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Old 18-09-2011, 16:13   #1
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Weatherfax Receive-Only Antenna Routing

Greetings Folks,

I have a Sony world band radio with with to receive weatherfax with (and no separate SSB unit etc..) and just when I was about to install my Long Wire Antenna, I made the mistake of thinking and googling.

The Sony unit is at the navstation, and I was planning on running a standard 12 to 14AWG single core wire through the boat, out the transom and attach this to the backstay.

The cable run from the navstation to the backstay however will be approximately 10m (30ft) and will pass within a foot of the autopilot motor (Simrad/Jefa DD15).

Having made the mistake of googling a solution, I have more questions than answers.

Should I just run the single core cable all the way and be done with it? Or as some suggest - should I run coax and connect the conductor and do something with the shield to shield from RFI from the AP?

I have no "official RF ground" on the boat, so if the coax path - don't know where to connect the shield.

Thanks in advance and looking forward to enlightenment...

AK.
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Old 19-09-2011, 02:56   #2
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Re: Weatherfax Receive-Only Antenna Routing

Why not try with a temporary antenna. Keep on fiddling round till you get something that works.

I've never been able to get consistently good shortwave reception in Sydney. I did manage to get weatherfax OK.

Once you're out of Sydney you're gunna be a lot closer to the big shortwave transmitters, there may be fewer hills to get in the way and there should be a lot less interference.
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Old 19-09-2011, 05:40   #3
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Re: Weatherfax Receive-Only Antenna Routing

For RX we use a length of wire, no ground. Reception is OK.

Now we got a stub 1 ft active antenna from NASA MArine.

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Old 19-09-2011, 15:25   #4
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Re: Weatherfax Receive-Only Antenna Routing

Hi,

Thanks for the replies.

Boracay, I know exactly what you mean about reception in Sydney, there's so much noise.. when testing from home, I managed to get a wefax image, but there was so much crap in it, the background was grey instead of white!

Anyway, hope to leave in a few months, but really want to sort this out as I expect it will be my primary weather tool. (Until I pass Darwin and buy some airtime for my satphone)


Barnakiel, that looks like a very interesting antenna (http://www.nasamarine.com/proddetail...rod=11_antenna) - am I right in assuming that you're using this with a Sony world band receiver and not Nasa's own receiver? Did you just cut their plug off and fit a 2.5mm mono plug?
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Old 19-09-2011, 15:40   #5
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Re: Weatherfax Receive-Only Antenna Routing

G'Day AK,

I think that you are over engineering this. Try taking any old bit of wire from the antenna terminal of the rx to the nearest shroud or stay chainplate and making a temporary connection. I bet that this will give you a very usable signal.

If you are in an area with very high ambient RF noise, you are stuffed for now, but once out of your marina/moorage area and out in the "wilds" of the harbour, you should be able to get a usable signal. We certainly have done so from Balls Head, Quarantine, and most places in Middle harbour.

Good luck, and perhaps we'll see you before too many more weeks.

Cheers,

Jim
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Old 19-09-2011, 15:57   #6
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Re: Weatherfax Receive-Only Antenna Routing

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Originally Posted by Jim Cate View Post
G'Day AK,

I think that you are over engineering this. Try taking any old bit of wire from the antenna terminal of the rx to the nearest shroud or stay chainplate and making a temporary connection. I bet that this will give you a very usable signal.

If you are in an area with very high ambient RF noise, you are stuffed for now, but once out of your marina/moorage area and out in the "wilds" of the harbour, you should be able to get a usable signal. We certainly have done so from Balls Head, Quarantine, and most places in Middle harbour.

Good luck, and perhaps we'll see you before too many more weeks.

Cheers,

Jim
Hi Jim,

It's the story of my entire refit, using technology to try to compensate for my deficiencies as a sailor.

The main concern is the 30ft length of the wire run to the backstay and it's proximity to the AP drive, so I'm worried about more RFI on top of the crap in the air already.

So you reckon coax won't help here? Or just man up and run single core simple stuff and suck it and see and replace if necessary?

As for being back in a couple of weeks great news. On my end, the boat finally looks like a boat again now since I have a mast and (a) sail again after 6 years (!), so please swing by when you have a chance!

Cheers!
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Old 19-09-2011, 16:09   #7
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Re: Weatherfax Receive-Only Antenna Routing

Quote:
Originally Posted by akio.kanemoto View Post
Hi Jim,

It's the story of my entire refit, using technology to try to compensate for my deficiencies as a sailor.

The main concern is the 30ft length of the wire run to the backstay and it's proximity to the AP drive, so I'm worried about more RFI on top of the crap in the air already.

So you reckon coax won't help here? Or just man up and run single core simple stuff and suck it and see and replace if necessary?

As for being back in a couple of weeks great news. On my end, the boat finally looks like a boat again now since I have a mast and (a) sail again after 6 years (!), so please swing by when you have a chance!

Cheers!
AK,

There is no specific need to use the backstay for your antenna... any of the standing rigging will do, so if there is a shroud chainplate nearby, try using it thus avoiding proximity to the a/p and any potential RFI.

And it isn't a couple of weeks, sadly, but hopefully in early November. Will likely be moving the boat down to the Pittwater area ASAP so that Ann can start up a physio program there until such time as we leave for Tassie (touch wood).

Cheers,

Jim
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Old 19-09-2011, 16:25   #8
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Re: Weatherfax Receive-Only Antenna Routing

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AK,

There is no specific need to use the backstay for your antenna... any of the standing rigging will do, so if there is a shroud chainplate nearby, try using it thus avoiding proximity to the a/p and any potential RFI.

And it isn't a couple of weeks, sadly, but hopefully in early November. Will likely be moving the boat down to the Pittwater area ASAP so that Ann can start up a physio program there until such time as we leave for Tassie (touch wood).

Cheers,

Jim

Jim,

Hmm, perhaps I should devote a day to sitting around with a piece of wire and trying to get a wefax every schedule and tying it to different things and seeing how I go then.

If you're going to be in Pittwater in Nov'ish hopefully, we might even be there already (really hoping!!!!). I've got most things sorted out already, but waiting on some hardware to turn up from the US to finalize the deck layout, then I can finally leave the harbour after I get the kiwigrip on!

Hope the physio goes well, I haven't been to Tas yet, however I hear that it's arguably the best place in Australia.
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Old 20-09-2011, 17:39   #9
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Re: Weatherfax Receive-Only Antenna Routing

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Originally Posted by akio.kanemoto View Post
Hi,

(...)

Barnakiel, that looks like a very interesting antenna (http://www.nasamarine.com/proddetail...rod=11_antenna) - am I right in assuming that you're using this with a Sony world band receiver and not Nasa's own receiver? Did you just cut their plug off and fit a 2.5mm mono plug?
Yes/No. I am using plain wire into a NASA receiver. I have also this stub antenna as per your link. Next time offshore I will test them side by side and see which one works best. This far, plain wire worked fine.

But if it works on NASA receiver it will also work on other receivers. An SSB antenna is an SSB antenna, no tricks. Probably just makes the signal stronger, hopefully not together with the noise ;-).

b.
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