VOR/ILS Interface Block Diagram
Figure 6 (Sheet 8)

EFFECTIVITY CONFIG 1 LH 011-099

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28V DC
BUS (P126)

VOR/ILS RECEIVER NO. 3 B301
ILS No. 3 Fail-Op Annunciators Schematic
Figure 7

EFFECTIVITY

CONFIG 1
LH 011-099
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 On LH 051-054; AF 152-154, 172-173, 191-194; GN ALL and MD ALL, the glide slope antenna system operates in the same manner as on prior airplanes but differs in system components. Only one capture antenna, which is located in the nose radome, and only one hybrid coupler are used. The hybrid couples glide slope rf to receivers No. 1 and 3. The hybrid coupler is not installed on LH airplanes. In addition, glide slope antenna test switches and associated annunciators on the pilots' center instrument panel (P2) provide a means for checking operation of the coaxial relays. Pushing the ANT TEST switch completes a ground through logic circuits in AP accessory box No. 1 or 2. This energizes the coaxial relay causing the associated annunciator to come on and the selection of the capture antenna as an rf signal source for the receiver(s). The logic circuits inhibit the VOR/ILS test circuits when the AFCS is operating in VOR/LOC, ILS or LAND mode and channel A, B or C of the AFCS is in command. On LH 011-050, 055-099, the glide slope antenna system operates in the same manner as LH 051-054 except that a 3rd coaxial relay, test switch and annunciators are installed. In addition, logic circuits in autopilot accessory box No. 3 in series with relay logic circuits in either the primary or alternate landing gear logic units control operation of coaxial relay No. 3, the VOR/ILS test inhibit logic circuit in autopilot accessory box No. 3 controls the test circuit for coaxial relay No. 3.
 H. Functional Description, Data Switching (Fig. 6)
 (1)  
All signals which interface with the three VOR/ILS receivers (except rf from the antennas) pass through the VOR/ILS relays. With the VOR/ILS transfer switch in the normal position the captain's VOR/ILS relay is in position No. 1 and the first officer's VOR/ILS relay is in position No. 2. In this mode input data, power, and control signals are applied to receivers No. 1 and 2. The outputs from receiver No. 1 are applied to the captain's instruments while the first officer views data from receiver No. 2.

 (2)  
In an alternate configuration receiver No. 3 sends data to either the captain's or first officer's instruments dependent upon the position of the VOR/ILS transfer switch.

 I. Functional Description, ILS No. 3 Fail-Op Annunciators (LH 011-099)
 (1)  Flag signals to drive the G/S-3 and LOC-3 fail-op annunciators originate within VOR/ILS receiver No. 3 as shown in Fig. 7. The annunciators display either a black (valid) or red (invalid) ILS mode of operation for receiver No. 3.
 EFFECTIVITY

 AF 101-120, 123-154,  CONFIG 1 172-173, 191-194; GN ALL;  01 Page 43 LH ALL AND MD ALL  Sep 25/94

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 VOR/ILS NAVIGATION SYSTEM - DESCRIPTION AND OPERATION
_____________________________________________________
 1.  General
_______
 A.  Two VOR/ILS (VHF omnidirectional range/instrument landing systems) navigation systems and a switchable 3rd receiver are installed. A system consists of a VHF NAV control panel, a VOR/ILS receiver, transfer switching, antenna switching, and displays on flight instruments. A VOR antenna, two localizer antennas, and six glide slope antennas (three on AT ALL and four on AZ 221-299, SN 351-399 and IB 406-499) provide radio frequency inputs to the receivers. Either the VOR or the LOC antenna is selected by means of the A/P-F/D mode logic circuits. Figure 1 shows the location of each of the units associated with the VOR/ILS navigation system.
 B.  The VOR/ILS navigation system determines airplane bearing with respect to ground-based VOR stations and airplane position with respect to a selected VOR radial, or to an ILS approach path. This data is provided to the autopilot/flight director (A/P-F/D) system and to displays on the captain's and first officer's instrument panels. On AT ALL; AZ ALL; SN 351-399 and IB 406-499, plus XA airplanes incorporating SB 34-2069, glide slope deviation information is also provided to the ground proximity warning system computer.
 C.  Airplane magnetic bearing to the VOR ground station signals received is determined by the VOR portion of the system. The ILS portion of the system provides lateral and vertical deviation information with respect to a radio beam positioned above runways for landing guidance.
 D.  Power is applied to the VOR/ILS system through circuit breakers on overhead circuit breaker panel P7. On AT ALL; AZ ALL; SN 351-399 and IB 406-499, the No. 1 ILS buffer amplifiers and VOR/ILS receiver No. 3 are supplied power through circuit breakers on overhead lightplate circuit breaker panel P126.
　
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