I have a number of western electric / AT&T capacitors that I need help identifying. For instance, one of them is clearly marked .1 2%, this is clear but it has no voltage rating only a part number 570bn, it is a yellow cap perhaps Polypropylene but not certain. I searched all over for western electric part number catalogs without any luck. Another example tantalum cap only marked 52 C and an electrolytic marked 10 NC83 (this is 10 uF but what else?). Anyway, just trying to find resources where I can decode these caps. Thanks for the help.

 

These are all telephoney leftovers. AT&T had many unique part numbers and part codes. Unless you are trying to rebuild any vintage phones or switchboards, I think the best place for these is the dust bin. Buy a handful of new ones.

 

That's what I figured. Thank you!