I was cleaning my garage and ran across this unusual resistor. I've never seen another one quite like it.
1% Precision low inductance wire wound that was commonly used as grid stoppers and cathode resistors in 1930's era electronics.
similar to chicago and visha/mills MRA series, but not as nice sounding.
What makes these resistors unusual is the tolerance, or lack of it.
Akra-Ohm resistors were manufactured for instrument use and were generally made within a tolerance range of .1% to .025%. On these examples there is no tolerance at all and the 206,700Ω resistance is designated as absolute.
John
Akra-Ohm resistors were manufactured for instrument use and were generally made within a tolerance range of .1% to .025%. On these examples there is no tolerance at all and the 206,700Ω resistance is designated as absolute.
John
Well, that's interesting... Apparently there was some elasticity in the definition of an ohm as late as 1948. From this page on the history of the ohm: "As instrumentation improved the need for units defined “reproducibly” declined. The CIPM finally did away with the international ohm and all the other practical units in 1946 (Resolution 2), replacing it with the new absolute definition first given above. This decision was adopted by the Ninth CGPM in 1948."
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