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Re: [TowerTalk] Broadband Match of 80/75M Dipole

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Broadband Match of 80/75M Dipole
From: john@kk9a.com
Date: Fri, 19 Apr 2019 20:34:29 -0500
List-post: <mailto:towertalk@contesting.com>
I saw dipole in the subject line and in K9YC's post. I did not notice that the antenna was switched to an inverted V.

John KK9A


David Gilbert wroteL

An EZNEC+ model of a 75M Inverted-V doesn't show any "deep nulls" on
30m, at least not compared to the pattern on 75m.  The broadside pattern
is simply quite a bit narrower, if that's what you mean. As Jim says,
though, the SWR is ridiculously high.

Dave  AB7E


On 4/19/2019 5:25 PM, john at kk9a.com wrote:

Besides the high SWR and associated feedline loss that Jim mentioned, the antenna pattern would have multiple deep nulls.

John KK9A


Jim Brown K9YC wrote:

In my limited experience, no. My high (120-140 ft), coax-fed resonant
80M dipoles exhibit VERY high SWR on 30M.  A good tuner might put some
power on the transmission line, but the loss would be very high. The
fact that they don't hear well on 30m is a clue.

73, Jim K9YC

On 4/19/2019 4:42 AM, Mpridesti wrote:
Hi Jim

Thanks for sharing the prez.

Question: am considering recabling my 80 Inverted Vee as suggested. Any speculation on its performance on 30 m?

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