Rotary Gaps

 * Original msg to: Jbiehler-at-teleport-dot-com
 * Carbons sent to: usa-tesla-at-usa-dot-net

Quoting Jerry Biehler <jbiehler-at-TELEPORT.COM>:

> Another option is you could use a fixed speed AC induction 
> motor. Since they come in standard speeds (1725, 3450, ect)that
> are regulated by the input frequency. You would have a gap that
> would have almost no fluctuations. If you used a belt to drive
> the spark gap it would also insulate the motor from the tank 
> circut a little better.

I have both a fixed speed rotary with insulated rotor, and a
variable speed with a hot rotor.

The problem with the fixed speed gap is that the break rate is
not always at the optimum BPS for the best coil performance. In
fact the break rate is rarely, almost never, the best rate for
the best performance.

The other thing that comes to mind concerning this debate is cost
and availability of these motors. I shop in the Grainger catalog
and in surplus catalogs and stores. The surplus 1 HP variable
speed 10,000 RPM motors are much more common than 1/2 HP variable
speed 10,000 RPM motors, and the surplus 1 HP motors run about
30% less than the 1/2 HP motors new. The fact that the 1 HP
surplus motors are generally more cost effective and available
(not to mention heavier duty) must weigh in the decision to buy.

Richard Quick

... If all else fails... Throw another megavolt across it!
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