Weighing apparatus of the electromagnetic load compensation type is disclosed, including a permanent magnet system connected with the stationary frame, a compensation coil connected with the movable scale member, a system for supplying compensating current to the coil to produce a force for returning the movable scale member to its initial no-load position, and an indicating device for displaying the magnitude of the load applied to the movable scale member as a function of the compensating current, characterized by the mounting of a slotted generally U-shaped conductive metal plate in spaced insulated relation concentrically about the core portion of the permanent magnet system. After the weighing apparatus has been completely assembled, the leg portions of the plate are transformer connected with an alternating-current source for calibrating and/or conditioning the permanent magnet system.