The invention relates to a tunable λ/4-filter subassembly whose frequency response can be adjusted. For this purpose, the λ/4-filter subassembly has a signal-conducting electrical conductor and an electrically conductive element that is at a reference potential. Furthermore, at least one short-circuit device is provided that electrically contacts the electrical conductor. An electrical coupling device is provided that couples the short-circuit device at a settable contact position to the electrically conductive element, wherein the electrical coupling device and the short-circuit device are movable relative to each other in order to set the length of the short-circuit device.