According to an embodiment, a scanning coil includes a bobbin, a conducting wire, and a resin for fixing the conducting wire. The bobbin includes a main body having a truncated conical cylindrical outer shape in an integrated or assembled state and made of an electrically insulating material, a wire-laying path which is formed in the main body and in which a conducting wire is installed, and a plurality of holding parts formed along the wire-laying path on an inner peripheral surface side of the main body and with axial intervals therebetween.

Systems and methods include using a magnetic core winder to install a powerline-mounted device with a non-gapped magnetic core, therefore reducing the weight of the powerline-mounted device while still harvesting equal or more power than a large cross-sectional and gapped magnetic cores. In particular, the methods include installing bobbin(s) and a core housing on a powerline and winding strip/ribbon core material onto the core housing. The bobbins may be wound axially opposed to on a toroid winder, which improves the accuracy of turns count of the magnetic core. The improved accuracy of turns count may increase the accuracy and/or tolerance of magnetic component(s) of the powerline-mounted device.