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Coaxial cable
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Automatic test equipment
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Antenna feedline.
Dry air or nitrogen pressurizes the antenna coupler at five to seven PSIGA. Pressurization is through the pressure valve on the front of the coupler.
Functional Description
The coupler has tuning elements and control circuits. The coupler constantly monitors the RF transmissions to automatically adjust the tuning elements. Typical tuning time is two to seven seconds.
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HF SYSTEM -HF ANTENNA COUPLER
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HF SYSTEM -HF ANTENNA COUPLER ACCESS AND INSTALLATION
Installation
The two HF antenna couplers are in the vertical stabilizer at the top of the HF communication antenna. Each coupler is on a shelf. A coaxial cable and control interface cable connect to the coupler front panel.
CAUTION: YOU MUST PREPARE EACH HF ANTENNA COUPLER FOR THE REMOVAL, YOU CAN EASILY CAUSE DAMAGE TO INTERNAL PARTS OF THE HF ANTENNA COUPLER.
Access
A panel on the left side of the vertical stabilizer allows access to the antenna couplers.
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HF SYSTEM -HF ANTENNA COUPLER ACCESS AND INSTALLATION
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HF SYSTEM -HF COMMUNICATION ANTENNA
Purpose
The HF communication antenna transmits and receives RF signals in the HF frequency range.
General Description
The antenna is a flush-mounted, slot-type antenna, approximately nine feet long. An inverted U-shaped insulation material on the leading edge of the vertical stabilizer surrounds the antenna driven element. The antenna insulation is composite material.
Location and Access
The HF antenna is a part of the leading edge of the vertical stabilizer. An access panel at the top of the antenna covers the connections to the antenna couplers.
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HF SYSTEM -HF COMMUNICATION ANTENNA
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HF SYSTEM -RADIO TUNING PANEL
Purpose
Use the radio tuning panel (RTP) to select the modes of operation, and to select the active and standby frequencies for each communication radio. Each RTP sends tuning and mode information to these components:
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The communication radios
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The other two RTPs
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The 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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A frequency transfer switch
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An offside tuning light
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Frequency selectors
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Radio tuning switches
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An AM switch
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A radio tuning panel off switch
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An HF sensitivity control.
Momentary switches have a light in them that comes on when the function is selected.
Controls and Indications
Push the radio tuning panel off switch to turn the RTP on. When the panel is on, the radio tuning panel off light goes off. When the RTP is off, the radio tuning panel off light comes on.
The active frequency window shows the frequency of the selected radio. The standby frequency window shows the frequency selected by the flight crew with the frequency selectors. The standby frequency window also shows auto-tune frequency information supplied by the AIMS cabinets during a data uplink.
You set the standby frequency with the frequency selectors. The outer knob adjusts the first three digits (10 MHz, 1 MHz and 100 KHz) in 100 KHz steps. The inner knob adjusts the fourth and fifth digits (10 KHz and 1 KHz) in 1 KHz steps.
The frequency transfer switch causes the active frequency to go to the standby frequency window, and the standby frequency to go to the active frequency window.
You use the radio tuning switches to select a radio. You select only one radio at a time. When a radio is selected, the light in the selected radio tuning switch comes on.
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