(57) A core unit (23) and method and apparatus for making it in which conductor pairs or units (38) have a single direction of twist and angles of twist lay change along lengths of the conductor pairs. In a preferred and practical construction, the angles of twist lay of all pairs change along their lengths on a continuous basis. This angle change is cyclical and with the cycles of the angles of the pairs being out-of-phase with one another. This achieves average twist lays of the units which are substantially equal to one anotherfrom conductor pair-to pair. The structure is achieved in a tandem operation of twisting conductors (30) into pairs and then forming them into the core unit, preferably by stranding.