geo-FENNEL FET 420K User manual

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Operators’Manual
Electronic Theodolite FET 420K

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IMPORTANT!
READ THIS BEFORE USING YOUR INSTRUMENT
1. Make a full check for the instrument before using it. Be sure that the
instrument’s functions, power, original settings and revised
parameters meet your requires before you operate it.
2. To avoid direct sunlight to the instrument’s lens, never leave the
instrument exposed to extreme heat longer than necessary, or it
could affect the instrument’s accuracy..
3. When mounting or dismounting the instrument to or from the tripod,
hold the instrument by one hand, turn the central screw on the tripod
by the other hand to prevent the instrument from falling. If the
instrument must be carried on the tripod, hold the instrument as
vertically as possible. Never carry the instrument horizontally over
your shoulder. Any long distance transport should be done with the
instrument in the carrying case.
4. Put the instrument in the carrying case to avoid extrusion, crash and
shock during the transportation. Shockproof cushion should be
necessarily put inside the carrying case during the long distance
transportation.
5. Clean the dirt on the surface of the organic glass and plastic by floss
or brush after using the instrument. Dry the instrument in time after
use in the rain.
6. Do not use harsh chemicals to clean the surface of the organic glass
and plastic components. A water dampened rag is all that is
necessary.
7. Use absorbent cotton or lenses tissue to clean the exposed optical
parts. Handkerchief, clothes or other things like that are forbidden for
cleaning.
8. The instrument should be stored in an area of low humidity and good
ventilation, where the temperature will not exceed 110º F(45ºC). It
should be necessary to replace the desiccant regularly in the
carrying case.
9. Always remove the batteries before storing the instrument.
10.Please contact our corporation if the instrument’s functions appear
abnormal. Non-professional repairers are forbidden to disassemble
the instrument.

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CONTENTS
1. Nomenclature
2. Display Marks
3. Operating keys
1. Mounting to prepare for measurement
2. Power on
3. Battery state indication
4. Battery replacement
1. Left/Right Observation
2. Target Aim
3. Horizontal Angle 0set (0SET)
4. Measuring Horizontal and Vertical angle (HR? VH or HL? V)
USAGE
NOMENCLATURE and FUNCTIONS
PREPARATION BEFORE MEASUREMENT
ANGLE MEASUREMENT

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5. Horizontal Angle Locked----Unlocked (HOLD)
6. Measuring Zenith Distance, Vertical Angle and Height Angle
7. Grade Percent Mode (Grade Angle Measurement)
8. Repeating Angle Measurement
1. Measuring distance by crosshair of the telescope
2. Incline Correction Function
3. Quadrant Buzzing Function
4. Illumination and Timing Close Function
ANGLE MEASUREMENT
OTHER FUNCTIONS
FUNCTIONS SETTINGS
ERRORS LIST
ASSEMBLY and DISASSEMBLY of BASE PLATE
CHECK and ADJUSTMENT
TECHNICAL SPECIFICATIONS

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USAGE
Electronic Digital Theodolite FET 420K series has adopted
increment-mode digits system for angle measurement.
The resolving power of horizontal and vertical angles can reach 10”.
The precision of angle measurement can reach 20”.
Electronic Digital Theodolite FET 420K can be widely used in 3-4 class
national triangle control measurement, precise lead measurement,
engineering measurement for mine?railway? water conservancy and so
on, landform measurement, and also could be used in the assembly of
the large machinery facilities.
The displays are illuminated so as to make it convenient to operate in
the darker environment.

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NOMENCLATURE AND FUNCTIONS
(1) Optical sight
(2) Objective lens
(3) Horizontal Clamp Knob
(4) Horizontal Tangent Screw
(5) Display
(6) Operating keys
(7) Tripod Base Plate
(8) Carrying Handle
(9) Handle Screw
(10) Instrument Center Mark
(11) Plate vial (12)Circular vial

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(1) Focusing Knob
(2) Optical plummet
(3) Communication Plug
(4) Footscrew
(5) Battery Compartment
(6) Telescopes Eyepiece
(7) Vertical Clamp Knob
(8) Vertical Tangent Screw
(9) Clamp of Tribrach

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DISPLAY and DISPLAY MARKS
DISPLAY
INDICATIONS DISPLAY INDICATIONS
1
2
3
4
5
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Ht
V
AVG
HR
HL
General value of
repeated values
Vertical angle
Number of repeated
measurements
Average of repeated
measurements
Right horizontal angle
Left horizontal angle
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8
9
10
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TILT
F
G
%
REP
BAT
Incline compensator function
Optional Function keys
Angle unit GON
Vertical slope %
State of repeated
measurement
Battery state indication

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OPERATING PANEL and OPERATING KEYS
KEY FUNCTION KEY FUNCTION
FUNC Optional function keys Lighting switch for display window
REP Repeated angle measurement HOLD Hold horizontal angle
V/% Vertical angle display
Vertical angle/percent display
R/L Option of left/right horizontal angle
0SET 0SET for horizontal angle Power Switch
vMove cursor leftward wMove cursor rightward
rAlter the number cursor indicated

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PREPARATION FOR MEASUREMENT
1. MOUNT INSTRUMENT and PREPARE FOR MEASUREMNET
Level and center the instrument precisely to get the best
performance.
a. Mount tripod
Firstly place the tripod legs to a suitable spot and tighten the locking
device.
b. Mount instrument
Attach the instrument to the tripod carefully, then move instrument
by loosening center screw. Fasten slightly the center screw when
the plummet is centered over the sign.
c. Roughly level the instrument with the circular vial
?Use footscrew 1, 2 to move the air bubble in the circular vial
so it is centered left to right.
?Use footscrew 3 to move the air bubble to the center of the
vial.
d. Fine tune level the instrument with the plate level
?Loosen horizontal clamp knob. Turn the instrument to place
the plate vial parallel with the footscrew 1, 2. Center the
bubble using these two footscrews. Attention: Turn the two
foot screws reversely when you adjust them.
?Turn the instrument 90°and center the bubble using level
screw 3.
?Repeat step ? ? ? every time the instrument is turned90°to
center all the bubbles in these positions.

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?Return to the original position in step A. Rotate the
instrument 180°. The plate vial is mounted correctly and the
instrument is leveled nicely if the bubble is centered no
matter the instrument is rotated in any direction.
?Please pay attention to the relations between the turning
direction of the level screws and the moving direction of
the bubble. Adjust plate vial if the bubble is not centered in
step 4.
e. Centering the instrument using the optical plummet
Adjust the eyepiece according to the observer’s eyesight, then move
the instrument by loosening center screw until the image of the sign
on the ground centered in the circle of the reticule. Move the
instrument carefully in case it appears incline.
f. Final leveling of the instrument
Level the instrument precisely in the similar way to step ? . Rotate
the instrument to see if the bubble in the plate vial is centered, then
tighten the center screw.

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2. FA
a. When pressing the button
by 1 sec. audio tone sounds and after
a test period of about 2 seconds in
which all segments are displayed
instrument is ready for use.
b. Move telescope to activate vertical
angle reading.
c. Push button to
show vertical angle “0”point.
c. Target “0”
The instrument has been equipped with
“0”pointer in the vertical scale panel in
order to set the vertical angle “0”point.
Rotate the telescope to pass a sensor
through the zero pointer and start angle
measurement. The “o”point is set near
the horizontal place, so it is easy to set
the vertical “0”by rotating the telescope.
?The instrument can
measure horizontal angle
without 0set for the
specification of the vertical
plate.
?For the instrument
equipped with the
automatic compensatory
“0”set device, the vertical specification can not be
compensated “0”set automatically if the degree out of the
vertical exceeds the design range , and the instrument will
display symbol “B”. The instrument will not be recovered
until it is releveled precisely and the symbol “B”
disappears.
POWER ON
?
V/%

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3.
The battery symbol on the display shows the current battery state.
Full power
Effective
Effective
Low power but effective, replace the battery
Instrument will shut off automatically shortly.
Replace batteries immediately.
?Battery operating time will vary depending on type and
brand and quality of the battery. We suggest always to
secure for a 2nd standby battery set.
?For any questions about replacing batteries, see this
chapter “4. battery replacement”.
BATTERY
STATE INDICATION

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4. BATTERY REPLACEMENT
a. Removing the battery
Push down the press button and remove the battery compartment.
b. Battery replacement
?Push down the hook to pull cover board away from the
battery compartment.
?Replace the old batteries by new ones.
Take care of correct polarity.
?Snap the battery cover back into place.
c. Mounting Battery Compartment
Slip the projection on the bottom of the battery compartment into the
slot. Push the press button on top of the battery compartment until it
clicks into place.

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ANGLE MEASUREMENT
1. Vertical Plate left/right observation
“Plate left”means the vertical plate is on the left side by the
telescope when the observer faces the eyepiece. “Plate right ”means
the opposite to the “plate left”. Taking the average reading of t he
“plate left”and “plate right”as the observation value can effectively
remove the corresponding effect on the observer from the system
errors in the instrument. Therefore, turn the telescope 180 °for the
“plate right”observation after the accomplish of the “plate left”during
the observation of the horizontal and vertical angle.
2. Target aim
?Point the telescope at the brightness and focus the eyepiece until
the crosshair can be seen clearly.
(Turn the focusing knob in the direction facing the observer, t hen
focus in reverse direction.)
?Aim at the target coarsely using the coarse aiming device. The
definite space can be kept between the device and the observer
when aiming coarsely.
?Focus the target by turning the focusing knob on the telescope.
Attention:
The visual errors of the target and retic ule crosshair will be created
in the horizontal and vertical direction if the telescope or the
eyepiece are not focused precisely, which can result in the
measuring errors. Focus for the telescope and eyepiece sho uld be
necessary to remove the visual errors.

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3. Horizontal angle 0set (0SET)
OPERATING PROCESS DISPLAY
? Aim at target “A” using
crosshair of the telescope.
? Press 0SET key oncetoset reading
ofhorizontalangle0°00’00”
?0SET key is only effective to the horizontal angle.
?Horizontal angle can be set “0”at any time except the holding
state(HOLD key).
4. Measuring horizontal and vertical angle (HR? V or HL? V)
Horizontal rightward turning increment and Vertical angle
measurement.( HR? V)
OPETATING PROCESS DISPLAY
? Aim at target “A”using crosshair
of the telescope.
? Press0SETkeyoncetosetreading
ofhorizontalangle0°00’00”
? Turn instrument clockwise and
aim at the second target “B”to get
its horizontal and vertical angle.

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4. 2 Mode conversion of horizontal rightward (HR) and leftward (HL)
turning increment
OPERATING PROCESS DISPLAY
? Aim at target “A” using
crosshair of the telescope.
? Press R/L key, transform
horizontal angle mode HR into
the mode HL.
? Measuring by mode HL.
?R/L key is of no effect to the vertical angle.?
?Press R/L key again, transform mode HL into mode HR..
5. Horizontal angle locked--unlocked
During the process of level observation, press HOLD key once to keep
the measuring angle. After the horizontal angle held, the value of the
horizontal angle on the display window blinks. There is no change to the
horizontal angle even if the instrument is rotated. When the direction
aimed correctly, press HOLD key once again to unlock the holding state.
The direction of the horizontal angle the instrument currently aimed is
just the angle locked before.

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OERATING PROCESS DISPLAY
? Turn the tangent knob and place
the required horizontal angle.
? Press HOLD key once , hold and
flicker the value of the horizontal
angle.
? Aim at the target.
? Press HOLD key, no blink and hold
to the value of the horizontal angle
? HOLD key is of no effect to the vertical angle.
? Measurement of zenith distance? vertical angle and height angle
The vertical angle should be originally set according to the needs
before the operation.
6. 1 ZENITH DISTANCE
If choose 0°for the vertical angle as the zenith direction, the
measured vertical angle V is the zenith angle.
ZENITH DISTANCE V=(L+360°-R)/2
SPECIFICATON ERROR i=(L+R-360°)/2
6. 2 VERTICAL ANGLE
If choose 0°for the vertical angle in left direction, the measured
vertical angle V is the vertical angle.
VERTICAL ANGLE V=(L+180°-R)/2
SPECIFICATION ERROR i=(L+R-540°)/2

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6. 3 HEIGHT ANGLE
If choose 0°for the vertical angle in both left and right direction , the
measured vertical angle V is the height angle.
HEIGHT ANGLE V=(L+R)/2
SPECIFICATION ERROR i=(L–R)/2
ATTENTION: If SPECIFICATION ERROR |i|=10?, inspect and adjust
according to the instruction manual.
7. SLOPE PERCENT MODE (slope angle measurement)
Measuring in angle mode, the vertical angle could be transformed into
percent of grade.
The percent of grade value = H/D*100%
The range of grade percent is from the horizontal direction to ±45°.
OPERATING PROCESS DISPLAY
? Press key to switch
from vertical angular
measurement shown in degrees
to percent.
? Press V % key once again
back to the angular measurement
shown in degrees.
?Any angle exceeding 100% the percent of grade will be
shown as “- - - - -”on the display
V %

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8. ANGULAR REPEATED MEASUREMENT
OPETATION PROCESS DISPLAY
? Press FUNC key
? Press REP key to put the
instrument in repeated mode
? Aim at target A and press 0SET key
once to set the first target reading 0°00’
00”.
? Turn the horizontal tangent knob to aim
at the second target B.
? Press HOLD key to hold the horizontal
angle and store in the instrument.
? Turn the horizontal tangent knob to aim
at the target A again. Press R/L key to
release the angle and keep the state.
? Turn the horizontal tangent knob to aim
at the target B again.
? Press HOLD key to hold the horizontal
angle and store in the instrument. Double
and average angle-value will be shown on
the display.
? Repeat step ? ? according to
measuring requires.
? Back to normal angular measurement,
press FUNC key, then press HOLD key.
?The reading of horizontal angle could reach at least ±2000°00’00”when
measuring in “Plate left”or “Plate right”mode. The five-seconds reading could
reach at least ±1999°59’59”.
?The repeated measurement should be limited within 15 times when the
instrument is in the repeated mode, otherwise an error will be shown.
? Error E04 will be shown on the display when measured error every time exceeds
or equals ±30”during the repeated measurement, go back to step ? .
? Press FUNC key, then press HOLD key to back to the original state.