Sanden SN3500, Installation Manual

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General Information
82005-IM-K Sandel SN3500 Installation Manual Page 1-5
sense the selection of the GPS1 and annunciate the selection. This is referred to as
“slave” mode. It allows annunciation of the selection on the SN3500 but does not use
the front panel NAV switch to select the GPS receiver. This mode is only available for
use with a single GPS.
Master/Slave mode selection is done in the NAV maintenance page.
When any relay is used, the SN3500 uses a wraparound RELAY SENSE input,
which provides feedback of failure of the switching relay. A pole on the external relay
is used to ground an SN3500 input pin when the relay is in the energized position. If
the low signal is not detected, the SN3500 annunciates the relay failure by redlining
the NAV source display.
1.4.3 Autopilot Course and Heading Datum
Course and heading datum outputs are provided. These can be selected to be AC or
DC in the Flight Control System (FCS) maintenance page and depending on whether
Datum Excitation is connected. The direction sense of these signals can be reversed
as required.
A Back-course discrete output is provided for annunciation or AFCS reverse-course
control when required. This operates during LOC operation when the aircraft is flying
with the tail of the Course Pointer up.
For older Century autopilots a Datum Excitation (5Khz) input is provided. However,
an external transformer coupler must be fabricated. See installation drawings.
1.4.4 GPS Annunciators
For receivers without serial communication capability, discrete annunciator inputs are
provided for ARM, ACT, WPT or HLD, MSG, OBS/LEG Mode, and Parallel Track.
Connect the pins appropriate to the installed receiver and select the receiver type on
the LNAV maintenance page. See GPS/SWITCH/ANNUNCIATORS Installation
drawing for the complete matrix of outputs and annunciators.
Discrete control outputs are provided for APPR ARM, OBS Mode (King KLN90) and
HOLD (II Morrow). These are open-drain outputs.
The Garmin GNS receivers use ARINC 429 for the annunciator functions so no
discrete connections are used.
1.4.5 VLOC Navigation – Internal NAV Converter
For new installations that do not already have an external NAV converter, the
SN3500 supports
internal demodulation of composite NAV and Localizer to supply
the display and autopilot outputs with L/R deviation and course selection. See the
appropriate installation drawings.
1.4.6 VLOC Navigation – External NAV Converter