(2)  
AF 121, 122, 155, 156, 158-160, 162-171, 174-182, 185-190, AND AF 157, 161, 183, 184 WITH SB 34-2264; VM ALL, Glide slope rf is fed to the three VOR/ILS receivers from either the capture antenna in the nose radome or the track antenna in the leading edge of each aft nose wheel well door through coaxial relays and a hybrid coupler. The hybrid couples the glide slope rf to receivers No. 1 and 3, while receiver No. 2 is fed directly from the coaxial relay.

 (3)  
AF 157, 161, 183, 184 WITHOUT SB 34-2264, glide slope rf is fed to the three VOR/ILS receivers through coaxial relays and hybrid couplers from two capture antennas and one track antenna in each aft nose whell well door. Relative position of the landing gear (doors closed or open) changes the polarity of the glide slope antennas, essentially selecting the capture antennas when the aft whell well doors are closed and the track antenna when the doors are open.

 (4)  
The coaxial relays are controlled by transistor switching logic in the primary and alternate landing gear logic units. The relays are energized to complete the glide slope capture antenna configuration when the landing gear are up and glide slope 28-volt dc power is available. When the landing gear are down, the relays are de-energized, to open the rf line between the capture antennas and the VOR/ILS receivers. This leaves the VOR/ILS receiver glide slope rf input connected to only the glide slope track antenna eliminating spurious capture signals which cause loss of glide slope capture when in track antenna configuration and the airplane is flown at high bank angles.

 EFFECTIVITY

 AF 121, 122, 155-171,  CONFIG 3 174-190, 195-199;  01 Page 13 VM ALL  Sep 25/94

34-31-00

VOR/ILS Power Block Diagram
Figure 3 (Sheet 1)

EFFECTIVITY AF 121,122,155-171,174-190,
CONFIG 3 195-199
799 Page 14
34-31-00
Sep 25/94

P7 OVHD CB PNL F/O VOR/ILS
RECEIVER 2

1
B XFR RLY VOR/ILS Power Block Diagram Figure 3 (Sheet 2)
EFFECTIVITY

CONFIG 3 VM ALL
799 Page 15
34-31-00
Dec 25/85

P126 OVHD LTPT CB PNL VOR/ILS Antenna Schematic Figure 5 (Sheet 1)
EFFECTIVITY AF 155,156,158-160,162-171,174-182,185-190,195-199 AND AF 157,
 CONFIG 3 161,183,184 WITHOUT SB 34-2264; 799 Page 18VM ALL
34-31-00
 Sep 25/94

VOR/ILS RECEIVER 1
VOR/ILS Antenna Schematic Figure 5 (Sheet 2)
EFFECTIVITY AF 155,156,158-160,162-171,174-182,185-190,195-199 AND AF 157,
CONFIG 3161,183,184 WITHOUT SB 34-2264; 799 Page 19 VM ALL
34-31-00
Sep 25/94

P126 OVHD LTPT CB PNL
DIODE M2311 USED
ON UT 301-349

VOR/ILS Antenna Schematic
Figure 5 (Sheet 3)

EFFECTIVITY AF 121,122 AND AF 157,161,183,
CONFIG 3184 WITH SB 34-2264 799 Page 20
34-31-00
Sep 25/94
 E48068

VOR/ILS RECEIVER 1
VOR/ILS Antenna Schematic
Figure 5 (Sheet 4)

EFFECTIVITY AF 121,122 AND AF 157,161,183,
CONFIG 3184 WITH SB 34-2264 799 Page 21
34-31-00
Sep 25/94
 E48102

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

EFFECTIVITY AF 156,158-160,162-171,174-182,
CONFIG 3185-190,195-199
799 Page 27
34-31-00
Sep 25/94

VOR/ILS Interface Block Diagram
Figure 6 (Sheet 7)

EFFECTIVITY AF 156,158-160,162-171,174-182,
CONFIG 3185-190,195-199
799 Page 28
34-31-00
Sep 25/94

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

EFFECTIVITYAF 156,158-160,162-171,174-182,
CONFIG 3185-190,195-199
799 Page 29
34-31-00
Sep 25/94
 (5)  AF 121, 122, 155, 156, 158-160, 162-171, 174-182, 185-190, AND AF 157, 161, 183, 184 WITH SB 34-2264; VM ALL, Glide slope antenna test switches and associated annunciators on the pilots' center instrument panel (P2) provide a means for checking coaxial relay operation. Pushing an 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 whenever the AFCS is operating in VOR/LOC, ILS or LAND mode and channel A, B or C of the AFCS is in command.
 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 transfer switch in the normal position the captain's and first officer's VOR/ILS relays are in the normal position. 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.
　
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