C. Functional Description, Glide Slope Mode of Operation (Fig. 2)
(1) BENDIX RNA-26C Receiver
(a) The glide slope receiver is a conventional crystal controlled, double conversion, superheterodyne receiver employing front end two-of-five tuning controlled by the frequency select switch on the VHF NAV control panel. The glide slope audio signal is applied from the audio amplifier through the 90/150-Hz glide slope filter to the glide slope detector. The glide slope deviation signal from the detector is used by the AP/FD system and also drives the ADI and HSI glide slope deviation displays.
EFFECTIVITY
AF 101-120, 123-154, CONFIG 1 172-173, 191-194; GN ALL; 06 Page 11 LH ALL AND MD ALL Sep 25/94
34-31-00
(b) The glide slope integrity monitor circuits which provide outputs to the flag logic circuits are functionally identical to the localizer monitor circuits discussed above.
(2) Bendix RNA-34A Receiver
(a) In glide slope operation, the 90-Hz/150-Hz signal output of the UHF receiver is fed through filters to the ILS multiplexer. The output of the multiplexer is fed through an analog-to-digital converter to the microprocessor. From this signal input, the microprocessor develops glide slope deviation voltages that are fed to the glide slope deviation displays in the flight instruments. As in VOR and LOC operation, the microprocessor monitors operation of the unit and produces a GS warning (flag) if a malfunction occurs.
D. Functional Description, VOR/ILS Self-Test Operation (Fig. 2)
(1)
On LH ALL EXCEPT 014-050, 061-081 and 084-099, only the VOR self-tests are used. The ILS self-tests circuits are not connected inside the VHF NAV control panels.
(2)
On LH 014-050, 061-081 and 084-099, both the VOR and the ILS UP/LEFT self-test circuits are operational.
(3)
BENDIX RNA-26C Receiver
(a) When a VOR self-test is actuated on the VHF NAV control panel, the VOR check switch operates and the 30-Hz reference phase signal is fed down both channels to the phase detector resulting in a zero degree heading readout on the OBI dial. If any error in the system exists, it should be calibrated out by the automatic calibration circuits which are still active during the VOR self-test.
(4)
Bendix RNA-34A Receiver
(a)
VOR/ILS self-test provides the VOR and ILS self-test audio signals, timing sequence for control of the flags during self-test. A self-test is initiated by the test switch on the VHF NAV control panel with control provided by a preprogrammed control panel with control provided by a preprogrammed Read-Only-Memory capable of generating VOR test, DN/R test, UP/L test and End test outputs.
(b)
The self-test oscillator and modulator provides a modulated rf carrier in self-test mode of operation. Since the synthesizer also tunes with a self-test input, the receiver does not need to be tuned off channel to receive the self-test input.
(c)
Modulated rf test signals, generated by the self-test oscillators, are applied to the input of the VHF and UHF receiver sections to simulate a VOR signal on any VOR channel or localizer and glide slope signals on any ILS channel. These signals provide an overall operational test for the VOR/ILS navigation system.
(d)
Prior to self-test initiation control logic will allow normal operation of the GS and VOR/LOC flags. When self-test is initiated the GS and VOR/LOC flags will be driven out of view and remain out of view through completion of test.
E. Control
EFFECTIVITY
AF 101-120, 123-154, CONFIG 1 172-173, 191-194; GN ALL; 06 Page 12 LH ALL AND MD ALL Sep 25/94
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VOR/ILS RECEIVER
VOR/ILS Receiver Block Diagram Figure 2 (Sheet 1)
EFFECTIVITY
CONFIG 1 AIRPLANES WITH BENDIX
799 Page 13/14RNA-26C VOR/ILS RECEIVERS Dec 25/85
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VOR/ILS RECEIVER
VOR/ILS Receiver Block Diagram Figure 2 (Sheet 2)
EFFECTIVITY CONFIG 1
AIRPLANES WITH BENDIX
799 Page 15/16RNA-34A VOR/ILS RECEIVERS
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Dec 25/85
(1) Turn-on Procedure (Fig. 3)
(a) Provide electrical power to system (Ref 24-22-00).
CAUTION: MAKE SURE THAT THE EQUIPMENT COOLING SYSTEM IS
_______ OPERATING BEFORE TURN-ON OF THE ELECTRICAL OR ELECTRONIC SYSTEMS OR HEAT DAMAGE COULD RESULT (REF 21-58-00, ADJUSTMENT/TEST).
(b)
Set the VOR/ILS transfer switch to the center position. (Capt 1 - F/O 2).
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