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Hi Q Quest (was sync TC latest results)
From: FutureT-at-aol-dot-com[SMTP:FutureT-at-aol-dot-com]
Sent: Friday, November 07, 1997 11:19 AM
To: tesla-at-pupman-dot-com
Subject: Hi Q Quest (was sync TC latest results)
Malcolm, all,
I replaced the 4 1/4" x 23", #28 formvar secondary with a 17" x
17" #24 pvc insulated wire secondary also on a polyethylene form.
The new secondary has 470 turns, L = 67mH, F = 110kHz with
toroid. The old one had 1500 turns, L = 105mH, F = 80kHz with
toroid. Based on wire resistance and reactance the new coil
should have a much higher Q, but I didn't measure it. Perhaps
the pvc insulation hurts the Q? Coupling is k = .1 for either
secondary.
Old secondary gave a 46" spark at 700 watts, new one needs 800
watts for same spark length, using large toroid. But using the
small toroid, either secondary gives about a 42" spark. Using the
old small secondary, sparks break out from more than one spot on
the small toroid, but using the new large secondary, sparks break
out from only one spot. It seems as if the large toroid is too large
when using the large secondary. It would seem that a certain
amount of input power can power up only a certain amount of
combined isotropic capacity within the secondary/toroid combo,
i.e. a small secondary can tolerate a large toroid, but a physically
large secondary cannot, at these power levels. But I am basing
these conclusions on the assumption that my new secondary
actually has a higher Q, and this is unknown since I haven't
measured it yet :^c I had to mount the toroid 8" above the
new secondary to obtain the stated results, a lower-set toroid
really weakens the spark. I did not scope the quench using this
new secondary.
Has anyone compared Formvar vs. pvc insulation's effect on Q?
Regards,
John Freau