General Radio 1482A Highlights
The GenRad 1482 Standard Inductors are the standard of choice in metrology labs. Used today by national metrology institutes and primary standards bodies around the world, these inductors have no peer or equivlent.
IET continues to produce the 1482 standard inductors to the same exacting specs as General Radio. These standard 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 40 years, including those of standard inductors that traveled to national laboratories in several countries for calibration, show long-term stability well within ±0.01%/year, typically <10 ppm/year.
Each standard 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 a po_ting compound into a cubical aluminum case.
Values of 500 _H and above have three terminals, 2 for inductor leads and the third connected to the case, to provide either a 2 or 3 terminal standard. Inductors with <500 _H inductance values have three additional terminals to allow for switching between a short circuit and the inductance value which minimizes connection errors. This allows the user to perform short compensation without disconnecting leads from the inductor. A ground strap is moved to the Lo terminal when short compensation is performed and back to L for measurement of the inductance. When the same connections are used in both measurements, the inductance value is independent of the external lead inductance even for values much less than 200 _H.
- Stability: Inductance change is less than 0.01% per year.