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747-400 MAINTENANCE MANUAL
S 865-370
(25)
Push the SETUP key on the test set and enter the appropriate range for the top and bottom antenna.
S 735-197
(26)
Do a check of the DIVERSITY TEST.
(a) Make sure the test set shows PASSED and the DIVERSITY ISOLATION is 20dB.
NOTE: To make sure the dynamic range is 20dB, do the
____ diversity test at a distance of less than 50 feet (15.2 meters) from the airplane's ATC antennas.
S 735-198
(27) Do a check of the MTL DIFFERENCE TEST.
(a) Make sure the Minimum Threshold Level (MTL) difference between mode A and mode C is 1.0dBm.
S 865-371
(28)
Push the PWR TEST key on the test set.
S 865-372
(29)
Use the SELECT key on the test set and select the bottom antenna.
NOTE: Make sure the top ATC antenna is not in the line of sight of
____
the test set antenna during the POWER TEST.
S 865-373
(30)
Push the antenna push button switch.
S 865-374
(31)
Slowly move the test set antenna 6 feet (1.8 meters) vertically from the ground, at less than 1 FT/SEC (30 CM/SEC).
S 865-375
(32)
Push the antenna push button switch a second time to stop the test when the test set antenna is approximately 6 feet high.
S 735-199
(33)
Do a check of the POWER TEST.
(a) Make sure the peak power output of the transponder is between 125W (EPR= 51.0 dBm) and not more than 500W (ERP = 57.0 dBm).
NOTE: Effective Radiated Power (ERP) is the product of the
____ antenna output power and antenna gain.
(b) Make sure the Minimum Threshold Level (MTL) sensitivity is -74dBm (|3dBm).
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747-400
MAINTENANCE MANUAL
(c) Make sure the test set shows PASSED for the BOT AVG (dBm).
S 865-377
(34)
Insert the antenna shield over the bottom ATC antenna.
S 865-378
(35)
Move the test set so that it is in the line of sight of the top ATC antenna.
S 865-379
(36)
Push the SETUP key on the test set.
(a)
Enter the appropriate range for the top antenna.
(b)
Choose the top antenna on the SELECTED field.
S 865-380
(37)
Push the PWR TEST key on the test set.
S 865-381
(38)
Use the SELECT key on the test set and select the top antenna.
S 735-382
(39)
Do a check of the POWER TEST.
(a) Make sure the peak power output of the transponder is between 125W (ERP = 51.0 dBm) and 500W (ERP = 57.0 dBm).
NOTE: Effective Radiated Power (ERP) is the product of the
____ antenna output power and antenna gain.
(b)
Make sure the Minimum Threshold Level (MTL) sensitivity is -74 dBm (|3 dBm).
(c)
Make sure the test set shows PASSED for the TOP AVG (dBm).
S 735-355
(40) Do the system test again for the right or No. 2 ATC system.
NOTE: On the test set, select the other ATC
____
antenna.
G. Put the Airplane Back to Its Usual Condition
S 845-048
(1)
Remove the ATC ramp test set.
S 865-383
(2)
Remove the DO-NOT-CLOSE tags and close these circuit breakers:
(a) P7 Overhead Circuit Breaker Panel:
1) 7F22, LANDING GEAR DSP & CONT PRI
2) 7F23, LANDING GEAR DSP & CONT ALTN
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：747-400 AMM 飞机维护手册 导航 NAVIGATION 3(65)
