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A
757
MAINTENANCE MANUAL
(q)
While you receive, turn the L HF listen switch through its full range on the captain's ASP (P8). 1) Make sure the audio level changes smoothly.
(r)
Set the mode selector to USB on the left HF communication control panel (P5).
(s)
Set the frequency selectors to an approved USB frequency.
(t)
Push and release the captains' PTT switch. 1) Listen for a 1 kHz tune-in-progress tone in the headset.
NOTE: A continuous or pulsed tone indicates that the
____ coupler is tuning to a new frequency. The coupler tune tone will sound no longer than 15 seconds. The average coupler tune time is 1 to 7 seconds.
NOTE: Some coupler types are able to tune quickly when
____ previously used frequencies are selected, in which case the tune tone may be only a momentary beep.
2) Make sure the status lights on the left HF communication transceiver front panel do not come on.
(u) Push and hold the PTT switch.
1) Make sure the status lights on the left HF communication transceiver front panel do not come on.
NOTE: A 1 kHz tone will be heard while the PTT switch is
____ pushed if an out-of-band-frequency has been set.
(v)
Release the PTT switch.
(w)
Push the PTT switch and speak into the microphone. 1) Listen for sidetone in the captain's headset.
(x)
Do a test message with a different HF radio. 1) Make sure there is no noise when you transmit and receive.
G. Right HF System Test (Dual HF system installations only)
S 915-043
(1) Do the HF System Test again but with the right HF communications system (if it is installed).
H. Put the Airplane Back to Its Usual Condition
S 865-044
(1)
Set the mode selector switch to the OFF position on the left HF communication control panel and the right HF communication control panel (if installed).
(2)
Put the captain's audio selector panel back to its usual condition.
(3)
Remove electrical power if it is not necessary (AMM 24-22-00/201).
S 845-047
S 865-048
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
757 MAINTENANCE MANUAL
HF COMMUNICATION ANTENNA COUPLER - REMOVAL/INSTALLATION
_______________________________________________________
1. General_______
A. The HF comm antenna couplers, M241 and M242, (if installed), are on the racks in the vertical stabilizer. The couplers weigh 17 pounds each and are pressurized with dry air at 5-7 psig.
TASK 23-11-01-024-001
2. Remove the HF Communication Antenna Coupler (Fig. 401)___________________________________________
A. References
(1)
AMM 06-42-00/201, Empennage Access Doors and Panels
(2)
AMM 20-10-01/401, E/E Rack Mounted Components - Standard Practices
(3)
AMM 24-22-00/201, Electrical Power - Manual Control
(4)
AMM 23-51-00/501, Flight Interphone System
B. Access
(1)
Location Zones 322 Vertical Stabilizer - auxiliary spar to front spar
(2)
Access Panels
322CL Antenna Coupler Bay Access Panel
C. Prepare for the Removal
S 864-034
CAUTION: YOU MUST PREPARE THE HF COMM ANTENNA COUPLER FOR THE REMOVAL.
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