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Re: Coupling constant for 4.25" secondary
In a message dated 3/16/99 4:52:58 AM Central Standard Time, tesla-at-pupman-dot-com
writes:
Bob
>
I have made many primary coils from aluminum ribbon from several hundred
watts to 10 kW. There has never been any break out from the pri. to sec. once
the coil is in tune. The voltage gradient is evenly distributed over the
tight spiral pri. giving the effect of a smooth surface.
A cheap source of aluminum ribbon is roof flashing sold at builder supply
centers. The rolls come in widths starting at 4" and lengths up to 50'. I
roll these on a 2" P.V.C. pipe tightly and run it through a fine tooth blade
on a table saw. The rough ends are sanded with a belt sander while still
rolled up until smooth. You can make any width ribbon this way. Wear
goggles. glove & mask while sawing! You don't want to breath alum. dust, and
the metal will get quite warm while sawing.
On smaller coils I space the ribbon with 1/4" poly. rope. The rope & alum.
are hot glued to a plywood base.
Beware of plumbers strapping, most are made from steel, and some are copper
plated steel. You want a non magnetic metal for the coil, however I have used
galvanized steel flashing one time, and did work OK.
Kevin E.
Are there problems from edge wound copper strap regarding spark break
> out from the sharp edges? Is there an optimum spacing between turns to
> get maximum resonance without sparking? Would insulation assist or hurt?
> Are there local suppliers of copper strapping (my hardware stores only
> have the strapping to support pipes-copper plumbers tape).
>
> Thanks, Bob Volk