NORMARC NM 7000 Series, Инструкция по установке и пусконаладке, Страница: 130 / 189

10 NM 3562 Dual antenna system adjustments - MKR
10.1 Mechanical alignment
10.1.1 Antenna mast
Utilise a waterlevel and align the mast vertically by adjustments of the base nuts.
10.2 Electrical measurements
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Connect a directional coupler terminated in 50* 10W to the N output connector of the Marker.
Then use the forward coupled port as the signal source for the measurements.
Always use a 20 dB attenuator at the I/P of the directional coupler in Fig. 1,2 and 3.
10.2.1 Antenna cable lengths (Electrical phase equality)
Each antenna cable must be electrically measured before the end connector is terminated in
the LPDA.
Utilise a vector voltmeter or network analyser. Establish antenna cable (A1) return phase as
0° reference phase.
Measure return phase for the other antenna cable (A2). Then take into account the phase
centres of the LPDA's given in the factory data sheet.
Tolerance: ±1.5° true electrical cable length.
See measurement set-up diagram Figure 10-1 below:
Figure 10-1 Cable phasing measurement set-up.
20dB
A B
VECTOR VOLTMETER
CABLE UNDER TEST
OPEN END
DIR. COUPL.
From Marker
Dir. coupler