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Thread: DIY Marine HF Whip

  1. #1

    Default DIY Marine HF Whip

    Hello all,

    New member and pretty inexperienced HF user, so please accept my apologies for any terminology mistakes and do not for one second assume that I know what I am talking about. I have my Australian standard HF radio license (VK5MJD), which I achieved a few years ago. I have had very little chance to use it so far, and I am sorry to say a lot of the theory has leaked out my head too. I also have my Marine Radio Operator's Certificate of Proficiency, the one that allows me to use marine HF frequencies from the boat. Finally, I have an ACMA issued ship's station license (VNZ2045).

    That's the license side, in terms of hardware, on the boat I have one of the Icom marine HF radios that will also transmit on HAM frequencies, coupled with an AT-130 antenna tuner. The radio works very well, and I have had a few conversations with a maritime HF group along the East Coast of Australia on the 40 meter band, over a range of 1000 to 2000 km. The radio uses the 10 mm 316 stainless wire backstay of the mast as an antenna, with insulators at the top and about 2.5 meters from the deck, giving me around a 18 meter single wire antenna if I include the antenna feed wire from the back of the antenna tuner.

    Now, my problem is, one of the more common issues on sailing boats is the tendency for the mast to fall down at a bad moment. This is annoying enough on its own, but when it takes out your only means of communication with the outside world because it is also the antenna, well... let's just say it's not good at all.

    So, I would like to add a HF whip to the mix, just in case. I looked around and sadly the sort of antenna I would like I really cannot afford. Something like the Moonraker 22W or 29W would be great, but just way beyond my budget.

    So I wondered how hard it would be to make my own antenna, given, like most owners of very old boats, I am reasonably practical with hands on stuff.

    I have been reading around but I am drowning in terminology and theory, which, like I mentioned, I am a little weak on after all this time.

    I am told that AT-130 would tune a nail if I needed it to, so I think I have an advantage there. I also have LOTS of space to mount something and length is not a problem as the mast means I cannot go under anything lower than 20 meters anyway.

    So far, I am thinking of something like an aluminium pole around 8 meters long (length based entirely on what Moonraker seem to thing is wise), with a coil of insulated wire wrapped around it, but depending on what I have read online, this will either work very well or not at all.

    Can anyone point me to a helpful resource, or share their own wisdom, on such a construction?

    Matt
    VK5MJD

  2. #2
    Super Moderator 5B4AJB's Avatar
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    G0OEK sent me this on DRM a long time ago, maybe its something like you describe...
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  3. #3

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    Quote Originally Posted by 5B4AJB View Post
    G0OEK sent me this on DRM a long time ago, maybe its something like you describe...
    Ok, so PVC not aluminium. Is that a better option?

    Also, 70 feet of wire, is that optimal for a particular frequency range? (I feel I should be able to figure that out from my HF theory but then I do not understand the effect the spiral wind would have on resonant frequency.)

    Finally, that diagram shows a line running from the tip of the antenna back down at 45 degrees. Is that part of the antenna wire because if so it would not work in my situation.

  4. #4

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    Sorry for the delayed response, I thought I had answered but I cannot see it yet. I am new so my posts need to be moderated first.

    I am not sure if that is the sort of thing because the diagram is a bit confusing. There appears to be a wire from the top of the antenna to ground?

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