[Milsurplus] Carbon Comp Resistors: The Darkness Gathers?

[David Stinson]

I've always heard that the carbon comp resistors
that fail Hi-Z most often are those in the
Mega-Ohm range ("green band").  Oddly, over the
last four major projects:  TCS, ATD, RAX and now
SCR-522, haven't found that to be the case.  The
resistors most often failed-High are in the
15K-500K range, with the #1 "bad guy" being 47K
Ohms, followed by 470K.  I remember changing one
or two Mega-Ohm value resistor in the last three
projects.  Every 47K resistor in the last TCS
receiver and in the ATD had to go.

Which brings me to this:
I've got piles of NOS Carbon Comps that have been
following me around for eons.  The majority of
these have started reading Hi-Z by 5% or more.
Many by much more.  I just threw a half dozen NOS
100K away because they read from 107K- to
122K-Ohms.  Other values are showing similar
drift.

Has twilight come for Carbon Comp resistors?  I've
stopped buying them at hamfests and use only the
newer, ceramic looking thingies for projects now.
What do you think?


GL OM ES 73 DE Dave AB5S