Importance

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Abstract

A duct probe having a coaxial cable is provided to advance a microphone through an underground or other duct containing a cable in a pressurized sheath for sensing fluid leaks in the sheath. The coaxial cable is embedded in a resilient fiberglass rod of one-piece construction. The rod is sufficiently flexible so that it can be wound onto and unwound from a reel having a cage-like configuration. A stationary base is provided to rotatably mount the reel, and the base is provided with a length measuring device responsive to the movement of the duct probe as it is unwound from the reel so that the distance by which the duct probe penetrates a duct can be determined. At the outer end of the rod, a microphone is mounted for sensing the sounds caused by a fluid leak in the pressurized sheath in the duct. The coaxial cable in the rod couples the microphone to a telephone jack at the reel, one part of the jack being stationary and the other part of the jack being coupled to the reel so that the reel can rotate relative to the base, yet a signal can be taken from the coaxial cable and directed to a electronic signal processor unit for showing an indication of the leak. The rod can be repaired quickly and easily by an improved technique if the rod cracks as a result of being misused.

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First Claim