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Old 19-01-2012, 12:43   #1
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AIS Antenna Splitter

Hi friends

I am planning to install a VHF antenna splitter to be able to receive AIS signals and VHF traffic simultaneously from my existing antenna.

Any recommendations?

Has anyone any experience with this one: Ra201 Vhf/am/fm/ais Splitter, Glomex - Pleasure Boat Marine ? It's a lot less expensive than any other.

Thanks

Nick
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Old 19-01-2012, 13:15   #2
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Re: AIS antenna splitter

The best option is to use a separate antenna for AIS. I don't see any specs for the Glomex splitter with regards to insertion loss and if there is a fail-safe mode if it loses power. The splitter with the lowest insertion loss that I have found is the Vesper Marine SP-160. Most splitters seem to have an rx loss of around 3-4db with the SP-160 being 1.5db

Eric
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Old 19-01-2012, 14:41   #3
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Re: AIS antenna splitter

Nick, This is not a good idea but if you MUST use a splitter I recommend to use the splitters from Milltech Marine which include the one Eric suggests. Not all splitters are created equal. Talk with the folks at Milltech and give them the details for your equipment. They will point you in the right direction. Chuck
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Old 19-01-2012, 18:53   #4
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Re: AIS antenna splitter

I use Comar AIS-MULTI AIS Receiver & Antenna Splitter.
Tom
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Old 19-01-2012, 19:20   #5
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Re: AIS antenna splitter

We installed a Watchmate 850 from Vesper Marine last year. They offer a splitter that sounded like a good one. Love the Watchmate! We had a spare antenna so no splitter. I prefer to keep all devices mutually independant even if they share a network.
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Old 20-01-2012, 03:51   #6
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Re: AIS antenna splitter

Go for a dedicated antenna for AIS. With AIS, we started with an antenna that had both GPS-antenna and VHF-antenna combined. We were not pleased with it. The GPS-antenna should be mounted low for stable readings, but the VHF-antenna should be mounted high for range. For the sake of the GPS, we mounted the package to pushpit. It worked alright, however, we got only few miles coverage with that.

For the next seasons, we bought another VHF-antenna and mounted it on the top of our mizzen mast. Now we have the coverage! We virtually see all traffic hours ahead. To get another antenna and its cable to the mast top was after all not a major task. The outcome will clearly justify the effort. Now we also have a spare antenna for the VHF-radio if something should go wrong with its antenna or cabling on main mast.
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Old 20-01-2012, 06:13   #7
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I personally think using the main VHF antenna on the mast top for AiS , via a splitter, is a good thing. Firstly the antenna spends much of its life doing nothing and secondly is advantageously positioned for AIS.

Just keep a spare VHF antenna if all fails ( but that's good advice anyway even if you haven't AIS)

Dave
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Old 20-01-2012, 06:27   #8
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Re: AIS antenna splitter

Of course it's always better to use a separate antennas for AIS and VHF radio, provided that you have enough space, money and time to install new cables etc.

Otherwise, you should use splitter. I'm using one myself and it's OK (I'm using TrueHeading class B splitter together with SailCruiser by NavSim to see AIS targets on my laptop. It works perfect for me!
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Old 20-01-2012, 06:44   #9
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Re: AIS antenna splitter

Hi Nick,

having the AIS receiving antenna high is of course a good thing.

I have a Raymarine 250 AIS receiving blackbox that has a a VHF-AIS splitter included.
So I wired to use it. Super AIS data reception from ships 25 NM or more away.

But....I found out that the AIS receiver was giving interference on my marine VHF on frequencies adjacent to the AIS frequencies (161.975 and 162.025 Mhz if I'm not wrong). I had interferenc on Duplex CH27 which is used a lot by our coastal stations.
Furthermore I had no data on eventual VHF RX insertion loss throught he splitter. Values of 0.5-1.5 dB look acceptable to me.... but splitters with >3dB loss...that means losing half of the RX signal strength.... a no-go for me.

If you can buy a splitter with max 1.5dB insertion loss, I would install it using the masttop-VHF antenna.
But install a spare marine VHF antenna on the pushpit for redundancy, in case the splitter fails.

BTW most 50 Ohm coax cables installed routinely from masttop to navstation are thin RG-58 cables....on a RG 58 coax stretch of 20m or more one will have > 3dB loss (losses of 5 dB per 100 ft) which means only 50% of your transmitted power reaches the antenna...or vice versa on reception....
My advice to anyone is to replace the RG-58 cable by RG8 (or RG8X if RG8 is too thick to your taste)...

Jan
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Old 20-01-2012, 08:32   #10
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Re: AIS antenna splitter

Hi guys

i called Glomex in Italy and then got an email response:

Quote:
Dear Nick

The insertion loss beetwen antenna and VHF radio is near 0dB, between
antenna and AIS is 5dB and from Antenna and AM FM Input is 5dB.

Best regards
Mevoli Fabio
R&D division

Glomex S.r.l.
I have asked for more exactitude. But the unit does have a pre-amplifier, as does the Vesper.

Thanks,

Nick
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Old 20-01-2012, 08:43   #11
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Re: AIS antenna splitter

5 dB between antenna-splitter to AIS receiver? That is a lot! That is 66% loss....hard to believe....is that including the preamp?

So it seems the splitter is wired through more or less directly to the VHF for RX.
On transceive it will use a relay so no losses.

yes it is a good idea to get more details from Glomex....

Jan
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Old 20-01-2012, 11:09   #12
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Re: AIS antenna splitter

Quote:
Originally Posted by goboatingnow View Post
Just keep a spare VHF antenna if all fails ( but that's good advice anyway even if you haven't AIS)

Dave
You can always take it out of the loop and I think everyone should have a VHF handheld as backup...you can buy one for less than $50.
Tom
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Old 02-04-2015, 10:17   #13
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Re: AIS Antenna Splitter

Bringing the thread back after 3 years but I have the exact same question. I need a AIS splitter. Separate antenna is no option. I am mostly a day sailor in SF Bay and AIS receiver is when SF Bay gets fog and I need to know where the tankers are ;-) I have a separate handheld VHF I carry on my PFD so loss is less of an issue to me.

Glomex RA201 is indeed looks like an interesting candidate.

Glomex Leisure - RA201 - Splitter

ChannelIslander did you get to buy it? If so, are you happy?
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Old 02-04-2015, 20:15   #14
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Re: AIS Antenna Splitter

Tenedos,
I realize you are asking about a AIS/VHF splitter (splitter/relay), for your VHF radio and AIS receiver....and would probably consider $250 for the Vesper SP-160 splitter/relay to be out-of-the-question, but the fact is that the Vesper SP-160 is a GREAT piece of gear, works VERY well, meets/exceed its advertised specs, AND will work well for you when you upgrade to an AIS transponder in the future...
http://www.vespermarine.com/antenna-splitter-sp160.html

Vesper AIS SP-160 "relay/splitter" test results

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



Sorry, I do not have any experience with the Glomex splitter...
The Glomex splitter is about $90, but I do NOT know what its specs are, what its losses are, etc....and it will only work for a VHF radio and AIS receiver ONLY....

I'm not telling you that the Glomex is bad, 'cause I don't know....just letting you know about your other options...



I hope this helps...

Fair winds...

John
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Old 02-04-2015, 20:43   #15
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Re: AIS Antenna Splitter

Quote:
Originally Posted by ka4wja View Post
Tenedos,
I realize you are asking about a AIS/VHF splitter (splitter/relay), for your VHF radio and AIS receiver....and would probably consider $250 for the Vesper SP-160 splitter/relay to be out-of-the-question, but the fact is that the Vesper SP-160 is a GREAT piece of gear, works VERY well, meets/exceed its advertised specs, AND will work well for you when you upgrade to an AIS transponder in the future...
http://www.vespermarine.com/antenna-splitter-sp160.html

Vesper AIS SP-160 "relay/splitter" test results

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



Sorry, I do not have any experience with the Glomex splitter...
The Glomex splitter is about $90, but I do NOT know what its specs are, what its losses are, etc....and it will only work for a VHF radio and AIS receiver ONLY....

I'm not telling you that the Glomex is bad, 'cause I don't know....just letting you know about your other options...



I hope this helps...

Fair winds...

John
The above is the way to go. I have the Vesper and it works perfectly. Whatever John says about radios is always correct.
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