Nortel Passport 15000, Установка и обслуживание оборудования, Страница: 558 / 874

558 Chapter 17 Hardware procedures
241-1501-240 5.2S2
Installing a timing cable for E1 unbalanced NTHR75
Install a timing cable assembly for E1 unbalanced in Passport 15000 to
connect an E1 unbalanced timing signal from the site source to the
alarm/BITS module with PEC NTHR14.
Prerequisites
• You must be familiar with “Safety considerations and best practices”
(page 53).
• You need a timing cable assembly with PEC NTHR75. This timing cable
is a 46-cm (18-in.) red cable assembly that converts the site coax BNC
connector to a 2W2 interface at the BITS module for E1 unbalanced
applications. See the figure “A timing cable assembly NTHR75”
(page 560).
• For custom-made cables, see cable specifications in the 241-1501-200
Passport 15000, 20000 Hardware Description.
Procedure steps
1 Connect the cable end labeled Rx to the Tx of the site timing source. Do
not use the end labelled Tx. Wrap electrical tape around the Tx end to
prevent metal-to-metal contact.
2 Use a line analyzer to determine the signal strength for the timing signals
at the J3 and J4 connections from the site source. The signal strength
must be within the range indicated in 241-1501-200
Passport 15000,
20000 Hardware Description.
If the signal is not within the range, fix the problem between the point of
test and the site source. Depending on the length of cable from the site
source, you many need a thicker gauge cable to provide the signal
strength.
3 At the alarm/BITS module, plug the male D-sub connector of the cable
into the connector labelled J3.
4 Fasten the 2 small slotted screws of the D-sub connector to the
alarm/BITS module. Tighten to snug plus a 1/5 turn.
5 Repeat this procedure for the redundant timing setup. Connect the
second timing cable into the alarm/BITS connector labelled J4.