
8
3.3 GK-403 Readout Box (Obsolete Model)
The GK-403 can store gauge readings and apply calibration factors to convert readings to
engineering units. The following instructions explain taking gauge measurements using Mode
“B”. Consult the GK-403 Instruction Manual for additional information.
3.3.1 Connecting Sensors with 10-pin Bulkhead Connectors Attached
Align the grooves on the sensor connector (male), with the appropriate connector on the
readout (female connector labeled senor or load cell). Push the connector into place, and
then twist the outer ring of the male connector until it locks into place.
3.3.2 Connecting Sensors with Bare Leads
Attach the GK-403-2 flying leads to the bare leads of a Geokon vibrating wire sensor by
connecting each of the clips on the leads to the matching colors of the sensor conductors,
with blue representing the shield (bare).
3.3.3 Operating the GK-403
1)
Turn the display selector to position “B”.
2)
Turn the unit on.
3)
The readout will display the vibrating wire output in digits. The last digit may change
one or two digits while reading.
4)
The thermistor reading will be displayed above the gauge reading in degrees
centigrade.
5)
Press the “Store” button to record the value displayed.
If the no reading displays or the reading is unstable, see Section 5 for troubleshooting
suggestions.
The unit will automatically turn off after approximately two minutes to conserve power.
3.4 Measuring Temperatures
Each Vibrating Wire Convergence Meter is equipped with a thermistor for reading temperature.
The thermistor gives a varying resistance output as the temperature changes. Usually the white
and green leads are connected to the internal thermistor. The GK-403, GK-404, and GK-405
readout boxes will read the thermistor and display temperature in
°
C automatically
If an Ohmmeter is used, connect the ohmmeter to the two thermistor leads coming from the
convergence meter. (Since the resistance changes with temperature are so large, the effect of
cable resistance is usually insignificant.) Look up the temperature for the measured resistance
using Table 9 in Appendix B. Alternately, the temperature could be calculated using Equation
10, also found in Appendix B. When long cables are used, the cable resistance may need to be
taken into account. Standard 22 AWG stranded copper lead cable is approximately 14.7
Ω
per
1000 ft. or 48.5
Ω
per km. Multiply these factors by two to account for both directions.
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