On Wed, 8 Dec 2004 20:30:07 -0500, " Uncle Peter"
wrote:

Well, I test every component before I install it, and so far most of
the NOS carbon resistors have been well within tolerance.
Carbon resistors made much before 1950 do have some issues
with aging, and I find 50 to 75% well out of spec and they do get
changed. I'd bet most of the resistors
you were changing in 1959 are probably the same vintage that are
found bad today. I won't argue metal films aren't better, but I
haven't had problems with good quality carbons either.

Over the years, I have found that carbon comp resistors with a matte
finish are much more likely to increase in ohmic value that those with
a glossy finish. I surmise that the former are much more hygroscopic
than the latter.


Brian McAllister

Sarasota, Florida

email bkm at oldtech dot net