Tom,
Howard has been around longer than both of us put together, but I think the
fact is that most of the currently sold off center fed antennas use a balun
at the feed point and coax feed, like you have. The exception is the
Carolina Windom which uses a section of balanced line to try and put
feedline radiation to good use.
Here's a few random thoughts in no particular order: Your antenna seems
short. Alpha Delta, Buxcom, and Array Solutions OCF antennas are 135 feet
long. Antennas and More OCF has one at 132 ft. 4:1 balun is more common,
but there is some use of 6:1. There is also a debate on just where the
feed point should be located. All of this stuff will have some effect on
the final result.
Your 40 meter swr is high and 20 meters is out of sight. You should see
2:1 or so at band edges on 40 and 20, similar to what you are getting on 80.
You should be seeing the very high swr on 15, not 20. In fact there is a
mod to add 2 parallel wires to the feedpoint to get good swr on 15 and 30.
The fact that
If antenna design is ok, what else could it be? Maybe too close to the
tower? Is there any kind of standoff to get it away from the tower?
Sometimes changing feedline length can make a difference. Try using a
few barrel connectors and short coax jumpers to add various combinations of
coax length and see if things change.
Finally, these things can throw off some RFI. Any RFI in the house? . Did
you wind a coax choke at the feedpoint? (I had to do this.) Stray RF could
be throwing off your swr readings on your talking meter.
73 good luck, Steve KW3A
----- Original Message -----
From: "T Behler" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Saturday, September 27, 2008 9:56 PM
Subject: windom question
> Hi, folks.
>
> Here's one for all of you who have used a Windom antenna before.
>
> I am interested in what anyone knows about the characteristics of a normal
> Windom antenna, in relation to SWR readings.
>
> As many of you know, I put a Windom up last week, and am now in the
> process
> of testing it.
>
> The Windom itself is approximately 125 feet long--80 feet to the south,
> and
> 45 feet to the north.
>
> The center is fed with RG8U coax, and there is a 4 - 1 balun at the feed
> point.
>
> The antenna is up about 35 feet, both at the center which is attached to
> my
> tower, and the legs which are attached to conveniently-located trees.
>
> The antenna tunes on all bands from 80 through 10 meters, except for 30
> meters, using the auto-tuner on the TS480.
>
> I have already tried the antenna out on 80 meters, and have gotten very
> good
> signal reports from participants in a Michigan state-wide net. My SWR's
> on
> 80 meters range from about 2.1 to 1 at the top, to about 2.5 to 1 at the
> bottom of the band, with SWR's close to 1.1 to 1 a little above the center
> of the band.
>
> I did some checking earlier on 40 and 20 meters, and found my SWR's to be
> less encouraging.
>
> On 40 meters, my SWR's range from 3.1 to 1, to about 5.1 to 1.
>
> On 20 meters, my SWR's are about 6 to 1 at the bottom of the band, and
> around 2.1 to 1 at the top of the band.
>
> These SWR's are disappointing to me, although the auto-tuner in the TS480
> seems to tune the antenna fine at various frequencies throughout the 20
> and
> 40 meter band.
>
> Am I in trouble here, or is this typical of a Windom antenna like this?
>
> Thanks, and 73 from Tom behler: KB8TYJ
>
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