Re: New to this...

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Malcolm Watts" <m.j.watts@xxxxxxxxxxxx>

Hi Tyler,

On 16 Dec 2004, at 20:01, Tesla list wrote:

> Original poster: Tyler Pauly <rpggod714@xxxxxxxxx>
>
> I have a small coil with tank circuit resonating at
> 275 kHz. One of those handy tesla calculators tells me
> that a 1/4 wavelength is 892 feet. Will 892 ft of
> wire on my secondary resonate at 275 kHz, or do I have
> to put more wire on to compensate for my top load
> which will lower my freq.? Sorry if it's a stupid
> question.
>                         Thanks for any help,
>                            Tyler Pauly

     You will find that winding 892 feet of wire on a typical form
factor secondary will resonate at a frequency higher than you expect.
You will have to add topload to make it resonate at what you do
expect. However, the real benefit in adding a topload is not to force
the coil to resonate at some specific frequency but to add energy
storage capacity to the secondary and increased radius-of-curvature
to the top of the coil.

     The correspondence between wirelength and 1/4 wave frequency
applies to a whip (monopole) aerial.

Malcolm