File:Kreuzwickelspule.png

English: Ferrite slug-tuned radio frequency (RF) inductor from a medium wave radio receiver. It consists of a coil of wire wound around a plastic form, which contains a threaded ferrite slug which can be screwed further into or out of the coil with a screwdriver to adjust the inductance. The wire is wound in a basket weave pattern, with adjacent layers at angles to each other, to reduce parasitic capacitance and proximity effect power losses. The wire is probably a type called litz wire, consisting of several insulated strands braided together, which reduces resistance due to skin effect.