High-frequency filter of a coaxial construction, the high-frequency filter having the following features: - the high-frequency filter comprises at least one resonator having an internal conductor and an external conductor housing; - the external conductor housing comprises a housing base, a housing cover spaced apart from the housing base, and a housing wall extending around between the housing base and the housing cover; - the internal conductor is galvanically connected to the housing base and extends in the axial direction from the housing base towards the housing cover; - the internal conductor ends at a distance from the housing cover and/or is galvanically separated from the housing cover; - the resonator comprises a tuning element, which is arranged opposing the internal conductor, and which is movably held in the axial location thereof in the housing cover, at least indirectly, and protrudes into the resonator interior; - the internal conductor comprises a longitudinal recess, which extends from the face end of the internal conductor opposing the housing cover towards the housing base; - the tuning element can be introduced into the longitudinal recess of the internal conductor; - an internal thread, in which the tuning element provided with an external thread is rotatably arranged, is formed in the housing cover or in a socket which is provided in the housing cover and also connected with the housing cover; - the tuning element is formed from a dielectric material in such a way that current transitions are prevented between the external thread and the internal thread; and - the tuning element comprises a central portion, by means of which the tuning element is movably held, characterised by the following additional features: - the tuning element further comprises a peripheral wall, the tuning element and the peripheral wall being separated from one another by a recess extending around the central portion, in such a way that a separating space is formed between the central portion and the peripheral wall, the central portion and the peripheral wall being interconnected via a tuning element base; and - the face end of the socket opposing the housing base can be received in the separating space between the central portion and the peripheral wall of the tuning element or dips into said space, in such a way that the peripheral wall is arranged between the socket and the internal conductor in the region of the longitudinal recess thereof. - the high-frequency filter comprises at least one resonator having an internal conductor and an external conductor housing; - the external conductor housing comprises a housing base, a housing cover spaced apart from the housing base, and a housing wall extending around between the housing base and the housing cover; - the internal conductor is galvanically connected to the housing base and extends in the axial direction from the housing base towards the housing cover; - the internal conductor ends at a distance from the housing cover and/or is galvanically separated from the housing cover; - the resonator comprises a tuning element, which is arranged opposing the internal conductor, and which is movably held in the axial location thereof in the housing cover, at least indirectly, and protrudes into the resonator interior; - the internal conductor comprises a longitudinal recess, which extends from the face end of the internal conductor opposing the housing cover towards the housing base; - the tuning element can be introduced into the longitudinal recess of the internal conductor; - an internal thread, in which the tuning element provided with an external thread is rotatably arranged, is formed in the housing cover or in a socket which is provided in the housing cover and also connected with the housing cover; - the tuning element is formed from a dielectric material in such a way that current transitions are prevented between the external thread and the internal thread; and - the tuning element comprises a central portion, by means of which the tuning element is movably held, - the tuning element further comprises a peripheral wall, the tuning element and the peripheral wall being separated from one another by a recess extending around the central portion, in such a way that a separating space is formed between the central portion and the peripheral wall, the central portion and the peripheral wall being interconnected via a tuning element base; and - the face end of the socket opposing the housing base can be received in the separating space between the central portion and the peripheral wall of the tuning element or dips into said space, in such a way that the peripheral wall is arranged between the socket and the internal conductor in the region of the longitudinal recess thereof.