The RIDGID SeekTech ST-305 (21898) Pipe and Cable Line Transmitter (5 Watts) is used to energize a pipe or line with an "active" electrical signal, so that the underground line may be traced with a compatible receiver (such as the SeekTech SR-20). This allows the line's location to be correctly marked so it can be exposed for repair or avoided during excavation.

The ST-305 line transmitter can apply an active tracing signal to a target conductor in three ways:

Direct Connect: The transmitter's leads are connected directly to the target conductor and a suitable ground. The ST-305 line transmitter is capable of dual-frequency transmission (sending two frequencies onto a line simultaneously) in direct-connect mode.

Inductive Clamp (optional accessory): The jaws of the inductive clamp (sold separately) encircle the target conductor; there is no metal-to-metal contact.

Inductive Mode (internal coils): The transmitter is placed over and in-line with a conductor. Its internal antenna generates a dipole field which energizes the target conductor below ground, inducing a current into the target conductor.