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Trouble with AIS transmitter

Discussion in 'Ask A Hunter Owner' started by karellen, Aug 10, 2018 at 12:01 PM. Add this thread to a FAQ

  1. karellen

    karellen

    Joined Jan 5, 2017
    28 posts, 2 likes
    Hunter 356
    US Benicia
    I'm struggling with the AIS transmitter on my vessel. She is a 2003 Hunter 356. The masthead antenna whip was recently replaced and is a GAM SS-2. The cabling is original as far as I know.

    I hooked the AIS unit to a laptop and ran ProAIS2. After two transmits it throws a VSWR fault, with values seemingly all over the place but all very high. Some were around 6:1, some were 12:1, and a few were even higher (one read 47:1 and one result even showed 1635:1.)

    There is a splitter in place, but bypassing it didn't noticeably change VSWR numbers.

    Thoughts on where to start?
     


  2. Brian D

    Brian D Moderator

    Joined Feb 17, 2006
    3,962 posts, 633 likes
    Lancer 27PS
    US MCB Camp Pendleton, Ca KF6BL
    Since AIS is used on marine VHF (ch. 87B/88B - 161.975MHz/162.025MHz), you can use a regular VHF antenna. I would not recommend using a homebrewed antenna, but a real VHF antenna. Put the antenna on the rail and run a short length of RG58 to the antenna. Then run your test again. This will help rule out the AIS transmitter.

    Next I would use a length of coax that equals the length to top of the mast. Same test to the antenna on the rail. See if there is an appreciable amount of loss.

    Your next test would be to run the cable up to the top of the mast and connect to the current antenna. It could be the internal cable has gain moisture or the antenna is faulty. The results will tell you which.

    The simplistic version is either the cable is bad, or the connectors need to be re-soldered.

    I know, lots of work. But it is better if you follow a straight path and not jump around from part to part.

    Added - If you want you can use your regular marine VHF antenna for testing.
     


    dziedzicmj likes this.
  3. Gunni

    Gunni

    Joined Mar 16, 2010
    5,164 posts, 1,000 likes
    Beneteau 411 Oceanis
    US Annapolis
    Give someone your handheld, send them downrange about 10 miles, tune one of the recreational channels (NOT Ch.16) and see if they can receive your radio check. I’m guessing you have an antenna/co-ax/connector problem.
     


  4. karellen

    karellen

    Joined Jan 5, 2017
    28 posts, 2 likes
    Hunter 356
    US Benicia
    Thanks guys. I found someone with an emergency VHF antenna and cable for testing, but I believe I already found the culprit -- there is a nasty split in the coax cable between the deck and mast.

    Going to try a splice here until next time I drop the stick and can run a new wire. I assume factory cable is RG-213?
     

    Attached Files:



  5. Brian D

    Brian D Moderator

    Joined Feb 17, 2006
    3,962 posts, 633 likes
    Lancer 27PS
    US MCB Camp Pendleton, Ca KF6BL
    Could be, or it might be LMR-400. Either way, you will insert a SWR that will not be 1.x:1, but it should be consistent. Change out that bad cable as soon as possible.
     


  6. chuckwayne

    chuckwayne

    Joined Mar 20, 2004
    1,407 posts, 35 likes
    Hunter 356 and 216
    US Portland, ME
    Look closely at the coax- -my factory original 2002 356 had RG-8x, Not marine cable, and the connector at the mast base wasn't even soldered on! The cable was really corroded.
     


  7. Hunter Ad Bot

    Hunter Ad Bot

    Joined Oct 27, 2016
    0 posts, 10 likes
    US Seattle
    Hunter faucets and parts

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  8. karellen

    karellen

    Joined Jan 5, 2017
    28 posts, 2 likes
    Hunter 356
    US Benicia
    Chuck, do you know if there's room at the top of the mast to feed in a new cable with the connector already attached? If I do climb the mast, I'd like to avoid making multiple trips.
     


  9. chuckwayne

    chuckwayne

    Joined Mar 20, 2004
    1,407 posts, 35 likes
    Hunter 356 and 216
    US Portland, ME
    no, there isn't - the base connector has to be installed after the wire is fished thru the mast. the entry hole is small at the mast head, and the thick cable is really stiff. I plan to cut off the masthead connector, cut away a couple of inches of the shield, dielectric, and cover on the old and new cables and securely twist together the center conductor. normally I'd solder them, but the old cable is probably too corroded to solder. I then cover the splice with a thin layer of gaffer tape (like duct tape, but much stronger, used in theaters) and pull the cable thru. I think it would be really hard with the mast up. In any case, it wouldn't hurt to have the mast pulled for a thorough inspection. I found 2 damaged D2 stays that the yard missed in the mast in inspection I paid for every year