[Milsurplus] Fwd: Advice on which caps to keep ( even longer )

[Jim Whartenby]

Al is on to something, checked World Radio History for some period catalogs.
>From the Allied catalog, 1939 Page 62
BAKELITEMICACONDENSERSCompact "postage stamp type" condensers. Ideal for both high - frequency and audio by-pass circuits. Sealed in Bakelite cases against all climate and temperature conditions. Selected ruby mica dielectric. 
.00004 mfd.00005 .000075 .0001 .00015 .0002 .00025 .00035 .0005 .0015 .0025 .003 
Page 64DOMINO MOLDED CONDENSERS Paper condensers molded in Bakelite. They are resistant to heat and moisture. Flat, compact and small; long wire leads; plainly color coded for quick identification. .001     1000 .002     1000 .003     1000 .004     1000 .005     1000 .006     1000 .008     1000 .01       1000 .02       1000 .005     600 .01       600 .02       600 .05       600 .1         600 .02     400.05     400 .1       400 .25     400.1       200.25     200 .5       200 
Different manufacturers so there is some overlap between Mica and Paper Bakelite molded capacitors over three or so values.  Perhaps the voltage rating might give one a clue?Regards,Jim

Logic: Method used to arrive at the wrong conclusion, with confidence.  Murphy 

    On Tuesday, August 29, 2023 at 10:41:35 PM CDT, Al Klase <ark at ar88.net> wrote:  
 
  Not necessarily so!  The troublesome (paper) Micamolds have higher values, e.g.  0.1 uF.  The smaller ones, say 1000 pF and down, are likely mica.  there might actually be an indication on units with 6-dot color codes, but I don't remember the details.
 
 Al
 
 On 8/29/2023 9:53 PM, hwhall at aol.com wrote:
  
 
 " Toss any which say "Micamold". They aren't mica: they are paper..." 
  This is not 100% true. Micamold made real mica capacitors, too.  
  Wayne WB4OGM  
      On Tuesday, August 29, 2023 at 07:39:51 PM MDT, Kenneth G. Gordon <kgordon2006 at frontier.com> wrote:  
  
   On 29 Aug 2023 at 19:51, Hubert Miller wrote:
 
 > Also i have a box of maybe 1000 more or less of "postage stamp" type
 > caps. First level sorting, which makes and marks are bad news and can
 > be tossed without second thoughts ? thanks- -Hue Miller
 
 Toss any which say "Micamold". They aren't mica: they are paper and every one I have 
 tested was leaky, some very badly leaky, and some even dead-shorted.
 
 If you really want to test your caps, I can send you my other rebuilt Heathkit C-3. I have two.
 
 I recently rebuilt a couple of National NC-57s, which were full of those Micamolds. There 
 wasn't one single one of them which was worth keeping.
 
 Ken W7EKB 
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 Al Klase - N3FRQ
 Jersey City, NJ
 http://www.skywaves.ar88.net/
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