[R-390] Paper Capacitor Replacement II

[Barry]

Can someone explain why ceramics are better in RF applications (such as bypass) than film-and-foil (or point me to a source that explains it)?

Thanks,
Barry - N4BUQ


 On Fri 06/01/12 12:54 PM , 2002tii bmw2002tii at nerdshack.com sent:
> Norman wrote:
> 
> >Is this what we're talking about?
> >
> >http://www.vishay.com/capacitors/list/product-42016/
> >http://www.vishay.com/docs/42016/42016.pdf
> Yes, exactly.  The 225P series are the classic Orange Drop polyester 
> (Mylar) film-and-foil caps.  They are what most everybody means when 
> they say "Orange Drop."  The 215P series are similar, but with a 
> better polypropylene dielectric (they are also bigger due to the 
> smaller dielectric constant of PP compared to PE, and more expensive):
> 
> http://www.vishay.com/docs/42018/42018.pdf
> Note:  715P are not to be confused with the 715P HV caps rated for 
> AC, which are hybrid metallized/foil designs.
> 
> (But if you want bypass caps, I once again strongly recommend using 
> ceramics instead.)
> 
> Best regards,
> 
> Don