radio antennas question

[Don]

Connected to my Uniden radio I have an antenna that has 6dB (8') a 5206-C Shakespeare. How much
range should I have with this unit. 2nd question,
I am looking at one that is Collinear phased, 5/8-wave elements and is 35dB 42.00 vrs 100.00 I fish the Missouri river alot, will this help my distance by going to the more expensive unit.

P.S. 25 watt radio LOL Don

[Airwave]

Your range really will be determined by radio traffic and weather and how high you mount your antenna. I have talked 35 to 40 miles on that antenna and other times can't get out 5 miles. The higher dollar antenna in my experience won't help much for transmitting but will help in reception. Best thing is make sure you have good clean solid connections and I have found mounting the antenna as high as possible makes a big difference. Add a 4' extension if you have a means of supporting it...................... ---------------------------- -----OVER!!!! :)

[Moo]

I've found though past experince even before I mount ant. I test it with OHMS meter for a short. I've had bad ones right from the factory. If you mount a bad ant. it'll drive you crazy trying to figure out the **** is wrong with this radio
MOO

[Clint]

Some antennas including the 5206C will always test shorted with an ohm meter. Other's will check
open depending on their construction. The 5206c will always test as a short. Best way to test an antenna is with a VSWR meter. You can get one at
Radio Shack fairly cheap. Height is the most important element in the range of your antenna. Another key factor is the db rating. The higher the db rating, the more power is transmitted to the side of your antenna and the less that is transmitted (wasted) toward the sky or water.Most radios that come out of the factory are putting out less than their 25 watts. I've seen them as
low as 15. It's fairly easy to turn them up to
their rated power, and if you know a technician in the area, it should be fairly inexpensive to have him test the radio and turn it up! Any radio is only as good as the antenna it's connected to.
Clint, Three Rivers Marine Electronics, Board
Sponsor! http://www.threeriversmarine.com

[Sprinter]

Clint,
I see that you are a distributor of marine radio's and have expertise in this area. Do you offer a "Combo" package? Matched radio with antenna complete with pre shipment testing to insure the radio is putting out the rated 25 watts? I would think this "Value Added" service to be beneficial both for your sales and to the end user! I know you would have one more customer if this was offered.
Sprinter

[Dull Knife]

Trust in what Clint told you, its all true. The other stuff, particularly the distance stuff is nonsense.

The transmit distance of your VHF limited by the earth's curvature. All marine VHF signals are "line-of-sight" in case you didn't know. You can determine the maximum distance you can transmit by adding the height of both the transmitting and receiving stations, taking the square root of that number, and then multiplying it by 1.41. so, as an example, if you and the boat you are trying to talk with both have 8' antennas mounted 3' above the water the total height of both antennas is 22 feet. The square root of that is 4.69 and multiplying that times 1.41 give you 6.61 miles as your maximum distance. Under extemely rare circumstances you can get some atmospheric tunneling which will add slightly to the total distance but it isn't something you can count on.

Clint mentions that some radios, quite a few in fact, do not put out their rated power. Not only is he correct in that but what he didn't mention is that a lot of radios will come very close to their rated power output but not maintain it after only a relatively short time. So the point is to buy the best you can.

In my case I am using an ICOM M-127 radio and its power output is 28 watts (measured on a meter last week) with an SWR of 1.2 on channle 16 and 1.0 on USA-80. I use a Shakespear model 5399 antenna, which is a 5/8-wave 9'6" 6dB antenna (possibly the one you alluded to?). Oh, you can buy a SWR/Power meter through most any marine discount catalog outfit. They sell for between $30 and $35 and are made by Shakespear.

[Airwave]

So are you telling me I did not talk to a friend 35-40 miles away ? Both have 8' antennas'-just wondering what you meant by nonsense. Cuz I can prove it..

[Larry]

You've received some excellent advice on the above posts and I sure wouldn't get a burr under my saddle over a picky little thing like a fluke transmission that might have allowed you to communicate. I sure wouldn't want to bet my life against being able to count on it happening again in rough seas when you're taking on water and really need it to get help.

Posts like those above are from people that may have a bit of expertise in an area that you're asking about and they take the time to answer your question. THANK YOU...might be a better response and maybe the next time they might take the time to help someone else.

[Swat1]

Now don't go getting your hair in a knot. Both Airwave and I have talked over our radios when I was down off Ruggles Beach East of Huron and he was fishing out off the firring range at Camp Perry. When he gave me his coordinates and I punched them into the GPS it tlod me he was 32+ miles away. We both have 8 foot antenaes.

I also talked to Bull on a different day when I was east of Kellys Island and he was north of West Sister Island. Again this has to be close to 30 miles distance.

A quirk Maybe? But I too have talked to people a lot further away than 6 miles on many many days and people also further than 12 miles ( Horizon distance due to earths curvature) On many other times too.

Are our radios and equipment that much better than the other stuff on the market? I don't think so since I just went to a store and got mine off the shelf.

Wow I wonder what it could do if it was Peeked and Tweeked by someone who knew what they were doing.

Take it easy out there.

Dan

[Hans (KØHB)]

First, a colinear antenna probably has a gain in the range of 3db to 4db. If someone is advertising 35db they are smoking whacky weeds.

Having said that, a colinear antenna is the best design available for general marine band use. They are all generally about 8 feet tall. Several firms make them, and there is no rocket science to designing them, so they all PERFORM pretty much the same when new. The difference in price will be more related to durability. Do NOT buy the little short 3-footers -- they are not colinear and have no gain whatsoever.

The range will depend on many factors:

1 - How high is the antenna mounted? The higher, the better. Because shore stations usually mount their antennas up high, the range to shore stations is longer than 'boat-to-boat' communications.

2 - How much power do you have. If other stations have their receiver squelch two-blocked, then you need more power for them to hear you.

3 - How good is the other receiver? Even in "line-of-sight" if the other guy has a poor receiver, he won't hear you.

4 - Is your antenna vertical? A colinear antenna gets its' gain by 'compressing' the signal pattern from a "doughnut" shape to more of a "pancake" shape perpendicular to the antenna. If your antenna is tilted, then that 'pancake' is also tilted so it goes OVER the receiving antenna (on the high side of the pattern) or is absorbed by the water a few hundred yards from your boat (on the low side of the pattern).

5 - How much other traffic is on the channel. Take the following example. Suppose that the range for a given pair of stations is 10 miles.
You are 8 miles east of the station you wish to talk to, but another who is 4 miles west of him is also transmitting. You can't hear him, because he is 12 miles from you, but he is only 4 miles from your intended receiver. He will be much louder you, so will override your signal, even thought you don't even know he's on the air!

By the way, lots of folks hold "line-of-sight" as gospel, but generally most VHF communications over open water is reflected/refracted by waves and chop, and typically this adds up to 50% to your range.

Hans