Re: Best Primary Coil

Subject:   Re: Best Primary Coil
  Date:    Fri, 25 Apr 1997 10:04:50 -0400 (EDT)
  From:    FutureT-at-aol-dot-com
    To:    tesla-at-pupman-dot-com

<<  Hum...........this might
> be 
> another method of adjusting coupling.
> I had an idea of building a primary coil mounted in rollers.  100's of
> tiny 
> ceramic or plastic rollers every few inches the entire length of the
> primary 
> coil.  If coupling needs to be changed the entire coil can be rotated
> clock 
>wise or counter clock wise to make the primary coil larger or smaller
> and the 
> turn to turn spacing will stay the same.  The inside turn of the primary 
> could then be adjusted closer or further away from the secondary coil. 
> If a 
> larger cap, toroid or power supply is used the primary can be roatated
> adjust coupling and prevent arc over.  A primary coil of this type would 
> involve many hours of work.  Would it be worth it?  
 Gary Weaver

Yes, tapping "in" or "in and out" can be used to adjust the coupling
(just as
the normal tapping "out" changes the coupling).  Regarding the coil idea
the hundreds of rollers, whether it is worth it depends on your goals. 
you would like to see such a device operate then it may be worth it for
to build it, but it will function both as a coupling AND tuning device
simultaneously, since a larger diameter coil with the same turns spacing
have a greater inductance.  So you'd still have to change your tap point
stay in tune.  To keep the tuning constant but vary the coupling using
method would require that the turns spacing increases at the proper rate
the coil becomes larger -- this would be a mechanical nightmare to
design and
build.  To me it would not be worth the effort.  It is much easier to
build a
mechanized lift device that can raise and lower the secondary while the
is running (or not running) to change the coupling.  All my coils
a simple device which allows for adjusting the secondary height using a
handwheel controlled clamp.

John Freau