Triplett CableRater- PN: 3279 - Manual (Page 13)

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Observe the reading on the CableRater. If any reading is obtained, other than the
Underrange indication, ingress is occurring. The higher the reading, the more
ingress. This condition must be resolved before testing for Loss.
9.3.2 Fixing Ingress
The common cause of ingress is a coaxial cable with an open shield. The cable
itself may be OK, but the shield may be losing its connection where the F con-
nector screws on to the splitter or other device. If this connection is not clean
and tight, the shield may be losing contact and allowing ingress. Make sure the
screw-on part of the F connector is snuggly tightened. A small wrench can be
used, but do not overtighten and cause damage to the connector or the equip-
ment to which its attached.
Ingress might occur if the F connector on the cable or the attached device has
been exposed to the weather, and surface corrosion has caused the connector to
lose contact. If this occurs, replace the connectors/devices involved.
An open shield can also be caused by improper installation of the F connector on
the end of a cable. Install the connector properly.
A cable that is flexed or stretched excessively can develop a break in the shield.
Replace the cable.
If the over-the-air signals are especially strong in the vicinity of the test, ingress
can occur if the ends of the cable are left unterminated. The small center con-
ductor of the cable acts as an antenna, picking up over-the-air signals. There are
‘terminations’ that screw onto unused F connectors, preventing ingress and ‘re-
flections’ in the cable. The CableRater Transmitter can be used as a termination,
if left turned Off... but an actual Termination usually works better.
Searching for the ‘bad’ cable is relatively easy. When a good cable or device is
connected to the CableRater Receiver, the reading should be Underrange. Dis-
connect or reconnect cables until the source of the ingress is located. The
CableRater Receiver can be connected to any cable when searching for ingress...
even cables ends that are usually thought of as an input. Ingress can occur at
the input or the output, and any place within the distribution system.
Some old televisions are a notorious source of ingress. Old TV’s were not very
well shielded, and they can pick up over-the-air signals, and contaminate the
distribution system with ingress. If this is suspected, connect the CableRater
Receiver to the antenna connection of the TV, and see if the CableRater mea-
sures any ingress.