8 • 65-2397RK CO
2
Transmitter
Amplifier
The amplifier converts the electrical output from the detector to a 4 to 20 mA signal that corresponds
to the detection range and transmits the signal to a gas monitoring controller. A foam gasket that
orients the amplifier and keeps it from rotating is installed on the bottom of the amplifier. The
amplifier includes the controller terminal strip, detector terminal strip, span pot, zero pot, and test
points (see Figure 1).
Controller Terminal Strip
The controller terminal strip is a three position plug-in style terminal strip located near the top of the
amplifier. Use the controller terminal strip to wire the CO
2
transmitter to a controller.
Detector Terminal Strip
The detector terminal strip is a four position plug-in style terminal strip located below the controller
terminal strip. Use the detector terminal strip to connect the CO
2
transmitter to the amplifier.
NOTE:
The IR CO
2
detector is factory-wired to the detector terminal strip. See “Wiring the CO
Transmitter to a Controller” on page 10 for all wiring procedures related to the transmitter.
Zero Pot
The zero pot is located in the upper left corner of the amplifier (see Figure 1). Use a small flat blade
screwdriver to turn the zero pot’s adjustment screw and adjust the amplifier’s target gas-free output
during the start-up and calibration procedures. Turn the adjustment screw clockwise to increase the
zero output and counterclockwise to decrease the zero output.
Span Pot
The span pot is located to the right of the zero pot (see Figure 1). Use a small flat blade screwdriver to
turn the span pot’s adjustment screw and adjust the amplifier’s gas response output during the
calibration procedure. Turn the adjustment screw clockwise to increase the gas response and
counterclockwise to decrease the gas response.
CAUTION:
The amplifier includes two additional potentiometers. They are factory-set. Do not adjust
them.
Test Points
The test points are on the left side of the amplifier (see Figure 1). The test points produce a 100 mV to
500 mV output that corresponds to the transmitter’s 4 to 20 mA output. Use the test points and a
voltmeter to measure the amplifier’s output during the start-up and calibration procedures. The black
test point in the lower left corner is the negative (-) test point and the red test point below the zero pot
is the positive (+) test point.
Junction Box
Use the junction box to install the transmitter at a mounting site that is remote from the controller. The
junction box protects the amplifier and wiring connections made to the amplifier. Use the top 3/4 NPT
conduit hub to connect wiring from the amplifier to the controller. Use the cover on the front of the
junction box to access the interior of the junction box. The detector and amplifier are factory installed
in the junction box. Three spacers installed on the back of the junction box control the distance of the
junction box from a mounting surface and ensure that there is enough room to install a calibration cup
