NORMARC NM 7000 Series, Инструкция по установке и пусконаладке

Страница: 69 / 189

Example 1:
Item 1: A1/A12: +4.3% DDM
Item 3: A1+MF/A12: -2.0% DDM (MF in A1)
Example 2:
Item 1: A6/A7: -0.6% DDM
Item 3: A6 /A7+MF: +1.86% DDM (MF in A7)
Cable trimming length: 6.2 mm/°.
1.2.5 Phase and amplitude transfer measurement
Connect each antenna cable and monitor cable to LPDA load and source respectively. Utilise
a vector voltmeter or network analyser in a test set-up
Figure 1-2 Phase and amplitude transfer measurement set-up.
Measure relative transfer phase and amplitude for each Antenna/Monitor return cable in ref-
erence to A1/M1.
Then determine if one or more of the monitor cables must be trimmed in order to comply with
phase tolerance for the set of cables.
Tolerance: ±2°.
ϕ
9
°
4.3
⋅
4.3 2.0 +
---------------------
4.8
°
= =
ϕ
9
°
0.6
⋅
0.6 1.86 +
------------------------
1.7
°
= =
20dB
A B
VECTOR VOLTMETER
A(n)
M(n)
From cabinet
CSB BNC o/p
LPDA
DIR. COUPL.