Re: question about "lambda" (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Fri, 24 Aug 2007 15:58:39 -0500
From: Matthew Boddicker <shmerpleton_town@xxxxxxxxxxx>
To: tesla@xxxxxxxxxx
Subject: Re: question about "lambda" (fwd)

This is Matthew again,

the primary coil is helical and 12 inches in diameter.

So if I have a spherical top load, where do I hold the oscillascope probe?

Thanks,
Matthew Boddicker


>From: "Tesla list" <tesla@xxxxxxxxxx>
>To: tesla@xxxxxxxxxx
>Subject: Re: question about "lambda" (fwd)
>Date: Thu, 23 Aug 2007 20:04:26 -0600 (MDT)
>
>
>---------- Forwarded message ----------
>Date: Thu, 23 Aug 2007 18:36:49 -0700
>From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
>To: Tesla list <tesla@xxxxxxxxxx>
>Subject: Re: question about "lambda" (fwd)
>
>Hi Matthew,
>
>Tesla list wrote:
>
> >This is exactly what I needed, thank you! So with the wavelength being 
>taken
> >into consideration, where would be good spot for the primary coil to be? 
>I
> >am currently using a helical primary, but hope to switch to a pancake
> >primary soon.
> >
> >
>First, the primary should be at the opposite end of the hv end.
>Secondly, coupling will identify it's placement with a fixed geometry.
>Whatever your current helical coil is, you'll need to get the coupling
>to a usable level. If the helical is a wide as I think it is, your
>coupling may actually be very low (can you confirm the primary diameter
>again?). Often, when helical's are built, the secondary is adjusted
>above it. This occurs because the coupling was too high and coil to coil
>distance is the only thing that can fix that. But, if the helical is
>made wide enough, then it can be raised higher and higher.
>
> >Also, is there any tips on using a oscillascope to find the frquency of 
>the
> >secondary? I've tried it before, but the oscillascope wouldn't give a 
>clear
> >reading. I though I heard somewhere that a signal generator could be used 
>in
> >conjunction with a oscillascope somehow.
> >
> >
>Yes, use a signal generator connecting the base of the secondary to the
>generator output. You'll then be able to read the signal on the
>oscilloscope. Place the scope probe horizontal with the toroid and about
>1 coil length away with maybe a 4" piece of wire in the probe end to act
>as an antenna. Adjust the signal generator frequency until you see
>voltage amplitude rise. The point at which the amplitude is greatest is
>the fundamental frequency. It's good to calc your fundamental first,
>then adjust the generator below that frequency by some amount before you
>start adjusting the generator. It's good to do this with everything in
>position (primary and topload).
>
>Take care,
>Bart
>
>
>

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