[R-390] killer and mica caps

[kc9ieq]

Conversely, if a film/foil cap shorts, it stays that way and will DEFINITELY take out the filter.  I've contemplated placing a very small value ceramic or mica cap in series as an added safety measure. 
Thoughts?
Regards, Chris kc9ieq


Sent from my SMRTphone
-------- Original message --------From: Larry H <dinlarh at att.net> Date: 10/10/16  6:47 PM  (GMT-06:00) To: 'Chuck Collins' <chuckcollins at prodigy.net>, R-390 at mailman.qth.net Subject: Re: [R-390] killer and mica caps 
Chuck, There is a good type and poor type of C553 replacement - common manufacturing methods are 'film and foil' and 'metalized foil' (these are sometimes referred to as 'foil' caps and usually have a 'self healing' property).  The problem is that when a 'self healing' event occurs, an arc has occurred internally.  This arc (very high current pulse) may destroy the filters we are trying to protect.

Use a 'film and foil' type of cap and be safer.  An example of some are SBE 715P orange drops, but any high quality 'film and foil' type will work.  It should be 500v or higher.

Regards, Larry
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