Revision 4 - December 17,1998 Ryan TCAD 9900 Series Page 4-5
4.4.6 RAMP TEST, ANTENNAS (Model 9900B)
This test is best conducted using a transmitting test transponder sending mode C
replies, located more than 100 yards away from the host aircraft.
A. This test does not require interrogation of the host transponder, however it is
important to conduct the test in an area where signal reflections are minimal.
Outside and away from hangars and other buildings is usually best. Disregard
range indications for this test.
B. Place the aircraft so the test transponder is oriented 45°, forward and right of
the host aircraft.
NOTE: If another transponder is transmitting very close to the host aircraft, the
receiver will detect the close transponder on all four channels, and the test will not work.
C. Verify TCAD shows the target forward and right.
D. Disconnect J3.
E. Verify TCAD now shows the target aft and right ±45°.
F. Reconnect J3.
G. Verify TCAD again shows the target forward and right.
H. Disconnect J4.
I. Verify TCAD shows the target forward and left ±45°.
J. Reconnect J4 and verify all connections are secure.
K. Verify TCAD shows the target forward and right.
4.5 INTERFERENCE CHECK
These checks are designed to insure interference-free operation of the TCAD, to insure
the TCAD causes no interference, and the equipment onboard the aircraft does not cause
interference with the TCAD.
4.5.1 INTERFERENCE CHECK, TRANSPONDER
This check is designed to insure the TCAD has adequate data to acquire and track aircraft.
It is critical that the transponder does not ‘squitter’ as a result of on-board interference. If
it does, the data available to the TCAD for traffic avoidance is reduced.
A. Turn off all avionics except the transponder.
B. Turn off the transponder tester.
C. Verify the rate of reply light flashes is reasonable for the location.
D. Turn on all the avionics, one at a time. Observe if the reply light flash rate
changes. Pay special attention to the DME and select different frequencies to
verify there is no interference. The frequencies from 109.2 to 115.2 are
especially important and should be specifically checked.
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