[R-390] Orange Drop vs ceramic disc

[2002tii]

Ben wrote:

>I'm working on a radio and now need to buy some capacitors.  My 
>understanding is that the old round flat ceramic disc don't 
>age.  Any opinions either way on Orange drops vs  ceramic disc.

For RF bypass applications (which covers almost all of the paper caps 
in boatanchors), ceramic caps are clearly superior to any film cap, 
including  Orange Drops.  They are also generally much easier to 
install.  Use the shortest leads possible, which may involve using a 
different ground point than the original cap used.  Use spaghetti 
tubing on the leads as necessary to avoid accidental shorts.

That said, Orange Drops are better than the paper caps were on the 
day they were installed, so you wouldn't do any harm using them.  Do 
NOT use ceramic caps for signal coupling, particularly at audio 
frequencies.  Wherever you do use film caps in tube equipment, make 
sure they are film-and-foil types (such as Sprague Orange Drop series 
P225), not metallized film.

Saying that ceramic capacitors "don't age" is an overstatement.  Old 
stock ceramic disk caps do last very well, unless they have been 
stored for long periods under humid conditions.  If they have ever 
been underwater (as indicated by water damage to boxes, etc.), avoid them.

You can find more discussion on this topic than you ever thought 
possible in the list archives.

Best regards,

Don


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