(2)
34-55-00, Operational Test - DME System
B. Equipment and Materials
(1) DME Ramp Test Set - Collins 475D-1 (modified for AUTO 5-180 feature) or equivalent
C. Prepare for Test
(1)
Calibrate ramp test set as indicated in test set instruction book.
(2)
Ensure that following circuit breakers at P7 panel are closed:
On LH 001-010, 031-050, 071-080; AF 101-171; AZ 201-220, IB 405; SN ALL,
DME 1 - AC
DME 1 - DC
DME 2 - AC
DME 2 - DC
On LH 011-030, 051-070, 082-099; AF 172-199; AZ 221-299; IB 406-499; AT ALL; GN ALL; MD ALL; VM All,
DME 1 - AC
DME 2 - AC
(3) Provide electrical power. Refer to 24-22-00.
CAUTION: MAKE SURE EQUIPMENT COOLING IS OPERATED BEFORE TURN ON OF
_______ ELECTRONIC SYSTEMS OR DAMAGE TO EQUIPMENT MAY RESULT. EQUIPMENT COOLING SYSTEM MUST BE SET FOR NORMAL COOLING AS DESCRIBED IN 21-58-00.
D. Test DME System
(1)
Perform DME system operational test. Refer to 34-55-00.
(2)
Place DME test set approximately 30 to 40 feet from DME antennas. Be sure there are no obstructions between the test set and DME antennas. (Run test on line-of-sight basis.)
(3)
Turn test set on and set TR ATTEN DB tester control to 15 db position.
(4)
Set function selector on tester to 5 MI position.
(5)
On captain's VHF NAV control panel, select 108.00 MHz and position mode switch to DME (XA ALL EXCEPT LH 011-030, 051-070, 082-099). On first officer's VHF nav control panel, select 109.00 MHz.
EFFECTIVITY
ALL 42 Page 502 Dec 25/8834-55-00
(6) Actuate DME 1 switch on audio control panel and verify presence of
DME audio tone at captain's position headphones.
NOTE____ If interphone system for more than captain's position or
speaker system is to be used: close interphone circuit
breakers on panel P7 (MAIN, FLTAML, CAPT, F/O).
(7) Verify that DME indicators read 005.0 (| .1) in DME 1 section of
indicators. DME 2 section of indicators will show dashes.
(8) Switch captain's DME to different channel; then back to 108.00 MHz.
Check for lock-on and presence of audio tone.
(9) Repeat steps (3) through (8) using first officer's DME system and
DME 2 indications. Check that warning flags appear in DME 1 section
of indicators.
(10) Remove electrical power if no longer required. Refer to 24-22-00.
EFFECTIVITY
ALL 20 Page 503 Dec 25/8834-55-00
AUTOMATIC DIRECTION FINDER SYSTEM - DESCRIPTION AND OPERATION
_____________________________________________________________
1. General (Fig. 1 and 2)
_______
A. The automatic direction finder system (ADF) is a navigational aid which receives radio signals from 190 to 1750 kilohertz and determines the direction to the station. Signal sources used are low frequency and standard broadcast radio stations. The system is used for either automatic or manual determination of bearing to a transmitting station, for flying radio ranges, and for reception of weather information and other broadcast programs.
B. Two separate and completely independent automatic direction finder systems are installed in the airplane. Each system consists of a receiver, sense antenna, sense antenna coupler, fixed loop antenna, quadrantal error corrector, and control panel.
C. Operation and mode selection of each automatic direction finder receiver is controlled from the flight deck. The receiver uses signals from both the sense and the fixed loop antennas to compute the bearing of the radio station being received. The bearing information if provided to flight instrument displays. Station audio is routed to the flight interphone system (23-51-00) for monitoring.
D. The direction finder system operates on 26 volts, 400 Hz and 28-volt dc power through circuit breakers on panel P7.
E. The 26VAC power for RMI ADF pointer excitation is routed through the ADF control panel where it may be broken when the system is switched off (Fig. 2).
2. Loop Antenna (Fig. 1)
____________
A. The fixed loop antenna is a sealed, nonrotating, direction-sensitive rf pick-up device for the automatic direction finder system receiver. The antenna consists of two pairs of ferrite core coils, one pair oriented parallel to and the second pair oriented perpendicular to the fore and aft axis of the airplane. Both coil pairs are coupled to the system receiver through the quadrantal error corrector and loop antenna transmission cable.
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