Doug, at that height, close to 1/2 wavelength, any and everything can
effect the vswr of the 40m antenna.
Even the moisture content of the soil will have an influence. Has it rained
since the initial readings?
My advice is to monitor the vswr over a several month period of time to see
if it continues to degrade. If it does, then there is a case to look into
why.
73,
Gerald K5GW
In a message dated 12/3/2013 7:26:48 A.M. Pacific Standard Time,
dscribner@myfairpoint.net writes:
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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