Mailing List lml@lancaironline.net Message #5270
From: Ron Galbraith-CFII <cfi@instructor.net>
Subject: Transponder/DME antenna
Date: Mon, 24 Apr 2000 20:56:32 -0600
To: <lancair.list@olsusa.com>
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The problem is not having the DME fry the transponder, or scramble the
signal.  If properly installed, there is a muting line that goes between the
two radios that prevents this.  The problem is that it's difficult to duplex
a transponder and DME into a single antenna.  Even if done properly with a
duplexer/bp/br type setup, there will be about 3db or more loss, which will
make you non-radar much sooner than you should be when you are far away from
the ATC antenna.  So for my sake (I'm an Air Traffic Controller) use 2
antennas.  It would be cheaper anyway.. Thanks

Ron


I wouldn't do it, Rob - even if you didn't fry one or the other of the
units
(particularly the DME receiver circuits, as the Xponder transmits with
some
ooomph and they are sorta close, frequency-wise), the interaction would
probably scramble the encoded data in each, giving you erroneous results
on
your DME and the Xponder output would drive ATC bonkers!



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