Re: Pri./Sec. Tuning

["Tesla list" <tesla@xxxxxxxxxx>]

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

Hi Mike,

On 19 Apr 2005, at 14:39, Tesla list wrote:

> Original poster: "Mike Knowlton" <amdx@xxxxxxxxxxx>
>
>    Hi all,
> I have been reading this group for about six weeks now and
> see confusing info on pri./sec. tuning. ( to me anyway)
>    My understanding is you have a secondary coil with toroid (tophat)
>    that
> is resonant at a fundumental frequency.
>    Then you wind a Primary, and wire it with capacitors in parallel,
>    then
> adjust a tap on the primary until the primary is resonant at the same
> frequency as your secondary. (I understand this is performed with the
> secondary in place.)

You want to tune the primary _without_ the secondary being present or
you'll get a bunch of confusing frequencies to deal with.

>    My confusion is sometimes I see people say tune your primary lower
>    or
> higher. Shouldn't they ring at the same frequency?

I've had good results where both are tuned to the same frequency and
better where the primary tuning was lower. Detuning in this fashion
is somewhat equivalent to changing the coupling.

Malcolm

>    Also as a tuning method, could you lightly couple a scope probe to
>    the
> circuit and drive the primary with a signal generator, then watch for
> double peaks, then adjust the primary inductance (or capacitance)
> until you have a single peak.
>                       Just curious,
>                                    Mike
>
> P.S. I aquired an 8.5" x 42" clear plastic tube today, I think it's my
> start to building a TC !
>   "clear plastic"? How do I find out what type of plastic this is? It
> has a 1/4" wall thickness.
>
>
>
>