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Options and Accessories
3–4
1503C MTDR User Manual
H
Use the shortest pulse width possible.
H
Do not use Auto pulse width mode. If it selects the 100 ns or 1000 ns pulse, it
might disrupt traffic on working networks.
H
Use the simplest possible test first.
H
Operate the 1503C on AC power when using the option chart printer.
H
Changes made in the menus do not take effect until the instrument is returned
to normal operation. This prevents erroneous menu selections from creating
disruptions.
H
Have the network documentation ready. If available, have prior TDR profiles
of the network that you will be comparing.
H
If possible, turn off repeaters and bridges to other networks to minimize the
extent of a possible disruption the 1503C might cause.
H
If you use a jumper cable, make sure that it matches the network cable
impedance. The three-foot jumper furnished with the instrument is 50 .
The IEEE 802.3 standard recommends only one earth ground per segment. When
connected to AC power, the 1503C provides an earth ground to the coaxial shield.
There is no connection to ground when the 1503C is used with the optional battery
pack and the AC power cord is disconnected.
The first test usually run on an active network is the normal sweep with the 2 ns or
10 ns pulse and the DC 50
W
termination is: On from the Ethernet Menu. This test
provides basic TDR tests with a 50 termination for the net. If the network traffic
is low (3 to 4%), this test is very effective. The 2 ns and 10 ns pulses are narrower
than the time occupied by a single bit and usually will not cause any collisions. All
other tests in the Ethernet Menu have potentially destructive effects on working
networks.
CAUTION.
The test just described should find most problems. Before going any
further, know what you are doing. Carrier and collision tests have the potential of
causing problems on an active network. Read the warnings and instructions
carefully. Try to limit tests to one segment during times of low traffic.
The second test is the Single Sweep with Carrier is: Off/On. This test asserts the
carrier signal of -1.05 V, then single-sweeps the network and drops the carrier signal.
The test occupies the network for one to 20 seconds, depending on the NOISE
FILTER setting.
The third test, Carrier Test is: Off/On, helps track down transceivers suspected if
ignoring the carrier sense signal. This test holds the carrier signal of -1.05 V, turns
off the pulse, and turns on MAX HOLD. The 1503C then acts as a traffic monitor.
Introduction
Summary of Contents for 1503C
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Page 92: ...Appendix A Specifications A 6 1503C MTDR User Manual...
Page 104: ...Appendis B Operator Performance Checks B 12 1503C MTDR User Manual...
Page 122: ...Glossary Glossary 6 1503C MTDR User Manual...
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