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Re: [TowerTalk] 80m 4Square Comtek box

To: "Frank Mayer" <>
Subject: Re: [TowerTalk] 80m 4Square Comtek box
From: "Jim Lux" <>
Date: Thu, 18 Nov 2004 07:20:28 -0800
List-post: <>
----- Original Message -----
From: "Frank Mayer" <>
To: "Jan Erik Holm" <>
Cc: "'towertalk'" <>
Sent: Thursday, November 18, 2004 6:29 AM
Subject: Re: [TowerTalk] 80m 4Square Comtek box

I use a variable phasing network for my 2 4BTV verticals that I use on 40
and 20 meters.  The phasing unit consists of a roller inductor in series
with one antenna and a 500pf variable in series with the other antenna.  The
outputs of those 2 components are joined and feed an antenna tuner connected
to the rig.  I have a DPDT toggle switch so I can switch the 2 components to
the opposite antenna to change directions.  The antennas are 17' apart and
have a cardioid pattern on both bands with at least 20 to 30 db front to
back.  I just wish there was some way I could measure the forward gain.  It
is within 1 s- unit of my 2 element yagi on 40 to VK and ZL.

This isn't a bad approach, and works well with 2 elements. There might be a
fair amount of reactive power circulating through the feedlines, but,
feedline loss is reasonably low, so it's not all that bad.   One can do a
similar thing with a pair of screwdrivers or compact loop antennas (tune one
a bit high, and the other a bit low, and the ATU takes care of transforming
the parallel combination to something the transmitter likes to see).

1 S-unit is 6dB, and in the phased array business, 6 dB is a huge variation
in gain, especially for a 2 element array.  Consider that the 2 element yagi
only probably has about 4-5 dBi gain in the first place. The F/B is mostly a
matter of nulling, which your setup will do quite nicely.

It's really tough to make work with 4 elements.  Greg Ordy has a great web
page talking about his "adventures" with various strategies.


See:  for "Self Supporting Towers", "Wireless Weather 
Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any questions 
and ask for Sherman, W2FLA.

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