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Re: [TowerTalk] elevated short vertical dipole orquarterwave monopole?

To: "Jan Erik Holm" <>,"'towertalk'" <>
Subject: Re: [TowerTalk] elevated short vertical dipole orquarterwave monopole?
From: "Tom Rauch" <>
Reply-to: Tom Rauch <>
Date: Sun, 5 Dec 2004 06:18:29 -0500
List-post: <>
> Strange. I´ve used gamma matched yagis for 35 years
> or so and also used (at times) very high power, never
> had a failure or any problem with it.
> Sure a gamma match isn´t a perfectly balanced feed
> method but IMO it´s simple and reliable.

I never really noticed a pattern problem, but then how do
you A-B test between a gamma and a balanced feed?

I noticed a voltage (and thus current) on the shield

Power levels and cable lengths have a lot to do with it. In
the USA we have an extreme power limit. They allow us to use
1500W output and most amplifiers will run a bit more. The
higher the power and more congested the environment the more
frequently problems show up.

I found my problem because of TVI to neighbors.

Think about this Jim. If the voltage from the element to
boom mechanical and electrical junction was truly zero, how
would any current flow in the other non-excited half of the
element? Even if we are happy, it doesn't mean the system is
good. It was just my luck that 1/4 wl away from the gamma
the cable shield had enough voltage to arc to the tower leg.
I don't like machines or antennas that work because I'm

73 Tom


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