User's Manual

TT21/TT22 Transponder Installation Manual 13 July 2009
00560-00 Issue AF
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Page 34 Trig Avionics Limited
17. On the static test set, drive the altitude to 30,000 feet.
18. Read the primary altimeter value, and turn the right knob on
the TC20 until the altitude displayed on the TC20 matches
the altitude on the primary altimeter.
19. Press ENT on the TC20; the display moves to the test screen.
To complete the testing you should leave the TC20 screen displaying the
encoder altitude, and exercise the altitude on the static test set across the
altitude range of the aircraft. Use at least 10 test points, and verify that in each
case the altitude displayed on the primary altimeter and the altitude displayed
on the TC20 correspond within the 125 foot tolerance. Lightly tap the
altimeter at each test point to eliminate friction effects.
When the correspondence test is complete, press ENT again on the TC20, and
power off the system.