TM 55-1510-222-10 (b) NORM.      Blocks   speech   from interphone system unless microphone switch is keyed. (c) ICS OFF. Deactivates interphone system. c. Normal Operation. (1) Turn-on procedure: Both     audio control  panels  are  activated  when  electrical  power  is applied to aircraft. NOTE It is presumed the AVIONICS MASTER POWER     switch     is     ON,     and     that normally used avionics circuit breakers    remain    set.        The    circuit breakers    of    routinely    used    avionic systems are normally left set. (2) Receiver operating procedure: 1. Master volume control Adjust as required for interphone audio level. 2. Receiver    audio    switches    ON and adjusted as required. NOTE Audio    select    switches    and    volume controls  are  routinely  left  in  positions of normal use. 3. Move each receiver audio switch on then off, separately, to verify audio presence in   headphones   for   each   system.      Adjust   volume   as desired. (3) Transmitter operating procedure: 1. Transmitter-interphone   selector switch Set for transceiver desired. 2. Microphone jack selector switch (fig.  2-14) As desired. 3. Control wheel microphone switch Depress to XMIT position;  or  depress  floorboard transmit switch to transmit. 4. Microphone   switch   Depress   to transmit. (4) Intercommunication procedure: 1. Transmitter-interphone   selector switch ICS. 2. Microphone jack selector switch (fig.  2-14) As desired. 3. ICS  select  switch  (fig.    3-1)  As desired. 4. If  HOT    MIC  is  selected  Speak directly into microphone. 5. If NORM microphone is selected   Depress   microphone   switch   and   speak   into microphone. 6. If ICS OFFE is selected intercom function is switched off. d. Emergency Operation.  Not applicable. e. Shutdown Procedure. 1. AVIONICS   MASTER   POWER switch OFF. 2. Leave controls, and circuit breakers positioned for normal operation. 3-7. UHF COMMAND SET (AN/ARC-164). a. Description.    The  IJHF  command  set  is  a line-of-sight radio transceiver which provides transmission   and   reception   of   amplitude   modulated (AM)  signals  in  the  ultra  high  frequency  range  of  225. 000    to    399.        975    MHz    for    a    distance    range    of approximately 50 miles.  Channel selection is spaced at 0.    025  MHz.    A  separate  receiver  is  incorporated  to provide    monitoring    capability    for    the    UHF    guard frequency (243.  0 MHz).  UHF audio output is applied to the audio panel where it is routed to the headsets. NOTE The    PRESET    channel    selector    and manual frequency selectors are inoperative when the mode selector is set  to  GUARD  position.   The  receiver- transmitter will be set to the emergency frequency only. Existing capabilities of the HAVE QUICK modified radio  are  preserved  to  the  maximum  extent  possible when  it  is  operated  in  the  normal  (non-hopping)  mode. No    new    procedures    are    required    for    normal    radio operation. To operate in the AJ mode, the radio must first be initialized.   This  initialization  requires  the  setting  of  two control  entries  into  the  radio,  Word-of-Day  (WOD)  and Time-of-Day  (TOD).    The  WOD  defines  the  choice  of frequency   hopping   pattern   for   the   day.      The   WOD choice  is  a  mnanagerial  function  and  the  same  WOD may be used for one or more days.  The TOD must be loaded into the clock contained within the radio. 3-4