vhf/am-fm splitter

Personal opinion - not a good idea

you get a 50% loss of signal (3 db)

better to have an additional aerial on the stern rail if its for AIS, if it is for a radio, a bit of bare wire is practically all you need!
 
I get a bit fed up with all the reponses to this question saying that all you need is a bit of bare wire or a coat hanger to receive radio. That may be all right in the deep South where transmitters are all over the place. However, based on the West Coast of Scotland, I find I need the extra height of a masthead aerial to pick up the important things in life like "Sorry I haven't a clue".
I haven't noticed any issues with VHF, communicating perfectly well with Clyde coastguard from Antrim.
 
I fitted one to my last boat, and found it worked very well, good long range reception on the stereo + no noticable lack of transmission power on the Comms set. But the height of mast has a big part tyo play in transmission range and we had 18m.

One of the bits of kit where I felt it was money well spent.
 
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I get a bit fed up with all the reponses to this question saying that all you need is a bit of bare wire or a coat hanger to receive radio. That may be all right in the deep South where transmitters are all over the place.........

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This response was to a thread where the poster was in Kent!
 
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I get a bit fed up with all the reponses to this question saying that all you need is a bit of bare wire or a coat hanger to receive radio. That may be all right in the deep South where transmitters are all over the place.........

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This response was to a thread where the poster was in Kent!

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Well being in the middle (Lancashire) I know where you are both coming from /forums/images/graemlins/grin.gif
 
Thanks for all the helpful comments. Talbot is there any evidence that it reduces the comms by 50 %. Or how does it work - I mean why would it reduce the comms by 50 %? can you explain more?


Thanks

Stephen
 
The receive signal from the antenna is split in two and sent down two tubes, so to speak. So on receive the signal strength at each radio is half that (-3db) as if the radio was alone using the antenna.

Probably not a big deal in working shore stations that you can hear cos due to their greater power if you can hear them they will hear you. But will certainly reduce the range from which you can hear them and will certainly reduce the range at which you can work other vessels. That may or may not be of concern to you - we wander far from shore stations and like to maximise our range.

On the transmit side, full power will go to the antenna (minus a small insertion loss from the splitter) but in my view it is foolish putting some extra gizmo into the transmission line of your VHF upon which you may need to rely on for your life and which may fail, just for the sake of being able to use the same antenna to listen to entertainment radio.

Also, in my experience marine VHF antennas often make poor FM radio antennas and abysmal AM MF/LF ones compared to a purpose made antenna (at MF/LF frequencies they are often shorted to ground at the base of the antenna by the matching coil). The best solution is to use a seperate antenna. A piece of wire behind the set if normally operate in reasonable signal strength areas (and the boat is not made of metal) or otherwise a proper AM/FM marine quality whip of around 1.5 - 1.8m length, such as Glomex and Shakespeare make (we have used both and consider them fine), mounted at the stern of the boat (will be as good as a smaller AM/FM whip up the mast and in any event AM MW/LW works best down low).

John
 
Thanks John - really good explanation - very helpful.

Definately will mount a different ariel now

Happy sailing

Stephen
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actually a coat hanger or bare wire might be stretching it a bit, but I installed a length of coax around ten feet long and run out of sight behind port side shelves and get great reception. Before paying out why not buy a few feet of coax and a 99p plug from Maplins and try it?
 
Coax has no special properties whatsoever for the antenna itself and so is a waste of money using it. It may also introduce problems cos would also be pathetic as an antenna if one was silly enuff to ground the shield on your bit of coax.

A common old bit of any insulated copper wire (or uninsulated if no possibility of it contacting anything live or grounded) connected directly to the back of the set is better and practically/probably free.

John
 
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