; ny CHAPTER Il, SECTION 6 (Neg. No. W-V-340-8) Figure No. 2-157. Dial Exchange, Building 224 — Elmer. to disconnect six trunks to each of these sites in order to free cable pairs to meet User require- ments. These changes caused numerous “All Trunks Busy” conditions, as the remaining two trunks could not handle the traffic load. In many of the Scientific Stations and on all shot barges, the Users required a dial line to the nearest local exchange and a dial or magneto ring-down line into the Elmer exchange as an emergency back-up. This duplication of services resulted in the trunk disconnection from the sub-exchanges. Transmission was satisfactory throughout the atoll, with the exception of service to Janet, where voice levels were weak due to the excessive cable attenuation. Very little trouble was experienced with the Stromberg-Carlson XY automatic dialing equipment located on Elmer, Yvonne and Janet; however, routine trouble was caused by dust from the cement floors of these exchanges. This was eliminated with the installation of floor tile dur- ing the middle of the Operation. The Yvonne and Janet exchanges experienced heavy overpressures but remained in operation without interruption or damage. Page 314 A late requirement of JTF-7 for the construction of a Command Post in Building 221 had a one-week deadline. The schedule was met, and the communications system was ready at the completion of the construction. A one-position PBX, previously located at Janet, was used to meet the requirements. Fifteen miscellaneous circuits were terminated at this PBX for service to specially lighted fixed and plug-in telephones. The telephone system at the Bikini Atoll consisted of a two-position, manual, 140-line PBX at Nan and single-position 39-line PBX’s at Oboe and How. Another 39-line board was added to the How installation in March 1958 during the ABMA build-up. The switchboards at How were removed when the site was rolled up in April 1958. Telephone service at Bikini Atoll was satisfactory during the major portion of the build-up and early operational periods but became inadequate in late March and early April at the peak of the test activity. The size of the Nan PBX was the limiting factor of the system. In addition, the equipment was in poor condition, and the operating room in Building 14 was too small to permit efficient operation.