Detune the tower ?
I am also trying to figure out how to deal with the inverted L coupling to the tower. I
tried an L with the vertical wire suspended 3 feet away from the tower and it was coupling
quite a bit. I had a horizontal pennant loop for receive about 30 feet away from the
tower and when I rotated it was affected by the tower too. I lowered the Inverted L so
it wasn't influencing the receiving loop and it was definitely affected by the tower.
I am thinking that I need to detune the tower so it is invisible to both the L and the
receiving loop. I am researching on how to do this but haven't come up with much on
how to go about it. There must be a easy way to do this.................
BobK6UJ
On Tuesday, January 15, 2019, 10:01:42 AM PST, Speer, Douglas via TowerTalk
<towertalk@contesting.com> wrote:
I read somewhere, and can't remember where, that sloping the vertical segment of the "L" ~15 degrees away from the tower will minimize coupling and loses into the tower. I have a 140 foot inverted L I use on 160m. It has 60 feet of vertical suspended off a Rohn 45g tower with about 3 feet of separation at the top. I sloped it 15 degrees away from the tower in line with but in the opposite direction of the 80 foot horizontal segment. My radial system is very minimal with only 16 each, 18 foot radials. With no science to back it up, I think this is working. I am able to work anything I can hear on 160m.
WRT reception, so far this season working what I hear is not saying much out here in North West
Texas. We are simply not hearing what stations a few hundred miles in any direction are hearing.
I am using both the inverted L and a K9AY loop for receive switching back and forth for best copy and many
times using both in diversity reception mode. If it were just me I would say I have a receiving antenna
issue but other experienced 160 operators in the area are experiencing the same thing this season. I'm
baffled. Sorry to go off on a tangent.
Very 73,
Doug, W5WTX
Amarillo, TX
Message: 1
Date: Tue, 15 Jan 2019 04:38:03 +0000 (UTC)
From: RVZ <rlvz@aol.com>
To: towertalk@contesting.com
Subject: [TowerTalk] 160m. Inverted L question
Message-ID: <369232969.276333.1547527083313@mail.yahoo.com>
Content-Type: text/plain; charset=UTF-8
Guys,
I've got a 160m. Inverted L with the vertical wire spaced 4' from a grounded
steel tower at the base and 6' at the top.? The radial system isn't perfect but
it's decent.??Based upon the Inv. L's poor performance, I believe I may have a
lot of power being coupled to the tower and shorted to ground.? A?couple
questions:
1) I'd appreciate some guestimates on what percentage of input power may be
getting shorted to ground?
2) Any guestimate on what percentage of power may be saved if the Vertical wire
spacing is increased from 4' to 12" from the tower??
Thanks & 73,
Dick- K9OM?
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