B KRA 405
Rev 6, June 2003 IM 006-00104-0006.dwd Page 2-12
2.5.3.2 Test Method 2
KRA 405 Radar Altimeter Post Installation Test Procedures using audio generator.
2.5.3.2.A Purpose of Test
This test simulates altitudes of 0 to 2,500 ft to the IF and altitude processor. This test
does not check the RF output, but may indicate poor coax cables and connectors.
2.5.3.2.B Required Equipment
The items listed below or their electrical equivalent may be used to conduct the tests
in this section.
2.5.3.2.C Test Procedure
2.5.3.2.C.1 Connect the equipment as shown in Figure 2-12
NOTE: It may be necessary to remove the aircraft from the hanger, away from
the other aircraft and/or sources of reflections in order to achieve an un-
lock condition with the microwave absorber.
2.5.3.2.C.2 Set the attenuators to maximum. Adjust the output level at the terminals of
the audio oscillator for 226 mV (0 dBm into a 50 ohm load). The attenuation
in the line then represents the input signal level. Readjust the oscillator each
time the frequency range is changed.
2.5.3.2.C.3 Apply each of the following frequencies to TP 201 and then by slowly in-
creasing the attenuation, determine the input signal level at which the unit un-
locks. The minimum attenuation level and the displayed altitude are listed be-
low.
TABLE 2-5 IF and Altitude Processor Test Equipment (Audio Generator)
QTY TYPE CHARACTERISTICS REPRESENTATIVE MODELS
1 Audio Generator 100 Hz to 250 kHz mini-
mum range
Hewlett Packard 200CD
1 Audio Attenuator 0-12 dB in 1 dB steps Hewlett Packard 355C
1 Audio Attenuator 0-120 dB in 10 dB steps Hewlett Packard 355D
1 RMS Voltmeter Ballatine 310B
2 Microwave Absorber 1 ft square Anlon ML 74
2 TNC Female Barrel Americon 3180-0000
2 TNC Male Load Microlab FXR TA-SMT
RELEASED FOR THE EXCLUSIVE USE BY: AIRCRAFT ELECTRONICS ASSOCIATION
UP536434
To Next Page
Loading...
