Re: More facts: Coil size to faraday cage size ratio

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Dr. Resonance" <resonance@xxxxxxxxxx>


Terry:

Which part number did you use?

What was xmfr size?   Total cap size?

Dr. Resonance

Resonance Research Corporation
E11870 Shadylane Rd.
Baraboo   WI   53913
----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Tuesday, November 23, 2004 7:58 PM
Subject: Re: More facts: Coil size to faraday cage size ratio


> Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>
>
> Hi,
>
> I also second the use of big ferrite cores liberally placed around the
> primary and especially at the spark gap.
>
> Right before the spark gap fires, there is a lot of energy stored as
> capacitance between the gap electrodes.  When the electrodes fire, that
> energy is shorted out without much R and L in the way which causes giant
RFI.
>
> All my spark gap coils have ferrites but I never think about them much
> since they are passive things.  Note my big gap that has ferrites directly
> on the electrodes:
>
> http://hot-streamer.com/TeslaCoils/MyCoils/BigCoil/Rgap.jpg
>
> I can't really quantify how much they help, but they do reduce RFI "a
bunch".
>
> DigiKey sells them from very small to pretty big:
>
> http://dkc3.digikey.com/PDF/T043/0793.pdf
>
> Maybe you just need to cage the spark gap.
>
> Also, streamer just to air will have far less RFI than streamers striking
> to ground.
>
> Hope this helps!
>
> Cheers,
>
>          Terry
>
>
> At 11:53 AM 11/23/2004, you wrote:
> >Since the signals of concern are fairly HF (i.e. >30 MHz), it would be
> >interesting to find out where they are coming from.  Is it high order
> >harmonics from the LC ringdown (unlikely... we're talking VHF frequencies
> >here, and 100 MHz would be 1000th harmonics of the 100kHz fundamental).
> >Probably more likely radiation from primary circuits (as Terry had noted
> >some years back) or from the streamers themselves.
> >
> >So, maybe something to kill the HF content in the primary circuit
(ferrite
> >cores on the wires to/from the sparkgap?  Have to choose an appropriate
> >material, so they don't absorb too much energy at the fundamental and
> >overheat.
> >----- Original Message -----
> >From: "Tesla list" <tesla@xxxxxxxxxx>
> >To: <tesla@xxxxxxxxxx>
> >Sent: Tuesday, November 23, 2004 9:00 AM
> >Subject: Re: More facts: Coil size to faraday cage size ratio
> >
> >
> > > Original poster: "Bob (R.A.) Jones" <a1accounting@xxxxxxxxxxxxx>
> > >
> > > Hi Fin
> > >
> > > Its probably cheaper and less demanding on the each cage to have a
double
> > > one.
> > > Two poor performance cages can be more effective than one good one and
> > > possibly two are essential if the inner is going to be in the
discharge
> > > path
>
>
>