[Amps] grid resonance

[Bill Turner]

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