Abstract: A coil suitable for use as a radio component, for example, an FM trimmer coil, is formed of a self-supporting wire coil enclosed in a housing comprising two halves molded of insulated material and ultrasonically welded together to captivate the coil, ribs on the housing interior extend between turns of the coil in contact therewith to securely contain the coil turns and prevent axial movement thereof. Optionally, a threaded tuning slug is adjustably located within the coil supported by the inner ends of the ribs at a fixed spacing from the coil. Integral coil terminals extend through the housing and a window in the side of the housing allows an additional terminal to be welded to a coil turn intermediate the ends of the coil.