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Re: Cap question

                 
 NTAC> To: tesla-at-grendel.objinc-dot-com (Nikola Tesla aka Chip Atkinson)
 NTAC> From: "SROYS"  <SROYS-at-radiology.ab.umd.edu>
 NTAC> Date:         Thu, 19 Jan 1995 15:03:47 EDT
 NTAC> Subject:      Re: Cap question
 
 > I would try running a Q test on the capacitor. It may not be designed 
 > for High pulse current service.

 NTAC> What would be some quantative ways to test the 'Q' of a capacitor?  Or
 NTAC> would you just hook it up and see how well it works in a coil?

 MG> You could just hook it up, but I would use low power, like less than
     500 watts. A better and maybe safer way is if you have access to a signal
     generator that will provide a least a 1v p-p output, and a VTVM or other
     hi-z meter with a RF probe, or even a scope. You can get an idea about
     the cap by checking for any low frequency series resonant points say less
     than 1 Mhz. Take the generator and hook the capacitor to its output using
     short leads and a 1k ohm resistor in series with the capacitor. Hook your
     meter or scope across the 1k ohm resistor, now slowly sweep the generator
     from approximately 50Khz to about 3 or 4 Mhz. looking for any peaks in 
     the voltage across the 1k ohm resistor.
      All capacitors have a series resonant point due to internal inductance,
      and operating the capacito at or close to this point can set up
      heavy parasitic currents within the cap. And also, any off-coupled
      inductance does'nt contribute to the field being linked to the secondary
      coil causing it to be nothing but a addtional series resistance and it
      limits the peak current through the primary coil. In short, what you're
      hoping for is that the capacitor has a good dielectric, and that its
      of a "end-foil" type construction.

                                   Mark Graalman  TCBA# 1399
                                   mark.graalman-at-mediccom.norden1-dot-com

     


... Alias, Mark the spark
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