Re: scoped coils

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Paul Arrowsmith by way of Terry Fritz <twftesla-at-qwest-dot-net>" <p_t_arrowsmith-at-hotmail-dot-com>




>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: scoped coils
>Date: Fri, 29 Mar 2002 15:44:31 -0700
>
>Original poster: "Chris Swinson by way of Terry Fritz <twftesla-at-qwest-dot-net>" 
><exxos-at-cps-games.co.uk>
>
>Hi all,
>
>I have 2 coils which are both 360khz, one is wound with 0.315mm magnet 
>wire,
>the other is wound with 1.5mm^2 plastic covered wire.  The strange thing is
>that on my scope the tune point for the magnet wire coil is effected VERY
>easily. I need only place my had about a foot away from it and its enough 
>to
>knock the coil totally out of tune on the scope.  The plastic wire coil
>stays in tune and you can hardly get it to move even if you place you hand
>right on it. Does anyone know whys these 2 coils behave the way they do ?
>
>Thanks,
>Chris
>
>
>
Chris,
My educated guess is that the coil with the plastic insulated wire is of a 
lower Q. A lower Q will make the resonant frequency point lower in amplitude 
but having a wider bandwidth. This would make your secondary less critical 
to tuning changes but also less efficient also. The insulation may be lossy 
at R.F. thus lowering the Q factor.
Paul A, Australia