Re: Tesla Coil RF Transmitter (long)

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Original poster: boris petkovic <petkovic7@xxxxxxxxx>

Hi Bart,

Nice to hearing from you.
-----

> Interesting. A 9 kHz coil could be built at a little
> over 3"ft
> diameter with a 4.75:1 h/d and an appropriately
> sized toroid. The
> coil size, in my mind, is why coilers don't build
> coils down at this
> frequency (for most of us).
-----
OTOH,I wonder why would coilers even bother to build a
garage coil at this frequency in the first place?
If some sparking action is the primary goal, I don't
see points  in doing that.

-----
I would be interested in
> how you could
> build a similar coil of lesser size.
-----
Here is more general question :IOW,how one should go
about making a very low frequency TC which is
acceptable by size while having good operating
parameters and decent performance in the same time?

It depends ,to the great extent,on how much of
processing power for a given coil size one finds to be
decent (the requirement in concern with wire gauges
used-> joule heating stress ; with wire looses
overall).
The tastes are different.
Somebody will be satisfied with 300 W input and 30 cm
discharge lenght from 1 meter tall winding,and
somebody else won't be satisfied even with 250 cm
discharges at 5000 W input from the same winding.

Furtherly,consider other related things .
If a very thin superconductor wire can be employed,the
answer to the question can be given
straightforwardly.Otherwise,winding too many turns of
ordinary wire per unit lenght of a classical  solenoid
may also spoil associated Q factors.
And,as known,that  adds nothing good to overall TC
characteristics.
Coiler might try to escape from such problems by
designing effectively *squashed* cross-section areas
of the turns,but careful insight would show that this
won't improve the situation considerably.Besides,the
process of making/winding that resonator could turn to
be troublesome for amateurs.

To overcome many of mentioned obstacles,I would
suggest trying some multilayer winding techniques and
to make a pseudohelical type of an air-core coil which
can provide an experimenter with significant secondary
inductances.For constructing a reasonable scale TC
that can fit into the typical garage,and can process
appropriate power levels, I think this is the way to
go.
Neverthless,an exaggeration in special methods of
winding to gain a very large air-core inductance
structure over smaller volume has its side-effects
too.Generally speaking, the effect of increased
internal capacity is undesirable.Unfortunatelly,the
helical structures described are plagued with it..
One way or another, aspect ratios (H/D) lesser than 3
or maybe more are to be avoided at any cost if  a
relatively efficient sparking action is expected under
these circumstences.

Best Regards,
Boris