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Multiple Radio Desense



Last week, 3 AMSAT volunteers (OE1DMB, N6IZW, and
ZL3RX took some radio measurements for FM desense 
just to see if we were in the ballpark for multiple radio 
operations at one site.  This data will be useful for you  at 
FieldDay and your EOC or other operations where multiple 
radios will be used.

At separations of 100' between antennas:

2 meters:             (the spread is worst-to-best radios)
25 KHz separation blocks at  1 mw to 100 mw
600KHz separation blocks at  about 100 mw to 1 W

70cm:
25 KHz separation blocks at 30 to 80 mW
1 MHz separation blocks at  2 to 5 Watts

Thus, at two meters, even at lowest power levels you
are going to get desense and even blockage with any
pair of radios on 2 meters.  SO plan accordingly with
better antenna separation and beams if needed.

At 70cm, with a little thought, you can operate dual 
radios simultaneously easier...

de WB4APR, Bob


>>> "Robert Bruninga" <bruninga@usna.edu> 3/11/05 12:16:30 PM >>>
>>> "Robert Bruninga" <bruninga@usna.edu> 3/10/05 12:12:12 PM >>>
>We need a volunteer ...[to assess radio desense when 
>two radios are operating in close proximity (say 100') 
>and on the same band]...

Thanks AMSAT!  I got many responses and three have already
produced good data.  I am assembling it now and will post 
the results.  Generally it only takes a few 10's of milliwatts to
desnse one radio with another on an adjacent channel
(25 KHz away).  At 100 KHz, it is on the order of 100 mw
and for the normal 2m split of 600 KHz it is on the order
of a watt.  And of course some radios are better than others.

Thanks to  ZL3RX,  N6IZW,  OE1DMB 
and also PE1RAH and Gerry

More later.
Bob
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