SSB Balun at TOP of Backstay

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Geoff Schultz - 11 Jun 2009 14:42 GMT

I'm posting this for a friend from the forum on www.FreedomYachts.org. I
know that there are a lot of good radio people here and not many on that
forum.

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I have one of these catketches, no shrouds and an overhanging mizzen boom.
In the next two years, I need to install an SSB transceiver antenna. I have
two stainless adjustable backstays with block and tackle at the bottom.
Normally, in their idle mode, they are athwart ships of the mizzen. When in
use, The luff backstay tackle is set on the luff transom corner and
tensioned. I know some people use this backstay as an antenna.

What I want to know is if someone has experience with positioning the balun
at the TOP of the backstay and feeding the coax cable from the top of the
mast down to below decks. Normally, the balun is at the bottom end of the
antenna and the coax is fed in from there. This is not possible (or at
least practical) with a backstay that is moved around at the bottom end. As
far as my limited knowledge goes, the coax has to be included in
calculating the required antenna length.

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-- Geoff
www.GeoffSchultz.org

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Robert Miles - 11 Jun 2009 18:56 GMT

You would probably have to install the ATU at the top of the mast as well,
and the voltage maximum would likely be at the deck level, and this might be
interesting for those leaning against the backstay?

Regards

Bob
GM4CAQ

Simply Blue Too
Clyde

> I'm posting this for a friend from the forum on www.FreedomYachts.org. I
> know that there are a lot of good radio people here and not many on that
[quoted text clipped - 25 lines]
> -- Geoff
> www.GeoffSchultz.org

Reply to this Message

Chuck - 11 Jun 2009 23:32 GMT

>I'm posting this for a friend from the forum on www.FreedomYachts.org. I
>know that there are a lot of good radio people here and not many on that
[quoted text clipped - 21 lines]
>-- Geoff
>www.GeoffSchultz.org

Hi Geoff,

What is the purpose of the balun in the installations you described?
Both the coax and the antenna are typically unbalanced and a balun is
not required. Is the device an unun to transform impedances?

Chuck

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Geoff Schultz - 12 Jun 2009 00:20 GMT

>>I'm posting this for a friend from the forum on www.FreedomYachts.org.
>> I know that there are a lot of good radio people here and not many on
[quoted text clipped - 30 lines]
>
> Chuck

I'm not a radio person and am simply repeating the question. If you'd
like to ask directly, please go to

http://www.freedomyachts.org/viewtopic.php?f=7&t=10132

You'll have to register to reply, but that's quick.

-- Geoff
www.GeoffSchultz.org

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Wayne.B - 15 Jun 2009 13:50 GMT

>I'm posting this for a friend from the forum on www.FreedomYachts.org. I
>know that there are a lot of good radio people here and not many on that
[quoted text clipped - 16 lines]
>far as my limited knowledge goes, the coax has to be included in
>calculating the required antenna length.

Baluns are almost never used in a marine SSB installation. Their
primary use is for center fed horizontal dipole antennas which is
quite uncommon on boats.

Your friends best bet for an unstayed rig is to install a 23 ft whip
on the stern and feed it with an antenna coupler working against a
good ground system.

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Boat Forum / Electronics / June 2009

SSB Balun at TOP of Backstay