EXFO CableSHARK P3 VF/DSL Cable Qualifier - Manual (Page 139)

CableSHARK P3 User Guide
127
Test completed. At least 2 load coils detected.
MAIN
MENU
E F CHG
SAVE/
UPLOAD TEST
SETUP
1000 3200 5400 9800 Hz 7600
3000
SHOW
REF
Ohm
2000
1000
0
Press or to move cursor
Impedance
Cursor position = 745 ohms
= 5390 Hz
4000
3000
2000
1000
0
4000
ZOOM IN
HORIZ ZOOM IN
VERT
F IGURE 8.6.2B - R ESULTS OF A S INGLE E ND L OAD C OIL D ETECTION T EST
As shown in the figure above, the CableSHARK will indicate whether or not there are load coils on the line. If
the Load Coil Detection Test indicates that there is a load coil on the line, the user can use the TDR test to
quickly locate and remove any load coils on the cable.
When finding the location of load coils with TDR, remember that the waveform will generally show a more
rounded appearance than an open at the location of a load coil. Loading coils come in two values: the H88
(88 mH), which is normally placed every 6000 ft apart, and the D66 (66 mH), which is normally placed every
4500 ft apart. Depending on the location in the section, load coil spacing is very particular – at 3000 feet
(914 m) or 6000 feet (1829 m) intervals for H88 load coils. Suspect a load coil if you see an open-like
reflection on the waveform at approximately 6000 feet (1829 m) from the TDR, although not all load coils
look the same. The first load coil is all that you will see, since the TDR’s signal cannot pass through a load
coil. Once you have found the first load coil, remove it and retest the cable.
At the completion of a test, the function button command selection at the bottom of the LOAD COIL TEST
RESULT screen consists of several options available to the operator for a LOAD COIL RX test. The
following are brief descriptions of each of the function button options:
Pressing the SAVE / UPLOAD button shows a pop-up window where the user is allowed to upload results,
and save results to internal memory or to external USB memory.