Sonde with replaceable electronics and a rotatable, tubular inner shell wherein a battery is located

摘要

A sonde for tracing an underground conduit has a separable casing which receives a removable inner shell, the transmitter electronics being located in the shell. The electronics may be permanently potted in the inner shell or removable therefrom. The interchangeability of the transmitter facilitates the use of different types of transmission signals without requiring the more expensive casing for each such transmitter. The shell also advantageously supports the battery, and further is free to rotate within the housing such that, as the cap is screwed onto the housing, the shell and battery are free to rotate, precluding damage to the battery leads which may be caused by twisting of the leads.