TM 55-1510-222-10 (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. When pressed, activates transponder identification reply. 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. 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  that  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  the 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    the    required    codes.        The remaining  switches  should  be  left  in  the  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  a  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 3-79