OPERATING INSTRUCTIONS
13
4.
When the
2 Hz
range is selected, the gate time is 10 seconds and
the display is updated once every 10 seconds. The result of a
frequency change will not be displayed until 10 seconds later.
Adjust the frequency in progressively smaller steps, waiting for
the display to update until the desired frequency is obtained.
5.
When outputting square waves or when using the TTL output,
terminate the cable into 50
Ω
to minimize ringing. Also, keep
cables as short as possible.
6.
Remember that the output signal swing of the generator is
limited to ±10 volts open circuited or ±5 volts into 50
Ω
, and
applies to the combined peak-to-peak signal and DC offset.
Clipping occurs slightly above these levels. Fig. 3 illustrates the
various operating conditions encountered when using the DC
offset. If the desired output signal is large or if a large DC offset
is required, an oscilloscope should be used to make sure that the
desired signal is obtained without undesirable clipping.
DUTY CYCLE CONTROL
The
DUTY CYCLE
control can be used to alter the symmetry of
the output waveform, to produce waveshapes such as those shown in
Fig. 4. For a square wave, symmetry variation amounts to changing
the duty cycle (ratio of "high" to "low" time), effectively converting
the instrument into a pulse generator. For a triangle wave, the result is
a ramp, and with a sine wave, a distorted waveshape called a slewed
sine is produced. The Model 4040 provides for symmetry variation
from 15% to 85%.
1.
Select the waveform desired either SINE, SQUARE or
TRIANGLE.
Figure 4. Effects of Symmetry Variation.
2.
Engage the
DUTY CYCLE
switch (2) and adjust
the
DUTY CYCLE
control (7) for the desired
waveshape. Clockwise rotation from center results
in an increase in square wave duty cycle, and
changes the sine and triangle waves as shown in the
top waveform of each pair of Fig. 4. Counter-
clockwise rotation results in the bottom waveform
in each pair.
