Question about capacitors for coil

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Original poster: John <guipenguin@xxxxxxxxx>

Hello.

For my 9kv @ 30ma AC transformer, I will need a capacitance of about 
0.0088 MFD. I have been looking at some 40kv 2000pf Strontium 
Titanate ceramic caps on ebay. These have a "DC" voltage rating of 
40KV.  I have been told that I can de-rate this rating to around 
40-50% min for use with a High voltage AC circuit.

Would these be an OK choice in parallel to give as close as possible 
to 0.0088uF? I am fairly new to coiling and would like an opinion 
before I buy these caps.

Thanks.