737 AMM 飞机维护手册 导航 NAVIGATION 2(13)

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E.  The NAV and GS warning flags are provided to give an indication of their associated system malfunction. They come into view whenever power is lost to their systems, or whenever the input signals fail, or fall below a certain predetermined value. Warning indicators, to indicate VOR/LOC or GS system malfunctioning, are located on annunciator panels and are described in 34-29-0, Navigation Warning System.
F.  Frequency selection, in a navigation unit, is controlled from the control panel. The GS portion of the unit becomes operative only when a localizer frequency is selected. Localizer frequencies extend from 108.10 to 111.95 MHz, with 40 channels spaced at 50 kHz on the odd tenths megahertz and the odd tenths megahertz plus 50 kHz. Glide slope frequencies range from
329.3 to 335.0 MHz and are paired with the localizer frequencies as shown in Fig. 2. VOR frequencies also spaced at 50 kHz, extend from 108.00 to 118.00 MHz except for the localizer frequencies.
5C8
Jun 20/85 34-31-0 Page 1
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.

K76391
VOR/ILS Navigation System Component Location  5C8 
34-31-0  Figure 1 (Sheet 1)  Feb 20/89 
Page 2 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

K76625
5C8  VOR/ILS Navigation System Component Locations 
Jan 20/83  Figure 1 (Sheet 2)  34-31-0 
Page 3 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

 

G.  In VOR operation, two signals (30 HZ REF and 30 Hz VAR) radiated by a VOR ground station are fed to both the manual and automatic sections of a navigation unit. The 30-Hz REF signal is fed to both automatic and manual resolvers. The signal from each resolver is then phase compared against the 30-Hz VAR signal to produce the station bearing, VOR deviation and TO-FROM signals. In LOC operation, the deviation signal is produced by a comparison of the amplitude difference between two tone modulated signals (90 and 150 Hz) radiated by a runway localizer transmitter. Portions of these signals are summed to produce the warning flag signals. The GS deviation and warning flag signals are produced in much the same manner as the LOC deviation and warning flag signals.
H.  A VOR/ILS (LOC and GS) test circuit is provided in each VOR navigation unit to enable a check to be made of the VOR/ILS circuit function. Test switches are provided for this purpose on the control panels. Function of the test circuits is described under Operation.
2.  Navigation Unit
A.  Each navigation unit contains planar construction-type circuit boards and an interconnect unit. The circuit boards consist of VOR/LOC and glide slope receiver assemblies with associated instrumentation, digital instrumentation and self-test circuit board assemblies, an RMI driver and a power supply. These assemblies process VOR, localizer and glide slope signals and provide outputs to drive deviation, flag and to-from flight instrument displays.
B.  The chassis provides the mounting surfaces for connectors, support for two swing-out mounting frames, and a center mounting board.
C.  The center mounting board consists of a removable printed circuit board that contains the power supply, audio amplifier, and RMI driver circuits.
D.  The left swing-out mounting frame supports the VOR/LOC receiver board and the glide slope receiver board. Each board contains tuner, synthesizer, self-test, and injection oscillator circuitry. The VOR/LOC receiver is on the outer board and the glide slope receiver is on the inner board.
E.  The right swing-out mounting frame supports board for interconnections and the remaining VOR/ILS circuits. The VOR/LOC instrumentation and 2 out of 5 circuits, and optional expanded VOR monitor, programmable bearing filter, and digital bearing output circuits are on the inner board. The glide slope instrumentation, digital instrumentation, and optional VOR/ILS self-test and expanded ILS monitor circuits are on the outer board.
3.  VOR/LOC Antenna
A.  The VOR/LOC antenna assembly is a fin cap type installed on top of the vertical stabilizer. The antenna consists of two balanced half loops with a hybrid coupler added for increased reliability under fault conditions. The hybrid coupler is composed of two quarter wavelength lines with the dual outputs to the receivers shunted by a 100-ohm resistor. In addition, a 18.5-inch tuning stub is connected to each half loop.
5A7 
34-31-0 Page 4  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  May 15/81 

H24765
540  ILS Frequency Chart 
Feb 1/74  Figure 2  34-31-0 
Page 5 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 
　
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