How to rise the secondary?

From:  Antonio Carlos M. de Queiroz [SMTP:acmq-at-compuland-dot-com.br]
Sent:  Monday, June 29, 1998 1:30 PM
To:  Tesla List
Subject:  Re: How to rise the secondary?

John H. Couture wrote:

>   What are the advantages of raising the secondary? This will change the
> coupling and tuning but that can be done by proper design of the primary. Or
> have you found other reasons for raising the secondary?

The energy transfer from the primary circuit to the secondary circuit is
complete only for particular values of the coupling coefficient (k). Ideally,
the maximum voltage at the secondary terminal shall occur when the primary
current and voltage are at zero level. This is always true for the envelope
of the secondary voltage, but for the peak voltage this occurs only for certain
values of k, that cause the right phase relationship. For low values of k, 
the difference is not significant, but for high values it can be. 
>   I would expect that moving the secondary away from the primary would
> reduce the spark output.

True, because it takes more time for the secondary voltage to rise, and the
losses have more time to drain energy from the system. But if the Qs of the
tanks are sufficiently high, the expected result of varying the coupling is
a periodical variation of the spark output as function of the coupling (or

Antonio Carlos M. de Queiroz