| 摘要 |
PURPOSE:To prevent the possibility of generation of an adjustment error as well as to easily perform a tracking adjustment operation by a method wherein the winding pitch on the extended wound part of the coil opposing to a magnetic piece on its outer circumference is made coarse, and the magnetic piece is attached by screw fitting in such a manner that it is facing inside a bobbin. CONSTITUTION:When a magnetic core 12 is fully immersed into a bobbin 2, the constitution same as the case where the long-sized magnetic core formed as if the tip of which is extended is sunk into the bobbin formed by winding a coil in such a manner that the winding pitch at the lower end is made coarse is obtained. In the lowermost limit region of a frequency characteristic curved line, the steep drooping tendency of the curved line is suppressed. On the other hand, in the uppermost limit region of the frequency characteristic curved line where the magnetic core 12 comes off from the coil 6, the bobbin 2 is not brought to a hollow-core state, and as there is the residual inductance generated by the magnetic coupling of a magnetic piece 4 and a coil 6, the steep rising tendency of said curved line is suppressed. As a result, the entire frequency characteristic curved line can be corrected rectilinearly, and the tracking adjustment between each variable inductance element can be performed in a highly effective manner.
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