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Re: Tuning Observations "parasitic tuning"


From: 	William Noble[SMTP:William_B_Noble-at-msn-dot-com]
Sent: 	Wednesday, July 23, 1997 4:45 PM
To: 	Tesla List
Subject: 	RE: Tuning Observations "parasitic tuning"

wouldn't this effect then suggest that for big coils you want to dynamically 
tune the coil while it is running - once the streamer reaches a certain length 
the coil should be retuned (with the streamer formed) to keep it growing???? 
I'll bet that a longer streamer would result.  this is of course an 
interesting electromechanical design problem (and not one I need to tackle for 
my baby coil that I don't have time to play with)

-----Original Message-----
From:	Tesla List 
Sent:	Wednesday, July 23, 1997 8:12 PM
To:	'Tesla List'
Subject:	Re: Tuning Observations


From: 	Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent: 	Wednesday, July 23, 1997 2:54 PM
To: 	tesla-at-pupman-dot-com
Subject: 	Re: Tuning Observations

Hello Julian,

> From:   Julian Green[SMTP:julian-at-kbss.bt.co.uk]
> Sent:   Tuesday, July 22, 1997 11:51 AM
> To:     tesla-at-pupman-dot-com
> Subject:    Tuning Observations
> 
> Has anyone noticed that the tune a coil is affected by spark length?

Yes
 
> I noticed this effect when tuning my coil at very low power where 
adjustments
> on the primary tap are extreemly sensetive.   (By low power I mean output 
> spark of 2".)
> 
> Has the power of the coil is increased and output spark length increases to 
a
> point where the coil goes out of tune and spark length does not increase as 
> power increases.   Adding an extra turn of primary corrects the problem.
> 
> I also notice that this effect is greater with a small toroid.
> 
> The conclusion I have drawn from my observation is that as a streamer emits
> from the toroid it is in effect adding to the conductive surface area of the
> toroid and hence increases capacitance of the toroid.   Perhaps the ion 
cloud
> also effects the capacitance of the toroid and hence tuning.

Your musings are absolutely correct. You might call it parametric 
tuning :)

> Therefore use a larger toroid so these effects are minimized.

Reduced as you say.

Malcolm