Figure 2-4.—AN/SPS-55 block diagram

Figure 2-4.—AN/SPS-55 block diagram. receiver-transmitter (R/T), the radar set control (RSC), and the antenna safety switch. Although the AN/SPS-55 radar is electronically reliable, the antenna pedestal has been a source of mechanical maintenance problems. A field change kit, developed in FY89, provided an improved antenna pedestal. Delivery and installation of the pedestal modification are coordinated by the Restoration Program Manager. SIGNIFICANT INTERFACES.— The AN/SPS- 55, like all radars, has an impact on other systems, subsystems, and equipment. The RVC modification developed for the FFG-61 and the antenna pedestal modification not only improved the radar set, but improved the interface capabilities. The RVC enables the FFG-61 Integrated Automatic Detection and Tracking System (IADT) to use the AN/SPS-55 data. The pedestal modification allows interface with IFF. The AN/SPS-55 interfaces with the following equipment: Blanker/Video Mixer Group, AN/SLA-10 Indicator Group, AN/SPA-25( ) or equivalent Mk 27 synchro signal amplifier or equivalent Mk XII IFF (pedestal mod only) AN/SYS-2(V)2 IADT (FFG-61 RVC mod only) FOR THE MAINTAINER.— The AN/SPS-55 radar has various built-in features to protect the maintainer and the equipment. The transmitter has a voltage standing wave ratio (vswr) alarm. Fault detection indicators, located on both the transmitter and the RSC unit, show when the high-voltage power supply, modulator, or magnetron exceeds predetermined safe limits. A low-power condition in the radar automatically places the radar in the standby mode and activates an indicator at the RSC when low power exists. The antenna safety switch, when activated, opens the radiate interlock, removing power from the drive motor. It also activates a “Man Aloft” indicator on both the R/T and the RSC unit to ensure that no one tries to operate the radar during maintenance. Maintenance Maintenance of the AN/SPS-55 consists primarily of module replacement, with limited repair or replacement of certain individual components. The equipment is designed for rapid fault isolation to the 2-7