STX 165 Operation
The STX 165 is a Mode C transponder capable of transmitting 4076 different codes in response to ground radar interro-
gations. 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 recommended
that power to the STX 165 is 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 momen-
tarily. This will cancel all programming and show his 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 programing the
squawk code and to select the counter function in the lower right display when not in the cod
selection mode.
The Data know can also be pressed to Enter data after it has been programmed.
