TM 1-1510-218-10   3C-45 used to set the 10 kHz digits when pushed in.  When pulled out it is used to set the 1 kHz digits.  When the display is changed to 2182 kHz the smaller knob will change   the   ones   digits   (from   2180   to   2189   kHz) whether pushed in or pulled out. (b)   Frequency Active Entry Mode.   When   in   the   active   entry   mode,   the   tuning   knobs operate   the   same   as   they   do   in   the   standby   entry mode,    but    will    change    the    active    digital    display frequency rather than the standby frequency. (c)   Channel  Mode.    When the unit is in the   channel   mode,   turning   either   tuning   knob   will change the channel number in the upper display and the corresponding frequency in the lower display. (d)   Program  Mode.    When the unit is in the program mode, the tuning knobs are used to select the   channel   number   in   the   upper   display   (when flashing), or the channel frequency in the lower display (when flashing). (4)   Mode Switch.  A momentary push-button switch,    placarded    MODE,    is    used    to    select    the operating  mode  of  the  ADF  receiver.    Each  press  of the MODE switch cycles the system through the  ANT, ADF,  ANT/BFO, and  ADF/BFO  modes.    The  current mode is shown on the display. (5)   Channel   Switch.      A   momentary   push button switch, placarded  CHAN, located on  the lower portion of the ADF control unit, is used to put the unit into  the  channel  and  program  modes.    Momentarily pressing the  CHAN switch while in a frequency mode puts   the   unit   into   the   channel   mode.      Holding   the channel switch pressed for longer than  2 seconds puts the unit into the program mode. (6)   OFF  /  VOL  /  PUSH  Control.    A  control knob  on  the  front  of  the  ADF  control  unit  placarded OFF  /  VOL  /  PUSH controls the operation of the unit.   Turning  the  knob  in  the  clockwise  direction  from  the OFF position   (detent)  applies  power  to  the  unit,  and audio volume output is increased as the knob is turned further   to   the   right.      Pressing   PUSH  overrides  the automatic     squelch     circuitry.          Turning     the     knob clockwise past the automatic squelch threshold, while the automatic squelch circuitry is overridden, will allow background audio to be heard through the headphones  or  speaker  and  demonstrate  whether  the receiver  is  working  or  not,  and  allow  setting  of  audio volume.        To    return    the    transceiver    to    automatic squelch control, press the PUSH control knob again. c.   Frequency/Channel Selection Modes.    The ADF   receiver   control   unit   may   be   operated   in   the frequency mode (either standby entry or active entry), channel mode, or program mode. (1)   Frequency   Modes.      The   ADF   receiver control unit may be operated in standby entry or active entry. (a)   Standby   Entry.      When  the  unit  is operated in the standby entry frequency mode, a new frequency  is  set  on  the  standby  digital  display,  using the  tuning  knobs.    When  the  operator  is  ready,  the frequency  is  then  transferred  to  the  active  display  by pressing the frequency transfer switch. (b)   Active    Entry.       When   the   unit   is operated  in  the  active  entry  frequency  mode,  a  new frequency is set on the active digital display using the tuning  knobs.    The  active  entry  mode  is  entered  from the standby entry mode by pressing the transfer switch for longer than 2 seconds.  The standby digital display will be blank while the unit is in the active mode. (2)   Channel  Mode.    When  the  ADF  receiver control  unit  is  in  the  channel  mode,  the  upper  digital display will show a channel number (1 through 9), and the   lower   digital   display   will   show   the   frequency assigned  to  the  channel  number  in  the  upper  digital display.    The  tuning  knobs  will  change  the  channel number   and   corresponding   frequency  shown  on  the displays. The channel mode is entered by momentarily pressing the CHAN button located on the ADF   receiver   control   unit.      If   there   are   no   valid frequencies  programmed,  the  unit  will  display  a  CH  1 in  the  upper  display  and  dashes  in  the lower display.   The unit can be changed from the channel mode to the frequency mode in three ways. (a)   Momentarily    pressing    the    transfer switch   will   return   the   unit   to   the   frequency   mode, placing the channel frequency in the active display and the previous active frequency in the standby display. (b)   Momentarily     pressing     the CHAN switch will return the unit to the frequency mode, and will return the active and standby displays to what they displayed prior to entering the channel mode. (c)   The  unit  will  return  to  the  frequency mode  if  no  knob  activity  takes  place  for  5  seconds after   the   unit   was   put   into   channel   mode.      When returned in this manner, the channel frequency will be put into the standby display with the active frequency remaining  as  it  was  before  entering  channel mode.  If no frequencies were programmed, the frequencies will remain the same as they were before entering channel mode.