[Milsurplus] Carbon Comp Resistors: The Darkness Gathers?

[Peter Gottlieb]

I’ve gone through my old resistors and had to discard most of them due to all being out of tolerance high. I have gone to properly rated carbon or metal film ones for repairs. 


Peter

> On Jul 2, 2018, at 4:15 PM, David Stinson <arc5 at ix.netcom.com> wrote:
> 
> 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
> 
> 
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