GW Instek GFC-8010H User manual

FREQUENCY COUNTER
USER MANUAL
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CONTENTS PAGE
1. PRODUCT INTRODUCTION.............................................
1-1.Description……………………………………………….
1-2.Feature…………………………………………………...
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2. TECHNICAL SPECIFICATION…………………………... 2
3. PRECAUTIONS BEFORE OPERATION…….…………...
3-1.Unpacking the Instrument………………….…………...
3-2.Checking the Line Voltage…………………..………….
3-3.Equipment Installation and Operation………………...
3-4.General Preparation……………………………………..
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4. PANEL INTRODUCTION……………………..…………… 5
5. APPLICATION……………………………………………….
5-1.Sensitivity…………………………………………………
5-2.Input Sensitivity Characteristic………………………...
5-3.Maximum Input Voltage………………………………...
5-4.Typical Applications……………………………………..
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6. CIRCUIT DESCRIPTION……………………………...…...
6-1.Theory of Operation………………………………..…....
6-2.Frequency Measurement Accuracy…………………….
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7. MAINTENANCE……………………………………………..
7-1.Standard Method for Calibration………………………
7-2.Cleaning…………………………………………………...
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1. PRODUCT INTRODUCTION
1-1. Description
The GFC-8010H frequency counter is a general-purpose counter
with a measurement range from 0.1Hz~120MHz and 20mVrms
high input sensitivity. The incorporation of the most updated
semiconductor techniques develops a compact, high performance,
highly reliable and high resolution instrument.
1-2. Features
Additionally, the frequency counter offers several other features:
zExtremely high resolution to 1μHz.
zWorst case guarantee of X’tal stability specifications.
zThe line filter is enclosed in a static shield to resist noise.
zLow pass filter for accuracy measurement of low frequency.
zCompact & lightweight.
zLow power consumption.
zHigh quality crystal allows an extremely accurate measurement
of frequencies.
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2. TECHNICAL SPECIFICATIONS
Sensitivity
(rms)
10Hz~10MHz 15mV
10MHz~40MHz 20mV
40MHz~80MHz 35mV
80MHz~120MHz 50mV
Input Impedance 1MΩ35PF.
Max. Input Voltage 150Vrms.
Coupling System AC coupling.
Time Base Oscillation Frequency 10MHz.
Aging rate: ±1×10-6 Month.
Temp. stability: 25℃±5℃±5×10-6.
0℃~50℃±2×10-5.
Accuracy 1Hz + 1 digit + Time base error.
Counting Capacity 8 digit decimal.
Display System Digital LED’s display.
Gate Time 0.1 sec, 1 sec, 10 sec switch selectable.
Max. Resolution 1μHz on 10Hz range with 10 seconds gate time.
0.1Hz on 100MHz range with 10 seconds gate time.
Operating Temp.
Range 0℃~40℃
Storage Temp. Range -10℃~+70℃
Power Consumption Approx. 5W.
Power Requirement 100V, 120V/220V/230V±10%, 50/60Hz.
Dimension Approx. 245(W) × 95(H) × 280(D) m/m.
Weight Approx. 1.7kgs.
ACCESSORIES Instruction manual……………× 1
Test lead GTL-101 …………..× 1

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3.PRECAUTIONS BEFORE OPERATION
3-1.Unpacking the Instrument
The instrument has been fully inspected and tested before shipping from
the factory. Upon receiving the instrument, please unpack and inspect it to
check if there is any damages caused during transportation. If any sign of
damage is found, notify the bearer and/or the dealer immediately.
3-2.Checking the Line Voltage
The instrument can be applied any kind of line voltage shown in the table
below. Please check the line voltage indicated in the label attached on the
real panel to replace correct fuses.
WARNING. To avoid electrical shock the power cord
protective grounding conductor must be connected to ground.
When line voltages are changed, replace the required fuses shown as below:
Line voltage Range Fuse Line voltage Range Fuse
100V
120V 90-110V 108-132V T160mA 250V 220V 230V 198-242V 207-253V T100mA 250V
WARNING. To avoid personal injury, disconnect the power
cord before removing the fuse holder.
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3-3.Equipment Installation, and Operation
Ensure there is proper ventilation for the vents in the case. If this
equipment is used not according to the specification, the protection
provided by the equipment may be impaired.
3-4.General Preparation
1) When the impedance is 1MΩ, the maximum voltage applied to the input
depends on the frequency and the position of the SENSITIVITY switch.
This relationship is shown in Fig. 6, and the values given in this table
must be strictly observed. Initially set SENSITIVITY to 1/10, if the
counter doesn’t count, set the switch to 1/1 range and then perform
measurement. This procedure will reduce the danger of damaging the
input circuit.
2) Use an AC power source within 100V, 120V, 220V, or 230V±10%.
3) Use the instrument within an ambient temperature range of 0~40℃. Do
not put the counter on the top of high temperature equipment and be sure
not to block the ventilation of the instrument.
4) Never permit water to enter the interior of the instrument and never
subject the instrument to severe mechanical shock.
5) When the instrument is operated in an especial noisy environments, insert
a noise filter into the power source.
6) When low frequencies are measured, push the low pass filter switch can
attenuate high frequency components to prevent probable false triggering.

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4. PANEL INTRODUCTION
(1). Counter Input BNC type connector.
(2). ATT, 1/1, 1/10 Attenuation button of input sensitivity.
1/1 : Directly connect input signal to input amplifiers.
1/10: Attenuate input signal by a factor of 10.
(3). LPF ON/OFF Set to ON position, insert a 100kHz Low Pass Filter into
input for low frequency measurement.
(4). FREQ/PRID Frequency or period measurement by setting the button.
(5). Gate Time Selector Press the gate time button to 10 sec, 1 sec or 0.1 sec for
measurement.
(6). Power ON/OFF Power on or off by using the button.
(7). Gate Time(LED) The gate time of 10 sec, 1 sec or 0.1 sec will be
displayed in the LED by setting the Gate button.
(8). Over (LED) Overflow indicator shows that one or more of the most
significant digits are not displayed.
(9). Displayed (LED) Display 8 digits of frequency data.
(10) Exponent and units
(LED) LED indicator shows S and Hz of the unit and indicate the value of the measurement exponent as shown below:
k=1000 M=1,000,000 G=1,000,000,000
m=1/1000 μ=1/1,000,000 n=1/1,000,000,000
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zFront Panel
Fig. 1 Front panel

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5. APPLICATION
5-1. Sensitivity
The role of the SENSITIVITY (or attenuator) switch in a common
measuring instrument is to protect the input circuit and prevent the meter
from going off scale.
For a counter, SENSITIVITY is still one of the large roles. Generally,
hysteresis occurs in the waveshaping circuit of the counter. In order for the
instrument to put up resistance to noise, the circuit will not work even
when the noise is lower than the hysteresis applied. The waveshaping
circuit is a Schmitt circuit and the operation of this circuit is described
below:
Fig. 2 Operation of the Schmitt circuit
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As refer to Fig. 2, when input voltage is at V+, the output voltage is high
(VOH), while input voltage is at V-, the output voltage is low (VOL). The
difference between these two voltage VH=(V+)-(V-) is called the hysteresis
voltage.
But if both V+and V-don’t react each other, no output will be obtained
and the Schmitt circuit will not work out with the states of (1), (2) and (3)
of Fig. 3 shown as below.
Fig. 3 States under which the schmitt circuit doesn’t work
From above description, it can be easily understood whether or not the
Schmitt circuit works is attributed to the SENSITIVITY (Attenuator) to
determine the magnitude of the input voltage.
An example of preventing erroneous counting by correctly selecting the
SENSITIVITY shown as Fig. 4 below:
(a) Correctly counting a distortion signal by selecting suitable
SENSITIVITY. However, when the input voltage is too high, a
frequency doubles the unknown frequency will be indicated.
(b) Erroneous counting occurs when high frequency noise is
superimposed on the unknown signal and the input voltage of the
Schmitt circuit is too high. However, a correct counting can be
obtained by selecting suitable SENSITIVITY.

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(a) When unknown signal is distorted
(b) When high frequency noise superimposed on unknown signal
Fig. 4
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The erroneous counting can be prevented by satisfying two conditions
below:
a)To make peak-to-peak value of the noise voltage smaller than VH.
b) When peak-to-peak value of unknown signal is larger than VH, perform
measurements by first setting SENSITIVITY to 1/10, then set it to 1/1
range to protect the input circuit and avoid erroneous counting. One
good method is to conduct measurements at the smallest possible input
within the counter display value “dispersion” range. When the signal is
a pure waveform, it will not occur erroneous counting with any
magnitude input lower than the input destroyed voltage.
5-2. Input Sensitivity Characteristic
The input sensitivity of this instrument is shown as Fig. 5.
Fig. 5 Input Sensitivity Characteristic

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5-3. Maximum input voltage
The maximum input voltage Vs frequency characteristics is shown as
Fig. 6.
Fig. 6. Maximum Input Voltage-Frequency
5-4. Typical Applications
Several examples for typical applications are described below:
1).The output frequency of a transmitter or transceiver can be measured
(if the output power is about 1W) by merely connecting a one turn clip
cord to several tens of centimeters from antenna. The length of the
distance is determined by the magnitude of the output.
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2).Measurement can also be easily performed when calibrating the
oscillation frequency of a grid dip meter by merely connecting the one
turn clip cord.
3).Measurement of tracking the frequency through the oscillator stage,
multiplier stage, and output stage can be performed by making a small
2-3 turn coil and coupling it to each turned circuit (the oscillations may
be produced by the input capacitance and its resonant frequency with
too many turns of coil.)
Note: As the product has a high sensitivity, induction may cause
erroneous counting if you touch the red end (ungrounded side) of
the clip cord. Therefore, hold the black clip or coaxial cable when
performing measurements according to above method.
Measurement by connecting the accessory cable directly to the test
circuit is described below.
4).Measurement can generally be performed by merely connecting the
black side of the clip cord to ground (GND) and the red side to the test
point.
5).When the capacitance of the cable will have an affection on the test
circuit (When measuring turned circuits or high output impedance
circuit), perform measurement by inserting a high resistance in series
with the red side of the clip cord. Always be sure to ground the cord
when perform the measurement of 4) and 5) above. If possible, ground
the cable to the ground point of the test circuit. This procedure will
reduce the affection of noise. A wide variety of measurement can be
conceived in addition to (1~5) fully utilizing the special features of the
counter.

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6. CIRCUIT DESCRIPTION
6-1. Theory of Operation
In order to get the most benefit from the frequency counter, it’s useful to
comprehend the circuit thoroughly. We have attempted every possible to
utilize the latest developments in large-scale integration to provide the
greatest performance for the money and, at the same time, to reduce the
complexity of circuit and increase reliability.
Ignoring the prescaler for the moment, let us assume the input signal
arrives at the 10MHz to 100MHz input labeled CHA in main board. This
signal is first amplified by the Q201~Q202 pair. The three amplifier
stages identified as U202 in the schematic are ECL logic stages biased in
its linear region, each stage having a gain before feedback of about 5. A
positive feedback at the output of the third amplifier when reflected
through the gain of the proceeding three amplifier states (including the
Q201~Q202 pair) results in about a 5mV hysteresis in the input triggering
levels to aid in noise rejection. Q203 and Q204 translate the ECL levels to
TTL levels. The signal is presented directly to the counter IC U301.
The IC U301 provides all the functions of the counter and display result
through LED.
U201 regulates the input 9 volts signal from the line voltage transformer
and rectifier circuit. When the power switch is set to “on” position,
approximately 5.0 volts is applied to the circuit.
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6-2. Frequency Measurement Accuracy
Measurement Accuracy
Frequency measurement accuracy is determined by the following two
conditions:
1) ±1count.
2) Time base accuracy.
The ±1 count error is inherent to digital meters and is produced by the
phase relationship between the gate signal and the input signal shown in
Fig. 7. The counted result of 1 count increased or decreased depends on
the phase difference.
Fig. 7 ±1 count error

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High Accuracy Measurement
The accuracy of the time base oscillator is almost completely determined
by the characteristics of the crystal oscillator. The specifications of the
time base are:
Oscillation frequency 10MHz
Aging rate: 1×10-6/month
Temperature stability 5×10-6(25±5℃)
±2×10-5 (calibration ambient temperature
0~40℃)
The temperature characteristics for the crystal oscillator used in this
instrument shown in Fig. 8, in which you can see the temperature
coefficient is as large as 25℃.
Fig. 8 Temperature characteristics of the crystal oscillator
0℃25℃33℃60℃
Accuracy (temperature coefficient)
Temperature
4x10-5
2x10-5
2x10-5
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The temperature stability of the crystal oscillator is: 2×10-5 (temperature 0~60℃)
with 25℃as reference. The temperature of 0~60℃is given here because the
internal temperature rise is approximately 20℃and the 0~40℃ambient
temperature is because the crystal oscillator is similar to it. If the temperature of
the crystal oscillator is assumed to be 25℃and set to 10MHz that is over the
worst case temperature stability of 2×10-5 (0~60℃) temperature range and since
the frequency is 10MHz, a variation of only (10×106)×(2×10-5) =2×102=200Hz is
possible. In actual use, worst case conditions are produced in two circumstances:
1) Frequency calibration is performed as soon as the switch is set to ON at an
ambient temperature of 0℃and measurement is performed after ample time
has elapsed after the switch is turned ON at an ambient temperature of 40℃.
2) Calibration is performed after ample time has elapsed after the switch has been
turned ON at an ambient temperature of 40℃and measurement is performed as
soon as the switch is turned ON at an ambient temperature of 0℃.
Under these worst case conditions, the guarantee accuracy is 4×10-5 (calibration
temperature:0~40℃) and becomes 0.004%.
Fig. 9 Example of crystal oscillator rise characteristics
0
5
30min 60min 90min Time elapsed after
Switch on
X10-6
Switch ON
Ambient temperature 23℃

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In actual practice, the worst case conditions described above are almost never
encountered, and furthermore, the high accuracy state is maintained. An example
of rise characteristics given in Fig. 9 and the frequency changes following after the
change of temperature. As shown from the figure, the crystal oscillator of this
instrument reached the thermally balanced state for about 50 minutes after turning
on the switch. This instrument is calibrated about 60 minutes before shipment at
the place of 25℃ambient temperature.
If measurement is performed more than 1 hour after switching on and an
instrument is calibrated under 20~30℃ambient temperature, 5×10-6 can be
guaranteed even when the worst crystal oscillator is used.
The 5×10-6 (25±5℃) represented as a percentage becomes 0.0005%. Aging rate
1×10-6/month means that the change after one week under the constant ambient
temperature state, as a percentage of 0.0001%.
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7.MAINTENENCE
The following instructions are executed by qualified personnel only. To
avoid electrical shock, do not perform any servicing other than the operating
instructions unless you are qualified to do so.
7-1.Standard method for calibration
After 50 minutes warm-up, apply the STD OUT signal of a standard or
high accuracy of 1×10-7 to the input of the frequency counter. Adjust
Trimmer SVC301 to display value of 10.000000MHz with the standard of
10MHz and the resolution of 1s. An accuracy of over 1×10-7 can be
obtained through this procedure. Use a screwdriver (not metal tip) to
adjust the trimmer.
7-2.Cleaning
To clean the instrument, use a soft cloth dampened in a solution of mild
detergent and water. Do not spray cleaner directly onto the instrument
because it may leak into the cabinet and cause damage.
Do not use chemicals containing benzine, benzene, toluene, xylene, acetone,
or similar solvents. Do not use abrasive cleaners on any portion of the
instrument.