4
RT8872 Transmitter
Controls and Indicators
Locating Mode -
Simultaneous Peak and Null
In the line locate mode the unit will operate the audio, the signal
strength and the graph in a peak function, while also displaying
line direction indicators (operating on null antenna).
When the receiver is directly above the cable or pipe, a PEAK
(Highest graph reading and highest audio tone) will occur.
When moving the receiver to left or right of the PEAK point,
the graph reading will decrease. When the receiver is moved
beyond the PEAK, the meter reading will begin to fade. The
3-digit signal strength reading will read the highest when
directly over the target conductor. (see below)
Trace the path by walking away from the transmitter at a
moderate pace. Move the receiver to the left and right while
walking, following the indications.
As you trace the path, the meter reading may slowly fade as
you move away from the transmitter. Press and release the
GAIN Buttons as needed to compensate for changes in level
(higher or lower). One of the following may occur:
• a junction where the signal divides and goes several
directions.
• a break in the cable or shield.
• a change in the depth of the cable or pipe.
• an insulated pipe fitting.
• a slack loop of cable.
If you can no longer trace the path, even with the GAIN set to
maximum, connect the transmitter to the far end of the path
and trace back to the point where you lost the signal.
• Mark the straight sections of the path every few feet.
• Mark sharp curves, loops, and cable bundles every few
inches.
Sharp changes in the path cause the receiver PEAK and NULL
indications to behave differently than when tracing a straight
path. Practice on the path that you know has turns and
laterals in it. This will help you to recognize the conditions
within the field.
Transmitter Output Jack
The Red/Black Cord, Coupler
and Flexicoupler connects here
to create a direct connect
or coupler inductive circuit
on the buried utility.
Load Rate Indicator
Indicator symbol flashes
to indicate signal
transmission via coupler
induction or direct
connection.
2
2
2
3
1
1
1
3
3
Relative Resistance,
Voltage and Current
The transmitter can display
the resistance, voltage and
amperage of the transmitted
frequency.
NOTE: This is a relative measure-
ment based on the feedback
from the transmitted signal.
Output Signal Level
Adjusts the power output from
the Transmitter.
Frequency
Selects frequencies by toggling
through available frequencies.
8kHz, 65Hz, 200 Hz, 480Hz,
33kHz & 82kHz are standard on
the 8872.
Transmitter
Power ON/OFF
Frequency and
other LCD segments
visible indicates
unit is on.
INDICATORS
CONTROLS