Experience on Operation Sandstone dictated that to make certain that communications would be available for emergency use at critical periods during test operations, a radio back-up be provided. However, it was not necessary to use this radio back-up. The telephone system is illustrated in block diagram form in Figure 5.17-1. The equipment functioned satisfactorily and only normal maintenance was required. The quality of voice communication was good. The growth of system requirements was so large, however, that all, or most of the reserve capacity originally provided was utilized and it was necessary to provide party lines in some instances, (See Table 5,17-1 above), Furthermore this heavy increase in requirements came at a time when considerable effort was required to provide and install additional instruments, lines and drops. The resulting heavy traffic during busiest hours made a wait of several mimites necessary during the peak of operations, and preferred service had to be extended to certain individuals. Had the magnitude of requirements been known during the design stage of this work, 3~position or 4-position boards would have been provided rather than 2-position boards for Eniwetok and Parry and the capacity of the l-position boards at Runit, the Aomon-BiijiriRojoa Group, and Engebi would have been increased. Maintenance of underground lines on experiment islands offered some difficulty. To avoid delay in construction, materials were ordered for these lines before job requirements were fully settled. Therefore, underground telephone pairs were used instead of paper-insulated lead covered cables, because individual pairs permitted greater flexibility for future design requirements. Furthermore, the pairs were less expensive than cable, and there was a shortage of skilled cable splicers for the required work at the Jobsite. RADIO SYSTEM At the time the first Holmes & Narver forces arrived at the Jobsite,there was a need for radio communication to supplement the limited inter-island telephone facilities established by the beachhead party by utilizing existing submarine signal cables, The need for radio to facilitate construction and operational activities on islands not served by the telephone system contimued from the time the first group of surveyors reached the Atoll through the entire progran. The first sets, portable Military Type SCR-300 and SCR-619, were used by the survey teams for inter-island communication. In January of 1950 there were 12 SCR-619 units and several SCR- 300 radio tranamitter-receivers in use, The SCR-619 has a power cutput of 2 watts, voice (FM), with two preset frequencies in the range of 270 to 38.9 megacycles. The SCR~300 has a power output of approximately 1 watt, voice (FM), within a range of 40 to 48 megacycles. 5~2L2