TM 55-1510-222-10 Figure  3-2.  UHF Control Panel (AN/ARC-164) 2. Preset   channel   selector   switch Rotate to desired channel. (4) To use non-preset frequency: 1. Mode selector switch - MANUAL position. 2. Manual frequency selectors (5) - Rotate each knob to set desired frequency digits. NOTE The    PRESET    channel    selector    and manual frequency selectors are inoperative   when   the   mode   selector switch is set to the GUARD position. 3. Volume - Adjust. NOTE To  adjust  volume  when  audio  is  not being   received,   turn   squelch   switch OFF,   adjust   volume   for   comfortable noise  level,  then  turn  squelch  switch ON. 4. Squelch - As desired. (5) Transmitter operating procedure: 1. Transmitter-interphone   selector - No. 3. position. 2. UHF control panel - Set required  frequency  using  either PRESET CHAN control or MANUAL frequency select controls. 3. Microphone jack selector switch - As desired. 4. Microphone switch - Depress to transmit. (6) Shutdown procedure: Function selector switch (fig.  3-2) - OFF. 3-8. VOICE SECURITY SYSTEM TSEC/KY-58 (PROVISIONS ONLY). a. Description. The TSEC/KY-58 voice security   system   provides   secure   (ciphered)   two-way voice    communications    for    the    pilot    and    copilot    in conjunction  with  the  UHF  and  VHF  FM  command  sets, and the voice order wire set.  The control indicators are located in the forward avionics rack behind the pilot. 3-6