(b.)   MIC.  Enables   either   control wheel   POS   IDENT   switch   to   activate   transmission of  ident  signal  from  transponder. (c.)  OUT.  Disallows  outgoing  signal. (10.) MODE 4 reply indicator light.  Illumi- nates  to  indicate  a  reply  has  been  made  to  a  valid Mode   4   interrogation. (11.) MODE 4 AUDIO OUT switch.  Selects monitor  mode  for  mode  4  operation. (a.) AUDIO.  Enables  sound  and  sight monitoring  of  mode  4  operation. (b.)  LIGHT.  Enables  monitoring REPLY  indicator  for  mode  4  operation. mode. (c.)  OUT. Deactivates monitor (12.)   MODE   3/A   code   selectors.  Select desired  reply  codes  for  mode  3/A  operation. (13.) MODE 1 code selectors. Select  desired reply  codes  for  mode  1  operation. (14.)  MODE  4  TEST-ON-OUT  switch. Selects  test  mode  of  Mode  4  operation. (a.)   TEST.   Activates  built-in-test  of mode  4  operation. tion. (b.) ON. Activates  mode  4  operation. (c.)   OUT.  Disables   mode   4   opera- (15.)  MODE  4  code  control.  Selects  preset mode  4  code. (16.)   M-C,   M-3A,   M-2,   and   M-1   switches. Select  test  or  reply  mode  of  respective  codes. (a.)  TEST.  Activates   self-test   of selected  code.  Transponder  can  also  reply (b.)  ON.  Activates   normal   operation. (c.)  OUT.  Deactivates   operation   of selected  code. (17.) MODE 2 code selectors. Select  desired reply  codes  for  Mode  2  operation.  The  cover  over mode  select  switches  must  be  slid  forward  to  display the  selected  mode  2  code. (18.)   POS   IDENT   pushbutton   (control wheels, jig. 2-17).  When  pressed,  activates  transpon- der   identification   reply. TM  55-1510-221-10 c. Transponder - Normal Operation. (1.) Turn-on procedure: MASTER switch - STBY.  Depending  on  the  type  of  receiver  installed, the   TEST/MON   NO   GO   indicator   may   illuminate. Disregard  this  signal. (2.)  Test  procedure: NOTE Make  no  checks  with  the  master  switch  in EMER,  or  with  M-3/A  codes  7600  or 7700  without  first  obtaining  authorization from  the  interrogating  station(s). 1. 2. 3. 4. 5. 6. 7. 8. 9. Allow  set  two  minutes  to  warm up. Select   codes   assigned   for   use   in modes  1  and  3/A  by  depressing and   releasing   the   pushbutton   for each   switch   until   the   desired number  appears  in  the  proper window. Lamp  indicators  -  Operate  press- to-test  feature. M-1   switch   - Hold  in  TEST. Observe  that  no  indicator  lights illuminate. M-1  switch  -  Return  to  ON. Repeat  steps  4  and  5  for  the  M-2, M-3/A   and   M-C   mode   switches. MASTER  control  -  NORM. MODE  4  code  control  -  A.  Set  a code  in  the  external  computer. MODE  4  AUDIO  OUT  switch  - OUT. (3.)  Modes  1,  2,  3/A,  and/or  4  operating procedure. NOTE If  the  external  security  computer  is  not installed,   a   NO   GO   light   will   illuminate any  time  the  Mode  4  switch  is  moved  out of  the  OFF  position. 1. MASTER  control  -  NORM. 2.   M-1,   M-2,   M-3/A,   and/or   MODE 4  ON-OUT  switches  -  ON.  Actu- ate   only   those   switches   corre- sponding   to   the   required   codes. The  remaining  switches  should  be left  in  the  OUT  position. 3-81