CAUTION: NEVER PLACE REMOTE TEST SET ANTENNA CLOSER THAN 15 INCHES TO AIRPLANE ANTENNA WITH TEST SET ON. DAMAGE TO TEST SET WILL RESULT.
(2)
Route and connect coax from remote test set antenna to test set which should be located in cockpit.
(3)
Set test set controls as follows:
PWR switch -AC or BAT (as appropriate)
Mode switch - DME Velocity Select switch – RANGE
Velocity HI/LO switch – HI
Squitter ON/OFF switch – ON
X/Y switch - X
C. Test DME System
(1)
On both VHF NAV control panels, select 109.00 MHz and position DME mode selector to NORM or ON. DME indicators should display dashes.
(2)
Actuate DME self-test. Verify that in approximately 1.5 seconds, indicators DME display 000 +0.5 miles.
(3)
On appropriate VHF/NAV control panel tune:
(a)
On GJ ALL EXCEPT B-2504 and B-2505,
1) Left frequency display - 108.00 MHz
2) Right frequency display -108.05 MHz
3) Position TFR switch -108.00 MHz
(b)
On GJ B-2504 and B-2505,
1) Frequency display -108.00 MHz
(4)
Position test set controls as follows:
(a)
Squitter ON/OFF - OFF
(b)
Distance Display - Slew to 6 miles. DME indicators display dashes
(c)
Squitter ON/OFF -ON. DME indicators displays 6 +0.5 miles.
(5)
Repeat step (4) for 60, 100, and 188 miles.
(6)
Repeat step (4) for 220 miles. Verify DME indicators display dashes.
(7)
Position captain's DME mode selector to O'RIDE. Verify DME displays 220 +0.5 miles.
(8)
On audio selector panel, select NAV-1 and place VOICE/BOTH/RANGE switch to BOTH or RANGE.
(9)
Hold test set IDENT switch in IDENT and verify presence of DME audio.
(10)
Release IDENT switch.
NOTE: DME will break lock-on if IDENT is held for longer than 12 seconds.
(11)
On GJ ALL EXCEPT B-2504 and B-2505, position VHF NAV control panel TFR switch to 108.05 MHz.
(12)
On VHF/NAV control panel, position DME mode selector to NORM or ON. DME should display dashes.
(13)
Position test set controls as follows:
(a)
Squitter ON/OFF - OFF
(b)
X-Y- Y
(c)
Distance Display - Slew to 180 miles.
(d)
Velocity Select - 600
(e)
Velocity IN/OUT - IN
(f)
Squitter ON/OFF -ON. DME will search, lock on, and track smoothly inbound.
(14)
Repeat step (13) with Velocity IN/OUT in OUT and distance display beginning at 5 miles.
(15)
Restore airplane and test set to original configuration and remove electrical power if no longer required.
5B9
Jun 20/85 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 34-55-0 Page 503
5B9
34-55-0 Page 504 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. Jun 20/85
DME SYSTEM - DESCRIPTION AND OPERATION
EFFECTIVITY
GJ B2509 and B2510
1. General
A. The DME (Distance Measuring Equipment) system continuously measures the slant range distance between the airplane and a selected ground station and displays it on appropriate DME indicators as nautical miles. The DME interrogator and VHF navigation receiver are tuned simultaneously by the VHF NAV control panel.
B. The interrogator unit transmits a pulse-coded interrogation signal that actuates a corresponding ground station reply. This reply signal is received and processed by the interrogator. The time interval between the interrogation signal transmitted from the airplane and the ground station reply signal received by the airplane is measured, converted into distance (nautical miles), and displayed on appropriate DME indicators.
C. Two DME systems are installed in the airplane. Each system consists of an interrogator (receiver-transmitter) unit, an antenna, and a VHF NAV control panel.
D. The DME system operates on 115-volt, 400-Hz power supplied through circuit breakers DME 1 - AC on load control center P18 and DME-2 AC on load control center P6.
E. The DME system interface is shown in Fig. 2. The output of the interrogator is applied to the appropriate DME-1 and DME-2 readouts on captain's and first officer's RDDMIs. A sample pulse is taken from the interrogator and coupled to the ATC system, which operates in the same general frequency range. This pulse acts as a suppression pulse. An audio signal from the DME interrogator is applied to the flight interphone system. On airplanes with a performance data computer, the DME interrogator provides distance information to the performance data computer system by an analog pulse pair and DME valid signal output (Ref 34-18-0).
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