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Re: Microwave caps.
Original poster: Bert Hickman <bert.hickman@xxxxxxxxxx>
It really depends on the capacitor. It turns out that some newer
microwave caps use a polypropylene (PP) dielectric system (GOOD!).
However, many older ones use Polyester (Mylar - BAD!). While Mylar
caps will rapidly overheat when used in a tank circuit and possibly
explode, polypropylene caps should work just fine. Unfortunately,
there's no way to tell which is which without testing, dissection, or
getting the information from the manufacturer.
Tesla list wrote:
Original poster: "Christoph Bohr" <cb@xxxxxxxxxxxxxxx>
> is is possible to use a whole lot of microwave capacitors in series
> to bring up the voltage rating and bring down the capacitance to a
> useful value?
depends on what you call usefull. You get a HV cap for sure,
but it will most likely not be useable as tank cap in a TC.
The dielectric can't deal with the high frequencies and the caps
might blow up from heating.
Additionally the connections inside the cap might be to weak for
the large currents involved.
However, a fellow coiler ,Alex Boeckeler, proved me wrong,
he used such a construction and got away with it.
But I doubt this is the general case....
> if so this would be a really cheap alternative for
> capacitors. where i live i can get just about as many old microwaves
> as i want (i suppose i would need lots if each capacitor is about 1-2
> uF, supposing all 1 uF you wold need at least 32)
Ideally they would all be of the same value the spread the voltage stress
> has anyone done this before, wouuld just like to know before i go
> out and find 32 old microwaves!
sound like free workout.... I guess even a 32-MOT-Stack would
sound like a better idea ;-)