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11.3.1 Pre-Power Testing
Before plugging the RJ45 from the lower LPU (or if not fitted the ODU) into the PIDU, check
the following resistances at the RJ45:
1. Check the cable resistance between pins 1&2, 3&6, 4&5 and 7&8 at the RJ45. Check
against column 2 in Table 23. Resistances for each pair should be within 1 ohm of each
other.
2. Check the cable resistance between pins 1&3 and 4&7 at the RJ45. Check against
columns 3 and 4 respectively in Table 23.
3. Ensure that there is greater than 100K ohms between pins 1&8 for all cable lengths.
4. Ensure that there is greater than 100K ohms between pin 1 and ODU ground for all cable
lengths.
5. Ensure that there is greater than 100K ohms between pin 8 and ODU ground for all cable
lengths.
CAT-5
Length
(Meters)
0
10
20
30
40
50
60
70
80
90
100
Table 23 - Resistance Table Referenced To The RJ45 at the PIDU+
Resistance between
pins 1&2, 3&6 , 4&5 and
pins 7&8 (ohms)
0.8
2.5
4.2
5.9
7.6
9.3
11.0
12.7
14.4
16.1
17.8
161
11 Lightning Protection
Resistance between
pins 1&3 (ohms)
1.0
2.7
4.4
6.1
7.8
9.5
11.2
12.9
14.6
16.3
18.0
Resistance
between pins 4&7
(ohms)
1.6
3.3
5.0
6.7
8.4
10.1
11.8
13.5
15.2
16.9
18.6
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