In order to ensure good contact with the resonant rod and at the same time ensure a good electrical connection between the filter resonant rod and the cavity, so as to greatly improve the electrical performance of the tunable filter, a built-in spring can be installed on the tuned filter. The sheet, beryllium copper material is wound into a cylindrical structure, a plurality of reed racks are connected between the cylindrical structures at both ends, and the plurality of reed racks surround the edge of the cylindrical structure in a circle. The structure is simple, and the processing and assembling are convenient.