Besides looking for the obvious changes of nearby objects or antenna
direction, is anything in your feedline different such as coax or coax
switches! When I connect a SixPak or StackMatch the SWR of my monobanders
changes slightly.
John
To: "Towertalk" <towertalk@contesting.com>
Subject: [TowerTalk] Change in SWR
From: "Doug Scribner" <dscribner@myfairpoint.net>
Date: Tue, 3 Dec 2013 10:24:10 -0500
I know, I probably should not get too hung up about this, but...
Six weeks ago I finished my second tower... 66 feet of guyed Rohn 45. I
have a
Mosley Pro-67B @ 68 feet and an 80 Meter Inverted V, with the apex at 64
feet.
Following the completion I went through all of my antennas and checked the
SWR
at various places in the bands. I wanted a "baseline" to make comparisions to
should anything go wrong.
About a week ago I made a few spot checks. The only significant change that I
found was on the Pro-67 and ONLY on 40 Meters.
Initial check - 7.0 - 1.6, 7.1 - 1.4, 7.2 - 1.5, 7.3 - 1.5
New check - 7.0 - 1.8, 7.1 - 1.9, 7.2 - 2.2, 7.3 - 2.1
All other bands/freqs are VERY close to what they were initially.
On the Mosley, the 40 Meter driven element is shared with 12 and 17. The
director is shared with 10, 15 and 20. My guess is that a yagi problem would
affect these other bands.
The only addition I have made is to add a 160 Meter Low Dipole for
receive. It
is 10 feet high with the feedpoint at the tower.
Is there a chance that it is interacting with the yagi 58 feet above it? I
grounded the feedpoint of the dipole with no change.
I know I should drop the dipole to the ground but it was such a hassle
snaking
it through the woods I have held off doing that.
Any advice?
Thanks and 73
Doug - K1ZO
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