CHAPTER Ii, SECTION 4 was provided to permit operation between the USS Curtiss and Elmer in the event of station failure at Nan or when the Curtiss was out of station range. This airborne repeater was also provided for service between Elmer and the USS Curtiss in case of transmission path disruption between Nan and Elmer caused by ionized areas resulting from test operations. Before the test operations, there was some concern as to the effect of thermonuclear detonation on the propagated signal of the tropospheric scatter system. However, no difficulties were encountered in this respect and after the Zuni event the use of the aircraft repeater was discontinued. A serious delay in activating the VHF system was caused by a late change in frequency assignments. This change necessitated redesigning two of the antennas under manufacture and resulted in a three-week delivery delay. The system was activated on 28 April 1956 and was very effective in meeting demands. TELEPHONE. The telephone system existing after the CASTLEroll-up consisted of the 400-line dial switchboard on Fred and the 280-line manuallyoperated switchboard on Elmer; interconnection was through the existing submarine cable system. For the REDWING Operation, this system was expanded as shown in the telephone layout diagrams, Figures 2-172 and 2-173. In addition, local systems were provided at various other island complexes primarily for use in instrumentation of the various stations. These local networks were connected to the general telephone system thru the nearest switchboard. A typical local system is shown in Figure 2-174. Interconnections between phones of Bikini and Eniwetok Atolis were made through a radio link between Figure 2-163. Antennas Used in VHF Propogation Tests sites Nan or the AV 4 and Elmer, and phone A ground repeater station, which operated unattended, was installed at Station 70 to act as a relay to the USS Curtiss and as the primary radio link during evacuation of Bikini Atoll. An airborne (in a C-54) repeater station ELMER GENE URSULA YVONNE NAN FOX TARE TOTAL Page 2-180 connection to Honolulu or the Continental US could be made through the Fred switchboard then over the ACAN radio network. A summary of telephone instruments is shown in the following table: COMMON BATTERY DESK COMMON BATTERY WALL MAGNETO DESK MAGNETO WALL ARMY FIELD SWITCHING KEYS 356 18 12 24 142 22 30 604 216 12 14 12 36 6 8 304 12 1 1 0 1 0 0 15 17 2 2 3 5 0 6 29 23 9 8 26 21 14 11 112 42 1 1 1 4 1 1 51