Abstract: In a method and apparatus for coupling a test piece to the transmitter and the receiver of an apparatus for measuring the attenuation of light waveguides, either a large area light emitter is inserted into the measuring path on the input side of the test piece, or a large area photo receiver is inserted on the output side of the test piece. The insertion of the large area photo receiver can be accomplished by means of a semitransparent or hinged mirror.

Abstract: To localize a conductor break occurring in a conductor being twisted into a communications cable in a two stage twisting operation the faulty wire is first ascertained and the fault in that wire then subsequently located using a probe placed between the twisting apparatus and a take up drum, with the twisting process then stopped and the fault corrected. In one particular embodiment which is disclosed all wires are short circuited, for example, at the end of the twisted cable which is wound on the take up drum, the wires entering the twisting arrangement are divided into two groups of equal size with each of the groups connected to one end of an a-c voltage source symmetrical with respect to ground through high resistance series resistors with the voltage drop at the series resistors then detected to locate the faulty wire and the probing of the twisted structure done capacitively using a probe for determining the exact fault location.