Northern Airborne Technology AA21-4xx - Manual (Page 41)

SM34 Rev. 4.00 AA21-400 Cabin PA System Manual
Nov 10, 2003 Page 3-3
ENG-FORM: 806-0105.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
3.4.4 Mode Switches
Siren Mode Switch
Internal/External Mode Switch
3.4.4.1 Siren Mode
The siren mode switch is a three position, centre-off locking switch on the front of the
AA21-400. The siren is operated by selecting the mode (YELP or WAIL) and then
activating a remote Siren key. The siren will sound only as long as the mode is selected
to WAIL or YELP and the Siren key is activated. It should be noted that in some
installations, the remote Siren key is connected directly to ground. In this case, the
siren will sound as soon as either YELP or WAIL is selected.
Note: Siren audio is only available when the INT/EXT switch is selected to EXT. (See
section 3.4.4.2.)
3.4.4.2
Internal/External Mode Switch
The INT/EXT mode switch is a two position locking switch that routes the selected audio
either to the internal 8
Ω speaker (INT) or to the PA via an amplifier such as the NAT
PA250/700 or PA110/220 (EXT).
3.4.5 Remote Power Switch
The AA21-400 provides a switched 28 Vdc low current output that is typically used to
control the dc power circuit of an NAT PA110, PA220, PA250 or PA700.
Note: This output is only available when the power switch is in the ON position.
End of section 3.0