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Old 13-01-2013, 04:38   #1
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Where to Mount Antenna For SSB DSC

I have acquired an Icom M802 SSB and am planning the installation now.

It needs a separate antenna for DSC.

Should this go up the mast somewhere? Or is it better to mount it on the rail, so that it will work in case of (God forbid) dismasting?

What do you guys think?

And any recommendations for an antenna? I understand that the frequency involved requires only a very small whip antenna, similar to a VHF antenna.
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Old 13-01-2013, 05:10   #2
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Re: Where to Mount Antenna For SSB DSC

DSC is VHF.

Of course height is king with antennas but many folks take the easy route and mount it on a rail.

George
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Old 13-01-2013, 05:29   #3
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Re: Where to Mount Antenna For SSB DSC

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Originally Posted by Sunspot Baby View Post
DSC is VHF.

Of course height is king with antennas but many folks take the easy route and mount it on a rail.

George
Sorry George, DSC is VHF and MF/HF
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Old 13-01-2013, 05:46   #4
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Dockhead. Radar arch height if possible or mount on the spreader. It's only a receive only antenna. Not key in an emergency

It will work on the rail too

Dave
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Old 13-01-2013, 06:06   #5
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Re: Where to Mount Antenna For SSB DSC

Sorry, I should be more specific. The extra antenna needed for the 802 is VHF.

George
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Old 13-01-2013, 06:07   #6
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Re: Where to Mount Antenna For SSB DSC

Dockhead

The DSC antenna for the MF/HF radio is a receive only antenna. I know that the METZ weather fax antenna will work as a DSC antenna for the ICOM.
As MF propagation goes everywhere dependent on the transmit power, I would have thought that rail mounted would be OK.
The metz unit is between 4 to 5 feet in length, which is pretty small.
I'm looking at our Furuno DSC whip, thats about 25 feet in length, bit long for your needs.
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Old 13-01-2013, 06:41   #7
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Re: Where to Mount Antenna For SSB DSC

On the Icom M802, DSC is HF, not VHF.

A suitable antenna is the Metz 201 such as this one: METZ METZ 201 | GENERAL COV/WEATHERFAX ANTENNA

I recently installed one on a client's boat. The whip antenna is quite bendy, so it's not really suitable for installing on a spreader. Best to install on the pushpit or on an arch.

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Old 13-01-2013, 06:53   #8
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Re: Where to Mount Antenna For SSB DSC

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Sorry, I should be more specific. The extra antenna needed for the 802 is VHF.

George
No, it's HF.
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Old 13-01-2013, 07:45   #9
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Re: Where to Mount Antenna For SSB DSC

The height is not so important on a HF DSC reception antenna and there is absolutely no reason to mount it on the masthead. Remember as stated above, all this antenna is doing is receiving inbound DSC messages.

I have the same radio you purchased. My DSC antenna is the metal whip type, which is mounted on my stern antenna tree about 12 feet off the water.

I have received HF DSC messages from as much as 5000 miles away, it all depends on propigation and the orginating vessel's power output.
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Old 13-01-2013, 07:49   #10
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Re: Where to Mount Antenna For SSB DSC

I am very much a beginner so take what I say iwth a grain of salt. I use a plain wire running inside the boat that is about 10-12 feet long. This sounds like it should not work but I think it does. I think. One way I have been told to check is to use your regular SSB antenna and listen and talk on a channel. Then swithch your regular antenna to your SSB DSC antenna and compare results in receiving and broadcasting. To be more clear, the connections for each antenna are right next to each other so you can easily compare the performance of each antenna while using regular channels and communication.
My 2 cents,
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Old 13-01-2013, 07:59   #11
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Re: Where to Mount Antenna For SSB DSC

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Originally Posted by goboatingnow View Post
Dockhead. Radar arch height if possible or mount on the spreader. It's only a receive only antenna. Not key in an emergency

It will work on the rail too

Dave
Not key in an emergency? It is how you will receive your reply to a DSC SOS! Your SOS will still be broadcast using your SSB antenna but you will know it is received (DSC acknowledged) on the DSC antenna so it is my understanding that you will not get a reply to your DSC SOS if you do not have this working.
Do not take this as expert advice but I am not a dummy,
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Old 13-01-2013, 10:18   #12
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Re: Where to Mount Antenna For SSB DSC

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Originally Posted by Sunspot Baby View Post
DSC is VHF.

Of course height is king with antennas but many folks take the easy route and mount it on a rail.

George
Height is king only for line of sight propagation like VHF.

Whether or not the frequencies used by SSB DSC are line of sight or not, I don't know. That was kind of my question.

I do know that Navtex signals, which are also in the HF band somewhere, are not line of sight and actually work better if the antenna is closer to the water.
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Old 13-01-2013, 10:37   #13
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Re: Where to Mount Antenna For SSB DSC

Has anyone successfully sent the HF DSC 'Test' message to the USCG and received an acknowledgement?

I've tried various times and never received an ack.
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Old 13-01-2013, 10:55   #14
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Re: Where to Mount Antenna For SSB DSC

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Has anyone successfully sent the HF DSC 'Test' message to the USCG and received an acknowledgement?

I've tried various times and never received an ack.
Never tried the USCG, but here in Europe, have no problem with most coast stations. Best is Lyngby Radio in Denmark, they always acknowledge.
Sometimes its best to call on a working channel first and advise them you are going to make a test call. That way, if you dont get an acknowledgement, you can call them after the test to see if they received your DSC call
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Old 13-01-2013, 10:59   #15
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Re: Where to Mount Antenna For SSB DSC

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Never tried the USCG, but here in Europe, have no problem with most coast stations. Best is Lyngby Radio in Denmark, they always acknowledge.
Sometimes its best to call on a working channel first and advise them you are going to make a test call. That way, if you dont get an acknowledgement, you can call them after the test to see if they received your DSC call
I had assumed the reply to the 'Test' message was automated. But you are right in that calling them would at least let me know if they received my request.
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