TM 1-1510-225-10 3C-51 c.    Normal Operation. To   prevent   electromagnetic   radiation   in ramp,   terminal,   taxiway,   or   other   areas occupied by personnel, operate radar only in standby mode. CAUTION Do    not    operate    radar    system,    even    in standby   mode,   without   115-Vac,    400-Hz power  applied  to  the  system.  Without  ac power, the receiver-transmitter-cooling blower will not operate, which could result in circuit damage and/or automatic shutdown. (1)   Before     Startup.          Place     the     system controls   in   the   following   positions   before   applying power from the aircraft electrical system: 1.   INT    /    OFF    Switch    –    OFF    (fully counterclockwise in detent). 2.   GAIN – PRESET (fully counterclockwise in detent). 3.   TILT – +10 (fully clockwise). 4.   STAB –  ON. 5.   TGT ALERT – OFF. 6.   AZ MK – OFF. (2)   Precautionary  Procedures.    If  the  radar system is to be operated in any mode other than STBY or  TEST  while  the  aircraft  is  on  the  ground,  perform the following steps. 1.     Direct    nose    of    aircraft    such    that antenna  scan  sector  is  free  of  large metallic  objects  such  as  hangars  or other aircraft for a distance of 100  feet (30 meters) and tilt antenna fully upwards. 2.     Avoid   operation   during   refueling   of aircraft  or  other  refueling  operations within 100 feet (30 meters). 3.     Avoid    operation    if    personnel    are standing     too     close     in     the     270 forward sector of the aircraft. (3)   Self-Test   Displays.      A   distinctive   test pattern    is    displayed    when    the    TEST    function    is selected.  The following procedures may be performed to   verify   the   operational   status   of   the   entire   radar system. 1.   Verify    that    the    preliminary    control settings  have  been  made;  then rotate INT / OFF control to mid-point to turn system    on.        Verify    that    STBY    is displayed in MODE  field and that 100 is displayed as selected range. 2.   Press   WX/C   push   button   and   verify that WAIT is displayed in MODE field. NOTE A time delay circuit prevents the transmitter   from   operating   and   maintains the   display   blanked   until   the   magnetron has warmed up.  When the radar is turned on   by   pressing   the   WX/C   or   MAP   push buttons, it will display WAIT and will be in standby  for  the  1-minute  warmup  period, automatically   become   operational   in   the selected mode. If   none   of   the   push -button    switches    is pressed,  the  radar  will  display  STBY  and be in the standby mode. 3.   Press   the   TEST    push    button    and, when  the  test  pattern  displays,  verify operation  of  the  intensity  control and adjust to desired viewing level. 4.   Observe  the  display;  verify  that  TEST is   displayed   in   the   MODE  field  and that test pattern exhibits the following characteristics. a.   Range   marks   and   alphanumerics are displayed in cyan. b.   Color bar and 123 are displayed  in auxiliary field. c.   The  colors  of  the  first  three  target bands are green, yellow, and red. d.   The color of the fourth target band (65 to 75 nm) is red. e.   The two red target bands flash on and  off  approximately  once  each second. WARNING