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[TowerTalk] Reduced size receiving antennas

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Subject: [TowerTalk] Reduced size receiving antennas
From: "Craig D. Smith" <>
Date: Wed, 9 Dec 2009 09:21:32 -0700
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Larry ...

Yes, I recently built a 2/3 sized K9AY RX antenna and am thrilled with the
results.  My situation was that it needed to be completely stealth due to
HOA restrictions here.  Just happened to have a small ornamental plum tree
in the front yard that was 2/3 K9AY sized.  Used black stealth AWG 26 wire
in the tree to form the elements. My elements aren't the traditional
triangular shaped loops but rather kind of ovals with the longer dimension
vertical.  The total capture area is about 2/3 of the published K9AY design.
The remote control box is mounted in the crotch of the tree about 3 ft above
ground and painted with camouflage paint (hee hee).  Coax and control cable
routed down the trunk and underground for run into the shack.  This sucker
is completely invisible from 3 feet away, even now with the leaves gone from
the tree.

During the design and construction, I had some Email correspondence with
Gary, K9AY, about my changes to the dimensions and shape.  He assured me
that the shape wasn't too critical and that the capture area would have just
the expected effect on received signal strength - nothing dramatic.  He also
felt that the normal range of terminating resistances could be used.  He was
totally correct on all counts.

Results have been everything I hoped for.  Greater than 20 dB F/B on MW, 80
and 160 meters.  Adequate sensitivity on 160 so that I need no external
preamp and have the internal preamp in the K3 turned off.  In fact, the
attenuator is on more often than not.  This antenna is quite usable up
through 17 meters, although the F/B goes away on 20 meters and above.  The
smaller size could actually be a benefit if you want to use it on 40, 30 and
20.  Just used it for 900 Qs in the 160 meter contest, and it was a joy.

            73    Craig  AC0DS


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