Triplett CableRater- PN: 3279 - Manual (Page 15)

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make sure it is making good connection. The nuts on the F connectors on the
patch cable should be snuggly tightened to the connectors on the Transmitter
and Receiver. If the patch cable turns freely on the connectors, the nuts are not
tightened properly. Observing the reading on the Receiver’s LCD display, rotate
the ZERO CALIBRATE knob on the Transmitter, either clockwise or counterclock-
wise, until the LCD reads 00.0 dB. The Transmitter is now ‘calibrated’. Do not
alter the setting of the ZERO CALIBRATE knob for the duration of the testing.
Important Note:
The level of the test signal from the CableRater Transmitter can change slightly if
the Transmitter temperature changes. Consider this behavior if moving the Trans-
mitter from a warm to a cold location, or vice versa. The affect is generally less
than +/- 0.5dB, so it doesn’t make a big difference in the measurements. How-
ever, if trying to obtain the most accurate measurements, allow the Transmitter
to acclimate itself to the new temperature for at least 30 minutes before calibrat-
ing it to the Receiver.
A Simple Transmitter Test:
If the user suspects the Transmitter is not working properly, it can be tested by
connecting it to the antenna input of a television set to Channel 3. The TV should
display a ‘blank’ screen... no snow. Different TV’s will display a blank screen
differently. Common displays are a white, gray, black, or blue screen. The
CableRater Transmitter does not produce a ‘sound’ signal, so the TV may pro-
duce no sound or a hissing sound.
9.5 Testing Loss in a Cable
‘Loss’ is a pretty self descriptive term. It’s the amount of signal, in dB, that is
‘lost’ in a cable, splitter, or other device. All cables have Loss... some more than
others.
Two types of cable are commonly used in Cable TV distribution systems... RG-
59 and RG-6.
In general, all RG-59 cables share similar Loss characteristics, although there
are numerous variations that affect the cable’s durability, shielding, and quality
of construction. Some constructions can result in less Loss, but not dramati-
cally.
RG-6 has less Loss than RG-59. Again, all RG-6 cables share similar Loss char-
acteristics, and variation in constructions abound, with some types being slightly
less ‘Lossy’ than others.
Loss is usually expressed in dB per 100 ft. Loss varies with the test frequency,
with more Loss being experienced as the frequency rises. Cable TV systems