[ARC5] Carbon Comp Drift

[Robert Eleazer]

I never suspected that resistors could change value without first being overloaded with current, but around 1982 I bought a TS-34 scope at a ham swap meet for $1.00 and found that it worked - but would not focus.  I found that all of the 2W resistors, all high resistance value units, had just about opened up.  I walked down to the local Layfayette store and bought some replacements; installing them instead of the originals fixed the scope.

I inherited a large number of carbon comp resistors from a friend some years back.  I found that many of them now exceed their original tolerances on the high side.  In the GRC-9 I found a 230 ohm that went to something like 550 ohm, a 33K that went to 45K, but also a 27K that is still at about 27.5K 

I am tempted to ask if there is a vanish or coating that would arrest this process, but the GRC-9 was MFPed in 1950 and that did not help it.

Wayne
WB5WSV  
  

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