Sandia Aerospace STX 165 User Guide - Manual (Page 3)

STX 165 Operation
The STX 165 is a Mode C transponder capable of transmitting 4096 different codes in response to ground radar
interrogations. All operations of the STX 165 are controlled through the front panel controls. The controls are
as follows:
Power/Mode Control
VFR Pushbutton
Ident Pushbutton
Select Knob
Data Knob
Enter Pushbutton
The Power/Mode
Control
The STX 165 will come on anytime power is applied to the rear connector. It is recom-
mended that power to the STX 165 be supplied through a panel mounted avionics master
switch. The STX 165 can be turned off by pressing and holding the Power button for three
seconds. It can be turned on again by momentarily depressing the Power button.
The Power button has two additional functions. One is as an Escape mode. If the operator
is in a programing mode and wishes to escape to the main page, he can press the Power
button momentarily. This will cancel all programming and show the normal display page.
The power pushbutton is also used to start the counters. This is explained in the counter
section.
SBY: The STX 165 is in standby mode and will not respond to radar interrogations.
ON: The STX is on and responding to radar interrogations but is not reporting altitude.
This is often referred to as Mode A
ALT: The STX 165 is responding to radar interrogations with altitude information.
This is often referred to as Mode C
Data Knob
Enter Pushbutton
These are dual concentric knobs with a pushbutton action. The larger Select knob is a
momentary switch that is spring loaded. It can be turned clockwise and counter clockwise
and will return to center when released. It is used to move the cursor during Code selection
and to toggle through the display options in the lower left display ( PALT, DALT and OAT).
Note that DALT and OAT are only available if the optional Sandia OAT probe model STP
78 is installed.
The smaller inner knob is the Data knob and is used to select the digit value when program-
ing the squawk code and to select the counter function in the lower right display when not
in the code selection mode.
Photocell
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