The present invention relates to a guided wave radar level gauge comprising a transceiver, processing circuitry and a single conductor probe comprising at least two elongate probe sections. A connector extending from a first end of the probe section comprises: an abutment portion having a diameter smaller than a diameter of the probe section, an intermediate portion, having a diameter smaller than the abutment portion, arranged between the probe section and the abutment portion and an outside threaded portion. A second end portion of the probe section comprises a sleeve comprising an inside threaded receiving portion receiving the connector; a passage through a sidewall of the sleeve being located off-center in relation to a longitudinal central axis of the probe section. The probe further comprises a locking pin to be arranged in the passage locking two assembled probe sections by limiting movement of the abutment portion in a longitudinal direction.