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Re: [Amps] grid resonance

To: "Tom W8JI" <w8ji@w8ji.com>
Subject: Re: [Amps] grid resonance
From: Bill Turner <dezrat@copper.net>
Reply-to: dezrat@copper.net
Date: Sun, 06 Aug 2006 09:50:51 -0700
List-post: <mailto:amps@contesting.com>
ORIGINAL MESSAGE:

On Fri, 4 Aug 2006 21:43:49 -0400, you wrote:


>A mobile whip loaded with a coil is a series resonant 
>system.
>
>Are you saying a GDO will not dip on a mobile whip Bill?
>
>73 Tom 

------------ REPLY SEPARATOR ------------

When you include the car body, it is a parallel resonant circuit, not
series. The whip is electromagnetically coupled to the car body and
that makes it parallel resonant. It's similar to taking a two element
series resonant circuit and connecting the two open ends together. You
now have a parallel resonant circuit.

Try this:

Disconnect the whip from the car and lay it on a table. Now it is
purely a series resonant circuit, i.e., the coil is the inductor and
the shortened whip is the "capacitor". Now try to find a dip at its
series resonant frequency. You will not be able to.

I should point out that you will be able to find a dip at some higher
frequency where the now-disconnected whip is acting like a dipole, but
that is not the series resonant frequency we are talking about. As
before, that higher frequency is a parallel resonant mode anyway.

Bill, W6WRT











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