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Re: ~44kV primary tests
Tesla list wrote:
> Original poster: FutureT-at-aol-dot-com
> Hello coilers,
> In considering another issue:
> In previous tests using the 6.5" by 24" secondary wound with
> #28 wire, I obtained 42" sparks using 570 watts. I had thought
> that the performance of the narrow and wide secondaries were
> about the same.... but it appears that they are not. Either that,
> or I have a shorted turn in the narrow secondary. That secondary
> has 7 burned spots from previous higher power abusive tests.
> I know from past experience that a shorted turn in the secondary
> can reduce the spark length by about 10%. Most of my comparisons
> between the narrow and wide secondaries were made at higher
> powers at which it was more difficult to measure the spark lengths.
> Continuing with the secondary wideness issue:
> In any case, if the performance of the wide secondary is better, this
> would make sense because the higher inductance would reduce
> the gap losses, by forcing more primary turns to be used. It would
> seem that any negative effect of the wider secondary, due to an
> increased secondary Cself, may be small compared with the
> benefits of the larger primary surge impedance.
I think your right about this. The amount of Cself is "nill" in comparison to
the inductive increase on the secondary with the wider size bringing Fo down
and therefore increasing primary turns. It should be noted also that there is
only about a 100 turn difference between the two coils (if my quick calc is
right). This "seemingly" small difference actually has secondary benefits
(regardless of their net effect to the total picture) such as lower Fo, lower
Sd losses, and higher Q.
BTW, what type of adjustment was required on the SRSG?
> That is my thinking
> at present. I cannot easily go back and test the wide secondary,
> because that is the one that I rewound with thicker wire to test
> the relative merits of thick vs. thin wire. (I lost 10% spark length
> using the thicker wire.)
> I should have more results on these issues eventually.
> John Freau