A magnetic amplifier includes a permeable core having multiple legs. Control windings wound around separate legs are spaced apart and connected in series in an anti-symmetric relation. Harmonic filters are positioned adjacent to the control windings to attenuate even-ordered harmonics generated by alternating load current passing through a portion of the legs. The control windings bias magnetic flux arising from control current flowing through one of the control windings which is substantially equal to the biasing magnetic flux flowing into a second control winding. The flow of the control current through each of the control windings changes the reactance of the permeable core reactor by driving those portions of the permeable core that convey the biasing magnetic flux into saturation. The phasing of the control winding limits a voltage induced in the plurality of control windings caused by a magnetic flux passing around a portion of the permeable core.

Devices and related methods use a decoupling loop near closely spaced inductors that couples to each inductor and adds an additional coupling path between them, canceling the effects of the direct coupling between the inductors. When two inductors are close enough that undesired magnetic coupling between the inductors is possible, a decoupling loop adjacent the inductors is added that is configured to cancel the undesired magnetic coupling between the inductors. The decoupling loop is positioned, with respect to the first and second inductors, such that coupling between the decoupling loop and the first inductor induces a decoupling loop current around the decoupling loop and induces a second induced current on the second inductor that is equal and in an opposite direction to a first induced current on the second inductor caused by the first inductor. The undesired magnetic coupling between the conductors is reduced, and may even be totally cancelled.