I am going to fit an AIS receiver and need a VHF feed. Do splitters work and can anyone suggest a good one?
I would recommend a separate antenna and feed. A new antenna is not that expensive after all. Your VHF is really a piece of life-saving equipment so (for me at least) a splitter is a bad idea.
Let's make better mistakes tomorrow
I have a Glomex RA201 AIS splitter and it does a great job of driving my ICOM VHF, DigiYacht AIS Receiver and stereo. I've not seen any issues with it and AIS performance seems excellent, VHF performance also.
It's available for about £65 online, but be careful not to accidentally buy the cheaper non AIS version (which just splits out for the VHF and stereo).
If you do get a problem with the VHF, the splitter goes into a bypass mode when power is removed from it, and in the worst case you can always just disconnect it and plug the antenna in directly to the VHF.
That said, if you can do it, the extra antenna option *is* superior.
Which AIS receiver are you getting? Some of the cheaper ones aren't dual channel, they just switch between channels every X seconds. But the Digital Yacht ones are brilliant - mine is the AIS 100 which I picked up for about £120.
The glomex splitter has a VHF connector labelled as VHF and a BNC connector output labelled as AIS.
I'm not sure whether they are designed to filter the signals based on frequencies, putting the AIS frequencies down the AIS line or not.
Therefore I don't know if it would be suitable for the task you want it to do, and I suspect the only people that would be sure are the manufacturers.
For not all that much more than the splitter you could buy an ICOM MC-411 radio with integrated DSC. Not as posh as the 501 but brand new and a lot more compact...
Some vhf antennas have relatively narrow bandwidth and may not perform very well, lets say worse than 2.0:1 SWR, beyond 160 MHz. Such an antenna might have an SWR of 3.0:1 by the time 163MHz is reached so AIS performance might be compromised.
An AIS optimised antenna will be centred further to the right of the band so that its performance is good at 163 MHz.
If you ever intend to use your AIS antenna as a back up for your radio antenna, choose a good quality standard vhf antanna. If you want an antenna specifically for AIS, by all means select an AIS optimised antenna.
With a splitter, you should use a standard vhf antenna of good quality.