3-7. External Control Of VCF
Within a given range, the FREQ. dial setting normally controls the output
frequency of generator. However, applying voltage at the VCF IN BNC on the front
panel also may control it. There are three basic possible modes of external VCF
control as detailed below,
A. Applying an AC voltage produces FM modulation(previously described in
“Use as FM Signal Generator” paragraph.
B. Applying a specific fixed DC voltage will produce a specific output frequency
described in following “Programmed Frequency Selection”paragraph)
C. Applying a ramp voltage(or other type waveform if desired)provides
externally controlled sweep generator operation(described in following “Use
as Externally Controlled Sweep Generator” paragraph)
The following consideration apply to all modes of operation involving external
control of the VCF(voltage controlled frequency)
A. The output frequency of generator is determined by the voltage applied to the
VCF. First of all, this voltage is established by the setting of the FREQ. dial.
Any voltage input drives the VCF TO A HIGHER FREQUENCY. However.
The VCF can never be driven beyond its range limits (the highest and lowest
frequencies that can be attained with the dial on a given range.)
B. With the FREQ. dial set at minimum and 0 volts at the VCF in BNC, the
generator output frequency is at the lower limit of the selected range.
Increasing the voltage to + 10 volts drives the generator frequency to the
upper limit of the range. Between 0 and + 10 Volts, the generator output
frequency is proportional to the VCF IN voltage. The VCF IN voltage can be
correlated to equivalent dial settings as given in Table below.
Equivalent dial Setting
VCF voltage
8102
8103
8105
8110
0
0.02
0.03
0.05
0.1
1
0.2
0.3
0.5
1
2
0.4
0.6
1.0
2
3
0.6
0.9
1.5
3
4
0.8
1.2
2.0
4
5
1.0
1.5
2.5
5
6
1.2
1.8
3.0
6
7
1.4
2.1
3.5
7
8
1.6
2.4
4.0
8
9
1.8
2.7
4.5
9
10
2.0
3.0
5.0
10
Correlation between VCF IN voltage and equivalent dial setting(dial set to Min.)
Summary of Contents for FG-8102
Page 29: ...Square Wave Selected Dual Trace Oscilloscope Preferred...
Page 34: ......
