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[aprssig] APRS buoy - transmit power and antenna?

Wes Johnston, AI4PX wes at ai4px.com
Mon Sep 10 14:19:20 UTC 2007


Why not make the bouy from 4 or 6 inch pvc pipe?  Use a reducer to neck it
down to 3/4 and make a tv twinlead jpole to go inside the 3/4 top section?
I think Bob Bruninga has a diagram of such a bouy on his web site.

Do they have 6" pvc pipe in the rest of the world?  or is it called 150mm
pipe? lol
Wes


On 9/10/07, Robert Rochte <rochte at gmail.com> wrote:
>
> After having my last balloon payload traverse the entire length of Lake
> Erie intact, I'm now floating the idea of an APRS buoy...
>
> I have no experience with transmitting from the water and I'm wondering if
> there are any basic rules of thumb.  Ron, VE2JOR, has described a couple of
> grounding techniques used in a boat to me (a plate below the water and
> another involving a metal lining inside the hull) - I'm wondering what would
> be best for a buoy.
>
> Would a simple wire dipole work, or should I somehow use the lake as the
> ground plane (this would be over fresh water - the Great Lakes - if that
> makes a difference)?  Is there a "best" height to have the antenna above the
> surface ( e.g., a particular fraction of a wavelength)?
>
> Also, what kind of power output will I likely need to reliably reach
> terrestrial APRS stations?  Any chance that a bare Microtrak (300 mw) will
> make it??
>
> Thanks and 73,
> Robert
> KC8UCH
>
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>


-- 
In theory there is no difference between practice and theory.
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