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vhf antenna 2nd wire ?

Old 08-23-2017, 06:19 AM
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Default vhf antenna 2nd wire ?

The purpose of the second wire is to transmit coordinates from gps correct ? Do I really need this or can I just use one wire just for vhf ? I need a new antenna, any recommendations welcome , it's on a 31 oceanmaster with tower.
Old 08-23-2017, 06:29 AM
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Not sure what your actual question is. The antenna itself only has one wire, the coax, coming from the antenna to the radio.

The radio can be interfaced with a GPS or Chartplotter. If you just connect the GPS, then the radio can receive GPS coordinates and send them using the "emergency" button. If you also connect the chartplotter to the radio, then the chartplotter can receive AIS signals and display other boat information (if the chartplotter is capable of that)
Old 08-23-2017, 06:35 AM
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A coax has two conductors, the inner and the shield.
Old 08-23-2017, 06:40 AM
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I'm sorry for the description. The one wire coming from ant. goes to gps unit , the other wire goes directly through to vhf. It is older equipment and was just curious if it would be better to buy a new ant. with two wires instead of just one.
Old 08-23-2017, 06:46 AM
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I think you are talking about cables, not wires.
Old 08-23-2017, 06:52 AM
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Pictures would really help.
Old 08-23-2017, 09:21 AM
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Originally Posted by abbor View Post
A coax has two conductors, the inner and the shield.
And a coax is ONE WIRE, which includes the center conductor and the shield.


I've never seen a regular VHF antenna with two 'wires' (or coax)... you might have a splitter in-line somewhere between the antenna and the radio (although not usually a good idea). Are you sure you don't just have two antennas... a small GPS antenna somewhere and the large VHF antenna?
Old 08-23-2017, 09:47 AM
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Default Emergency button

Connecting the GPS to the VHF is not enough to make the Emergency or Distress button on the radio work.

You need to contact Boat US and get a MMSI number, and then program that number into your VHF.

Boat US and the Coast Guard report that over 90% of the Distress button calls the USCG gets do not have any boat/owner/GPS information associated with the contact - all details you provide when setting up your MMSI account.

If you are unsure about wires and cables associated with your VHF and GPS a few $$ spent with a competent marine electronics contractor would be money well spent for your safety.
Old 08-24-2017, 10:29 AM
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There is two seperate coax cables coming from one vhf ant. One goes to vhf , other to gps. Does this have any advantage over just going strictly from ant. to vhf ?
Old 08-24-2017, 10:34 AM
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I have never seen a VHF antenna with more than 1 wire in 20 years.
Old 08-24-2017, 10:34 AM
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I believe he's talking about the antenna coax and the wire from a GPS to the VHF for the DSC function.
Old 08-24-2017, 10:41 AM
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Originally Posted by lmannyr View Post
I have never seen a VHF antenna with more than 1 wire in 20 years.
my either, until 30 seconds ago.

Digital Yacht GV30 VHF/AIS/GPS Combo Antenna
Old 08-24-2017, 10:56 AM
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Originally Posted by diver dave View Post
my either, until 30 seconds ago.

Digital Yacht GV30 VHF/AIS/GPS Combo Antenna
That's another story all together. It's a combo...
Old 08-24-2017, 11:16 AM
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Ocean basher in Boynton. What antenna? length, maker, ??
Old 08-24-2017, 05:09 PM
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Originally Posted by nomad36 View Post
Connecting the GPS to the VHF is not enough to make the Emergency or Distress button on the radio work.

You need to contact Boat US and get a MMSI number, and then program that number into your VHF.

Boat US and the Coast Guard report that over 90% of the Distress button calls the USCG gets do not have any boat/owner/GPS information associated with the contact - all details you provide when setting up your MMSI account.

If you are unsure about wires and cables associated with your VHF and GPS a few $$ spent with a competent marine electronics contractor would be money well spent for your safety.
I recognize, concur with, and applaud the intent of your post, i.e. that the boat owner should get an MMSI number, provide all the associated information, and key that MMSI into the VHF radio.

However, your first sentence is quite incorrect.

The VHF radio can be installed with just the antenna and power connections. If the Emergency or Distress button is activated, the radio will indeed send a DSC distress signal out, but it will have NO ADDITIONAL INFORMATION for responders. They will have to use VHF direction finding from two or more shore stations to get a "search area", it may be rather large, and they will have no idea what they are looking for.

Connecting the GPS/chartplotter to the VHF, to provide positional information to the VHF, will add that bit of critical information to the distress signal. Now the responders will know WHERE YOU ARE, but nothing else about you or the vessel.

Getting an MMSI number and keying it in to the VHF will add that information to the outgoing distress signal. Now the responders will know where you are, who you are, what safety equipment you have onboard, as well as a description of your vessel.

As you noted, the vast majority of VHF radios don't even have positional information from the GPS, and even fewer have the MMSI programmed in. Many dealers don't bother, and most owners are clueless.
Old 08-25-2017, 05:45 AM
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vhf.jpgvhf1.jpg
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Old 08-25-2017, 05:46 AM
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vhf.jpg
Old 08-25-2017, 06:13 AM
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I believe the 156 won't do DSC anyway. The 157 will.
Old 08-25-2017, 06:23 AM
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There is such a beast as a gps/vhf antenna. Not sure if this is what he has.

http://www.milltechmarine.com/Tram-C...nna_p_346.html

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