TM 55-1510-219-10 M-C, M-3A, Select test or reply mode of re- M-2, and M-1 spective codes. switches TEST Activates  self-test  of selected code.  Transponder can also re- ply to ground interrogations in the selected mode during test. ON Activates normal operation. OUT Deactivates operation of selected code. MODE 2 code Select desired reply codes for selectors Mode  2 operation.  The  cover over mode select switches must be slid forward to display the se- lected Mode 2 code. POS IDENT When  pressed, activates tran- pushbutton sponder identification reply. (control wheels, fig.  2-16) c. Transponder - Normal Operation. (1) Turn-on   procedure.      MASTER   switch   - STBY.  Depending on the type of receiver installed, the 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     indicator lamps 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 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.          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 and/or observe (for Mode 4 interrogations and replies). 9. IDENT-MIC  switch  - Press to IDENT momentarily. 10. MODE  4 TEST/OUT  switch - TEST. 11. Observe   that   the   TEST   GO indicator lamp illuminates. 12. MODE  4 TEST/OUT  switch - ON. 13. ANT switch - BOT. 14. Repeat   steps   4,   5,   and   6. Observe   that   the   TEST   GO indicator illuminates. 3-76