Please Recommend a Quality VHF Masthead Antenna

[bobmcd625]

I have been looking at various sources for the VHF antenna and find reference to "cut lengths" depending on the use: 35" for VHF or 33.5" for AIS. I want to get both. What do I do? 34.25"?
A related question is the size of the cable. I guess the answer is larger is better as long as it gets through the conduit inside the mast. My conduit is 3/4 in and has to carry a N2K cable from the wind sensor plus the VHF cable and three wires for lights (mast head, steaming and spreader lights). I am temped to go for RG8X which is 1/4" dia. I figure a 75 foot run to the radio. Sailing will be mainly in the SF Bay plus 50 mi up or down the coast. No circumnavigation. Wonder also if having AIS as well I should squeeze the RG213 in. Thoughts?
B

[a64pilot]

Originally Posted by bobmcd625

I have been looking at various sources for the VHF antenna and find reference to "cut lengths" depending on the use: 35" for VHF or 33.5" for AIS. I want to get both. What do I do? 34.25"?

When I replace mine, I will likely use this one as its both a VHF and an AIS antenna.
But I should say that I believe it seems my AIS works really well on my VHF antenna now and it is just an old VHF antenna
http://www.vespermarine.com/antennas...-antenna.html/


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[bobmcd625]

[QUOTE=a64pilot;2178314]When I replace mine, I will likely use this one as its both a VHF and an AIS antenna.
But I should say that I believe it seems my AIS works really well on my VHF antenna now and it is just an old VHF antenna
AIS antenna designed to be shared with VHF radios | Vesper Marine


Sounds like a winner. Even if I don't plan to have an AIS transponder now (just plan to receive AIS info through a new radio) it will save the hassle of changing the antenna if/when I (or a future owner) do get an AIS transponder.
What about the cable? Does this antenna require anything special in the cable?
Thanks very much.
Cheers
B

[bobmcd625]

Hartley, et co.
I have discussed this with the electronic wizard at my boat yard (the man who will do the installation) and he recommends a Shakespeare Galaxy 5400 XT with LMR 240 Ultra Flex cable. By my own reading the 5400 XT (or the newer 5400 XP) seems to be a good choice. For the cable I was surprised at the choice of LMR since it is not "marine grade". But apparently, if the connections are made waterproof through heat shrink tube it will do.
There is also a "DP" version is said to be "water tight". What do you think?

[Don C L]

I put rg8x in mine but I had something less than 50' total. Bigger doesn't hurt but I'll defer to others as to whether the difference will be noticeable. I believe the info does recommend rg8x up to 75' but I'd have to check. You may have a hard time getting either one in your tube. I avoided the tube and ran all my wires taped together with a short piece of foam pipe insulation around them every couple of feet. No mast slapping inside, but then my halyards aren't in there, yours may be. Rg8x may have to work then. I'm holding out for ais with splitter. I also have a vhf whip antenna on stern I could use. Hope something in there helped.

[kmacdonald]

Anything labeled "Icom"'

[bobmcd625]

My run will be about 65' so the RG8X will probably be just fine, especially since I don't plan huge voyages. I have a 3/4" conduit inside the mast and no hallyards so I should be able to get a larger cable down the tube, but running the smaller cable from the foot of the mast to the radio would be easier with the smaller cable. I will probably leave it to the yard to determine if they can get the larger cable in with no hassle then go for it.
Fair winds.

[artisanmach]

5215 Classic AIS Squatty Body® Antenna
3′ (0.9m) VHF/AIS Marine Band 3dB Gain

[s/v Jedi]

Originally Posted by bobmcd625

Hartley, et co.
I have discussed this with the electronic wizard at my boat yard (the man who will do the installation) and he recommends a Shakespeare Galaxy 5400 XT with LMR 240 Ultra Flex cable. By my own reading the 5400 XT (or the newer 5400 XP) seems to be a good choice. For the cable I was surprised at the choice of LMR since it is not "marine grade". But apparently, if the connections are made waterproof through heat shrink tube it will do.
There is also a "DP" version is said to be "water tight". What do you think?

Your installer is exactly right and you should take his advice and get that cable and that antenna. Make sure the cable is from Times Microwave and you get the ultra flex variant of it.


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[bobmcd625]

Thanks, Jedi. Appreciate your advice.
Fair winds

[Emerald Sea]

Originally Posted by artisanmach

5215 Classic AIS Squatty Body® Antenna
3′ (0.9m) VHF/AIS Marine Band 3dB Gain

2nd that!

[bobmcd625]

I thought I had settled on the Shakespeare 5400XT but when I visited the yard yesterday I found that they had installed a Shakespeare 5215 Classic AIS. I see that some of you prefer this over the 5400. What's the difference? Should I complain?
My main use will be voice, but of course want decent AIS reception as well.
Thanks in advance
Bob

[Dockhead]

Originally Posted by bobmcd625

I thought I had settled on the Shakespeare 5400XT but when I visited the yard yesterday I found that they had installed a Shakespeare 5215 Classic AIS. I see that some of you prefer this over the 5400. What's the difference? Should I complain?
My main use will be voice, but of course want decent AIS reception as well.
Thanks in advance
Bob

The 5215 is a loaded coil antenna and may be cut for the AIS band (read the literature).

The 5400 is an internal dipole definitely cut to cover the VHF marine band as well as possible.

The 5400 will be more efficient and give you a stronger signal. The 5215 is lighter and will have less windage -- a pretty important point on a sailboat. It might be better on AIS.

Take your pick. I picked the 5400. It's so good, that it may even be overkill, so perhaps there wouldn't really be anything wrong with choosing the somewhat less efficient 5215.

[ka4wja]

Bob,
You'll be fine with the 5215!

I gave up trying to argue against the myths...but, fact is you will see little, to no, difference at all between these two antennas.....(see #2, below for details as to "why" some will need to choose one or the other...but for most, it's a non-issue!)


1) If you look at my earlier postings here in this thread, you'll see that "a half-wave antenna" is a "half-wave antenna"!!

And, no matter what the layperson sailor grapevine says, the 5215 is NOT a "loaded" antenna, but a full half-wave vertical....the "coil" is just part of the tuned impedance matching network, allowing you to feed the antenna directly with 50-ohm coax (NOT a "loading coil"), just like the bottom one foot of the 5400 is the "decoupling"/"matching" section (allowing you to directly feed the 5400 antenna with 50-ohm coax)...

I know that many will tell you a 1/2-wave dipole antenna is "better" than a 1/2-wave, end fed antenna...and in some special cases, this is true...BUT...
But, in our applications, it is not true!
(and when comparing well-designed and built antennas, such as these Shakespeare's....there is NO truth at all to that myth!)




2) But, having said all the above....if you need an flexible antenna to get under 65' bridges, etc....then you WILL choose a 3' SS whip (1/2-wave end-fed antenna)...like the 5215...
And, if you must have a rigid antenna (if you have extreme winds and no bridge clearance issues), then the 5400 is a good choice....

BUT...
But, understand that there will be little to no difference in their performance....
The raves that most VHF marine antennas get, are almost always due to it being "new", with clean (and/or new) connections, and many times new coaxial cable as well....(and sometimes 'cause their old antenna was crap!



I hope this helps!

Fair winds....

John

[bobmcd625]

Many thanks for those explanations. I am trying to absorb all this. I am sure that the 5215 will suit me fine. Regardless of any electronic differences I like the lower (skinny) profile and shorter length of the 5215. Maybe some day I'll understand how these things work!
Your advice is greatly appreciated.
Bob