[R-390] r-390A capacitor question?

[Chris Kepus]

Not trying to bust any chops here, either.  However, certain subjects, i.e.
tube shields, capacitor types, line filters, ballast tubes, etc., are like
periennal weeds or flowers, they come up every year.  The discussions cover
pretty much the same ground and due to the fortunate abundance of subject
matter experts on this list, some explanations of (fill in one of the above
topics) are text book quality.  

Soooo, if anyone new to the list REALLY wants to know anything about one of
the above subjects, they can search the QTH R-390 archives or likely find
the topic in a amazing summary of group discussions on these subjects:
http://www.r-390a.net/Pearls/ group 

Of course, there's always the possibility that another discussion of
capacitors might result in new data.

Respectfully,
Running and Ducking, with Keilbasa for breakfast,
10 year lurker and r-390A user,
Chris
W7JPG

-----Original Message-----
From: R-390 [mailto:r-390-bounces at mailman.qth.net] On Behalf Of
kirklandb at sympatico.ca
Sent: Friday, May 30, 2014 6:27 AM
To: Dave Sampson; r-390 at mailman.qth.net
Subject: Re: [R-390] r-390A capacitor question?

yes some of the sp-600's use ceramic disks.

Not all capacitors are created equal. There are many types of ceramic disk
capacitors.
I suggest going to a capacitor manufacturer's website and reading some of
their application notes.
A couple of the reasons for different ceramics:
 - temperature drift
 - getting a small physical size

Ceramic capacitors can be like little Piezoelectric devices, i.e. they turn
ac into sound waves.
 Can be much more of problem in modern electronics where we fit large
value's in extremely small packages
  


> Date: Fri, 30 May 2014 06:11:37 -0700
> To: r-390 at mailman.qth.net
> Subject: [R-390] r-390A capacitor question?
> From: r-390 at mailman.qth.net
> 
> hello
> 
> im not busting any chops here, i simply don't have the experience that
many of you have...
> lets say that you are replacing all the capacitors in an r-390a for
example: and you were quite satisfied with the stock communications grade
audio.
> 
> would it really make a discernible difference in performance depending on
what type of capacitor you used...metalized film, foil/film, polystyrene,
disc ceramic?
> 
> ive heard that some sp-600's used disc ceramics throughout (except for the
electrolytic of coarse).
> 
> would love to hear some opinions
> thanks
> dave
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