Ground Checks - Interfaces (Normal Mode); Discrete Switch Interfaces; Air Data Interface - Garmin GTX 335 w GPS Installation Guidance

7.1.3

Discrete Switch Interfaces

Perform the following procedure for each optional remote switch interfaced to the GTX transponder.
For panel mounted GTX 335 transponders:
1. Start the GTX 335 in configuration mode (hold the OFF key to power down the unit, then hold the
ENT key and push the ON key).
2. Navigate to the DIAG page (push the FUNC key to cycle through pages).
3. Set the Discrete Inputs that are interfaced and configured for the GTX.
4. Observe the Discrete Input States while activating each optional switch (for the squat switch this
may require the switch to be manually pulled LOW or HIGH, depending on configuration).
5. Verify Discrete Input State indicates when each optional switch is activated.

7.2 Ground Checks - Interfaces (Normal Mode)

The performance and checkout procedures contained in this section must be completed for each installed
transponder. Certain test procedures require the use of a Mode S transponder ramp tester such as an Aeroflex
IFR-6000 or TIC TR-220. Specific instructions for operating the ramp tester are contained in the applicable
operator's manual.
7.2.1

Air Data Interface

The GTX receives altitude data from an external source or internally from the optional GAE. If a GAE is
included in the installation along with a second air data source, it must be configured OFF for portions of
the following procedure. Refer to section 6 for configuration instructions.
If the following steps do not perform correctly, check the electrical connections and configuration setup for
the interfaced data source.
NOTE
After applying power to an altitude source it may take several minutes to warm up. During
the warm-up period the Altitude display on the GTX will be dashed out.
1. If there are multiple air data sources, configure the GAE OFF if it is included in the installation.
2. Power up the GTX in Normal Mode.
3. If there are multiple sources providing air data to the GTX, remove power from all but one source.
4. For panel mounted GTX 335 transponders: make sure that the appropriate data on the GTX is
displayed and agrees with the active source.
5. If there are multiple sources, remove power from the currently active source and apply power to
another source that has not been checked.
6. Repeat steps 3 and 4 until all available sources have been checked.
7. Configure the GAE ON if it is included in the installation.
8. Remove power from all external air data sources.
9. Repeat step 4 to check the GAE.
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GTX 335 w/GPS Installation Guidance
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