777 AIRCRAFT MAINTENANCE MANUAL
VHF SYSTEM -VHF COMMUNICATION ANTENNA
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D633W101-BEJ Jan 05/2002
777 AIRCRAFT MAINTENANCE MANUAL
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Page 26 D633W101-BEJ Jan 05/2002
VHF SYSTEM -RADIO TUNING PANEL
Purpose
The radio tuning panel (RTP) selects the modes of operation, and selects the active and standby frequencies for each communication radio. Each RTP sends tuning and mode information to:
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Communication radios
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Other two RTPs
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Airplane information management system (AIMS) cabinets.
Description
Each RTP has these features:
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Active and standby frequency windows
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Frequency transfer switch
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Offside tuning light
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Frequency selectors
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Radio switches
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AM switch
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RTP off (OFF) switch
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HF sensitivity (HF SENS) control.
The frequency windows show this additional information:
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Messages from selected radio systems
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Transfer frequencies from the AIMS data communication management function (DCMF).
Operation
When the RTP is off, the PNL OFF light comes on. Push the RTP OFF switch to turn the RTP on. When the RTP is on, the PNL OFF light goes off.
The active frequency window shows the current frequency of the selected radio. The standby frequency window shows the frequency that the flight crew selects with the frequency selectors. The standby frequency window also shows autotune frequency information from the AIMS cabinets during a voice uplink.
BEJ 006-999
The flight crew sets the standby frequency with the frequency selectors. The first digit is always 1. The outer knob adjusts the second two digits (10 MHz and 1 MHz) in 1 MHz steps. The inner knob adjusts the fourth, fifth and sixth digits (100 KHz, 10 kHz, and 1 kHz) in 8.33 kHz steps. The RTP automatically selects 25 kHz spacing for 121.425 to 121.575 for the 121.5 MHz emergency frequency.
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VHF SYSTEM -RADIO TUNING PANEL
BEJ 006-999 (Continued)
BEJ 001-005
The flight crew sets the standby frequency with the frequency selectors. The first digit is always 1. The outer knob adjusts the second two digits (10 MHz and 1 MHz) in 1 MHz steps. The inner knob adjusts the fourth, fifth and sixth digits (100 KHz, 10 kHz, and 1 kHz) in 25 kHz steps.
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The frequency transfer switch causes the active and standby frequencies to change windows. The active frequency goes to the standby frequency window, and the standby frequency goes to the active frequency window.
You use the radio switches to select a radio. You select only one radio at a time. When a radio is selected, the light in the selected radio switch comes on.
When the flight crew selects an off-side radio, two offside tuning lights come on. One light is on the RTP that the flight crew uses to make the selection. The other light is on the onside RTP of the selected radio.
The HF SENS control sets the RF sensitivity level of the onside HF transceiver. The left RTP sets the left HF sensitivity. The right RTP sets the right HF sensitivity. The center RTP HF SENS control does not connect to any transceiver.
Use the AM switch to select between AM and SSB modulation modes for the selected HF transceiver. When you select AM mode, the light comes on in the AM mode switch on its onside RTP if any of these conditions exist:
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Flight crew selects any VHF communication transceiver while in the AM mode
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Flight crew selects the onside HF transceiver while in the AM mode.
The AM mode light bar goes off when the flight crew selects SSB mode.
Push the PNL OFF switch to stop the operation of the RTP. When the RTP is off, the PNL OFF light comes on and all functions stop except these:
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Displays continue to show any current fault
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RTP continues to receive 28v dc
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RTP continues to send BITE information to the AIMS central maintenance computer function (CMCF).
BITE
The RTP does a test of itself continuously. The RTP shows PANEL FAIL in the two frequency display windows when the RTP has an internal failure or there is a system failure.
The two frequency windows show all dashes if the flight crew selects a failed radio.
EFFECTIVITY BEJ ALL 23-12-00
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