Sandia Aerospace STX 165 Installation Manual - Manual (Page 14)

3.6 Electrical Connection
The STX 165 and STX 165R are designed to operate on 11-32Vdc without any special wiring con-
siderations. Power should be supplied from aircraft power through a 1 amp fuse or circuit breaker to
protect the transponder. The STX 165 and STX 165R also output unswitched aircraft power to oper-
ate other avionics. If this output is used (a Maximum of 1 Amp), the fuse or breaker size should be
adjusted to accommodate the other system. Power and ground wires are 20 AWG. All other wires
are 22 AWG unless otherwise noted.
3.6.1 STX 165 Panel Mounted Unit
The minimum installation for an operable STX 165 is Aircraft Power, Aircraft Ground, Antenna and
Static Line. Aircraft power and ground are both found on J3, the 9 pin connector. The STX 165
outputs encoder altitude data in either RS 232 or Gilham Gray Code. The data format of the RS-232
altitude output corresponds with the baud rate selection. At 1200 baud, it outputs in extended altitude
(#AL xxxxxT+15cc<CR>) format, and at 9600 baud it outputs in standard ICARUS format (ALT
XXXX<CR>). The data formats are described in Appendix 1.
For a yoke mount ident switch, an external ident input is provided. Grounding the External Ident line
will activate the ident mode.
3.6.2 STX 165R Remote Mounted Unit
The minimum installation for an operable STX 165R is Aircraft Power, Aircraft Ground, Antenna,
and pressure altitude from an altitude encoder. It is equipped with two serial ports, Tcmd/Tstat and
Altitude Input/Output.
The Tcmd/Tstat port accepts transponder mode commands and encoder altitude at 9600 baud in ex-
tended altitude format ( #AL xxxxxT+15cc<CR>, #MD A,I,234584<CR>).
Altitude Input/Output port accepts and outputs data at 1200 or 9600 baud. Default baud rate is 9600
baud and grounding Pin 6 of J2 changes baud rate to 1200 baud. It follows standard ICARUS format
(ALT XXXX<CR>) at 9600 baud and extended altitude format ( #AL xxxxxT+15cc<CR>) at 1200
baud. The data formats are described in Appendix 1.
STX 165R is also equipped with a select/de-select pin to be used in cases where the aircraft has one
active and one stand-by transponder. Grounding Pin 15 of J2 makes the STX 165R a standby tran-
sponder.
13
306100-00
Figure 3-5
J2/J3 Connector Wiring
For Ref Only
Figure 3-6
J2/J3 Connector Hood Assembly
For Ref Only