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[aprssig] APRS buoy - transmit power and antenna?

Robert Bruninga bruninga at usna.edu
Mon Sep 10 15:03:37 UTC 2007


See my BUOY web page...
http://www.ew.usna.edu/~bruninga/buoy.html
 
>> 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?

Yes exactly our design.

> Would a simple wire dipole work... 

I think  Jpole in a 5 foot piece of 3/4" PVC pipe would get the
radiating 1/2 wave element up higher...

> Any chance that a bare Microtrak (300 mw) will make it??

Possibly, depending on how close the digis are to the lake.  But
in busy areas, a 300mw signal pretty well gets stepped on by
everything around it.  Our designs plan on using 5W HT's.  The
8W microtrack would be ideal.

The TX power is actually quite small since it is only on for a
second at a time...

Our hope was to use the standard APRS 5 channel telemetry with
these asignments:

CH-1 Battery Volts
CH-2 Water Temp (at bottom of buoy)
CH-3 Air Temp (in the antenna mast)
Ch-4 Water conductivity (two Stainless screws)
Ch-5 Luminosity (A photocel)

Bob, WB4APR






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