Boonton 1121A, Instruction Manual

Page: 69 / 181

Maintenance Section 5
5-7
calibrator and recorded. The Model 1121A flatness is
then measured at the same test levels and compared to
the measurements using the calibrator thereby
eliminating the Analyzer measurement errors.
5-29.
Depress the LCL/INIT key to initialize the instru-
ment and enter special function 17 to enable the slow
detector mode. Connect the Wideband Calibrator output
using the balanced cable and adapters to the Analyzer HI
and LOW inputs and connect the 50 ohm load across the
binding post adapters at the Analyzer input. Perform the
following procedure for each test level listed in Table 5-8.
a. On the Calibrator enable the wideband source
output and enter the Model 5100B test level at a
frequency of 1 kHz.
b. On the Audio Analyzer enter the calibrator level in
the ANALYZER display window to set and hold the input
level range.
c. Enable the Analyzer level ratio mode to set the
flatness reference.
d. On the Calibrator enter the test frequencies
between 10 Hz and 100 kHz indicated in Table 5-8 and
record the Analyzer ratio measurements in the REFER-
ENCE column.
5-30.
Depress the LCL/INIT key to initialize the in-
strument. Connect the HI and LOW outputs using the
balanced cable and adapters to the Analyzer HI and LOW
inputs. Enter special function 75 (50 ohm output). Enable
the input floating mode and connect the 50 ohm load
across the binding post adapters at the Analyzer input.
Perform the following procedure for each test level listed
in Table 5-8.
a. On the Model 1121A enter the test level at a fre-
quency of 1 kHz. Before entering the 6.0 mV down-scale
test level, the 300 mV range must be held by entering the
special function 18 while the 300 mV level is set.
b. On the Audio Analyzer enter the Model 5100B test
level in the ANALYZER display window to set and hold
the input level range.
c. Enable the Analyzer level ratio mode to set the
flatness reference.
d. On the Model 1121A enter the test frequencies
indicated in Table 5-8.
e. Note the display and calculate the actual flatness
by subtracting the value in the REFERENCE column in
Table 5-8 from the displayed measurement and record
the result in the ACTUAL column. At the 140 kHz test
frequency subtract the 100 kHz value in the
REFERENCE column from the displayed measurement
and record the result.
5-31. Analyzer Low Level AC Accuracy.
Depress
the LCL/INIT key to initialize the instrument. Enter special
function 75 (50 ohm output). Connect the Model 1121A HI
output to the input of the HP 355D step attenuator and
connect the output of the attenuator to the Model 1121A
HI input. Perform the following procedure for each test
frequency listed in Table 5-9.
a. Set the attenuator to 40 dB.
b. Set the Model 1121A output level to 3.000 volts at
1 kHz.
c. Depress the RATIO key to enable the ratio mode.
d. Set the Model 1121A output level to 30.00 mV and
the attenuator to 0 dB.
e. Record the analyzer ratio measurement in the
REFERENCE column in Table 5-9.
f. Depress the RATIO key to disable the ratio mode
and set the attenuator to 40 dB.
g. Multiply the analyzer measurement by the ref-
erence value from step e above, divide the product by
100.00% and record the result in the ACTUAL column
in Table 5-9.
5-32. Frequency Accuracy.
Depress the LCL/INIT
key to initialize the instrument. Connect the Source HI
and LOW outputs using the balanced cable and adapters
to the Analyzer HI and LOW inputs and enter a source
level of 2 volts. Connect the SYNC output on the rear
panel of the Model 1121A to the Frequency Counter
CHANNEL A input and set the Frequency Counter
controls as follows:
FUNCTION....................................... FREQ A
GATE TIME ...................................... 10 sec
DISPLAY POSITION ........................ AUTO
LEVEL .............................................. PRESET
SLOPE ............................................. +
ATTEN.............................................. 1 MEG, X1
AC/DC .............................................. AC
CHECK/COM/SEP ........................... SEP
5-33. Source Frequency Accuracy.
For each test
frequency listed in table 5-10 set the Source to the test
frequency, verify the Source frequency accuracy by
comparing the setting and external counter
measurements and record the results, pass or fail.
5-34. Analyzer Frequency Accuracy.
For each test
frequency listed in table 5-11 set the Source to the test
frequency, verify the Analyzer frequency measurement
accuracy by comparing the external counter and Analyzer
frequency measurement and record the results, pass or
fail.