Boonton 1121A, Instruction Manual

Page: 87 / 181

Maintenance Section 5
5-25
j. Observe the Wave Analyzer and adjust A0R7 for a
minimum indication. The null measurement should be in
excess of 75 dB. If a 75 dB null cannot be achieved,
alternately adjust A0C32 or A0C33 flatness adjustments
and A0R7 for a null in excess of 75 dB.
5-63. A0C5 and A0C32 Flatness Adjustments.
Perform the adjustments as follows:
a. Depress the LCL/INIT key to initialize the instru-
ment.
b. Enable the input floating mode and connect the
Source HI and LOW outputs to the Analyzer HI and LOW
inputs, respectively, using the balanced cable and
adapters.
c. Set the Source frequency to 100 kHz and level to
3.000 volts.
d. Enter special functions 17 and 28.
e. Depress the RATIO key to enable the Analyzer
level ratio mode.
f. Enter special function 27, note the display and
adjust A0C32 for an indication of 100.00% ± 0.1%
g. Enter special function 26, note the display and
adjust A0C32 for an indication of 100.00% ± 0.1%
5-64. A0C10 and A0C33 Flatness Adjustments.
Perform the adjustments as follows:
a. Depress the LCL/INIT key to initialize the instru-
ment.
b. Enable the input floating mode and connect
the Source HI and LOW outputs to the Analyzer input
LOW and HI, respectively, using the balanced cable and
adapters.
c. Set the Source frequency to 100 kHz and level to
3.000 volts.
d. Enter special functions 17 and 28.
e. Depress the RATIO key to enable the Analyzer
level ratio mode.
f. Enter special function 27, note the display and
adjust A0C10 for an indication of 100.00% ± 0.1%.
g. Enter special function 26, note the display and
adjust A0C33 for an indication of 100.00% ± 0.1%
5-65. A7 Output Board Adjustments.
The Output Board adjustments consist of three attenuator
adjustments which trim the most significant bits of the
programmable attenuator for optimum level accuracy.
5-66. A7R21, A7R17, and A7R15 Adjustments.
Perform the adjustments as follows:
a. Depress the LCL/INIT key on the Model 1121A to
initialize the instrument. Connect the Model 1121A HI and
LOW outputs to the Multimeter HI and LOW inputs using
the balanced cable and adapters and enter special
function 75 (50 ohm output).
b. Set the Multimeter to measure AC level.
c. Set the level (open circuit) to 511 mV.
d. Observe the multimeter display.
e. Set the level to 512 mV and adjust A7R21 for an
increase of 1 mV ± 0.3 mV above the measurement in
step d above.
f. Set the level to 1023 mV.
g. Observe the Multimeter display.
h. Set the level to 1024 mV and adjust A7R17 for an
increase of 1 mV ± 0.5 mV above the measurement in
step g. above.
i. Set the level to 2047 mV.
j. Observe the Multimeter display.
k. Set the level to 2048 mV and adjust A7R15 for an
increase of 1 mV ± 0.5 mV above the measurement in
step j above.
5-67. A6 Source Board Adjustments.
The only adjustment on the Source Board is the Output
Level adjustment which sets the full scale output level of
the Model 1121A.
5-68. A6R23 Output Level Adjustment.
Perform the adjustments as follows:
a. Connect the 50 Hz - 50 kHz Calibrator output to
the Multimeter input using the balanced cable and
adapters and set the Multimeter to measure AC level.
b. Set the Calibrator to 1.000 kHz and 3.000 volts
and enable the Calibrator output.