RE: Primary coil configuration

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Lau, Gary" <Gary.Lau@xxxxxx>

Increasing the coupling until racing sparks occur, then backing off, is
the only way I have ever heard of to set the coupling.  Since the exact
mechanism responsible for racing sparks is still unknown, we are unable
to predict the coupling threshold at which they'll occur.  As setting
the coupling much lower than that threshold will degrade performance, we
strive to keep it as high as possible.  Some may consider it "horrible
engineering", but it's the best that can be done.   How do you propose
to determine that threshold without ever crossing it?

I agree that running a coil with racing sparks with reckless abandon
will permanently damage the secondary, but I think most of us have
briefly coupled too high, seen the sparks, backed off, and have had no
further trouble.  Or are you suggesting that a brief racing spark will
permanently lower the critical coupling threshold?  An interesting and
reasonable suggestion, but very difficult to prove.

I don't know that it's ever been conclusively demonstrated that any
secondary sealing technique will render it invulnerable to racing
sparks.

Regards, Gary Lau
MA, USA

> Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>
>
> Someone advocated adjustment until racing sparks occur and then
> backing off. This is horrible engineering.  Once a spark punctures a
> solid insulation it does not "cure" or repair itself.  Once the
> damage is done it is permanent unless the coil is rewound.  You can
> back off the coupling to reduce sparkover, but then you always have a
> weakest link in your coil system. Properly sealing the sec coil and
> then not puncturing it will produce a long lasting coil.
>
> Dr. Resonance