Re: tapped primary

[Clearspring1-at-aol-dot-com (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

> Subj:  Re: tapped primary
>  Date:    6/3/00 7:43:58 AM Pacific Daylight Time
>  From:    tesla-at-pupman-dot-com (Tesla List)
>  To:  tesla-at-pupman-dot-com
>  
>  Original Poster: "Finn Hammer" <f-hammer-at-post5.tele.dk> 
>  
>  Jeremiah!
>  
>  When you start to design your coil, there are unknown factors that need
>  to be accounted for. So you build some slack into it.
>  Relating to your specific question, this means that you build the
>  primary coil with more turns than you really need, and then "tap" it at
>  a point further in on the coil, than at it`s outher end. The connection
>  to the coil that can be moved is then called the tapping point.
>  
>  When you set the coil up for the first run, it will at best be in
>  marginal tuning, that means that the resonant frequency of the primary
>  and the secondary cap/coil circuits are not quite equal. To bring the
>  coil into tune, resonnance, you then move the tap point, untill the coil
>  is in tune.
>  
>  When you have got it into tune, you will probably want to make
>  alterations to the coil, in attempt to get longer sparks, and this can
>  be done by making the topload (toroid) bigger, which will lower the
>  resonant frequency of the secondary circuit. To make the primary circuit
>  follow, you then need to add turns to the primary coil, you tap
>  outwards. This will make longer sparks with the same power input.
>  Or you might want to increase the tank capacitor to a point where this
>  means that you actually have to decrease the amounts of turns on the
>  primary coil, even with a bigger topload.
>  
>  As you will see, the tapping point, in conjunction with a primary coil
>  that has a generous amount of turns, is the key to obtaining initial
>  tuning, as well as allowing further experiments to be performed.
>  
>  Hope this helps, 
>  
>  Cheers, Finn Hammer
>  

Finn,

Those with only a starting grasp of coiling thank you for an exceptionally 
clear explanation of tuning a new coil!

Michael Tandy