just not much of a factor. I have never seen a Marine antenna with a SWR higher than 1.3 to 1 unless it had a bad connection or a broken antenna wire or cut coax. One thing I see lots of larger boat do and some even with the 9 db antennas. They lay their antenna back at a 30 to 45 degree angle, I guess they think it looks cool but to me just looks dumb.<br /><br /> http://mastercatalog04.westmarine.com/0075.asp <br /><br />Rabbit<br />I have never seen a Morad antenna but do not dout that there is a exception to the norm. I have mixed felling about the antenna coming with the coax attached. I have found the good antenna have good coax. Also it attached in a way to make good warerproof connection. On the other hand if it breaks form bending when laying down the antenna or gets cut where where it goes thru the deck it is hard to fix and keep it water proof.
 

kd6nem

Chief Petty Officer
Joined
Jul 25, 2003
Messages
576
Re: VHF radio

Its a matter of which direction and perspective viewing from. 360 degrees as seen from above, yes it is all directions. More gain is indeed a flatter, closer to the horizon pattern, less is wasted on useless higher angles (we're not talking HF here). Question: how do the 5/8 wavelength antennas work without a ground plane? My truck is my ground plane for my gain 5/8 440 mobile ham antenna. Fiberglass makes a lousy ground plane! (Seawater, conversely is great) I'm pretty rusty with this, half wave needs no ground plane, but 5/8 does, right?<br /><br />Edit: Boatist beat me to the answer while I was typing!
 
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