TM 55-1510-220-10 (c)  No. 1.  Permits audio reception from VHF-AM  No.  1  transceiver.    Routes  key  and  microphone signals to VHF-AM No.  1 transceiver. (d)  No. 2.  Permits audio reception from VHF/AM/FM  and  SATCOM  transceivers.    Routes  key  and microphone signals to VHF/AM/FM and SATCOM transceivers. (e)  No. 3.   Permits audio reception from No. 1 UHF transceiver.  Routes key and mic signals to No. 1 UHF transceiver. (f)  No. 4.  Permits audio reception from HF   transceiver.      Routes   key   or   microphone   signals   to transceiver. (g)    No.  5  Permits  audio  reception  from No. 2 UHF or VOW.  Routes key and microphone signals to transceiver. e. Normal Operation. (1)   Turn-on   procedure.      Both   audio   control   panels   are activated  when  the  Avionics  Master  switch  is  placed  to  the ON position. 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.        Receiver    audio        switches    (audio control panel) -As required. 2.    Master  volume  control  (audio  control panel) -As required.  (Adjust volume control of system being used.) 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. 4.  Microphone select switch - As desired. (3)  Transmitter operating procedure. 1. Transmitter-interphone            selector    switch (audio   control   panel)   -   Set   for   transceiver desired. 2. Microphone  jack  selector  switch  (instrument panel, fig. 2-30) - As desired. 3. Use  either  one  of  the  following  microphone switches to key a selected transmitter; a. Control   wheel      microphone   switch   - Depress fully to the XMT position. b. Floorboard microphone switch - Depress. (4) Intercommunication procedure. 1. Transmitter-interphone selector switch (audio control panel) - Select ICS or PVT as desired. 2. Microphone  jack  selector  switch  (instrument panel, fig. 2-30) - As desired. 3. Microphone    select    switch    (audio    control panel)  -  Select  HOT  MIC,  NORM,    or  ICS OFF as desired. a. If  HOT    MIC    is  selected  -  Talk  when ready. b. If NORM  is selected - Depress control wheel microphone switch or floorboard microphone  switch  and  speak  into  the microphone. c. If   ICS   OFF   is   selected   -   Intercom function is switched off. 4. Volume    control  (selected  transceiver)  -  Set for comfort. f.  Emergency Operation.  Not applicable. g.  Shutdown Procedure. 1.  Avionics  master  power  switch (overhead control panel, fig. 2-12) - OFF. 2.  Leave controls and circuit breakers positioned for normal operation. Change 3   3-4