4. GS Antenna
A. The GS antenna is a single horizontally polarized unit and is installed above the weather radar antenna in the nose radome.
5. Glide Slope Antenna Director Bar
A. The glide slope (G/S) antenna director bar is a passive element of the glide slope antenna used to alter the G/S radiation patterns such that the navigation units have maximum glide slope sensitivity.
B. The bar consists of a 13-inch strip of aluminum foil, pressure sensitive tape, installed horizontally inside the nose radome approximately 22 inches forward of the aft edge of the nose radome top centerline.
6. Control Panel
A. The controls for each navigation unit are on separate VHF NAV control panels.
B. On GJ ALL EXCEPT B-2504, B-2505 and B-2524, the controls on the VHF NAV section of each panel consist of a volume control, two sets of frequency selector knobs with associated frequency displays, three NAV tests buttons and a combination DME function selector and test switch. A transfer (TFR) switch permits selection of either of two preset frequencies.
C. On GJ B-2504 and B-2505, the controls on the NAV section of each panel consist of two frequency selector knobs with associated frequency display, a volume control, a combination ILS NAV TEST selector switch and VOR test pushbutton and a combination DME function selector switch and DME TEST pushbutton.
D. On GJ B-2524, the controls on each VHF NAV panel consist of two sets of frequency selector knobs with associated frequency displays and two active display indicator lights, three NAV test switches, a DME function selector, and a DME test switch. A transfer (TFR) switch permits selection of either of two preset frequencies.
7. VHF NAV Transfer Switch
A. A toggle actuated transfer switch is installed on the instrument switching panel located on the overhead panel. The switch controls the associated NAV transfer relays which enables VOR/GS system to feed both captain's and first officer's indicator's flight director computers and the autopilot.
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8. VHF NAV Transfer Relays
A. The nav transfer relays are stepping type relays. When the VHF NAV transfer switch is in the NORMAL position, the captain is on system No. 1 and the first officer is on system No. 2. Placing VHF NAV transfer switch to BOTH ON 2 position supplies a ground through the contacts of the VHF NAV transfer switch, transfer relay No. 2 and transfer relay No. 1 to the coil of nav transfer relay No. 1. This momentarily energizes transfer relay No. 1 and the relay steps to the BOTH ON 2 position. Positioning the VHF NAV transfer switch back to the NORMAL position, again momentarily energizes transfer relay No. 1 and the relay steps back to the normal position. The first officer's transfer relay is controlled in the same manner as the captain's by positioning the VHF NAV transfer switch to BOTH ON 1.
9. NAV Transfer Switches
A. The NAV transfer switch with RADIO--OMEGA positions, are installed on the pilots' lightshield panel. The switches control the radio-ONS relays to enable the captain and first officer to select course presentation from either the VOR navigation system or from the Omega navigation system (ONS) for display on the HSI.
10. Radio/ONS Transfer Relays
A. Two radio/ONS transfer relays are installed in rach E3. The relays connect the HSI course deviation, to-from and nav warning displays to either the ONS or the VOR/ILS navigation systems as shown in Fig. 3.
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11. Flight Instrument Accessory Unit
A. A flight instrument accessory unit is located in electronic equipment rack E-1. The unit contains relays and printed circuit for signal conditioning and interface between the navigation systems and the flight instruments. In addition, the unit contains a solid-state circuit for automatic dimming of the approach progress display lights in the flight director system.
B. The flight instrument accessory unit circuits associated with the VOR/ILS navigation system consist of the diodes across the solenoids of the nav transfer relays and two instrument transformers. The transformers provide 26 volts ac to the navigation units and to the RMI's.
C. On GJ B-2504 and B-2505, the flight instrument accessory unit also contains the VOR/ILS self-test inhibit relay. The relay is energized to prevent actuation of a VOR/ILS self-test when channel A of the autopilot system is engaged in any mode other than manual.
12. Operation
A. To operate the VOR/ILS navigation system, energize load control center P6 and P18 and close the circuit breakers shown in Fig. 3. Also, position the VHF NAV and COMPASS transfer switches on the overhead panel to NORMAL, the NAV transfer switches on the captain's and first officer's instrument panels to RADIO, and select VOR for the RMI bearing pointers. Tune the systems to the local VOR/ILS station and check that the station audio output is available through the interphone system.
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