TM 1-1510-225-10 3B-182 bandwidth is widened to enhance the identification of small targets. (6)   Radar Stabilization. The radar stabilization    system    is    designed    to    maintain    the antenna beam at the selected tilt angle relative to the earth's   surface.      The   stabilization   system   uses   the aircraft vertical gyros as a reference and is comprised of   electronic   amplifiers   in   the   Receiver/Transmitter interconnected  with  electromechanical components in the antenna. (7)   Level Flight.  Trim aircraft for straight and level   flight   in   smooth,   clear   air,   over   level   terrain.   Select a 50-mile range and set STAB to off. Rotate tilt control upward until all ground returns disappear  and  then  rotate  tilt  downward  until  ground returns  just  begin  to  appear.    After  several  antenna sweeps, check to see that ground returns are equally displayed.  If returns are only on one side of the radar screen  or  uneven  across  the  radar  antenna  mounting and  should  be  corrected  before  proceeding.    Repeat this procedure until a balanced display is achieved. Once the radar display is correct with stabilization off, select stabilization  ON and tilt upward once again to remove all returns.  Rotate tilt downward and  check  for  even  displays  of  ground  returns.   If  this test  indicates  improper  display,  possible  errors  in  the radar stabilization circuits or aircraft gyro exist. NOTE It is typical of a precessing aircraft gyro to cause  ground  returns  to  first  appear  on one   side   of   the   display,   then   have   them shift  to  the  opposite  side  of  the  display.   This precession may not be readily apparent    with    respect    to    flight    control instruments.  (8)   Turns. Once proper operation is established   in   level   flight,   rotate   the   TILT  control upward   in   1   increments   until   ground   returns   just disappear, then rotate an additional 2 upward. Place  the  aircraft  in  a  standard  rate  turn  to  the right.    Note  the  radar  display.    It  should  be  free  of returns throughout the turn indicating proper stabilization alignment. If   returns   display   on   the   right   side   of   radar indicator, the radar system is understabilizing.  Targets on the left side of radar display indicate the system is overstabilizing. In  prolonged  turns,  gyro  precession  may  occur which  will  be  tracked  by  the  stabilization  system  and appear as undesirable ground targets on the indicator. e.   Maximum     Permissible     Exposure     Level (MPEL).      Heating   and   radiation   effects   of   weather radar  can  be  hazardous.    Personnel  should  remain  at a distance greater than R  from the radiating antenna in order  to  be  outside  of  the  envelope  in  which  radiation exposure levels equal or exceed 10 mW/cm₂.  Refer to Figure 3B -141.  The distance (radius R) of the MPEL boundary  is  calculated  for  the  radar  system  on  the basis  of  radiator  diameter,  rated  peak-power  output, and duty cycle. 3B-33.  TRANSPONDER (APX-100). For   information   on   the   APX-100  Transponder, refer to Chapter 3, Paragraph 3-5.