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Re: [TowerTalk] Broadbanding 80 meter dipole

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Broadbanding 80 meter dipole
From: "Roger (K8RI) on TT" <K8RI-on-TowerTalk@tm.net>
Date: Fri, 18 Aug 2017 04:01:34 -0400
List-post: <mailto:towertalk@contesting.com>
Mounted on the tower would put the tuners about 75 to80 feet from the feed points and although center fed they are a LONG way from being balanced, requiring 2 common mode chokes to keep RF out of the shack on 75.

73, Roger (K8RI)

On 8/17/2017 Thursday 8:17 PM, Steve Maki wrote:
If the tuner(s) are mounted on the tower.

-Steve K8LX

On 8/17/2017 7:53 PM, Steve Maki wrote:
Except Roger is envisioning sloping *dipoles*, FIVE of them. Somehow I can't picture five tuners hanging out there in mid-air at the feedpoints, begging to be tuned up and down the band. Not to mention that whatever pattern he's hoping for will be hopelessly compromised by common mode currents on the feedlines between the antenna and tuner.

-Steve K8LX

On 8/17/2017 4:16 PM, Kimberly Elmore wrote:

Rod's idea is by far the best. Slopers are weird creatures. While you can broadband antennas by making the elements with a large diameter (as in a cage) the mechanical complexity isn't worth it. If they absolutely positively must be resonant, well...

Kim N5OP

       From: Rod Greene via TowerTalk <towertalk@contesting.com>
To: Roger (K8RI) on TT <K8RI-on-TowerTalk@tm.net>; "towertalk@contesting.com" <towertalk@contesting.com>
  Sent: Thursday, August 17, 2017 2:25 PM
  Subject: Re: [TowerTalk] Broadbanding 80 meter dipole
Or use an auto tuner at the feedpoint to match the slopers on whatever band/freq you want to use. That's what I do.
73, Rod/w7zrc


       From: Roger (K8RI) on TT <K8RI-on-TowerTalk@tm.net>
  To: "towertalk@contesting.com" <towertalk@contesting.com>
  Sent: Thursday, August 17, 2017 12:33 PM
  Subject: [TowerTalk] Broadbanding 80 meter dipole
I've seen a few possibilities in the past, but I'd like to add a dew
slopers to come up with the 5 used for some directivity, gain and front
to back. Switched coils at the feedpoint with frequency sensing would
likely work.  I've had excellent results with just a couple switched
slopers on 40.

To complicate things I'd like to do this and maintain the dual band 75 /
40 meter operation, which would likely require separate feedlines. The
unused line would / could end up as a stub.  I could possibly use the
frequency sensing to disconnect the coax for the unused band.

Thoughts?


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--

73

Roger (K8RI)


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