Caps for CEM & SSM Filters?

[Romeo Fahl]

Got a quick question:  Seems like somewhere I've heard that for CEM based
(and SSM?) filters you're supposed to use polystyrene caps.  I can't find
any with values as low as the designs I've been building call for.  Here's
what I have found in Mouser's catalog:

"Thomson Ceramic Capacitors

NPO: Class 1

Temperature compensating capacitors, suitable for resonant circuits where
stable capacitance and low D.F. are desired.  They are made of non
ferro-electric materials yielding superior stability."

So, can one of you experts tell me if this would be a suitable substitute?
If not, can you tell me what would work?

Romeo

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(http://psyche.cs.monash.edu.au/psyche-index-v2.html)