NOTE: Annunciator lights can be dimmed by pushing on PUSH-TO-DIM bar.

(4)
Remove electrical power if no longer required (Ref 24-22-0 Electrical Power).

597 
Feb 20/86  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  34-29-21 Page 401 

VOR/ILS NAVIGATION SYSTEMS - DESCRIPTION AND OPERATION
EFFECTIVITY
GJ ALL EXCEPT B-2509 and B-2510
1.  General
A.  The VHF omnidirectional range (VOR) and instrument landing system (ILS) provides information of airplane position with respect to, and deviation from a selected VOR course, or localizer (LOC) and glide slope approach beams. Information is also provided of airplane magnetic bearing to the VOR ground station under reception.
B.  Two systems, captain's and first officer's, are installed. Each is comprised of the following components: navigation unit (combined VOR/ILS receiver and instrumentation unit), VOR antenna, GS antenna and control panel. Location of the components is shown in Fig. 1. The standby bus supplies 115 volts ac and 28 volts dc to the system through VOR/LOC, GS and instrument circuit breakers on P18, load control center.
C.  VOR/LOC course deviation information is displayed by the course deviation bar in the horizontal situation indicator (HSI) and by the localizer pointer (runway symbol)in the attitude director indicator (ADI). Glide slope (GS) information is displayed by the GS pointer in the ADI and HSI. VOR station bearing information is displayed by the pointers in the radio magnetic deviation indicators (RMI). VOR/LOC and GS information is also supplied to the flight director computers and to the autopilot. GS deviation information is also supplied to the ground proximity warning system (GPWS) computer. The ADI and HSI are described under 34-26-0, Flight Director System, and the RMI under 34-21-0, Compass System.
D.  Switching is provided to enable either system to feed both captain's and first officer's indicators, flight director computers, the autopilot, and the GPWS computer. Switching is accomplished through the NAV transfer relays, and controlled through the VOR/ILS (VHF NAV) transfer switch.
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.
　
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