>On the top of the case are painted in Orange the markings" G. E. CO, >CAT 7472230, 564647, 8800-C. This is definitely the T-101 modulation transformer made by GE for the AN/ART-13A. T.O. 12R2-2ART13-2 (AN/ART-13A Maintenance Instructions) identifies one of the three possible T-101 devices as the General Electric M-7472230. Mike / KK5F