15
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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