P139-HD Audio System User Manual
GA063-3 Rev G 08/25/2015
Page 14 of 35
7.3. Radio Functions
Radio transmit and receive select are controlled by a rectangular TX Select button, indicator LED, and a
pot/switch directly above it.
Transmit operation:
1.
To select a radio to transmit on, press the rectangular TX Select button assigned to that radio.
The TX Select LED above the button will light. Selecting transmit will also automatically enable
receive for that radio regardless of whether the knob (pot/switch) is in or out.
2.
To transmit on a radio press the PTT switch assigned to that headset. This control may be on the
pilot cyclic, passenger drop cord or footswitch depending on aircraft configuration.
3.
Transmit may also be keyed by pressing the ICS/TX toggle switch on the control panel down to
the TX position. On control panels serving multiple headsets this function may be disabled.
4.
Some installations may have dedicated PTT switches to allow one headset to transmit on a radio
without having to select it on the control panel first. Commonly the Pilot has a direct COM1 PTT
and the Co-pilot a direct COM2 PTT.
5.
The TX LED between the EMERG/NORMAL and ICS/TX switches will light while transmit PTT is
active.
6.
If a radio has been set with Sidetone Generation enabled (see Configuration Web Page, Section
9.6), then the Audio System will provide sidetone when transmitting. For the person transmitting
the sidetone level is fixed (adjustable from the Configuration Web Page) and for others it is
adjustable using the ICS Volume pot.
Receive Operation:
1.
To listen to a radio without selecting it to transmit, press the pot/switch above the TX Select
button assigned to that radio so that it is in the Out position.
2.
To adjust the radio listen volume, adjust the receive switch/pot. Clockwise increases the volume.
3.
To adjust the receive volume level for all radios, turn the MVOL (Master Volume) pot on the
bottom-right of the panel clockwise to increase the volume. Certain devices, such as alerts, may
have a fixed volume that cannot be adjusted by the MVOL pot.
4.
In some configurations, fixed-volume receive-only devices may be assigned to the four multi-
purpose buttons at the bottom-left of the control panel. Press the button to enable/disable. An
LED indicator to the left of the button indicates the listen state. As there is no volume pot, only the
MVOL pot has any effect on the volume level in normal operation. This fixed volume may be set
in the Configuration Web Page.
5.
On G13116 control panels three of the multi-purpose buttons may be set to control two fixed-
volume receive-only devices. In Figure 4 an example is the RX11/RX12 button at the bottom left
of the control panel. The two LEDs to the left of the button indicate which of the devices is
enabled. Pressing the button cycles through the possible combinations e.g.
OFF → RX11 → RX12 → BOTH → OFF