AA12S Series Compact Audio Controller
SM69 Installation and Operation Manual
Section 3 Rev: 1.00
Issue 4
Page 3-2
3.3.1.2
Transmit
The TX select switch is a 4-position rotary control that provides radio selection for up to three transceivers
and a PA. By selecting the desired transceiver and pressing the external TX PTT switch, the AA12S is
activated for transmit operation, connecting the respective mic to the selected transceiver. The
transceiver that is selected by the TX select switch is also automatically selected for receive. The front
panel annunciator will illuminate green to indicate transmit operation (see section 3.3.1.3.)
TX selections are available only to the pilot and copilot. Activation of either TX PTT input connects the
user’s MIC to the selected COM, and activates the output PTT to the selected COM. When PTT is
pressed, all audio except the sidetone of the selected COM and NAV inputs is removed from the
headphone of the particular PTT user. The sidetone of the active COM is provided from the COM radio.
The PA position provides PA mic audio and PA keyline to an external amplifier (e.g. AA21, AA23, PA250)
for use as either a Loudhailer or Passenger Address system.
A priority transmission feature allows the pilot to override the co-pilot.
3.3.1.3
VOX/TX Annunciator
The VOX/TX Annunciator is a bicolour LED that indicates the intercom status.
During VOX activity, the annunciator LED is illuminated red. If TX is keyed with no ICS or sidetone, the
annunciator LED is illuminated green. If TX is keyed with mic or sidetone, the combination of red and
green will cause the LED to appear amber.
Note:
If the LED is still illuminated green after transmission is concluded, this indicates a possible stuck
mic.
3.3.2
Intercom
ICS VOL/VOX Squelch Control
VOX/TX Annunciator
The VOX and ICS VOL control is a fluted concentric knob, with the ICS volume on the centre knob, and
the VOX control on the outer knob.
ENG-FORM: 806-0112.DOT
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