[R-390] The OD discussion

[ken]

2002tii wrote:
>
> Use dipped silver micas for everything under 10,000 pF.  These will 
> all be part of tuned circuits or RF coupling caps, and ceramics are 
> generally not as good in this application.
>
> Disk ceramics are actually better than film caps in bypass 
> applications.  Film-and-foil ODs (or other film-and-foil caps of equal 
> quality) are fine -- they work at least as well as the original paper 
> caps, and will outlast you and your heirs.  If you want the best film 
> caps for bypass applications, those would be the OD 779P series.  But 
> for the BEST performance, use disk ceramics in all bypass applications.
>
> Use film-and-foil ODs (or other film-and-foil caps of equal quality) 
> in all IF and audio coupling applications.  Note that ODs are made 
> with both polyester and polypropylene film.  The PP film-and-foil 
> types (715P/716P series) are the best, but the PE film-and-foil types 
> (225P) are better than the original paper caps ever were.
Thanks Don,

That's a good post...so now I have decided to add Disk Ceramics to the 
mix and use them at all the bypass positions. I have an EAC unit that 
uses Disk Ceramics and some of them are leaky, but I would assume that 
modern manufacturing techniques would mean that Ceramics of today are 
far superior to Ceramics of yesterday.

73
Ken