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Re: Frequency Split

In reply to some queries....

>     I've seen frequency splitting on my scope while watching my TC
> run, seen it in spice simulations but, I am not sure how to apply it.
> I have also observed the effect of over coupling between my primary
> and secondary; last night  6" arcs ran down my secondary and blew pits
> into its winding:(   I deburred and recoated those sections today.
> During the same run, I watched the secondary E field display itself as
> a cone of corona between the top turn of my secondary and the strike
> ring above my primary.  I had raised my toroid up only 1 inch and the
> top turn of the secondary formed a corona to the strike ring.
> 
> Questions:
> 
>     1.  Why are you calling these K values sweet?
>         Because they couple in an integer number of 
>         cycles?

The maximum amplitude of the two frequencies coincide in the secondary 
when these values of k are used. The tighter the coupling, the fewer
the half cycles of oscillation needed to achieve this. This means
fewer pri gap fires with consequently fewer gap losses. For example,
with k=0.6, just 2 gap conductions are required for this condition to 
be met. This is typically what they use in SF6 surrounded 2-coil
accelerator systems.
 
>     2.  Once I've picked a coupling constant, do I use it
>         for setting my spark gap commutation time?

Yes. The optimum gap conduction time (read switch closed time) is
set by this. If the gap opens too soon, the maxima won't get to
coincide and too late, and the energy starts oscillating back into 
the primary circuit. At the time the maxima coincide in the secondary
circuit, primary energy is ideally nil (zero Vcp and zero Ip). You
can see when the maxima occurs by single-shot scoping the secondary 
with no discharge rod. The relation is:

    gap conduction time = 2/(Fhi-Flo)

Malcolm