TM 1-1510-224-10 (b) LIGHT.    Enables  monitoring   REPLY indicator for mode 4 operation. (c) OUT.  Deactivates monitor mode. (12) MODE  3/A  code  selectors.    Select  desired reply codes for mode 3/A operation. (13) 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. (14) MODE   1   code   selectors.      Select   desired reply codes for mode 1 operation. (15) MODE  4  TEST-ON-OUT  switch.      Selects test mode of Mode 4 operation. (a) TEST.  Activates built-in-test of mode 4 operation. (b) ON.  Activates mode 4 operation. (c) OUT.  Disables mode 4 operation. (16) MODE    4    code    control.        Selects    preset mode 4 code. (17) 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. (18) POS   IDENT   pushbutton   (control   wheels, fig.        2-24).        When    pressed,    activates    transponder identification reply. c. Transponder Normal Operation. (1) Turn-on procedure: MASTER switch STBY.    Depending  on  type  of  receiver  installed,   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. Allow set two minutes to warm up. 2. 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. 3. Lamp    indicators    Operate    press-to- test feature. 4. M-1  switch  Hold in   TEST.    Observe no annunciators illuminate. 5. M-1 switch Return to ON. 6. Repeat steps 4 and 5 for the  M-2, M- 3/A and M-C mode switches. 7. MASTER control NORM. 8. MODE   4   code   control   -   A.      Set  a code in external computer. 9. 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    annunciator    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.    Actuate only those switches corresponding  to  required  codes. The   remaining   switches   should be left in OUT position. 3. MODE  1   code   selectors   Set   (if applicable). 4. MODE 3/A  code  selectors  Set  (if applicable). 5. MODE   4    code    control    Set    (if required). 6. MODE 4 REPLY indicator Monitor to determine when transponder set is replying to SIF interrogation. 7. MODE 4 AUDIO OUT switch Set (as   required   to   monitor   mode  4 interrogations and replies). 8. MODE   4   audio   and/or   indicator Listen  and/or  observe  (for  mode 4 interrogations and replies). 3-89