Test head for inductive surface testing having plural resonant coils held in conductive holder

A test head for the inductive surface testing of metallic workpieces brought into proximity with said test head for areal scanning of the surface of such workpieces, comprising a holder of an electrically conductive material, a plurality of parallel spaced holes extending through said holder, a plurality of resonant circuits each including a coil having a ferrite core and each of said plurality of resonant circuits being mounted in each of said holes and coaxially therewith so that the axes of said coils extend at right angles to the workpiece surface, whereby the resonant frequencies are increased, thereby increasing sensitivity of said testing, the distance between adjacent said holes in said holder being less than the diameter of each said ferrite core so that the magnetic field built up under the test head loses little in intensity between adjacent holes, thereby maximizing accuracy in indicating longitudinal and transverse flaws of the workpiece surface.