IET continues to produce the GenRad 1482 Standard Inductor Series to the same exacting specs as General Radio These inductors are accurate, highly stable standards of self inductance for use as a low frequency reference of working standard in the laboratory. Records extending over 25 years, including those of inductors that traveled to national laboratories in several countries for calibration, show long-term stability well within ±0.01%.
Each inductor is a uniformly wound toroid on a ceramic core. It has a negligible external magnetic field and hence essentially no pickup from external fields. The inductor is resiliently supported in a mixture of ground cork and silica gel, after which the whole assembly is cast with potting compound into a cubical aluminum case.
Sizes of 500 µH and above have three terminals, two for the inductor leads and the third connected to the case, to provide either a two- or three terminal standard. The 50-, 100-, and 200 µH sizes have three additional terminals for the switching used to minimize connection errors.
For comparing other inductors with these standards, the 1632-A Inductance Bridge is recommended.
The GenRad 1482 Standard Inductor Series are the standard of choice in metrology labs, and still used today by standards bodies around the world.
