65-2405RK-05-04 Combustible Gas Transmitter • 7
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. A label on
the amplifier indicates the detector drive current. This drive current is factory set and is dictated by the
combustible gas to which the detector is calibrated. Consult RKI Instruments, Inc. if you plan to
change the calibration gas for the transmitter, for example from a methane calibration to a hexane
calibration. The amplifier includes the detector terminal strip, controller terminal strip, span pot, zero
pot, and test points.
Figure 2: Amplifier Component Location
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 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 detector to the amplifier.
NOTE:
See “Wiring the Amplifier to a Controller” on page 12 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 2). Use a small flat blade
screwdriver to turn the zero pot’s adjustment screw and adjust the amplifier’s zero (fresh air) output
during the start-up and calibration procedures.
Span Pot
The span pot is located to the right of the zero pot (see Figure 2). 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.
PWR
/
S
IG
S
Controller Terminal Strip
Detector Terminal Strip
G
B
ZE
R
O
SP
A
N
Span Pot
Zero Pot
R
LE
L
W
- Test Point
Factory Adjust Pot, x2
+ Test Point
