|[AMRadio] Mica vs Paper|
Michael D. Harmon
mharmon at att.net
Thu Dec 14 22:29:40 EST 2017
According to the Construction Practices chapter in the 1955 ARRL
Handbook, if you hold a 6-dot cap so the arrows point to the right, the
upper leftmost of the 6 dots indicates whether the cap is a mica or
If the dot is black, it's mica, if it's silver, it's molded paper. This
designation is in accordance with the AWS (American War Standards) or
JAN (Joint Army-Navy) specs. If the cap has only 3 dots, it is ALWAYS
an RETMA 500 volt 20% mica cap.
If there are 6 dots, and the upper-left dot is NOT black or silver, the
cap is an RETMA mica cap.
I am attaching a PDF file of the page which describes these caps. If
they don't come through, email me at mharmon at att dot net and I'll
send it to you.
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