Maintenance and dissemination of the magnetic field unit at PTB

Based on the value of 1 mT as provided as SI unit for a /spl gamma//sub p/ experiment about 20 years ago, the flux density scale as currently maintained at PTB over a range from 20 /spl mu/T to 2 T by different NMR setups, and the measuring methods used to disseminate the unit in the case of DC- and AC-fields are presented.