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Re: Topband: 4SQ Arrays in proximity

To: topband@contesting.com
Subject: Re: Topband: 4SQ Arrays in proximity
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Tue, 28 Jan 2020 01:43:19 -0800
List-post: <mailto:topband@contesting.com>
On 1/28/2020 12:32 AM, Paul F. Merrill wrote:
HI - I have a couple questions -

--I am planning a 160m TX 4SQ and another for 80M.   Their centers are
going to be about 300' apart - is this far enough away?  I have a little
bit of room to move them apart, but am lucky enough as it is to have the
space to get this.  The closest verticals will be about 200' apart.

I have no experience with this, but physics suggests minimal interaction between the two arrays because of their 2:1 wavelength relationship.

--I'll be using N6BT vertical dipoles, so there will be no radial issues.

Love this concept. First saw N6LF's take on vertical dipoles, did some work on it myself, then saw N6BT's excellent work on it.

--WRT TX chokes - I'm worried about constructing feedline chokes for the
feedpoints and still having enough cable (.85vf)

Paul and I have corresponded directly about this. I referred him to page 3 of my latest Choke Cookbook http://k9yc.com/2018Cookbook.pdf and to Grant, KZ1W, who initiated and facilitated my work on chokes for 4-sq arrays. I also noted Davis RF RG11 (VF 0.84), the 75 ohm versions of LMR-series coax, and 75ohm versions hard line like LDF4 or LDF5 (VF ~0.88) and cables made for the CATV world, where distribution runs at 75 ohms. All of the Teflon coax cables in that family have VF ~ 0.7

73, Jim K9YC

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