Garmin GTX 33 Installation Manual page 37

3.7.3 Operation/Performance Checkout
CAUTION
If the unit is removed from the aircraft and operated, always connect J3302, (and J3303
for GTX 33D) to an antenna or a 50 Ω, 5-Watt load. The GTX 33 transmits Mode S
acquisition squitter replies about once per second whether interrogations are received or
not.
Verify proper operation of the transponder by testing as specified in Appendix F of 14 CFR, Part 43, to AC
43-6B, and/or other appropriate regulations. The test is typically done as a ramp test using a transponder
ramp test set, such as the TIC TR-220, IFR ATC-601 or other suitable Mode S transponder test set.
Self Test
Verify that the unit does not display a failure indication when turned on.
Altitude Input
Verify that the displayed altitude matches pressure altitude (at 29.92).
External Inputs
If the external ident or standby inputs are connected, verify operation by:
a) Verify that the unit goes to standby when the external standby input is pulled low.
b) Verify that the ident indication turns on when the external ident button is pressed (must be in
the "ON" or "ALT" modes.
3.7.4 Performance (Ramp) Test
After installation, the transponder should be tested as specified in 14 CFR Part 43 Appendix F, AC 43-6B,
and other appropriate regulations. The test is typically done as a ramp test using a transponder ramp test
set, such as the IFR ATC-601A. The ramp test includes checks as follows:
Reference Part 43 Appendix F:
a) Reply Frequency
b) Suppression
c) Receiver Sensitivity
d) Reply RF Output Power
e) Mode S Diversity Channel Isolation (if applicable)
f) Mode S Address
g) Mode S Formats
h) Mode S All-Call
i) ATCRBS - Only All Call
j) Squitter
Reference AC 43-6B and 14 CFR Part 43, Appendix E (c):
Altitude Reporting
190-00906-00
Rev. F
GTX 33 Installation Manual
Page 3-7