[TowerTalk] Interaction Issues

Chuck Dietz w5prchuck at gmail.com
Sun Apr 9 13:22:00 EDT 2017

No reason to change the coax length, check the coax itself by disconnecting
and putting an analyzer at the remote switch on the tower, if there is one.

Chuck W5PR

On Sun, Apr 9, 2017 at 11:29 AM, <john at kk9a.com> wrote:

> Phasing will have no effect but I am not sure why you would change the coax
> length. If the 6m beam is 90 degrees to the C3 and the 6m boom length is
> around 1/2 wl on 20m or less than that but electrically 1/2 wl due to
> grounded elements there will be serious interaction.
> John KK9A
> To:     "towertalk at Contesting.com" <towertalk at Contesting.com>
> Subject:        [TowerTalk] Interaction Issues
> From:   Jeffrey Cantor <k1zn at att.net>
> Reply-to:       Jeffrey Cantor <k1zn at att.net>
> I recently had some tower work done.  Ihave a Rohn 25 tower up 60 FT.  I
> have
> a C-3 and a 6-element Cushcraft 6Mon it.  Both antennas were doing fine -
> essentially flat on the C-3and around 1.5:1 on the 6M.  They were both
> mounted
> on a 9 FT mast,separated by about 6 FT. The job was to replace the 9 FT
> mast
> witha 15 FT lighter mast and to install a new 12/17M WARC Cushcraft
> antenna.
> The new setup had the 12/17M antenna atthe top of the mast; the 6M in the
> middle, phased at 90 degrees to the otherbeams - - separated by roughly 6
> FT
> between it and the lower C-3 and the WARC. After the install, I am noticing
> a
> 2.0:1. 2.4:1 SWR on the C-3 on 20M only; 15M & 10M are OK.  On the 6M -3.0+
> SWR. Do I have an interaction problem betweenthe 6M and C-3? Should the 6M
> be
> at the top of themast?  Offset to the others, or not? Jeff/ K1ZN
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