NORMARC NM 7000 Series, Инструкция по установке и пусконаладке, Страница: 72 / 189

Move the directional coupler to A4 and compare readings with calculated value. If measured
DDM is lower than the calculated values for A4 then increase the SBO power, or vice versa,
until a fairly good matching set of values are obtained.
Adjust the SBO attenuator for the other Tx to the same setting.
Remove the 90°-stub
1.3.2 DDM field check
Set the localizer to normal radiation. From the centreline of the opposite threshold determine
points perpendicular to the CL 105 meter to both sides of the runway. Use the NM3710 with
portable antenna and measure DDM at these points. The readings should be close to -15.5%
at the 90-side and 15.5% at the 150-side. However, some unsymmetry may be expected due
to reflections and tolerances in the antenna system.
Check the CL DDM at two or three positions in order to estimate an average value.
Expected value: 0.0%±0.2% DDM.
1.4 Monitor combining unit (MCU) adjustments
1.4.1 Course Line
Connect the Field Test Set to the CL output connector of the MCU.
Adjust the CL line stretcher to obtain 0.0% DDM.
1.4.2 Course Sector
Connect the Field Test Set to the CS output of the MCU.
Adjust the CS line stretcher to obtain a reading of 15.5% DDM.
1.5 Near field monitor adjustments
The exact position of the near field monitor antenna cannot be determined until after the flight
check is completed, due to possible mechanical re-alignment of the antenna array.
1.5.1 Mechanical alignment
Align the near field (NF) monitor antenna mechanically in the extended runway centreline
position.
1.5.2 Final electrical position adjustment
Connect the Field Test Set to the NF monitor cable. The reading should be 0.0% DDM if the
antenna is aligned correctly and no reflections appear.
Otherwise, a small mechanical re-positioning of the antenna may be necessary in order to
obtain 0.0% DDM.