Specifications

Preliminary Procedure
1. Connect the Differential Amplifier to an AC power
source within the range listed in the Nominal
Characteristics in the Specification section.
1. Allow at least 20 minutes warm-up time for the
1820/1822 and test equipment before performing the
Verification Procedure.
2. Turn on the other test equipment and allow it to warm
up for the time recommended by the manufacturer.
The warranted characteristics of the 1820/1822 series
Differential Amplifiers are valid at any temperature
within the Environmental Characteristics listed in
Section 1. However, some of the other test equipment
used to verify the performance may have environmental
limitations required to meet the accuracy requirements
needed for the procedure. Be sure that the ambient
conditions meet the requirements of all the test
instruments used in the procedure.
NOTE
When the oscilloscope input is connected to the
1820/1822 AMPLIFIER OUTPUT, the oscilloscope
input impedance should be set to 50 .(-2 unless otherwise
stated Use a 50 .(2 inline termination when using an
oscilloscope without an internal 50 .(2 termination.
Position the oscilloscope display to center screen.
Unless otherwise noted, the oscilloscope position and
offset must remain at zero for the duration of the
adjustment procedure.
Set the 1820/! 822 front panel controls as follows:
HF -3 dB POINT All LEDs Off
(Maximum bandwidth)
LF-3dB POINT
All LED’s Off
(DC)
GAIN
Xl
ATTENUATOR .-1
INPUT RESISTANCE
1 MQ
+INPUT OFF
-INPUT OFF
VCOMP
OFF
VDIFF
OFF
PRECISION VOLTAGE 00.000 V
GENERATOR
4-3
1820/1822 Operator’s Manual
Procedure
1. CheckXl Gain Accuracy
a. Set the 1820/1822 +INPUT to DC.
b. Connect the High Amplitude Sine Wave
generator via a 50 f2 BNC coaxial cable, a
standard 50 f2 termination to a female BNC
to banana plug adapter.
c. Set the DMM to measure AC volts.
d. Connect the banana plug adapter to the
DMM.
e. Set the sine wave generator to 70 Hz and the
output amplitude to read 2 Vrms + 50 mV on
the DMM.
f. Record the DMM reading to 100 laV
resolution as ’Sine Wave Generator Output
Voltage’ in the Test Report.
g. Disconnect the sine wave generator output
cable with the 50 f2 termination from the
BNC to banana plug adapter on the DMM.
Leave the banana plug adapter installed on
the DMM for the remainder of the
procedure.
h. Connect the sine wave generator via the
coaxial cable with the standard 50 f2
termination to the +INPUT of the
1820/1822.
i. Connect the 1820/1822 AMPLIFIER
OUTPUT connector via another coaxial
cable and the precision 50 ~ termination to
the banana plug adapter on the DMM.
j. Press the XI GAIN button to remove any
residual DC offset from the input. (A DC
component may interfere with the RMS
computation in some DMMs.)
k. After the DMM has stabilized, record the
reading to 1 mV resolution as ’Amplifier
Output Voltage’ in the Test Record.
1. Divide the measured output voltage from
step 1-k by the sine wave generator output
voltage (amplifier input voltage) in step i-f.
Subtract 1.0 from the ratio and multiply the
result by 100% to get the error in percent.
I
Measured Output Voltage _ 11 x
Error = Amplifier Input Voltage 100%
I