Re: secondary core other than air

["Steve" <Steve-at-g8cyerichmond.freeserve.co.uk> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

This is a point I have often wondered about. Ferrites are used at very much
higher frequencies than Tesla coils generally operate at. In fact I have a
ferrite antenna from a paging receiver that was used at 156MHz!!! Think of
the ferrite antennas (loopsticks) used in bc receivers, they are ok at up to
about 3MHz. In fact I have used the last mentioned rods as the core of
transformers handling up to 50W without any trouble.
----- Original Message -----
From: Tesla list <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Monday, August 07, 2000 6:38 PM
Subject: Re: secondary core other than air


> Original poster: "Garry F." <garryfre-at-pacbell-dot-net>
>
> I often thought the reason telsa coils were air core was because Ferrite
> might not be capable of rapid magnetic change that would be required for a
> high frequency app such as tesla coils. I think the atoms would not be
able
> to spring back into their original orientation once the magentic field
> collapes fast enough.
>
> I could be wrong tho, but I tend to think this is why they reccommend only
> non-magnetic wire as conductors in Tesla coils
>
> ----- Original Message -----
> From: "Tesla list" <tesla-at-pupman-dot-com>
> To: <tesla-at-pupman-dot-com>
> Sent: Sunday, August 06, 2000 2:04 PM
> Subject: Re: secondary core other than air
>
>
> > Original poster: Terry Fritz <twftesla-at-uswest-dot-net>
> >
> > Hi Garth,
> >
> >         #21 enameled magnet wire is about 33.1 turns per inch.  So you
> probably
> > have #21 which is fine.
> >
> >         Don't worry about only 5 turns on the primary.  Just tune your
> coil
> > with
> > what you have and all should work fine.
> >
> >         I don't know of any way of lowering the secondary frequency
short
> of a
> > bigger or more top load.  Ferrites in or around the secondary are not
> > impossible, but that would take a lot of thought and design.  Perhaps a
> fun
> > project but too messy in this case.  Just tune with what you have and
all
> will
> > be well.
> >
> > Cheers,
> >
> >         Terry
> >
> >
> > At 03:09 PM 8/6/00 +0200, you wrote:
> > >
> > > Would it be possible to use something other than an air core to
increase
> the
> > > secondary inductance and Q factor?
> > >
> > > Are their any possible cores available?  I know something like ferrite
> core
> > > would create internal arcs, but surely there must be something out
> there!
> > >
> > > I have just wound my 6.4" secondary with what I was told to be #24
wire,
> but
> > > wintesla seems to use incorrect figures for wire guage and turns per
> inch.
> > > My secondary has 33 turns/inch.
> > >
> > > My secondary inductance is way too low and I now have re-calculated my
> > > primary with only 5 turns which I think will be terrible for spark gap
> > > losses.  My topload is 20" wide so I can't drop secondary resonance
any
> more
> > > unless I use some secondary core other than air or wind more turns on
> the
> > > secondary.
> >
> >
> >
> >
>
>
>
>