TM 55-1510-220-10 (8) PWR    indicator.        This    indicator    (white) illuminates   when   power   is   applied   to   the   TSEC/   KY-75 system   and   the   PWR/FILL   switch   is   set   to   one   of   the numbered fill positions. (9) FILL  connector.    This  connector,  located  on the front of the TSEC/KY-75 control panel allows connection to a fill device. (10) Processor connector.  This connector, located on    the    back    of    the    TSEC/KY-75    control    unit,    allows connection of the control unit to the processor via a cable. c. TSEC/KY-75 Operating Procedures. (1) TSEC/KY-75 system turn-on procedure: 1. PWR/FILL  switch  (fig.    3-8)  Set  to any  fill  register  number.    Check  that PWR indicator light is illuminated. 2. PLAIN/CIPHER switch CIPHER. Check  that  CIPHER  indicator  light  is illuminated. 3. PWR/FILL   switch   Set   to   each   fill register (1 thru 3).  If the position has not already been filled a steady alarm tone will be heard. (2) Filling   TSEC/KY-75   using   general   purpose tape reader (KOI-18/TSEC). 1. FILL connector Connect to tape reader using fill cable (ON5124204). 2. PWR/FILL switch Set to register to be filled. 3. Insert  the  tape  leader  into  the  IN  slot on   tape   reader.      Line   up   tape   feed holes   with   the   white   dots   on   tape reader. 4. RMT-LOCAL-SIG CLR switch Set to SIG CLR clear then release. 5. Pull   tape   through   tape   reader   at   a moderate rate.  The steady alarm tone heard   over   the   headset   should   stop, indicating a successful fill. 6. Repeat  procedure  for  each  register  to be filled. (3) Filling   TSEC/KY-75   system   using   transfer- device KYK-13/TSEC. 1. Verify that the transfer device contains the   variables   in   its   registers   that   are indicated on its writing surface by: a. Transfer device mode switch OFF/CK. b. PWR/FILL switch Set to register to be verified. c. Transfer   device   initiate   button   Press and release.  Transfer device indicator light will flash if the register contains a variable. d. Repeat   procedure   for   each   transfer device register to be verified. NOTE Insure  that  the  rubber  grommet  is  in the  KYK-13/TSEC  P1  connector  and that the TSEC/KY-75 PLAIN/CIPHER    switch    is    in    the CIPHER position. 2. FILL   connector   Connect   to   transfer device   (either   directly   or   with   a   fill cable). 3. Transfer   device   FILL   switch   Set   to register     containing     variable     to     be transferred. 4. Transfer device MODE switch ON. 5. RMT/LOCAL/SIG CLR switch  (fig.  3- 8)  Set  to  SIG  CLR  and  release.  Parity indicator     light     on     transfer     device should flash, and the steady alarm tone in  the  headset  should  cease,  indicating a successful transfer of the variable. 6. Repeat  procedure  for  each  TSEC/  KY- 75 register to be filled. 7. Transfer   device   mode   switch   Set   to OFF/CK and disconnect from TSEC/KY-75. (4) TSEC/KY-75 secure voice operating procedure: 1. PLAIN/CIPHER    switch    (fig.        3-8) CIPHER. Check that CIPHER indicator light illuminates. 3-18