TM 1-1510-225-10 3C-42 Table 3C-5.  IND-42 Diagnostics    CODE DESCRIPTION 94 IDENT word missing 95 Microprocessor RAM 96 Microprocessor ROM 3C-24.  AUTOMATIC DIRECTION FINDER (ADF). a.    Description.    The  ADF-60  system  provides aural   reception   of   signals   from   a   selected   ground station  and  indicates  relative  bearing  to  that  station.   The ground station must be within the frequency range of  190  to  1749.5  kHz.    The  ADF-60 system has three functional modes of operation.  In  ANT mode, the ADF receiver  functions  as  an  aural  receiver,  providing  only an aural output of the received signal.  In  ADF mode, it functions as  an  automatic  direction  finder  receiver  in which   relative   bearing-to-the-station  is  presented  on HSI,   and   an   aural   output   of   the   received   signal   is provided.    A   TONE  mode  provides  a  1000-Hz  aural output tone, when a signal is being received, to identify keyed CW signals. b.    Operating   Controls   and   Functions.      All operating  controls  for  the  ADF-60 system are located on the CTL-62 ADF Control.  Refer to Figure 3C-19. (1)   Compare Annunciator.   ACT momentarily illuminates when frequencies are being changed.  ACT flashes if the actual radio frequency is not identical to the frequency shown in the active frequency display. (2)   XFR   /   MEM    Switch.      This   switch   is   a 3-position, spring-loaded toggle switch.  When held to the  XFR  position,  the  preset  frequency  is  transferred up to the active display and the ADF-60 retunes.  The previously  active  frequency  becomes  the  new  preset frequency and is displayed in the lower window.  When this switch is held to the  MEM position, one of the four stacked  memory  frequencies  is  loaded  into  the  preset display.    Successive  pushes  cycle  the  four  memory frequencies through the display (…2, 3, 4, 1, 2, 3…). (3)   Frequency Select Knob.  Two concentric knobs control the preset or active frequency displays.   The  larger  knob  changes  the  1000's  and  100's  kHz digits.  The smaller knob changes the 10's, units, and tenths   kHz   digits.      Each   detent   of   the   larger   knob changes the frequency in 100-kHz steps.  Each detent of  the  smaller  knob  change  the  frequency  in  1-kHz steps   with   the   exception   that   the   first   two   detent positions  following  a  change  in  rotational  direction  will cause a 0.5-kHz change.  Rapid rotation of the smaller knob will cause frequency changes greater than 1 kHz as  a  function  of  the  rate  of  rotation.    Frequencies  roll over at the upper and lower limits.  The two frequency select  switches  are  independent  of  each  other  such that  the  upper  and  lower  limit  rollover  of  the  10-kHz digit will not cause the 100-kHz digit to change. (4)   ACT  Button.    Push  the    ACT  button  for approximately   2   seconds   to   enable   the   frequency select   knobs   to   directly   retune   the   ADF-60.      The bottom   window   will   display   dashes   and   the   upper window  will  continue  to  display  the  active  frequency.   Push   the   ACT   button   a   second   time   to   return   the control to the normal 2-display mode. (5)   TEST Button.  Press the  TEST button to initiate  the  radio  self-test  routine.    (Self-test  is  active only when the TEST button is pressed.) (6)   Light   Sensor.      The   built-in  light  sensor automatically controls the display brightness.