NAVAIR 17—2OAX—737
4.10.6 Verify that the difference between the 150 Hz DEMOD voltage recorded in step 4.10.3, and the
90Hz DEMOD voltage recorded in step 4.10.5, is ~2.75 mV rms.
4.11 GIS CENTERING TEST
4.11.1 Set the TI controls as follows:
LOC—G/S switch to
G/S
LOC DDM switch to
150 Hz
G/S DDM switch to
0
4.11.2 Record the 150 Hz DEMOD voltage as indicated on the DMM.
4.11.3 Set the TI LOC DDM switch to 90 Hz.
4.11.4 Record the 90 Hz DEMOD voltage as indicated on the DMM.
4.11.5 Verify that the difference between the 150 Hz DEMOD voltage recorded in step 4.11.2, and the
90Hz DEMOD voltage recorded in step 4.11.4 is, 2.75 mV rms.
4.11.6 Disconnect the DMM from the TI.
NOTE
Perform the appropriate Spectral Purity Tests subsection corresponding to the TI being
calibrated (4.12 for NAV—750, 4.13 for NAV—750A, and 4.14 for NAV—750B).
4.12 SPECTRAL PURITY TESTS (NAV-750 ONLY)
4.12.1 Set the TI controls as follows:
FREQUENCY MHz switches to
108.000
MASTER MOD control to
UNCAL [fullyccw (0)]
Output attenuator control to
—10 clBm
4.12.2 Connect the spectrum analyzer input to the TI RF output connector.
4.12.3 Set the spectrum analyzer for a center frequency of 108.0 MHz, and a frequency span of
100 MHz/div with a 3 MHz resolution bandwidth.
NOTE
For the following tests, set the spectrum analyzer frequency span and center frequency
controls as necessary to check the level ofthe harmonics of the TI signals.
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