[Test-Equipment] Re: Need Recommendation for LCR Meter

[WA5CAB at cs.com]

Actually, that isn't quite exactly what the article says. And he doesn't give 
any backup or justification for his statement. It's important to remember 
that just because you find something in print on the web, that doesn't make it 
true. My favorite radio related example is the US Army Signal Corps site where 
it is claimed that the BC-324 is a 12 volt version of the BC-348 (as everyone 
who knows anything about the subject knows, the BC-348 is a 28 volt version of 
the earlier 14 volt BC-224).

The paper production process uses acid to wash impurities out of the paper. 
It's been decades since I read up on the process, and I didn't bother to go do 
so tonight, so I can't recite the details. But so-called acid free paper isn't 
paper that was never exposed to acid, but paper that has been through 
additional fresh water wash baths. Unless the number of wash baths approaches 
infinity, it isn't really acid free. I haven't cut open a Black Beauty so can't say 
what they used for a dielectric. But it seems unlikely (principle of Occam's 
Razor) that if they used paper that the paper used would have been anything 
different from that used in the previous generation of Sprague capacitors. Or if 
it was different, that they would have deliberately used a cheaper paper at the 
same time as they introduced the plastic case.

The inovation, or at least the visible one, of the tubular axial lead Black 
Beauties was that they used a plastic case rather than waxed paper or soldered 
tinned brass as had their predecessors. Absent evidence to the contrary (and 
no one has produced any), it seems unreasonable to assume that they went to an 
improved (they thought) case but deliberately used a cheaper guts.

I have seen lots of split Black Beauties. All of the DY-17A's that I've been 
selling for the past 16 years have one Black Beauty or equivalent that appears 
to have been added during late production. And roughly half have split. But I 
have never had any oil in the end bell to clean up when I remove it for 
inspection. Sample base approximately 400. I don't know how many DY-17A's were 
produced but I'm sure I must have owned a significant fraction of them.

In a message dated 12/12/2006 4:43:03 PM Central Standard Time, k4pf at juno.com 
writes: 
> Here's an article from "Test and Measurement World" about Black Beauty
> capacitor failure modes. He claims the problem was that they didn't use 
> acid-free paper
> as a dielectric.
 

Robert & Susan Downs - Houston
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