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Re: Tuning Experiments



Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz <teslalist-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>

Tesla list wrote:

 > Original poster: "S & J Young by way of Terry Fritz 
<teslalist-at-qwest-dot-net>" <youngs-at-konnections-dot-net>

 > Assuming the streamer was really low impedance (like a wire), then a
 > typical 2 foot streamer drops the frequency by 10 kHz or about 5%.  This is
 > equivalent of adding about 3 pf to the toroid.  A 3 ft streamer drops the
 > freq by about 8% and acts like an additional 5 pf.

Consistent with what I observe with my transformerless coils, where I
use a telescopic antenna for tuning.

 > So, it looks like if a streamer impedance gets in the neighborhood of what
 > Terry uses in his simulations, the Q is greatly reduced and I would expect
 > a corresponding reduction in coil performance.

This circuit can be modeled as an LC parallel circuit (coil and normal
capacitance), in parallel with an RC circuit. Even without any loss
in the LC circuit, there is a certain value of R that produces a minimum
Q (of the two complex natural frequencies of the circuit), showing
the behavior that you observe. This value of R depends on the values
of the other elements (not easy to calculate), but doesn't appear
to be related to maximum power extraction from the coil.

 > This may account for the
 > amazing performance Richard Hull got with his 10 inch magnifier with the
 > huge toroid.  I would think the larger the toroid, the less effect a
 > streamer will have on Q and detuning.  Does our use of smaller toroids
 > (relative to secondary size) promote excessive Q spoiling?

Very possibly.

 > Am I interpreting these results correctly?  Does the same effect happen in
 > your simulations?

Simulations show this behavior.

Antonio Carlos M. de Queiroz