Topband: [W7lr at aol.com: Re: Two element phased array]

[Tree]

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 at aol.com -----

From: W7lr at aol.com
Date: Wed, 15 Jul 2009 11:24:11 EDT
Subject: Re: Topband: Two element phased array
To: tree at 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