Thought I would share Bob's comments with the list. The comments about
the K7TJR rx array is probably of interest to many.
----- Forwarded message from W7lr@aol.com -----
From: W7lr@aol.com
Date: Wed, 15 Jul 2009 11:24:11 EDT
Subject: Re: Topband: Two element phased array
To: tree@kkn.net
FB Tree. I have two verticals phased. Not quite the same setup as you
will have. Mine are the 90 foot verticals of 4" od aluminum irrigation
pipe.They are 90 feet apart, as far apart as possible for guys in the field.
And useful only endfire. Mostly I use just the one. When phased they are
for Europe or ZL. I used some system shown in ON4UN, I think a Christman?
phasing scheme? It was very tricky to get going. I used my GR RF bridge to
measure the mutual impedance, and then some ON4UN formulas or info to get
the right coax cables. It has about 4.5 db gain, and maybe 15 db f/b. I
don't find it greatly useful, there may be a slight benefit, but propagation
by far outweighs that benefit. I can switch it in or out with remote
relays. What really matters are good rx arrays. The one by K7TJR with 4 20'
verticals on a 70x320 foot rectangle is like a Beverage that you can't see
the end of - I used to get maybe 4 openings a season, but with this almost
every night during the season. I am also adding this season a 90' 4 square
of his design to try and hear HS XU etc.
73 Bob W7LR
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