An electrical overhead transmission conductor cable having a steel reinforcing core which exhibits improved characteristics and unexpected conductivity above about 64% IACS is manufactured of a steel core covered by at least one stranding layer which is formed of round or trapezoidal shaped wire strands subjected to annealing before heat treatment and drawn and stress-relieved/annealed after stranding is completed, to provide a finished cable which includes an aluminum conductive portion which is dead soft, or "O" temper. The steel core of the cable carries substantially the entire tension load of both the core and conductors when suspended between vertical towers. The overhead transmission cable may be formed of trapezoidal cross section conductors wires for improved vibration performance characteristics.