B KRA 405
Rev 6, June 2003 IM 006-00104-0006.dwd Page 2-2
Three altitude trips are provided in the KRA 405 Radar Altimeter R/T (P/N 066-01048-
0002) and set at 250, 500 and 1200 feet. Should the customer elect to have these
altitudes changed, the installing agency should follow the steps in paragraph 2.3.2.
2.3.2 RESETTING THE ALTITUDE TRIPS
2.3.2.A. Equipment Required
2.3.2.B. Procedure
NOTE: All test points and adjustment points are shown in Figure 2-11.
2.3.2.B.1 Remove the R/T cover by turning the two (2) quick connect screws one-half
turn counterclockwise.
2.3.2.B.2 Place a 50 ohm termination on the transmitter antenna connector (lower TNC
connector).
2.3.2.B.3 Connect +27.5 Vdc to Pin L and ground Pin N on the front connector.
2.3.2.B.4 Connect a DVM to TP 506. The DVM should indicate -28 +/- 1.5 Vdc.
2.3.2.B.5 Connect an audio frequency generator to TP 201. Adjust the frequency of the
generator to 3,000 Hz. Adjust the level of the generator until -8.01 +/- 1.5 Vdc
is present at TP 207.
2.3.2.B.6 Adjust the frequency until the voltage at TP 506 indicates the desired altitude
trip voltage according to the formula: V = A x (-0.01 V/ft),
Where: V = Voltage in volts at TP 506
A = Desired altitude trip level in feet
Example: 100 ft = 100 ft x (-0.01 V/ft) = -1 Vdc
2.3.2.B.7 To adjust Altitude Trip #1, connect the DVM to TP 605. Adjust R616 counter-
clockwise until -8 +/- 1.5 Vdc is present at TP 605. Then slowly rotate R616
clockwise until the voltage at TP 605 switches to +28 +/- 1.5 Vdc.
2.3.2.B.8 To adjust Altitude Trip #2, follow the procedures in steps 4 through 7 above
using TP 607 and R622 in step 7.
TABLE 2-1 Altitude Trip Set Test Equipment (Audio Generator)
TYPE CHARACTERISTICS REPRESENTATIVE MODELS
Audio Signal Generator Hewlett Packard 200CD or
equivalent.
Digital Voltmeter (DVM) Eldorado 1820A or equivalent
Power Supply 28 V @ 1.5 amps
RELEASED FOR THE EXCLUSIVE USE BY: AIRCRAFT ELECTRONICS ASSOCIATION
UP536434
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