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Old 15-10-2007, 21:07   #1
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ICOM M802 DSC antenna?

I have a new SSB. I replaced the old SEA32 with an ICOMM802. Had all the information I could use to insure I got the ground plain put back in right but when it comes to the antenna for the DSC tuner they are at best sketchy. Class D DSC. Ok what is that? Different from a VHF whip but how? I found a Metz WEFAX/DSC billed as the antenna for the job but is that the only way to go? I fear they donít want to give one maker as the one to use so they give none. Iím just trying to get it all up and running and get my license. Iím no short wave geek (I say that in the nicest way!) so Iím looking for a definitive description of what I am looking for. Any one ? Please. I take back the short wave Geek thing!
Thanks

Gary
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Old 16-10-2007, 08:11   #2
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I like the insulated back stay solution, but if you search the threads you will find a good discussion of using a whip antenna.

Love the Prout.

George
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Old 16-10-2007, 09:04   #3
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Well I’m using the back stay for the SSB but the M802 has a built in second receiver for the DSC and it has its own separate antenna. That is the type of antenna I am inquiring about. From what I can gather it is an HF class D DSC type but I just don’t know what that means
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Old 16-10-2007, 14:34   #4
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I own an 802 and we hooked up GPS via NEMA and simply used our backstay. Never had to use DSC but I can't imagine the pro who hooked her up did not wire it properly since he took the time to make the Nema connection. I will have to dig out my manual and look a bit but I think the DSC secondary antenna may be optional.
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Old 16-10-2007, 14:59   #5
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What follows is the response fro ICOM tech support to me
Good Morning......

Thanks for your e-mail.

In order for DSC to work with the M-802, you must have the DSC-receive antenna connected. This is the only way that the radio will be able to receive DSC signals since it is a class D DSC radio. You can use a
Metz weatherfax antenna or any SSB whip antenna to connect to the receive port. Without the antenna, you will still be able to transmit a distress call, however, the radio will never hear an acknowledgement nor would you be able to hear someone else in distress and come to their aid. Hope this will help.

Best Regards;


Mike --------
Technical Support Representative

ICOM America, Inc.
2380 116th Ave.NE
Bellevue
, WA98004
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Old 16-10-2007, 15:04   #6
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My original Email
EMAIL SUBJECT: Request from Icom America Website: Marine
BODY:

On my M802 - the antenna connector 2(DSC)
Do I need another antenna to recive DSC and if yes what am I looking for? The M802 is on my Prout37 S/V with a backstay for my primary anntenna.

Thanks for any help you may be able to give
Gary
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Old 16-10-2007, 15:06   #7
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Update: Checked my manual and it says the DSC antenna is the same type requred for regular SSB transmission on antenna connection #1.
r ANTENNA CONNECTOR 2 (pgs. 54, 56)
Connects a 50 Ω HF band antenna via a 50 Ω
matched coaxial cable with a PL-259 plug for DSC
receiver.


I guess you could simply use an antenna switch 2:1 to be able to use the DSC terminal rather than rig another antenna. You are right that the manual is almost silent on this issue.
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Old 16-10-2007, 15:30   #8
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Question, As I am using my back stay for the primary antenna and it runs through the AT-140. I assume it a poor idea to use a splitter or else you would just build that in. Going to the back stay again would expose the DSC antenna plug to the high voltage out put from regular TX. A splitter from the tuner would be tuned to the set freq. for the primary input and not to the DSC channels. Am I wrong? I’d be happy to be wrong headed on this one. ?
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Old 16-10-2007, 16:08   #9
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As the reply from ICOM states, the DSC antenna is only needed to RECEIVE DSC signals. If you send out a distress signal using DSC, it uses your primary antenna that is connected to your tuner - that's the important part. We also have an 802 but don't leave it on except for brief periods due to the battery drain. Therefore, we don't even have an DSC receive antenna since we aren't going to monitor the SSB for emergency traffic anyway

Tom
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Old 17-10-2007, 21:42   #10
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I found a bit of good info on the M802. A good blurb At Yachting Magazine.com

It explains a bit better about it can be a short whip for recive only but again it isn't just any ol' VHF whip. I found only one site that is selling a Metz just for the DSC. I was hoping I'd have more of a choice. But not as yet.

Gary
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Old 29-09-2009, 20:15   #11
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I know this is an old thread, but I had to post some thoughts that might help others here. The DSC receive antenna doesn't have to be anything special, unlike a transmitting antenna. An usable antenna can be as simple as a straight (or not so straight) piece of wire.

Figure out where you want that wire antenna to run, away from other wires and not too close to grounded structures or your transmitting antenna. This might be along the hull above the water line somewhere, under the coach headliner etc. To some extent, the longer the better. Now get a piece of coax as long as that planned antenna wire plus the length it would take to get back to the radio connection. Strip the outer insulation and shield from the coax starting at the point your antenna run should begin, and you will have your DSC antenna.

In the HF realm, you will have plenty of signal strength for receive with this antenna, even without the impedance matching that transmitting requires.. Unlike VHF, antenna polarization isn't important because HF polarizations are all over the map, so it doesn't need to be vertical. If you want to see how well it receives, temporarily hook it to your M802 primary antenna connector, and listen at different frequencies. You should hear plenty of signal or at least atmospheric noise with this antenna, telling you its working fine as a receive only device. You will have saved $80 for a Metz whip which I'm pretty sure is unlikely to perform any better, and you will have one less thing hanging off your boat ready to corrode or break.

Chip
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Old 30-08-2012, 10:34   #12
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Re: ICOM M802 DSC antenna?

I also know this is an old thread, but there is still lots of confusion on this topic.

SoonerSailor was the most correct in the above thread. Metz and Gamm Electronics both make a Stainless whip that will work fine. I have posted on my site similar instructions on a home-made antenna.

The key thing here is you need the DSC antenna as well as the GPS hooked up to the 802 and your VHF for that matter. You can send and receive MMSI calls without the antenna, but if you send a distress call, the acknowledgment and where to tune for voice comms comes through the DSC Emergency Reception Antenna (DERA). Be sure and add your MMSI number to your boat card so your friends have your phone number for VHF and HF SSB.

While all commercial ships monitor for DSC calls, it would be good if more cruisers, especially trawlers that are not worried about using batter power, keep the M802 in the DSC watch mode. Cruisers taking care of cruisers...

In DSC watch the radio is quiet and sounds a beep for a call and a loud tone for an emergency.

You can also extend the ship to ship range with a procedure on my web site you can download for free.

Kind Regards
Terry
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Old 09-12-2012, 18:24   #13
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Re: ICOM M802 DSC antenna?

Somebody tell me how the DSC function on the M-802 works. How does it broadcast? Does it broadcast through the AT140/backstay? How does it receive? Does it receive only through the whip/stripped-wire antenna? What's the range? Why do I need this in addition to my VHF DSC?
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Old 10-12-2012, 06:06   #14
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Re: ICOM M802 DSC antenna?

Quote:
Originally Posted by tampahokie View Post
Somebody tell me how the DSC function on the M-802 works. How does it broadcast? Does it broadcast through the AT140/backstay? How does it receive? Does it receive only through the whip/stripped-wire antenna? What's the range? Why do I need this in addition to my VHF DSC?
*******
The DSC on the M802 is divided into two pieces.
1. The DSC Emergency Reception Antenna (DERA) is connected to an internal receiver that scans all of the emergency digital frequencies starting whenever the radio is on. The calls that receiver is looking for are Distress, Distress acknowledgements, Urgent, and Ships Safety calls. When this receiver detects a message, it takes over the M802 and sounds a loud tone. It is important to have a DERA as without it you will not receive the above information.
2. The M802 has a mode called DSC watch which is activated when you press the DSC button on the left side of the control head. When in this mode, the normal receiver is now scanning 6 programmable frequencies looking for someone calling your vessel. From DSC Watch, you can also initiate calls to other vessels, safety calls to all ships, urgent calls, group calls, and distress calls. These calls are sent out using your normal transmission antenna such as a back stay or 24 foot fiberglass antenna. The information sent is basically the MMSI you are calling and your MNSI so they know who is calling. If an incoming MMSI is programmed in the receiving station address book, the vessel name will appear as the caller. If not the MMSI number will be displayed.

To recieve a call in you must be scanning the same frequencies as the calling station is calling on. As the M802 is programmed from the factory, ship to ship calling is only available on 2MHz. There is a procedure on my web site to re-program your radio to allow ship to ship calls on all 6 frequencies which significantly extends the calling range. In the downloads section, lower right side, called "DSC upgrade for Cruisers". It is important that all of your friends you will be making DSC calls to also do the upgrade programming or you will be limited to the 2 MHz for those vessels.

I hope that helps
Terry
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Old 23-02-2013, 23:44   #15
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Re: ICOM M802 DSC antenna?

Any thoughts on using a shroud as the DSC antenna? I have rather easy access to the chainplates inside the boat and am thinking of hooking up to this. Does the shroud need to be insulated for any reason? I'm using an insulated backstay antenna.
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