Aviation Electronics Technician 1 - Historic Naval Ships Association

AS-2146/APS-115 AntennaThe radar antenna radiates the transmitter pulsesin either a pencil beam mode or a cosecant squared(spoiled) beam mode. The mode of radiation is notoperator selectable. A spoiler must be physicallyadded to the antenna dish if the spoiled beamoperation is required. This spoiler causes the beam tobe a wide vertical beam.The basic characteristics of the antenna are asfollows:Scan speed:Radiation pattern:Scan modes:Manual tilt:6 RPM with 2.5 microsecondpulsewidth or 12 RPM with0.5 microsecond pulsewidthPencil beam 2.5 by3.8 degrees; spoiled beam2.5 by 20 degrees45-degree sector, 360-degreefull scan, 240-degree sector(single system operation)+10 to –20 degreesFREQ PUSH BUITON.— This push button hastwo positions. With FIXED selected, the system willbe in the fixed frequency mode of operation. WithAGILE selected, the system will be operating in thesweep frequency mode. This mode is used in highclutter areas to improve target definition.PULSE PUSH BUTTON.-— The operator usesthis button to select either LONG or SHORTpulsewidths for the system. In the LONG mode, thesystem has a 2.5 µsecond pulsewidth, 400 pps PRF,and 6-RPM antenna scan rate. In the SHORT mode,the system has a 0.5 µsecond pulsewidth, 1600 ppsPRF, and 12-RPM antenna scan rate.HV PUSH BUTTON.— This is the high-voltageselect switch. There are three indications on theswitch, of which only two are selectable. As soon asthe system power is turned on, the WARMUP sectionilluminates. This section will remain illuminateduntil the system has warmed up. The operator cannotapply high voltage until the system has warmed upsufficiently. After approximately 3 minutes ofTilt stabilization:Pitch and roll ±30 degreesA361 Antenna Elevation Parking ControlThe antenna elevation parking control is used tostow the aft antenna in a zero-degree elevationattitude, relative to the aircraft, when the aft radar is inthe standby mode.C-7512/APS-115 Radar Control PanelThere are two radar control panels (fig. 3-5), onefor the forward and one for the aft system. Thiscontrol panel enables the operator to turn the systemon and control most of the functions of each system.There are 12 function switches and 2 fail lights oneach control box.WARNINGEnsure power is applied to the RADARSCAN switch on the C324 TACCO controlpanel prior to applying power to theAPS-115 radar system. If the RADARSCAN switch is left off and then turned onafter power is applied to the APS-115, thesystem will automatically cycle to highvoltage on.Figure 3-5.-C-7512/APS-115 radar control panel.3-5