[Boatanchors] Postage Stamp Micas Again

[Richard Knoppow]

----- Original Message ----- 
From: "J. Forster" <jfor at quikus.com>
To: <ARC5 at mailman.QTH.net>; <boatanchors at mailman.QTH.net>
Sent: Friday, August 09, 2013 8:05 PM
Subject: [Boatanchors] Postage Stamp Micas Again


> Does anybody have a copy, or a link to a table, of 
> 'standard' values for
> the JAN postage stamp micas?
>
> As far as I can tell, some of the values are not in the 
> usual 5%/10%/20%
> sequence. For example, one cap appears to be 500 pF.
>
> Thanks,
>
> -John
>

     Much of what you are looking for can be found in 
_Reference Data for Radio Engineers_fourth edition, 
published by IT&T.  It can be found on line at 
http://www.pmillett.com/tecnical_books_online.htm

     This book shows the marking schemes used by RETMA and 
MIL or JAN components and has data on the method of 
calculating "preferred" values.
     Note that the dot pattern on RETMA and JAN caps are 
different.  On RETMA caps with six dots the upper right hand 
dot is white for mica and on a JAN cap its black for mica 
but silver for paper.
     There is more data in the ARRL Radio Amateur's 
Handbook. The handbook shows the three dot system in 
addition to the six dot one. I looked at a 1962 handbook, in 
which the civilian standard is now the EIA standard.  Some 
older handbooks are available at the site above.
     Note also that most military equipment handbooks have 
information on component color codes in the appendices.
     I know the system of specifying values was changed but 
don't remember where I read it. My memory is that is was 
sometime in the late 1940s.  Components following the older 
system seem to have been made after the system was changed 
especially for precision components.
     BTW, the old "Radio Handbook", a rival of the ARRL 
book, has similar information.  Some of these can also be 
found on Pete Millet's site.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com