I wonder if the carbon comp resistor value change is due to absorbed moisture.
I would expect moisture to send the value down, not up, which is what one
The other year, I took a 4k7, 1/4 watt, 5% resistor out of its NATO plastic
bags (one inside the other, both heat sealed) where it had been since 1964. It
was 18% high in value. A 50k 'body-tip-spot' 1/2 watt out of a 1939 HRO was
still within the 10% it claimed. Other wartime carbon comps of the 5 watt
variety are similarly in spec. In the days of carbon comps in ceramic tubes,
over here, we used to have them with an extra pink band to indicate 'high
stability' - I don't know if that was the case in the US. I have some of those
out of old gear of the 1950's and they are all in spec.I wonder what the
manufacturing difference was for 'high stability'. One point we can agree on is
that the carbon comp resistors do change value radically.
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