SKY899
Installation Manual
Page 2-28 - Installation
009-11900-001
July 18, 2013
Revision F
2.16 OPERATIONAL MODE OUTPUT (OPTIONAL)
Operational mode output can drive a lamp annunciating when the system is in operational mode (i.e., not
in standby mode). Output is switched to ground when system is in operation mode. The lamp requires a
separate dc source (constant or dimming circuit). If lamp voltage is an ac source then an isolation relay
must be used. Refer to Appendix A for electrical characteristics.
Operational mode connection:
OPER_MODE
P1-31
2.17 POWER INPUT
The SKY899 is a 28 V dc system (18 to 32 V dc) and requires a 5A circuit breaker. See paragraph 2.6.5
for cable and shield connection information.
Power connection:
+
28V
P8-A
+28V_RET
P8-B
SPARE
P8-C
2.18 RADIO ALTIMETER (OPTIONAL)
If available, connect the SKY899 to a radio altimeter. The TRC can accept radio altimeter input from
analog or ARINC-429 (label 164 required) source. Interface to a radio altimeter will add ground intruder
filtering. It will also improve the SKY899s ability to determine when to display a TA (i.e., adjust
sensitivity levels) and when to mute aural announcements to minimize pilot distraction (i.e., suppress
SKY899 audio). Without the benefit of radio altitude, ground speed or the landing gear position are used
to determine sensitivity level and audio suppression.
NOTE
The radio altimeter must provide full range output between 0 and 2500
feet. Not all altimeters provide this full range output. The full range
output can sometimes be obtained as a mod to the radio altimeter. Check
with the specific altimeter manufacturer for compatibility and availability
of modification, if necessary.
2.18.1 Analog
This interface allows a DC analog radio altimeter to be used to monitor own aircraft height above ground
and includes input for radio altitude valid signal. Some analog radio altimeters utilize a discrete
valid/invalid signal line to indicate radio altitude validity, while others set the analog data input line to a
high out-of-range value for invalid altitude conditions. If a discrete flag signal is not available leave
RADIO_ALT_FLG (P1-14) unconnected and select None in the Service Menu (Rad Alt Flag sub-menu).
The document reference is online, please check the correspondence between the online documentation and the printed version.