B&K Precision 4017A - Manual - Manual (Page 13)

12
OPERATING INSTRUCTIONS
TTL/CMOS OUTPUT
The TTL/CMOS output jack provides a fast rise time square
wave output. Either a fixed TTL or a variable CMOS output
level is available. The output is positive with respect to ground
and can be used as an external sync pulse for oscilloscopes or
as a variable frequency signal source for exercising logic
circuits. Because of the fast rise time of this output, cable
length should be minimized to limit ringing and overshoot.
1. Select the desired frequency range and adjust the
frequency controls as required. The OUTPUT LEVEL
and DC OFFSET controls have no effect on the signal at
the TTL/CMOS jack.
2. When the CMOS LEVEL switch (15) is OFF, a TTL
signal is output at the TTL/CMOS jack. Select a CMOS
signal by engaging the CMOS LEVEL switch and adjust
the level of the signal by rotating the CMOS LEVEL
control (8).
SWEEP OPERATION
3. Select LINEAR sweep by leaving the SWEEP LIN/LOG
switch (13) in the released position or LOG sweep by engaging
the SWEEP LIN/LOG switch.
4. Set the starting frequency (highest frequency) of the sweep by
adjusting the COARSE frequency control and observing the
counter.
5. Engage the SWEEP EXT/INT switch (12). The duration of the
sweep can be varied by adjusting the SWEEP TIME control
(18). Sweep time is the same whether the sweep is linear or
logarithmic, and is not affected by the sweep width.
1. The end frequency of the sweep (lowest frequency) can be
adjusted by rotating the SWEEP WIDTH control (16). This
adjustment should generally be made after setting the starting
frequency, because it is largely dependent on that setting.
2. The front panel VCG/SWEEP jack (9) provides the internal
ramp signal which can be used as the horizontal deflection
signal for an oscilloscope, to give an X-Y display of signal
amplitude vs. frequency. This method is commonly used when
testing the frequency response of audio equipment or the
bandwidth of amplifiers or other equipment. The response will
be displayed high frequency to low frequency from left to right
on the X-Y display.
If the output of the circuit to be tested is connected to the vertical
scope input, and the SWEEP output to the horizontal, setting the
scope to X-Y mode produces the amplitude vs. frequency plot
mentioned above. However, note that switching to LOG sweep still
produces a linear display on the scope. This is because the horizontal
sweeping signal, the internal log ramp, also becomes logarithmic
when the sweep does. To view a true logarithmic graph, put the
scope back in time base operation and use the Sweep output solely
as a scope trigger. Use the scope's linear time base as a horizontal
deflection source.
VOLTAGE CONTROLLED FREQUENCY OPERATION
The Model 4017A can be operated as a voltage-controlled
generator by using an external control voltage app lied to the
VCG/SWEEP input jack. The externally applied voltage will
vary the frequency which is preselected by the range switches
and the frequency controls. Applying approximately +l0 V
with the COARSE control at full clockwise decreases the
output frequency by about 100 times (a 100:1 ratio).