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Old 16-04-2015, 13:45   #1
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Antenna recommendation

I'm having to pull my mast and while its down I plan to rewire it along with new lights and antenna. I remember reading what size antenna wire but have lost that. I want the heavy duty larger wire but dont know the size number. Also need recommended antenna. I want a flexible one for the mast. Anyone have recommendations. Thanks all
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Old 16-04-2015, 14:26   #2
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Re: Antenna recommendation

I'll leave it to others to suggest an antenna which is largely a matter of personal preference. Note that antenna 'gain' numbers can often be nothing but marketing hype absent any reference they often omit when citing numbers.

As to the size of coax, you are likely referring to RG 8. The designation relates to a class size and not quality such as braid or dielectric material. Don't be mislead by cheap RG 8 coax as quality varies.

Buy from a reputable coax manufacturer/distributor paying attention to loss per 100 ft at VHF frequencies which can tell you how much of the transmitter power is lost to the antenna. The loss figures are represented on dB scale with a small figure of 2dB representing a significant loss given it is a log scale measure.
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Old 16-04-2015, 14:40   #3
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Re: Antenna recommendation

+1 on what S/V Illusion said. I recently ordered some new antenna cable and my choice was for DXE 400MAX (similar to LMR400-DB). Beyond checking the loss/ft, also check that what ever you pick offers a fully waterproof jacket (for obvious reasons) and stranded center conductor (for flexibility and fatigue resistance).
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Old 16-04-2015, 14:58   #4
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Re: Antenna recommendation

For the long run up a mast I use RG-213 cable. Lower loss than R-8 or RG-58. There is an even better grade that is used by Hams but cannot recall the designation.

Just as important as the right cable is to get a good connection on the ends.
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Old 16-04-2015, 16:12   #5
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Re: Antenna recommendation

Yes, RG-213, RG-214, or LMR-400 type coax is the right stuff for VHF installations atop the mast.

And, termination is extremely important. If you don't know how to properly terminate these coax cables, get a professional to do it for you.

A good source for coax of any type is the RF Connection:

The RF Connection Home Page

They can supply anything you need, including custom lengths and proper terminations with any type connector you like.

Bill
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Old 16-04-2015, 19:31   #6
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Re: Antenna recommendation

Thanks you guys and gals are great.

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Old 17-04-2015, 07:44   #7
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Re: Antenna recommendation

Badsanta,
1) First the cable/connectors...
I hope Bill doesn't mind, but I'd like to highlight what he wrote, 'cause it is VERY important!!!

Quote:
Originally Posted by btrayfors View Post
Yes, RG-213, RG-214, or LMR-400 type coax is the right stuff for VHF installations atop the mast.

And, termination is extremely important. If you don't know how to properly terminate these coax cables, get a professional to do it for you.

Bill
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You cannot go wrong with a good-quality, name-brand, RG-213 cable (Belden, Times, Davis, Commscope, etc.), with properly installed, name-brand connectors (Amphenol or Kings)!!
If done right, and connections weather-proofed, this will last you decades!!


Although, I buy coax and connectors from a few different companies (Davis RF, DX Engineering, Texas Towers, Tessco, etc...) as long as you buy good-quality, name-brand cable / connectors (properly installed), you're good to go...


Only if you have "space limitations" inside the mast conduit and cannot fit the 0.405" dia RG-213, would I then recommend LMR-240....loss is about the same, but it is a smaller and more complex cable...




2) As for the antenna....
Shakespeare, Digital, and GAM all make VHF 1/2-wave end-fed, 3' SS whip antennas....and while there are some quality variations and slight performance variations, any of these brands should give you good service....

But, if you want my personal fav...
It is Shakespeare....
Use one of their 3' SS whip antennas which have an SO-239 coax connector on it, NOT a length of coax....
This is what I use, and have had EXCELLENT results for many years!!! (In addition to my own testing, I actually have better VHF coverage than other boats, in almost any anchorage!!)

[No matter what you may read elsewhere....assuming that the antennas are designed and built properly, a 1/2-wave antenna is a 1/2-wave antenna, whether a "mono-pole" (end-fed), "coaxial-mono-pole" (coaxial end-fed, sometimes marketed as a "dipole"), or a "dipole" (center-fed), and the will ALL have the same gain and pattern....(although the "coaxial-mono-pole" antennas will need to be slightly longer to incorporate the decoupling network, otherwise the pattern will be skewed and gain will suffer....and a true "center-fed-dipole", of course would need the feedline to be run perpendicular for at least 1-wavelength, otherwise its pattern will be effected...
Bottom line: a 3' SS VHF whip antenna is as good as a 4' fiberglass radome-covered coaxial-mono-pole (marketed as a "dipole") VHF antenna...]

Their current line has these:
Shakespeare Classic 5242-A VHF Antenna

Shakespeare 5215 Squatty Body VHF Antenna


Here is a photo of mine, on the masthead....



You may find the info in these threads to be of help as well...
AIS Problems with Antenna

Vesper AIS SP-160 "relay/splitter" test results, lab/real world




I hope this helps..

Fair winds...

John
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Old 17-04-2015, 09:56   #8
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Re: Antenna recommendation

Great source thanks. I will wait till the mast is down to on check for space. I did try a search but nothing matched till after I posted. Thanks for the links.

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Old 17-04-2015, 10:19   #9
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Re: Antenna recommendation

If you are going to big cable LMR 400 Ultraflex cable has the best specs, is easier to pull because of its flexibility, and the extra cost of a single mast length isn't that great

Coaxial Cable by the foot

If big cable won't fit consider LMR-240.

There are also many online suppliers including guys on ebay who will make you a custom cable with connectors installed. Look for one in the US who brags about the quality of their connector installations. Much better odds of a good cable than using the average guy at the boatyard or doing it yourself.
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