TM 1-1510-224-10 If    the    power-on    test    or    the    on    line    built-in    test equipment  detects  a  fault,  either  prior  to  or  during  the operation of self test, the system will switch the displayed mode symbol to an amber LX/F.  A special fault message may  be  obtained  by  switching  to  the  CLR/TST  mode.    In the  CLR/  TST  mode  an  amber  LXmn  will  be  displayed, where   mn   is   a   failure   code   that   may   be   interpreted according to table 3-13. g. Lightning Sensor System Normal Operation. 1. LSS   mode   selector   switch   (radar   control panel) LX 2. Range  switches  (radar  control  panel)  -  Set desired range. NOTE If  radar  system  mode  selector  switch is set to OFF, LSS range will revert to 50 nautical miles. 3-33.  TRANSPONDER SET (APX-100). a. Description.      The   transponder   system   receives, decodes, and responds to interrogations from air traffic control  (ATC)  radar  to  allow  aircraft  identification,  altitude reporting, position tracking, and emergency tracking.  The system  receives  a  frequency  of  1030  MHz  and  transmits preset coded reply pulses on a frequency of 1090 MHz at a  minimum  peak  power  of  200  watts.    The  range  of  the system is limited to line-of-sight.  The transponder system consists  of  a  combined  receiver/transmitter/control  panel (fig.   3-34)   located   in   the   pedestal   extension;   a   pair   of remote   switches,   one   in   each   control   wheel;   and   two antennas,    located    on    the    underside    and    top    of    the fuselage.      The   system   is   protected   by   the   3-ampere TRANSPONDER,   and   35-ampere   AVIONICS   MASTER PWR   NO.      1   circuit   breakers   on   the   overhead   circuit breaker panel (fig.  2-9). b. Transponder  Controls,  Indicators,  and  Functions (fig.  3-34). (1) TEST-GO indicator.    Illuminates  to  indicate successful completion of built-in-test (BIT). (2) TEST/MON/NO  GO  indicator.      Illuminates to    indicate    system    malfunction    or    interrogation    by   a ground station. (3) ANT  switch.    Selects  desired  antenna  for signal input. Table 3-13.  Lightning Sensor System Failure Codes LX FAIL CODE HARDWARE/FIRMWARE (mn) FAILURE 00 No LX system failure (not displayed) 01 Power supply out-of-tolerance 02 Invalid configuration 03 Reserved 04 Data Processor RAM failure 05 Data Processor Checksum failure 06 Data Processor shared RAM failure 07 Reserved 08 Reserved 09 I/O Processor RAM failure. 0A I/O Processor Checksum failure 0B I/O Processor shared RAM failure 0C HN out-of-range 0D Hw out-of-range 0E Reserved 0F HNLF out-of-range 10 HwLF out-of-range 11 ELF out-of-range 12 No data from antenna BT03847 3-87