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Re: [TCML] Sprague 4000MMFD caps



I am using a couple of these or something similar in a small coil with no problems but when I ran with a 9000V 60 ma supply they got hot and cracked. I didn't realize that until the thing stopped working.. Parts not available right now so can't give better description than that they were about 2-1/4" dia by about 1-1/4" thick. I had similar failures with some larger one potted in brown epoxy. Can't remember DC voltage ratings.

Bottom line is keep track of the temperatuer and when you're run enough for them to feel warm to the touch shut down until cool.

Ed

David Rieben wrote:

Hi Dave, Looks like you were asking a question about .004 ufd being equal to 4000 mmfd (pFd). 4000 (10 e-12) Farads would indeed equal .004 (10 e-6) Farads :-) The mmfd (micro-microfarad ~10 e-12 or one-trillionth of a Farad) is now a pretty much archaic term and is now usually expressed as a pFd (picofarad). Of course, it could also be expressed as 4 nFd (nanofarads)
David Rieben

david baehr <dfb25@xxxxxxxxxxx> wrote:

' Hockey puck'    caps  30kv,  about  2 5/8"  x 1 1/2"  size .   Using on a 7500/60 neon right now, may move up to 9000/60.

How much abuse can these take ? I'm guessing heat is a concern. Working well on small coil now. Short runs . Maybe someone here has used them and can comment.
 4000MMFD  is  equal to    .004 mfd.  ?     Thanks, Dave

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