Re: Ratios

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

Original poster: Gregory Hunter <ghunter31014-at-yahoo-dot-com> 


--- Tesla list <tesla-at-pupman-dot-com> wrote:
 > Original poster: "torlin" <torlin-at-ghostmail-dot-net>
 >
 > I was always told (and probably assumed) that a
 > cone-shaped primary couples
 > more efficiently than a flat-wound primary.  Is this
 > true, or was I being
 > led wrong?
 >
 > Thanks for your reply.
 >
 > Chris
 >

Chris,

The inverted cone primary couples more tightly to the
secondary than a flat spiral primary. However, don't
confuse tight coupling with efficiency. Disruptive
coils require fairly loose coupling for satisfactory
operation. Too tight coupling is probably the hidden
cause of many Tesla coil gremlins including racing
sparks, secondary-to-primary arc-overs, poor
quenching, short spark gap electrode life, and weak
streamer production.

If you believe all this, then the flat spiral starts
to look pretty good from a number of standpoints:

*It is the simplest primary style to build.

*It offers more physical separation from the secondary
than other primary styles, reducing the chance of
secondary-to-primary arc-over.

*It is the least likely primary style to overcouple.

Perhaps the best feature of the flat spiral is that
the hobby coiler can simply set the bottom turn of the
secondary on the same plane as the primary and get
"close enough" coupling and good performance on the
first try--no k testing required. I should know--I've
been getting away with it for years!

Regards,

=====
Gregory R. Hunter

http://hot-streamer-dot-com/greg

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