TM 55-1510-220-10 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  (audio  panel control panel, fig. 3-1) - No.3 position. 2. UHF  control  panel  (fig.    3-3)  -  Set  required frequency     using     either     PRESET     CHAN control or MANUAL frequency select controls. 3. Microphone  jack  selector  switch  (instrument panel, fig.2-30) - As desired. 4. Microphone switch - Depress to transmit. (6) Shutdown procedure: 1. Function  selector  switch  (UHF  control  panel, fig.  3-3) - OFF. d. UHF  Command  Set  Voice  Security  Operation  (KY- 58). NOTE Disregard operating procedures involving the voice security control-indicator if unit is not installed. (1) Turn-on procedure: 1.  Power switch (Voice Security panel, fig 3-6) - ON. 2.  Function switch (UHF control panel) - BOTH. 2)  Receiver operating procedure: 1. Mode selector switch (UHF control panel, fig. 3-3) - As required. 2. Transmitter-interphone selector switch (audio control  panel,  fig.  3-1)  -  No.3  position,  or No.3 radio monitor control - On. 3. Set  required  frequency  using  preset  channel control or manual frequency selector. 4. Volume control - Adjust. NOTE To  adjust  volume  when  radio  signals  are not  being  received,  turn  squelch  switch OFF, adjust volume for comfortable noise level,   then   turn   squelch   disable   switch ON. 5. Squelch switch - As required. (3)  Transmitter operating procedure (PLAIN): 1. Transmitter-interphone selector switch (audio control panel) - No.3 position. 2. Plain/cipher   switch   (voice   security   control panel) - PLAIN. 3. Microphone switch - Press. (4)  Transmitter operating procedure (CIPHER): 1. Transmitter-interphone selector switch (audio control panel) - No.3 position. 2. Plain/cipher   switch   (voice   security   control panel, fig. 3-6) - CIPHER. (CIPHER indicator will  be  illuminated  as  long  as  switch  is  in CIPHER position.) 3. RE-X/REG    switch    (voice    security    control panel)- REG. 4. Microphone     switch     -     Press     momentarily (interrupted   tone   from   voice   security   unit should no longer be heard). NOTE No traffic will be passed if the interrupted    tone    is    still    heard    after pressing   and   releasing   the   microphone switch. 5. Microphone switch - Press (do not talk).  Wait until beep is heard then speak into microphone. 3-8