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Old 04-01-2010, 13:27   #1
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VHF and AM/FM Stereo - Common Antenna Possible?

I've just replaced the stereo unit and notice that the old (disfunctional) stereo was not connected to antenna.
The nearby VHF has antenna cable.
Can I patch the stereo onto this antenna line with a splitter?
Will this impact the stereo when the VHF is transmitting?
Any advice most appreciated.
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Old 04-01-2010, 13:30   #2
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VHF / Stereo Switch

there's almost always a way........sometimes not practical, but probable
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Old 04-01-2010, 13:44   #3
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Your VHF is safety equipment. Why take the risk of not having it work when you need it to work? You can also buy a separate FM antenna for around the price of the switcher.
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Old 04-01-2010, 13:45   #4
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Been doing this for 30 years on my last three boats. Works just fine and you get great reception on the stereo. Just need to get a HF rated coax switch automatic or manual versions are available. Defender Industries has them for about $40.

The antennae connects to the common lead on the switch and you will need two, short sections of coax with male connectors on each ends to go to the switched input/output connections (the switch obviously has to send the signal both ways to transmit and receive on the VHF). One goes the the VHF antennae connection the other to the FM Radio. I used PL-259 (marine VHF type connections) on all cables and used an adapter to connect the PL-259 to the FM stereo plug but you could rig a cable that connects directly if you're handy.

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Old 04-01-2010, 14:02   #5
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A quick search on the internet shows several fm antennas for $7 or use a scrap piece of coax and make an antenna. The I made one for Makai is a vertical bazooka for nothing and it works perfectly. Makai's is inside one of the cabinets or with PVC pipe can be made external for still a pittance.

More details on how to make one here The Vertical Bazooka Antenna - Ham Radio Library
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Old 04-01-2010, 15:47   #6
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It is pretty simple to make an antennae from a piece of wire or even a coat hanger. The advantage to hooking your stereo to the masthead VHF antennae is the increased range. With that setup I have been able to pick up south FL FM stations well into the Bahamas.

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Old 04-01-2010, 16:25   #7
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I have installed a commercially produced splitter designed for just this purpose
There appears to be no "crossover" into the FM when transmitting on the VHF
The only difference I can notice is the vastly improved FM reception now that the aerial is the VHF one at the top of the mast
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Old 04-01-2010, 17:15   #8
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I brought a splitter at Radio S. As EBCAU did. It works great. No problems.
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Old 04-01-2010, 17:24   #9
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David does bring up a valid point, ie VHF being safety equipment. If you choose to install a coax switch do so close to the VHF so if you have a problem you can just disconnect the switch and plug the antennae directly into the VHF.
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Old 17-01-2010, 15:53   #10
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I just can't get good reception on a boat no matter what kind of antenna I use. I drive down to the marina and park listening to a radio station, but down at the boat I can't pick it up. The boat is only 500 feet from the car and the mast is higher than the car. I have had the same experience on two different boats with three different radios and four different antenna systems. I am using one of those Shakespeare splitters designed for this. I have tried different splitters and different antennas with different leads. When I plug the splitter into the radio, reception improves somewhat, but when I then plug the vhf antenna into the splitter, nothing changes. What gives?

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Old 17-01-2010, 20:07   #11
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Quote:
Originally Posted by john556 View Post
I just can't get good reception on a boat no matter what kind of antenna I use. I drive down to the marina and park listening to a radio station, but down at the boat I can't pick it up. The boat is only 500 feet from the car and the mast is higher than the car. I have had the same experience on two different boats with three different radios and four different antenna systems. I am using one of those Shakespeare splitters designed for this. I have tried different splitters and different antennas with different leads. When I plug the splitter into the radio, reception improves somewhat, but when I then plug the vhf antenna into the splitter, nothing changes. What gives?

John
Perhaps you have already tried all the obvious tests and checks but just in case a few questions. What kind of antennae connector to you have on the stereo? What kind of wire, jumper or adapters are you using to connect the stereo to the splitter?

Try plugging the VHF antennae directly into the stereo FM, bypassing the splitter or any other connections or devices. Do you get more stations, better reception on weak stations? If yes, then you know the problem is in the splitter, how it's connected or the wires used to connect it.


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Old 18-01-2010, 10:28   #12
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Skip, the radio connects with one of those standard auto antenna jacks. The cable is RG62 with a radio type fm antenna connector at each end and comes with the splitter. The splitter has three jacks, antenna in VHF out and am/fm out. My next attempt will be to bypass the splitter entirely, but first I need to find or make an adapter. This has not been a high priority item with me.
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Old 18-01-2010, 11:01   #13
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Quote:
Originally Posted by john556 View Post
Skip, the radio connects with one of those standard auto antenna jacks. The cable is RG62 with a radio type fm antenna connector at each end and comes with the splitter. The splitter has three jacks, antenna in VHF out and am/fm out. My next attempt will be to bypass the splitter entirely, but first I need to find or make an adapter. This has not been a high priority item with me.
Hi John,

So the stereo radio receives a standard auto type, male antenna plug. If your splitter is like the ones I have seen all connections on the splitter are female PL-259. PL259 is the type of connector your marince VHF uses. So the masthead antennae wire should be a male PL259 that would plun into the splitter (or your VHF if you connect directly).

From the splitter to the marine VHF radio you should have a short jumper wire with a male PL259 on both ends, one to the splitter and the other to the marine VHF.

Going to the stereo you need a short jumper with a male PL259 on one end and a male auto stereo connector on the other.

The male auto stereo connector I do not see commonly but I found a way to buy an adapter to connect a male PL-259 to the stereo. Go to Radio Shack or similar and buy an adpater that is female PL-259 on one side and male RCA plug (this is the kind of plug that connects components to the back of your home stereo system) on the other. The male RCA plug fits right into the hole for the stereo antennae on the stereo radio.

Connect the masthead antennae male plug to the female side of the adapter and the RCA plug on the adapter will fit right into the back of the stereo. This will let you test the boat antennae/stereo connection to see if your reception improves. If it does then the problem lies with the splitter or how it's connected.

Good luck
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Old 18-01-2010, 12:37   #14
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Skip, I am skeptical of the RCA plugfitting into the antenna jack, but I may give it a try, I'm sure I have an RCA around here somewhere. Probably what I will do eventually is breakdown and cut the end off of one of my antenna cables and intalling a PL-259 on it. I will probably be doing away with the splitter anyway as I am installing an Icom AIS receiver on the boat and it has a built in splitter. I have two vhf antennas on the boat and I want to keep one clean and running straight to the vhf so the second will serve for both AIS and am/fm reception and can be swapped over to the VHF should the main fail.

The bottom line for me is that I really don't believe the problem lies in the splitter at all and have no faith that anything I do with the antenna system is going to improve reception. I am halfway convinced that auto manufactures know a secret for FM reception that they aren't sharing with the boating community.

John
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Old 18-01-2010, 18:28   #15
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Quote:
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I am halfway convinced that auto manufactures know a secret for FM reception that they aren't sharing with the boating community.

John
Of course they do. The secret is stored in the secret vault right next to the 100 mpg carburetor.
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