Dynamic Range Tests (Noise Tests) - HP 3580A Operating And Service Manual

Model 3580A PERFORMANCE TESTS
Section V
b. By alternately pressing and releasing DISPLAY -
CLEAR WRITE while adjusting MANUAL VERNIER,
center the display indication (a narrow spike).
c. Connect a properly terminated frequency synthesizer
to the input of the 3580A. Adjust the synthesizer for a
10 kHz - 20 dBv signal (- 20 dBm 900 n for Option 002)
output. (See Table 5-3.) Momentarily press DISPLAY -
CLEAR WRITE.
d. Adjust the FREQUENCY dial (pulled out for fine
tuning) for a peak display indication.
e. Reposition the following front panel controls:
AMPLITUDE MODE ........ LOG 1 dB/DIV
f. Readjust the FREQUENCY dial (fine tune position)
for a peak display indication of the IO KHz input. Adjust
CAL 10 KHz for a full scale 0 dB display, if not already so
adjusted.
g. Slowly rotate MANUAL VERNIER CW until the
display dot has dropped 3 dB in amplitude. (Remember,
the display is calibrated 1 dB/DIV). This is the upper 3 dB
point of the filter.
h. Momentarily press DISPLAY - CLEAR WRITE.
Slowly increase the frequency of the source. The dot will
move to a full scale display and then down to the lower
3 dB point of the filter.
i. Note the frequency of the source at this lower 3 dB
point_ Hz. This frequency, less the orfginal IO KHz start
frequency, is the 3 dB bandwidth of the 300 Hz filter. It
should be 300 Hz
±
45 Hz.
j. Repeat Steps f through i for the IOO Hz, 30 Hz and
10 Hz filters. See Table 5-11 for the start frequency of the
source, FREQUENCY dial setting, RESOLUTION BAND-
WIDTH, FREQ. SPAN/DIV, and the test limits. At the start
of each new bandwidth setting, always center the display
with MANUAL VERNIER, and adjust the FREQUENCY
dial, and CAL IO KHz for a full scale, peak display at the
appropriate start frequency. Then make the appropriate
adjustments for the upper and lower 3 dB points.
Table 5-11. 300 Hz thru 10 Hz Bandwidth Tests.
SOURCE START RESOLUTION
FREQ. SPAN/DIV 3 dB BANDPASS
FREQ. and 3580A
BANDWIDTH TEST LIMITS
FREQUENCY
10 kHz
300 Hz 50 Hz
300 Hz ± 45 Hz
1 kHz
100 Hz 50 Hz
100 Hz ± 15 Hz
1 kHz 30 Hz
10 Hz 30 Hz
±
4.5 Hz
1 kHz 10 Hz
5 Hz
10 Hz ± 1.5 Hz
k. Using Table 5-12 and the same technique used for
the 300 Hz, 100 Hz, 30 Hz, and 10 Hz Bandwidths, test the
60 dB Bandpass of the 3 Hz and 1 Hz filters. However, use
AMPLITUDE MODE ....... LOG 10 dB/DIV
and measure the frequency difference between the 60 dB
points. As before, always adjust the FREQUENCY dial and
CAL 10 KHz for a peaked full scale display before
attempting to measure the 60 dB bandwidths. Note: The
display is now calibrated 10 dB/DIV.
Table 5-12. 3 Hz and 1 Hz Bandwidth Tests.
SOURCE START
RESOLUTION FREQ. SPAN/DIV
60 dB BANDPASS
FREQ. and 3580A BANDWIDTH TEST LIMITS
FREQUENCY
1 kHz 3 Hz 5 Hz
30 Hz
±
4.5 Hz
1 kHz 1 Hz 5 Hz 10 Hz ± 1.5 Hz
5-30. Dynamic Range Tests (Noise Tests).
5-31. Dynamic range is the ability of the instrument to
detect large and small signals and display them simulta-
neously. The range and accuracy of the amplifiers is a
determining factor. This specification was tested in the
Amplitude Tests (Paragraph 5-18). The instrument noise
and spurious responses are the other determining factors of
dynamic range. These tests verify these parameters. If the
instrument will not pass any of these tests, see Section VII
for troubleshooting information. There are no adjustments
for these specifications.
Equipment Required:
Frequency Synthesizer (-hp- Model 3320B, 50 ohms)
50 Ohm Termination (-hp- 1 I048C)
Bandpass Filter (White Model 2640)
Proper input resistor for filter (550 n ± IO%,
Part No. 06984456)
1
% 1 kn film resistor (-hp- Part No. 0757-0280)
5-32. Noise Level Tests.
a. Connect the 1 kn resistor across the INPUT terminals
of the 3580A. Disconnect all signal sources.
b. Position the following front panel controls: (Only
those controls printed in
BOLD
require a change from the
previous tests).
ADAPTIVE SWEEP ................. OFF
DISPLAY ........ All pushbuttons released
AMPLITUDE MODE ...... LOG 10 dBv/DIV
AMPLITUDE REF LEVEL ....... NORMAL
dBv/LIN - dBm 600 n ............ dBv/LIN
INPUT SENSITIVITY ............. - 70
dB
VERNIER (Amplitude) . . . . . . . . . . . CAL
(Fully CW)
FREQUENCY ................. 00.0 kHz
START-CTR ................... START
RESOLUTION BANDWIDTH . . . . . . 300 Hz
5-9