Geokon GK-404 User manual

Instruction Manual
Model GK-404
Vibrating Wire Readout
No part of this instruction manual may be reproduced, by any means, without the written consent of Geokon, Inc.
The information contained herein is believed to be accurate and reliable. However, Geokon, Inc. assumes no responsibility for
errors, omissions, or misinterpretation. The information herein is subject to change without notification.
Copyright © 2003-2018 by Geokon, Inc.
(Doc Rev L, 1/25/18)

Warranty Statement
Geokon, Inc. warrants its products to be free of defects in materials and workmanship, under
normal use and service for a period of 13 months from date of purchase. If the unit should
malfunction, it must be returned to the factory for evaluation, freight prepaid. Upon examination
by Geokon, if the unit is found to be defective, it will be repaired or replaced at no charge.
However, the WARRANTY is VOID if the unit shows evidence of having been tampered with
or shows evidence of being damaged as a result of excessive corrosion or current, heat, moisture
or vibration, improper specification, misapplication, misuse or other operating conditions outside
of Geokon's control. Components which wear or which are damaged by misuse are not
warranted. This includes fuses and batteries.
Geokon manufactures scientific instruments whose misuse is potentially dangerous. The
instruments are intended to be installed and used only by qualified personnel. There are no
warranties except as stated herein. There are no other warranties, expressed or implied, including
but not limited to the implied warranties of merchantability and of fitness for a particular
purpose. Geokon, Inc. is not responsible for any damages or losses caused to other equipment,
whether direct, indirect, incidental, special or consequential which the purchaser may experience
as a result of the installation or use of the product. The buyer's sole remedy for any breach of this
agreement by Geokon, Inc. or any breach of any warranty by Geokon, Inc. shall not exceed the
purchase price paid by the purchaser to Geokon, Inc. for the unit or units, or equipment directly
affected by such breach. Under no circumstances will Geokon reimburse the claimant for loss
incurred in removing and/or reinstalling equipment.
Every precaution for accuracy has been taken in the preparation of manuals and/or software,
however, Geokon, Inc. neither assumes responsibility for any omissions or errors that may
appear nor assumes liability for any damages or losses that result from the use of the products in
accordance with the information contained in the manual or software.

TABLE of CONTENTS
1. INTRODUCTION...................................................................................................................................................1
2. INITIAL SETUP .....................................................................................................................................................1
2.1 ACCESSORIES.......................................................................................................................................................1
2.2 CONNECTING A SENSOR.......................................................................................................................................2
2.3 CONNECTING A LOAD CELL.................................................................................................................................2
3. OPERATION...........................................................................................................................................................4
3.1 POS (POSITION)BUTTON ....................................................................................................................................4
3.2 MODE BUTTON ....................................................................................................................................................5
3.3 CFG (CONFIGURATION)BUTTON ........................................................................................................................5
3.4 DEFAULT SETTINGS.............................................................................................................................................5
4. LOW BATTERY INDICATION AND AUTO-OFF............................................................................................6
5. MAINTENANCE ....................................................................................................................................................6
5.1 BATTERY REPLACEMENT.....................................................................................................................................6
5.2 CLEANING............................................................................................................................................................6
5.3 CALIBRATION ......................................................................................................................................................6
6. TROUBLESHOOTING..........................................................................................................................................7
7. LIMITS OF LIABILITY........................................................................................................................................8
APPENDIX A. SPECIFICATIONS...........................................................................................................................9
A.1 VIBRATING WIRE READOUT ...............................................................................................................................9
A.2 TEMPERATURE READOUT ...................................................................................................................................9
A.3 PHYSICAL ...........................................................................................................................................................9
APPENDIX B. CONNECTOR PIN OUTS ...............................................................................................................9
B.1 TRANSDUCER PLUG PIN OUT ..............................................................................................................................9
APPENDIX C. THERMISTOR TEMPERATURE DERIVATION.....................................................................10

FIGURES
FIGURE 1-LEMO CONNECTOR ALIGNMENT .................................................................................................................. 1
FIGURE 2-NECK STRAP CONNECTOR ........................................................................................................................... 1
FIGURE 3-CONNECTOR ON GK-404 ............................................................................................................................. 1
FIGURE 4-CONNECTOR POINTING DOWNWARD ........................................................................................................... 2
FIGURE 5-NECK STRAP CONNECTIONS ........................................................................................................................ 2
TABLES
TABLE 1-LOAD CELL CONNECTOR AND CABLE (STANDARD WIRING) ........................................................................ 3
TABLE 2-POSITION SPECIFICATIONS ............................................................................................................................ 4
TABLE 3-TRANSDUCER PLUG PIN OUT ........................................................................................................................ 9
TABLE 4-THERMISTOR RESISTANCE VERSUS TEMPERATURE ......................................................................................10
EQUATIONS
EQUATION 1-RESISTANCE TO TEMPERATURE .............................................................................................................10

1
1. INTRODUCTION
The Model GK-404 Vibrating Wire Readout is a portable, low-power, handheld unit that is
capable of running for more than 20 hours continuously on two AA batteries. It is designed for
the readout of all Geokon vibrating wire gages and transducers, and is capable of displaying the
reading in either digits, frequency (Hz), period (µs), or microstrain (µε). The GK-404 also
displays the temperature of the transducer (embedded thermistor) with a resolution of 0.1 °C.
2. INITIAL SETUP
2.1 Accessories
The GK-404 is sold with the following accessories:
•GK-404-1 flying leads
•Carrying case
•Nylon strap for the carrying case
•Neck strap for the GK-404
Before use, attach the flying leads to the GK-404 by aligning the red circle on the silver “Lemo”
connector on the flying leads with the red line on the connector on the top of the GK-404. Insert
the Lemo connector into the GK-404 until it locks into place (Figure 1). Remove the flying leads
before storing the GK-404 in the carrying case.
Figure 1 - Lemo Connector Alignment
To install the nylon strap onto the carrying case, clip both ends of the strap onto the plastic loops
on the sides of the case.
To install the neck strap onto the GK-404, locate the plastic connector on the neck strap (Figure
2) and place the larger circular hole onto the plastic nub on the back of the GK-404, with the
bottom of the connector positioned to the right (Figure 3).
Figure 3 - Connector on GK-404
Figure 2 - Neck Strap Connector

2
Slide the connector all the way to the right, so that the nub on the back of the GK-404 locks into
the smaller hole of the connector. Turn the connector clockwise until the part of the bottom of
the connector is pointing down (Figure 4).
Figure 4 - Connector Pointing Downward
Lastly, snap together the twin connectors located at the strap ends (Figure 5).
Figure 5 - Neck Strap Connections
2.2 Connecting a Sensor
Attach the GK-404-1 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).
Patch cables may be ordered from Geokon to enable sensors with connectors attached to the
readout cable to be read by the GK-404.
2.3 Connecting a Load Cell
Patch cables may be ordered from Geokon to enable load cells with connectors attached to the
readout cable to be read by GK-404.
If the load cell cable does not have a connector, the leads of the load cell may be connected to
the flying leads from the GK-404. The individual leads will be identified as shown in the wiring
diagram in Table 1. Each sensor is read in turn by clipping either the red or black clip to the lead
marked “common” and the black or red clip in turn to the leads marked #1, #2, #3, etc. The blue
clip should be connected to the cable shield and the green and white clips to the cable leads
marked “thermistor”.

3
10 pin Bulkhead
PT06A-12-10P
Function
3 Gage VW Load Cell
Geokon Purple Cable
4 Gage VW Load Cell
Geokon Purple Cable
6 Gage VW Load Cell
Geokon Orange Cable
A
Gage #1
Red
Red
Red
B
Gage #2
Red's Black
Red's Black
Red's Black
C
Gage #3
White
White
White
D
Gage #4
NC
White's Black
White's Black
E
Gage #5
NC
NC
Green
F
Gage #6
NC
NC
Green's Black
G
Shield
All Shields
All Shields
All Shields
H
Common
White's Black¹
Green
Blue
J
Thermistor
Green¹
Blue
Yellow
K
Thermistor
Green's Black
Blue's Black
Yellow's Black
Table 1 - Load Cell Connector and Cable (Standard Wiring)
Notes:
¹ White's black and Green wires are switched on Geokon three gage VW load cells prior to serial
number 3313.

4
3. OPERATION
To turn the GK-404 on, press the “ON/OFF” button on the front panel of the unit. The initial
startup screen will be displayed. After approximately one second, the GK-404 will start taking
readings and display them based on the settings of the POS and MODE buttons.
The unit display (from left to right) is as follows:
•The current Position (Set by the POS button) displayed as a letter, A through F.
•The current Reading, displayed as a numeric value, followed by the unit of measure (set by
the MODE button).
•Temperature reading of the attached gage in degrees Celsius.
The GK-404 will continue to take measurements and display readings until the unit is turned off,
either manually, or if enabled, by the Auto-Off timer. (See Section 3.3 for information on the
Auto-Off timer.) To turn the GK-404 off manually, press and hold the ON/OFF button until
Saving Settings is displayed then release. All user settings are stored on shut off and will be
restored the next time the GK-404 is turned on.
3.1 POS (Position) Button
The POS button is used to change the pluck settings of the GK-404. Each Position setting (A-F)
has different preprogrammed parameters that are optimized for certain instruments. Each option
also has different scaling and processing characteristics. Table 2 details the correct position to
use with the various models sold by Geokon.
Position
A
B
C
D
E
F
Use with Geokon
Model Numbers:
All
4300BX
4400 4500
4600 4700
4800 4900
4000 4200 4100 4300EX
MODE:
Dg
Hz
µS
Dg
Hz
µS
µE
Hz
µS
µE
Hz
µS
µE
Hz
µS
Dg
Hz
µS
Units:
Digits
Hertz
µSec
Digits
Hertz
µSec
µStrain (ε)
Hertz
µSec
µStrain (ε)
Hertz
µSec
µStrain (ε)
Hertz
µSec
Digits
Hertz
µSec
Calculation:
T = Period (1/F)
in
µ
Sec
F = Frequency in
Hertz
F2×10-3
F
T
F2×10-3
F
T
F2×10-3×4.062
F
T
F2×10-3×3.304
F
T
F2×10-3×0.39102
F
T
F2×10-3
F
T
Frequency
Sweep: (Hz)
450-6000 1500-3500 450-1200 450-1200 1500-3500 2500-6000
Table 2 - Position Specifications

5
3.2 Mode Button
Pressing the MODE button will select the format of the vibrating wire reading. The available
options are, Dg (digits), Hz (hertz), µS (period) and µE (microstrain). Only Positions C, D and E
support the µE microstrain format.
3.3 CFG (Configuration) Button
Pressing the CFG button will cause the GK-404 to enter the Configuration Menu. The LCD
screen will display:
GK-404 verX.XX
Config Menu
From this menu, several GK-404 operating parameters may be set. Use the POS button to select
the various parameters and the MODE button to select each parameter’s options. Press CFG
twice at any time to exit the Configuration Menu and return to the Readings Screen. Parameters
available from the Configuration Menu are as follows:
BACKLIGHT:
Press MODE to turn the LCD backlight ON or OFF.
BATTERY VOLTAGE:
This is a bar graph display of the power remaining in the two 1.5V AA cells, with Ffor FULL
and Efor EMPTY. The GK-404 is capable of continuous operation for greater than 20 hours on
a fresh set of batteries.
CONTRAST:
Press the MODE button to adjust the contrast of the LCD display in 10% increments.
AUTO-OFF:
Press the MODE button to select automatic shutoff after five minutes, 15 minutes, or 30
minutes. The Auto-Off may be disabled so that the GK-404 will only shut off if the front panel
ON/OFF button is pressed. The Auto-Off will only activate if no front panel buttons are pressed
for the specified amount of time. The timer will reset each time a button is pressed. When the
GK-404 powers down, all settings are saved to the internal memory, and will restore the next
time the GK-404 is turned on. (Note: The times mentioned above are approximate.)
3.4 Default Settings
Factory default settings may be restored at any time by pressing and holding the CFG and POS
buttons when turning the GK-404 ON. The factory default settings are:
POSITION: B
MODE: Dg
BACKLIGHT: OFF
CONTRAST: 50%
POWER-OFF TIME: Five minutes

6
4. LOW BATTERY INDICATION AND AUTO-OFF
The GK-404 continuously monitors the status of the two 1.5V AA cells. When their combined
voltage drops to 2V, the message Batteries Low is displayed on the screen. A fresh set of 1.5V
AA batteries should be installed at this point. If the battery voltage drops to 1.8V, the message
REPLACE BATTERIES will be displayed on the screen; the GK-404 will then shut off. All
settings are still saved in the internal nonvolatile memory.
5. MAINTENANCE
5.1 Battery Replacement
Alkaline batteries are the best choice for use in the GK-404. A set of two 1.5V AA batteries are
installed in the GK-404 at the factory. To replace the batteries, use a #1 Phillips screwdriver to
remove the battery compartment cover located at the back of the readout. Install a new set of
batteries following the polarities indicated inside the battery compartment. Reinstall the battery
compartment cover.
Never use two different types of batteries or mix old batteries with new. This could cause
batteries to leak and permanently damage the readout. Although alkaline batteries are highly
recommended, carbon zinc “AA” batteries can be used.
5.2 Cleaning
A clean cloth can be used to wipe down the GK-404 Readout. No solvents should be used as
they may damage the case of the readout.
5.3 Calibration
The readout should be sent periodically (every 12 months) to the manufacturer for inspection,
cleaning, and calibration. A nominal fee will be charged for the service, but it is highly
recommended.

7
6. TROUBLESHOOTING
Listed below are a few commonly experienced problems and remedial action. Contact the factory
should a problem arise not explained herein.
Symptom: Unit will not come on
Internal batteries are either dead or installed backwards.
Symptom: Vibrating wire gage measurement shows dashes
Check Alligator Clip connections to vibrating wire gage leads. If okay, check gage with
Ohmmeter. It should read between 90 and 180 ohms. If gage resistance is okay, check
Readout with another gage. If it still does not work, consult the factory to schedule return and
repair of Readout.
Symptom: Vibrating wire gage reading unstable
Improper position selected. Verify gage model number against the recommended setting.
(See Table 2.) If position setting is correct, the gage is either marginal or there may be a
strong source of electromagnetic interference nearby.
Symptom: Thermistor measurement shows dashes
Check Alligator Clip connections to Thermistor leads. If okay, check Thermistor with
Ohmmeter. It should read between 10K ohms and 2.4K ohms (0 to +30 degrees Celsius). If
the thermistor checks out okay, consult factory to schedule repair of Readout. Note: Dashes
will display if no Thermistor is connected.
Symptom: Display shows weird characters
Turn the GK-404 ON while pushing the CFG and POS buttons at the same time to restore the
unit to its factory default settings.

8
7. LIMITS OF LIABILITY
The GK-404 Vibrating Wire Readout has been developed specifically for use with Geokon, Inc.
vibrating wire gages and, as such, Geokon, Inc. assumes no responsibility for its use with other
systems. Every effort has been made to ensure reliable operation, but the user must be aware that
there is no warranty against uninterrupted or trouble-free operation. For the user conducting
particularly unusual or sensitive analysis, or for those not familiar with vibrating wire gage data
processing, it is recommended that the problems be double checked using another measurement
system.
In addition, the readout is provided 'as is' and Geokon, Inc. assumes no responsibility as to
results, performance, or interpretation associated with the GK-404 Vibrating Wire Readout.
Warranty shall cover parts (except batteries) and labor for a period of one year from the date of
purchase. In addition, there is a one-month grace period to the warranty for a total of 13 months.
Geokon reserves the right to revise this publication and/or readout from time to time with no
obligation to notify users of these changes.
Overall, Geokon, Inc., is not liable for any claims, injuries, or damages caused directly or
indirectly by the proper or improper use of the GK-404 Vibrating Wire Readout, beyond
the purchase price of the Readout.

9
APPENDIX A. SPECIFICATIONS
A.1 Vibrating Wire Readout
Excitation Range: 400 Hz to 6000 Hz, 5-volt square wave
Measurement Resolution: 0.1 Hz, 0.1 uS, 0.1 Digit
Measurement Accuracy: ±0.025% of Full Scale (6000 Hz)
A.2 Temperature Readout
Sensor Type: Thermistor, YSI 44005, Dale #1C3001-B3, Alpha #13A3001-B3
Sensor Accuracy: ±0.5°Celsius
Measurement Range: −20°to +50°Celsius
Measurement Resolution: 0.1°Celsius
Measurement Accuracy: ±1.0% of Full Scale
See Appendix C for more information.
A.3 Physical
Display: 16 columns x two lines LCD
Dimensions: 120 mm (4.72") x 65 mm (2.56") x 22 mm (0.87")
Weight: Approx. 145 grams (5.1 ounces) with two “AA” alkaline batteries installed
Temperature Range: -20°to +50°Celsius
Battery: Two “AA” 1.5 volt alkaline.
Operating Time: minimum 24 hours continuous at +25º Celsius
APPENDIX B. CONNECTOR PIN OUTS
B.1 Transducer Plug Pin Out
Pin # on 5-pin LEMO
(HGG.OB.305.CLLP)
Wire
Color
Flying Leads Alligator
Clip Boot Color
Description
1
Red
Red
VW Gage +
2
Black
Black
VW Gage -
3
White
White
Thermistor +
4
Green
Green
Thermistor -
5
Bare
Blue
Drain Wire
Table 3 - Transducer Plug Pin Out

10
APPENDIX C. THERMISTOR TEMPERATURE DERIVATION
Thermistor Type: YSI 44005, Dale #1C3001-B3, Alpha #13A3001-B3
Resistance to Temperature Equation:
T= 1
A+B(LnR)+C(LnR)3-273.2
Equation 1 - Resistance to Temperature
Where;
T =Temperature in °C.
LnR =Natural Log of Thermistor Resistance.
A =1.4051 ×10-3
B =2.369 ×10-4
C =1.019 ×10-7
Note: Coefficients calculated over the −50 to +150°C. span.
Ohms
Temp
Ohms
Temp
Ohms
Temp
Ohms
Temp
Ohms
Temp
201.1K
-50
16.60K
-10
2417
+30
525.4
+70
153.2
+110
187.3K
-49
15.72K
-9
2317
31
507.8
71
149.0
111
174.5K
-48
14.90K
-8
2221
32
490.9
72
145.0
112
162.7K
-47
14.12K
-7
2130
33
474.7
73
141.1
113
151.7K
-46
13.39K
-6
2042
34
459.0
74
137.2
114
141.6K
-45
12.70K
-5
1959
35
444.0
75
133.6
115
132.2K
-44
12.05K
-4
1880
36
429.5
76
130.0
116
123.5K
-43
11.44K
-3
1805
37
415.6
77
126.5
117
115.4K
-42
10.86K
-2
1733
38
402.2
78
123.2
118
107.9K
-41
10.31K
-1
1664
39
389.3
79
119.9
119
101.0K
-40
9796
0
1598
40
376.9
80
116.8
120
94.48K
-39
9310
+1
1535
41
364.9
81
113.8
121
88.46K
-38
8851
2
1475
42
353.4
82
110.8
122
82.87K
-37
8417
3
1418
43
342.2
83
107.9
123
77.66K
-36
8006
4
1363
44
331.5
84
105.2
124
72.81K
-35
7618
5
1310
45
321.2
85
102.5
125
68.30K
-34
7252
6
1260
46
311.3
86
99.9
126
64.09K
-33
6905
7
1212
47
301.7
87
97.3
127
60.17K
-32
6576
8
1167
48
292.4
88
94.9
128
56.51K
-31
6265
9
1123
49
283.5
89
92.5
129
53.10K
-30
5971
10
1081
50
274.9
90
90.2
130
49.91K
-29
5692
11
1040
51
266.6
91
87.9
131
46.94K
-28
5427
12
1002
52
258.6
92
85.7
132
44.16K
-27
5177
13
965.0
53
250.9
93
83.6
133
41.56K
-26
4939
14
929.6
54
243.4
94
81.6
134
39.13K
-25
4714
15
895.8
55
236.2
95
79.6
135
36.86K
-24
4500
16
863.3
56
229.3
96
77.6
136
34.73K
-23
4297
17
832.2
57
222.6
97
75.8
137
32.74K
-22
4105
18
802.3
58
216.1
98
73.9
138
30.87K
-21
3922
19
773.7
59
209.8
99
72.2
139
29.13K
-20
3748
20
746.3
60
203.8
100
70.4
140
27.49K
-19
3583
21
719.9
61
197.9
101
68.8
141
25.95K
-18
3426
22
694.7
62
192.2
102
67.1
142
24.51K
-17
3277
23
670.4
63
186.8
103
65.5
143
23.16K
-16
3135
24
647.1
64
181.5
104
64.0
144
21.89K
-15
3000
25
624.7
65
176.4
105
62.5
145
20.70K
-14
2872
26
603.3
66
171.4
106
61.1
146
19.58K
-13
2750
27
582.6
67
166.7
107
59.6
147
18.52K
-12
2633
28
562.8
68
162.0
108
58.3
148
17.53K
-11
2523
29
543.7
69
157.6
109
56.8
149
Table 4 - Thermistor Resistance versus Temperature
55.6
150