HP 3580A - Familiarization Exercise

Model 3580A BASIC OPERATING PROCEDURES
Section III
e. Connect the probe tip to the rear panel TRACKING
OSC OUT connector. Connect the ground lead of the probe
to case ground.
f. Adjust the front panel amplitude VERNIER so that
the horizontal trace is between 0 dB and - 10 dB on the
display.
g. Set the AMPLITUDE MODE to LOG I dB/DIV.
h. Adjust the probe so that its response is flat over the
entire frequency range (Figure 3-35).
PROPERLY
COMPENSATED
UNCOMPENSATED
Figure 3-35. Probe Compensation.
3-205. Familiarization Exercise.
3-206. The following procedure demonstrates the Digital
Storage, Adaptive Sweep and other operating features of
the 3580A.
a. Turn the instrument on as outlined in Paragraph
3-92. Perform the Frequency Calibration Procedure (Para-
graph 3-195) and the Amplitude Calibration Procedure
(Paragraph 3-199). Perform the amplitude calibration using
the 100 Hz BANDWIDTH and the LOG 10 dB AMPLI-
TUDE MODE.
b. Set the 3.580A controls as follows:
ADAPTIVE SWEEP ................. OFF
DISPLAY ..... STORE and BLANK STORE
Released
AMPLITUDE MODE ....... LOG 10 dB/DIV
AMPLITUDE REF LEVEL ....... NORMAL
dBv/LIN - dBm Switch ........... dBv/LIN
INPUT SENSITIVITY ............... CAL
VERNIER ...................... CAL
(Fully CW)
FREQUENCY ................• 00.0 kHz
START CTR .................... START
BANDWIDTH . . . . . . . . . . . . . . . . . . 100 Hz
DISPLAY SMOOTHING ............. MIN
FREQ. SPAN/DIV ................ 5 KHz
SWEEP TIME/DIV . . . . . . . . . . . . . . . 1 SEC
SWEEP MODE ....................• REP
c. The spectral components of the 10 kHz calibration
signal will now appear on the display. If the instrument is
properly calibrated, the peak of the 10 kHz fundamental
frequency component will be at full scale and the zero
response will coincide with the first line on the left-hand
side of the display graticule.
d. Set the BANDWIDTH switch to the 30 Hz position.
The ADJUST light will illuminate to indicate that the
sweep rate is too fast. As the trace is updated by a new
sweep, the amplitudes of the various frequency components
will be compressed because the IF Filter does not have time
to fully respond.
e. Rotate the SWEEP TIME control counterclockwise
until the ADJUST light goes out (10 SEC). When the
ADJUST light goes out, the instrument is sweeping at the
optimum rate.
f. Set the SWEEP MODE switch to the SING (Single)
position. Press and release the CLEAR WRITE button. This
will clear the display and initiate a new sweep. Allow 100
seconds for the display to be updated. The trace generated
by the single sweep will continue to be displayed until it is
cleared or replaced by a new sweep.
g. Press the STORE button and then press the BLANK
STORE button. The trace currently being displayed is now
permanently stored in memory and can be recalled at any
time by releasing the BLANK STORE button.
h. Using the ADAPTIVE SWEEP control, set the
baseline threshold about 10 dB above the noise floor.
i. Press and release the CLEAR WRITE button to
initiate a new sweep. Observe the fast and slow excursions
of the Adaptive Sweep. Note that the penlift relay clicks
each time the instrument begins to sweep slowly over a
response. The Adaptive Sweep takes only about 15 seconds
to trace the plot that previously took 100 seconds.
j. Set the ADAPTIVE SWEEP control to the OFF
position. Release the BLANK STORE button to compare
the 15 second trace and the 100 second trace. The two
traces will be identical except the 15 second trace obtained
using the Adaptive Sweep will not have a noise floor. Again
press the BLANK STORE button. The permanently stored
trace will disappear.
k. Set the SWEEP MODE switch to the REP (Repeti-
tive) position.
I. To examine the 20 kHz frequency component in
greater detail, set the START/CTR switch to CTR, set the
FREQ. SPAN/DIV to 0.5 KHz and set the SWEEP TIME/
DIV to 1 SEC. At this point, the center of the display is
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