[R-390] Paper Capacitor Replacement II

[Curt]

RF bypass caps can typically be much smaller capacitance value so the 
round disk with thick mica or other HV dielectric is sufficient and 
easier to make at HV ratings.  They also have much less 
inductance--important for RF Bypass application.

An audio bypass cap would be physically HUGE if it we made like a disk 
configuration.  Likewise for coupling application.

Curt
KU8L


On 1/6/2012 2:28 PM, Barry wrote:
> 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
>
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