EZ Digital FG-7002C User manual

G
FG-7002C/5C
2MHz/5MHz
SweepFunctionGenerator
OperationManual
___
_
BENCH-TOPINSTRUMENT
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WARRANTY
Warranty service covers a period of one year from the date of original purchase.
In case of technical failure within one year, our service center or sales outlet free of
charge will provide repair service.
We charge customers for repair after the one-year warranty period has been
expired. Provided that against any failure resulted from the user’s negligence,
natural disaster or accident, we charge you for repairs regardless of the warranty
period.
For more professional repair service, be sure to contact our service center or sales
outlet.
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Introduction
Thank you for purchasing our product, electronic measuring instruments
produced by us are high technology products made under strict quality control. We
guarantee their exceptional precision and utmost reliability. For proper use of the
product, please read this operation manual carefully.
Note
1. To fully maintain the precision and reliability of the product use it within the range
of standard setting (temperature 10 qC~35 qC, humidity 45%~85%)
2. After turning of power, please allow a pre-heating period of as long as some 30
minutes before use.
3. This equipment should be used with a triple line power cord for safety.
4. For quality improvement the exterior design and specification of the product can
be changed without prior notice.
5. If you have further questions concerning use, please contact our service center
or sales outlet
Safety Summary
Please take a moment to read these operating instructions thoroughly and
completely before operating this instrument. Pay particular attention to WARNINGS
used for conditions and actions that pose hazard to the user and CAUTIONS used
for conditions and actions that may damage the instrument.
zAlways to inspect the instrument and other accessories for any sign of damage
or abnormality before every use.
zNever ground yourself and keep your body isolated from ground.
zNever touch exposed wiring, connections or any live circuit conductors.
zDo not install substitute parts or perform any unauthorized modification to the
instrument.
zUse caution when working above 60V DC or 30V AC rms. Such voltages pose
a shock hazard.
zRemember that line voltage is present on some power input circuit points such
as on-off switches, fuse, power transformers, etc., even when the equipment is
turn off.
zAlso, remember that high voltage may appear at unexpected points in defective
equipment.
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Safety Symbols
1. Protective earth (ground)
To identify any terminal which is intended for connection to
an external conductor for protection against electric shock
In case of a fault, or the terminal of a protective earth
(ground) electrode.
2.Functional earth terminal on the rear panel.
3 “IN” position of a bi-stable push control
To associate the “IN” position of a bi-stable push control
with the corresponding function.
4. “OUT” position of a bi-stable push control
To associate the “OUT” position of a bi-stable push control
with the corresponding function.
5. Alternation current
To indicate on the rating plate that the equipment is
Suitable for alternating current only to identify relevant
terminals.
6. Caution, risk of danger
7. Caution, risk of electric shock
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CONTENTS
1. PRODUCT DESCRIPTION
1-1. Introduction ----------------------------------------------------------------- ( 6 )
1-2. Technical Specifications ------------------------------------------------- ( 6 )
1-3. Equipment Ratings -------------------------------------------------------- ( 8 )
1-4. Supplied Accessories ---------------------------------------------------- ( 8 )
2. INSTALLATION
2-1. Initial Inspection ----------------------------------------------------------- ( 9 )
2-2. Connecting Ac Power ---------------------------------------------------- ( 9 )
2-3. Cooling And Ventilation -------------------------------------------------- ( 9 )
2-4. Position ---------------------------------------------------------------------- ( 9 )
2-5. Warming-Up ---------------------------------------------------------------- ( 9 )
3. OPERATION
3-1. Controls, indicators and connectors ---------------------------------- ( 10 )
3-2 2. Operating instruction -------------------------------------------------- ( 13 )
3-3. Use As Function Generator --------------------------------------------- ( 13 )
3-4. Use As Pulse Generator ------------------------------------------------- ( 16 )
3-5-1. TTL/CMOS Output ----------------------------------------------------- ( 18 )
3-5-2. TTL/SYNC Output ----------------------------------------------------- ( 19 )
3-6. Use As FM Signal Generator ------------------------------------------- ( 19 )
3-7. External Control Of VCF ------------------------------------------------- ( 21 )
3-8. Programmed Frequency Selection ------------------------------------ ( 22 )
3-9. Use As Sweep Generator ----------------------------------------------- ( 22 )
3-10. Use As Externally Controlled Sweep Generator ----------------- ( 23 )
3-11. Use As External Frequency Counter -------------------------------- ( 23 )
4. MAINTENANCE
4-1. Fuse Replacement -------------------------------------------------------- ( 25 )
4-2. Adjustment And Calibration --------------------------------------------- ( 25 )
4-3. Cleaning and decontamination ----------------------------------------- ( 25 )
5. OTHERS
5-1. Introduction ----------------------------------------------------------------- ( 25 )
5-2. Troubleshooting By Signal Substitution ------------------------------ ( 26 )
5-3. Troubleshooting By Signal Tracing ----------------------------------- ( 26 )
5-4. Amplifier Overload Characteristics ------------------------------------ ( 27 )
5-5. Amplifier Performance Evaluation Using Square Waves -------- ( 28 )
5-6. Testing Speakers And Impedance Networks ----------------------- ( 31 )
5-7. Digital Frequency Selection --------------------------------------------- ( 32 )
5-8. Additional Applications --------------------------------------------------- ( 32 )
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1. PRODUCT DESCRIPTION
1.1. Introduction
This instrument is the Most Versatile Signal Source used as FUNCTION
GENERATOR, SWEEP GENERATOR, PULSE GENERATOR and a FREQUENCY
COUNTER, offering a wide range of applications in both analog and digital
electronics such as engineering, manufacturing, servicing, education and hobbyist
fields.
VCF(voltage controlled frequency) produces precision sine, square and triangle
waves over the 0.02 Hz to 2 MHz; FG-7002C, 0.05Hz - 5MHz; FG-7005C for sub-
audible, audio, ultrasonic and RF applications. A continuously variable DC offset
allows the output to be injected directly into circuits at the correct bias level.
Variable symmetry of the output waveforms converts the instrument to a pulse
generator capable of generating rectangular waves or pulses, ramp or sawtooth
waves and skewed sine waves of variable duty cycle. The sweep generator offers
linear sweep with variable sweep rate and sweep width up to 100:1 frequency
change. The frequency response of any active or passive device up to Maximum
frequency of each model can be determined.
1-2. Technical Specifications
OUTPUT CHARACTERISTICS
Waveforms : Sine, Square, Triangle, Skewed Sine, Pulse, Ramp
Sawtooth, TTL Leveled Square, DC
CMOS Leveled Square(FG-7002C only)
Frequency Range : In 7 Range (1, 10, 100, 1K, 10K, 100K,1M)
FG-7002C; 0.02 Hz to 2 MHz
FG-7005C; 0.05 Hz to 5 MHz
Frequency Drift Accuracy: ±2% (1, 10, 100, 1K, 10K, 100K,1M Range )
Output Level : 20 Vpp in open circuit, 10 Vpp into 50 :Load
Output Impedance : 50 :±5%
Attenuator : 20 dB fixed and continuously variable


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WAVEFORM CHARACTERISTICS
Sine wave -Flatness : ±3dB to 2MHz(FG-7002C),
5MHz(FG-7005C)
-Distortion : Less than 1% at 0.2 Hz to 100 KHz
Square wave -Rise and Fall Time : Less than 120 nS
Triangle wave -Linearity : More than 99% at 0.2 Hz to 100 KHz
TTL Output -Rise and Fall time : Less than 25 nS
-Output Level : TTL Level(H 2.4V, L 0.4V)
CMOS Output -Rise and Fall Time : Less than 160 nS(Max. Out)
(FG-7002C only) -Output Level : 4V to 15V ±2V, Variable
DUTY RATIO : 1:1 to 10 : 1
SWEEP FUNCTION CHARACTERISTICS
Mode : Linear
Width : Variable from 1 : 1 to 100 : 1
Rate : 0.5 Hz to 50 Hz (20 mS to 2 S)
External VCF Input :
Input Voltage : 0 to 10 V
Input Impedance : Approx. 1K:
FREQUENCY COUNTER CHARACTERISTICS
Display :
FG-7002C: 6 digit green LED, Gate time, MHz, KHz, Hz, mHz.
FG-7005C : 7 digit green LED, Gate time, MHz, KHz, Hz, mHz.
Frequency Range :
FG-7002C: 200 mHz to 50 MHz With Auto Range.
FG-7005C : 200 mHz to 100 MHz With Auto Range.
Accuracy : ±Time base Error ±1 count
Time base : 10 MHz Crystal, ±20ppm
Input Sensitivity : 100 mVrms
Max. Input Voltage : 250 Vpp
DIMENSION AND WEIGHT
Dimension : 240(W)x 270(D) x90(H)mm
Weight : Approx. 2.0Kg(FG-7002C), 3.0kg(FG-7005C)
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1-3. Equipment Ratings
zPower & Fuse Ratings
Input Voltage Fuse Power Max.
115VAC +/-10%, 50/60Hz F 0.5A 250V 15W
230VAC +/-10% , 50/60Hz F 0.2A 250V (FG-7002C)
F 0.25A 250V (FG-7005C) 15W
NOTE: AC Power is preset to 115V or 230V in factory according to the request
of customer. AC Power can be selected inside of unit.
zOperating Environment
TEMPERATURE: 0 °C to + 40 °C (Accuracy Specified at 23°C±5 °C)
HUMIDITY :up to 85% to 40°C without temperature extremes
causing condensation within the instrument.
zStorage Environment
TEMPERATURE: -20°C to +70°C
HUMIDITY : below 85% RH
zOvervoltage Category : CAT II,
Performed on circuits directly connected to the low voltage installation.
zInsulation Category II: Portable equipment of local level.
zPollution Degree : 2
zProtection to IEC 529: Ordinary
1-4. Supplied Accessories
zUser’s Manual ---------------------------------------------------------------------------- 1
zBNC Cable ------------------------------------------------------------------------------ 1
zPower Cord ------------------------------------------------------------------------------ 1
zSpare Fuse ------------------------------------------------------------------------------- 1
** Specifications are subject to change without notice.
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2. INSTALLATION
2-1. Initial Inspection
This instrument was carefully inspected both mechanically and electrically before
shipment. It should be physically free of damage. To confirm this, the instrument
should be inspected for physical damage in transit. Also, check for supplied
accessories are present and correct.
2-2. Connecting AC Power
CAUTION
AC POWER OF THIS INSTRUMENT IS PRESET TO 115V OR 230V IN FACTORY
ACCORDING TO THE REQUEST OF CUSTOMER. BEFORE POWERING ON
THIS INSTRUMENT, CHECK AND MAKE SURE THE VOLTAGE OF THE
POWER SOURCE IS SAME WITH THE MARKING OF UNIT.
This instrument requires 230V AC or 115V AC (50-60 Hz) power socket with
protective earth contact (PE-contact). If is available only a power socket without PE-
contact (so a 2-conductor ac power) then a power socket with PE-contact must be
installed before or the appliance should be provided with a PE-screw-terminal which
is not soluble by hand and not soluble before 2-conductor power lines.
2-3. Cooling and Ventilation
No special cooling and ventilation is required. However, the instrument should be
operated where the ambient temperature is maintained.
2-4. Position
This instrument is built as a bench-type instrument with rubber feet and tilt stand
in place. Stand-up angle can be adjusted by rotating angle of carrying handle.
2-5. WARMING-UP
Allow more than 30 minutes for the unit to warm up so that it is stabilized and ready
for use.
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3. OPERATION
3-1. Controls, indicators and connectors
FIG 1-1. FRONT PANEL OPERATOR’S CONTROLS(FG-7002C)
21
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,17 /3)
71411311 68 912
20 2 17318416 5 15 19
10
21
FIG 1-2. FRONT PANEL OPERATOR’S CONTROLS(FG-7005C,)
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LED DISPLAY. Displays Internal or External
Frequency.
INTERNAL/EXTERNAL SWITCH. PUSH IN : External Frequency
Counter.
PUSH OUT: Internal Frequency
Counter.
RANGE SWITCHES. Frequency Range Selector.
FUNCTION SWITCHES. Select Sine wave, Triangle Wave Or
Square Wave Output.
ATTENUATOR. Selects Output Level By -20 dB.
GATE TIME INDICATOR. Gate Time Is Selected Automatically By
Input Signal.
FREQUENCY DIAL.(Coarse,Fine) Controls Output Frequency in Selected
Range.
MHz, KHz , Hz, mHz INDICATOR. Indicates Unit of Frequency.
EXTERNAL COUNTER INPUT BNC. Used as an External Frequency
Counter.
SWEEP RATE CONTROL. On-Off Switch For Internal Sweep
Generator, Adjusts Sweep Rate Of
Internal Sweep Generator.
SWEEP WIDTH CONTROL. Pullout And Adjusts Magnitude Of
Sweep.
VCF INPUT BNC. Voltage Controlled Frequency Input
Permits External Sweep.
Frequency Control Sweep Rate Control
Should Be Off When Applying External
Voltage At This BNC.
SYMMETRY CONTROL. Adjust Symmetry Of Output
Waveform 1:1 to 10:1 With Push/Pull
Switch On.
TTL/CMOS CONTROL. Selects TTL Or CMOS Mode
Pull-out : CMOS Level Control, Push-
In: TTL Level.
TTL/CMOS OUTPUT BNC. TTL/CMOS Level Output.
DC OFFSET CONTROLS. Adds Positive or Negative DC
Component to Output Signal.
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MAIN OUTPUT BNC. Impedance 50 Ohm.
AMPLITUDE CONTROL. Adjusts Output Level from 0 to 20 dB.
TILT STAND. Pull Out to Adjust Tilt.
POWER SWITCH. Push type switch. turning on the power
when pressed.
LOW PASS FILTER
5(3/$ &(21/@> ,7+ )<6 ($1'),5(
Made in Korea
POWER MAX
32> (56<33/@%()25(
6$ 0(5$ 7,1* $ 1'7@3(
'21 275(02=(&2=(5
5()(56(5=,&,1* 72
230V ~
115V ~
VOLTAGE
S/N :
0.2A F
0.5A F
FUSE
3(56211(/
5(3/$ &,1* )<6(
',6&211(&7
2)
10W
10W
4<$ /,),('
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> $51,1*
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FIG 2-1. REAR PANEL(FG-7002C)
=
POWER MAX
S/N :
VOLTAGE
230V ~
115V ~ 0.5A F
0.2A F
FUSE 20W
20W
=
7235(=(17(/(&75,&6+2&.+ $A$5'$1'),5(
5(3/$ &(21/@> ,7+ )<6(2)6$0(5$ 7,1* $1'7@3(
',6&211(&732> (56<33/@%()25(5(3/$ &,1* )<6(
'21275(02=(&2=(55()(56(5=,&,1* 72
>$51,1*
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
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FIG 2-2. REAR PANEL(FG-7005C)
AC INLET For connection of the supplied AC power
Voltage Selector Switch For selecting AC Input Voltage
FUSE HOLDER. Replacing fuse with unscrewing.
Ground Terminal.
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3-2. Operating instruction
This instrument is capable of generating a wide variety of waveforms and counting
an external frequency with high resolution of 6 digits LED for FG-7002C (7digits
LED for FG-7005C). The most benefit and satisfaction can be gained from the
instrument by fully understanding its capabilities and versatility and becoming
familiar with operation procedure. One of the best ways to initially gain this
familiarization is to connect the generator to an oscilloscope. Observe the
waveforms and notice the effects of the various controls on the waveforms. Use this
manual as a reference until becoming accustomed to operating procedures.
3-3. Use As Function Generator.
1) Procedure
A. Connect AC power cord into receptacle on rear panel and plug into AC inlet.
B. To turn on equipment, push power on-off switch on.
C. To make sure that the output is symmetrical and unaffected by the sweep
generator, set the following controls as below.
CONTROLS POSITION
Sweep width OFF(push)
Symmetry OFF(push)
DC offset OFF(push)
Attenuator RELEASE(button out)
Counter INTERNAL(button out)
D. To select the desired frequency, set the Range Switch and FREQ. dial as
follows; The output frequency equals the FREQ. dial setting multiplied by the
Range Switch setting.
For example, a FREQ. dial setting of 0.6 and a Range switch setting of 10K
produces a 6 KHz output(.6x10 = 6K). A FREQ. dial setting of 2.0 and a
Range switch setting of 1M produces 2 MHz output(2.0x1M = 2M).
E. And also it can display the desired frequency by 6 digit LED
display(FG-7002C) – 7digit LED display for FG-7005C.
F. Select sine, square, or triangle wave output by pressing the corresponding
FUNCTION button. FIG 3. illustrates the output waveforms and their phase
relationships.
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G. Connect a cable from the 50:BNC to the point where it is desired to inject
the signal.
H. Adjust the 50:output to the desired amplitude with the AMPLITUDE control.
TTL Pulse 0V
Triangle 0V
Sine 0V
Square 0V
FIG. 3 OUTPUT WAVEFORMS AND PHASE RELATIONSHIPS
I. A positive or negative DC component can be added to the signal at the 50:
BNC by use of the DC OFFSET control, as required by the circuit into which
the signal is being injected.
J. A fixed amplitude TTL square wave is available at the TTL OUT BNC on the
front panel. This signal is unaffected by the AMPLITUDE, ATTENUATOR or
DC OFFSET. TTL output is a square wave for use in digital circuits, even
though FUNCTION SWITCH is on sine or triangle wave.
2) Considerations
CAUTION
KNOWLEDGE OF THE FOLLOWING FACTORS IS ESSENTIAL FOR PROPER
OPERATION OF THE INSTRUMENT:
A. The DC offset control can provide over ±10 volts open-circuited, or ±5 volts
into 50:load. Remember that the combined signal swing plus DC offset is
also limited to ±10 V open-circuited, or ±5 V into 50:. Clipping occurs slightly
next page these levels. FIG 4. illustrates the various operating conditions
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encountered when using DC offset. If the desired output signal is large or if a
large DC offset is used, an oscilloscope should be used to make sure that the
desired combination is obtained without clipping. Keeping the Amplitude
control in the lower half of its adjustment range reduces the probability of
clipping.
B. To set the DC offset to zero or a specific DC voltage, depress the Function
Switches slightly so that all switches are released(all buttons out). This
removes signal from the output and leaves the DC only. Measure the DC
output on an oscilloscope or DC voltmeter and adjust the DC offset control for
the desired value.
C. It is easier to accurately set the FREQ. dial if settings between 0.1 and
2.0(FG-7002C), 5.0(FG-7005C), are used. Since the dial rotation overlaps
ranges, it is not usually necessary to use readings below 1. Just change to a
lower range and use a higher dial setting.
FIG 4. USE OF DC OFFSET CONTROL
D. The main output BNC is labeled 50:. This means that the source impedance
is 50:, but the output may be fed into any circuit impedance. However, the
output level varies in proportion to the terminating impedance. If it is desired
to maintain a constant output level while injecting signal into various circuits
with various impedance, a constant terminating impedance is necessary.
A. Zero DC Offset
with maximum signal
B. Offset limits
without Clipping
C. Excessive Offset
all example
output terminated in 50
+5V
0V
-5V
+5V
0V
-5V
+5V
0V
-5V
Positive
DC Offset Negative DC Offset
Positive
DC Offset Negative DC Offset
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When the generator output is connected to a coaxial connector on the
equipment under test, it usually moderate to high impedance. A reasonably
constant terminating impedance may be maintained while injecting signal into
moderate and high impedance circuits(500:and up)by adding a coaxial tee
in the output cable and connecting a 50:termination to one leg. Remove the
50:termination when injecting into a 50:circuit. Also keep DC injection point,
the DC offset should be set to match the circuit voltage, or blocking capacitor
may be required to avoid DC loading with 50:.
E. When using the higher output frequencies and when using the square wave
output, terminate the cable in 50:to minimize ringing. Keep the cables as
short as possible.
F. To set output amplitude to a specific level, measure peak to peak amplitude on
an oscilloscope.
3-4. Use As Pulse Generator
In a symmetrical square wave, sine wave, or triangle wave, the positive and
negative transitions are of equal time duration, or 1:1 ratio. This is the condition
when the SYMMETRY control off. When the SYMMETRY control is pulled and
rotated, the positive transition can be stretched in relation to the negative transition,
up to at least, 10:1 ratio. Square waves can be stretched into rectangular waves or
pulses, triangle waves can be stretched into distorted wave shape called a skewed
sine wave. FIG 5. illustrates the types of waveforms possible and includes a
summary of control settings used to obtain the desired waveform.
1)Procedure
A. Setup generator as described for function generator operation. Display the
output of generator on an oscilloscope.
B. Select the desired type of waveform with the Function Switches. Press the
square wave button for pulses, triangle button for ramp waves or sine wave
button for skewed sine waves.
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FIG 5. PULSE, RAMP, AND SKEWED SINE WAVE GENERATION
Pulse
(Square)
Ramp
(Triangle)
Skewed
(Sine)
TTL
SYNC
Adjust Period Of Shorter
Duration With Freq. Controls
Adjust Period Of Longer
Duration With
Symmetry Controls
C. If both a specific pulse width and repetition rate (specific rise time and fall
time for ramp wave), :are required, The waveform may be obtained as
follows:
a. Adjust the shorter duration portion of the waveform(pulse width for pulse,
fall time for ramp waves)with the frequency controls FREQ. dial and
RANGE switch.
b. Adjust the longer duration portion of the waveform(rest time for pulses,
rise time for ramp waves)with the SYMMETRY control.
D. If a specific pulse width (specific fall time for ramp wave)is not critical, but a
specific repetition rate is required, the desired waveform may be obtained as
follows;
a. Observe the oscilloscope and adjust the SYMMETRY control to obtain
the approximate desired pulse width vs. rest time ratio(rise time vs. fall
time ratio for ramp waves).
b. Adjust the repetition rate with the frequency controls FREQ. dial and
RANGE switch. the frequency controls affect both the pulse width and
repetition rate.
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2) Considerations
A. When generating ramp waves or skewed sine waves, it may be easier to
measure the time periods on oscilloscope using the square wave mode, then
switch to the desired operating mode.
B. For ease and accuracy in measurement, use a higher sweep speed on the
oscilloscope to expand the pulse width for measurement, then reduce sweep
speed to measure the repetition rate.
C. Repetition rate may be expressed as a frequency or time period. Measure
the repetition rate as a time period on oscilloscope and convert to frequency
if required. The repetition rate includes the full cycle, both the pulse width
and rest time for pulses, the rise time and fall time for ramp waves.
D. Repetition rate can be measured accurately and easily as a frequency or
time period with a frequency counter.
E. Pulse width also can be measured on a frequency counter, but only with the
SYMMETRY control set off before the pulse waveform is “stretched”. Pulse
width equals one-half the time period of the square wave. If the counter is
not equipped for period measurement, calculate the frequency, which is
equivalent to the desired pulse width, and measure the frequency of the
waveform.
1
DESIRED PULSE WIDTH x 2
DESIRED FREQUENCY =
3-5-1. TTL/CMOS OUTPUT(FG-7002C only)
TTL/CMOS output is specifically designed for compatibility with TTL/CMOS digital
logic circuits. Set-up time is considerably reduced because the fixed logic levels
and polarity are ready for direct injection into TTL/CMOS circuits. there is a need for
protection from accidental Application of too high amplitude or incorrect DC offset
which might damage semiconductors. Another advantage is the extremely fast rise
time and fall time of signal. To use the TTL/CMOS output, connect a cable from
TTL/CMOS BNC on the Front panel to the point at which it is desired to inject the
signal. TL/CMOS output may be used in several modes of operation. Some
examples follow.
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A. Using the square wave generator or pulse generator modes, clock pulses can
be generated for testing, troubleshooting or circuit analysis. The instrument
could even be used as a substitute master clock generator as TTL/CMOS
circuits can be driven from the TTL/CMOS BNC.
B. The CMOS Level Control potentiometer (pull out position) provides CMOS
level output from 5V to 15V Variable and Continuously. For TTL/CMOS
output level, Rotate the potentiometer switch and Observe the TTL or CMOS
output : Push-in is TTL, Pull-out is CMOS.
3-5-2. TTL/SYNC OUTPUT (FG-7005C only)
TTL/SYNC output is specifically designed for compatibility with TTL SYNC digital
logic circuits. Set-up time is considerably reduced because the fixed logic levels
and polarity are ready for direct injection into TTL SYNC circuits. there is a need for
protection from accidental Application of too high amplitude or incorrect DC offset
which might damage semiconductors. Another advantage is the extremely fast rise
time and fall time of signal. To use the TTL SYNC output, connect a cable from TTL
SYNC BNC on the Front panel to the point at which it is desired to inject the signal.
TTL SYNC output may be used in several modes of operation. Some examples
follow.
A. Using the square wave generator or pulse generator modes, clock pulses
can be generated for testing, troubleshooting or circuit analysis. The
instrument could even be used as a substitute master clock generator as
TTL SYNC circuits can be driven from the TTL SYNC BNC.
3-6. Use As FM Signal Generator
1) Procedure
A. Set up equipment as described for function generator operation. Use the
frequency and amplitude controls to set the carrier to the desired frequency and
amplitude.
B. Connect an AC modulating signal with no DC component to the VCF IN BNC
on the front panel of generator.
C. Adjust amplitude of the AC modulating signal for the desired frequency
deviation.
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2) Considerations
A. The approximate frequency deviation for a given VCF IN signal can be
determined as follows, The 0.1 V change at the VCF IN BNC produces a
frequency change of 1% of the highest frequency obtainable on a given
range. For example(FG-7002C), the highest frequency obtainable on the 100
K range is 200 KHz. One percent of 200 KHz equals 2 KHz. Therefore, 0.1 V
change at the VCF IN BNC will deviate the output frequency 2 KHz on the
100K range. Following table summarizes the frequency deviation versus
VCF IN voltage for all ranges.
HIGHEST FREQ.
OBTAINABLE(Hz) FREQ. DEVIATION FOR EACH 0.1 VOLT VCF IN CHANGE(Hz)
RANGE
FG-7002C FG-7005C FG-7002C FG-7005C
1
10
100
1K
10K
100K
1M
2
20
200
2k
20k
200k
2M
5
50
500
5k
50k
300k
5M
0.02
0.2
2
20
200
2K
20K
0.05
0.5
5
50
500
5k
50k
Frequency deviation versus VCF IN voltage for each model.
B. For an example(FG-7002C), it is assumed that we wish to generate a 455
KHz signal with FM deviation of ±15 KHz (30 KHz swing). 1M range will be
used to obtain the 455 KHz carrier with the FREQ. dial set to 0.455. The
highest frequency obtainable on the 1M range is 2 MHz. One percent of 2
MHz is 20 KHz. Our requirement of 30 KHz deviation is 1.5 times greater
than 20 KHz deviation produced by a 0.1 volt VCF IN swing, thus we will use
1.5 times as much peak-to-peak voltage swing or 0.15 V.
STATED ANOTHER WAY: SUBSTITUTING THIS EXAMPLE:
desired deviation 30 KHz
1% deviation 20 KHz
x0.1 V = required VCF IN signal x 0.1 = 1.5 x 0.1V = 0.15V
C. Remember that the value of VCF IN signal is the peak to peak amplitude.
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