RE: twin coil system

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>" <wysock-at-ttr-dot-com>

To all on the List,

First, let me state that the pressures of setting up the Model 12
(dual) coil system at Chyanne Mountain High School in July,
1992, for the 5th bi-annual ITS Symposium, was a daunting
task.  I hardly had time to make the system work properly,
before showtime.  This was with a crew of 6 individuals, doing
all they could to help.  What I observed was this. Yes, the
individual secondary inductances were fixed and non-adjustable.
The two primary windings behaved like a "sea-saw" in that
one side would resonate strongly, while the other side would only
issue maybe 12" long streamers.  Given that I had a fixed primary
tank capacitance, and the associated transmission lines, all I could
do was vary the tap points on the two primary windings, and
adjust the free-air spacing of the two transmission lines, to try
to bring the two coils into equal power resonance.  As I noted in
my paper, this meant about 1/2 turn difference between the two
primary inductances.  As set in that auditorium, it workd out
very well.  The same tap points (when the system was again
checked in my back yard in early 1993 before shipping to Japan),
did not work at all!  Very critical tuning, and I must observe, that
the larger a coil system (regardless if it is a single, dual or
magnifer type system), all the more CRITICAL is the exact
tuning of the tank circuit (not like smaller coils where you
have a range of one or more turns of inductance in the primary
without any serious degredation in output performance).

I hope this answers your questions.

Best regards,
Bill Wysock.


> Date:          Mon, 08 Jan 2001 17:00:00 -0700
> From:          "Tesla list" <tesla-at-pupman-dot-com>
> To:            tesla-at-pupman-dot-com
> Subject:       RE: twin coil system

> Original poster: "Basura, Brian by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <brian.basura-at-unistudios-dot-com>
> 
> Terry/all,
> 
> I've experienced the same tuning issues on the Mini-Twin as Bill did on his
> Model 12 (needed to tap one of the primaries different than the other one).
> My gut tells me it has to do with the amount of primary coupling with each
> secondary (i.e. Tapping more primary turns on one side and removing turns
> from the other will keep the same total inductance BUT each secondary will
> have a different amount of coupling).
> 
> Looking further into twin coil coupling interactions is one of the may
> projects on my to do list :)
> 
> Regards,
> Brian B.  
> 
>  -----Original Message-----
> From: 	Tesla list [mailto:tesla-at-pupman-dot-com] 
> Sent:	Sunday, January 07, 2001 2:22 PM
> To:	tesla-at-pupman-dot-com
> Subject:	RE: twin coil system
> 
> Original poster: "Oxandale, Terry by way of Terry Fritz
> <twftesla-at-uswest-dot-net>" <Toxandale-at-SPP-dot-org>
> 
> To Bill and all,
> 
> In regards to the wonderful text about your twin model 12, I am puzzled
> about why one coil performed so differently than the other half with a
> given primary frequency. I read where the immediate surrounding of one
> of the the coils (switchgear, conduit, etc) made a difference, but I
> guess I am wondering how this required primary tap changes even though
> the secondary resonant frequency is fixed. I was under the impression
> that the tap points on the two individual coils was not too important as
> long as the sum of the two primary inductances was set to the correctly
> tuned inductance (i.e the off axis inductance issue). Could you please
> expand on this.
> 
> Terry
> 
>  
> 
> 
> 
> 
> 
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