[TowerTalk] Four Square notes
jim.thom at telus.net
Wed Apr 5 20:08:49 EDT 2017
Date: Wed, 5 Apr 2017 13:37:57 -0400
From: Dave Sublette <k4to at arrl.net>
To: Central KY CW/DX Operators <CW-DX-OPS at LSV.UKY.EDU>
Cc: towertalk at contesting.com
Subject: [TowerTalk] Four Square notes
For the past 10-15 years I have had a four square array on 80 M. I use the Comtek phasing system. My array consist of four, full sized, dipoles strung around my 160 meter vertical. The insulated feed point on the vertical is 27 feet above ground, which makes the tower 150 feet tall, perfect for the 80 meter stuff.
The centers of the dipoles are pulled out to 46.5 feet from the center, making the side of the square 66 feet as required for the array. The lower halves of the dipoles are brought back to the center and fastened about 20 feet up the tower, making the lower half sort of droopy and loopy. This configuration is not ideal, but I was able to get a 20 dB f/b out of it and it worked fine for many years.
I?m not quite finished with the job. I have one dipole restrung and am working on the second of the ?good? dipoles. The other two will have to wait until I get some fresh RG59/U in from somebody.
FYI? the ?80M? dipoles resonate at 3300 KHz for proper operation. The feed lines are cut to an electrical three-quarters wavelength measured at 3600 KHz.
## How close to the top of the tower are each of the 4 vertical sloping dipoles ? Do they require spreaders to space them out from the top of the tower ? Is any type of CM choke used at the feedpoint of each vertical sloping dipole?
Is there a CM choke on the main input of the comtek phasing box ?
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