PERFORMANCE TESTS
5-5
2. Amplitude Accuracy
This test measures the amplitude accuracy of the drive output. It should be within 2.0% of the nominal
value for all of the amplitude settings.
1) Connect the AC/DC volt meter across the two sides of the fixture. A small piece of wire inserted in
each side of the fixture is a convenient way to connect the DVM. Do not connect either end to ground.
Set the meter to AC volts, autoranging.
2) Set the SR715/720 to its default conditions ([Recall] [0] [ENTER]). Set the unit to constant voltage
mode. The output voltage should be 1.0 VRMS at 1 kHz. Verify that the voltage reading is between
0.98 and 1.02 VAC RMS. Record the result.
3) Repeat this for 100 Hz, 120 Hz, 10 kHz and 100 kHz (SR720 only). All voltage readings should all be
between 0.98 and 1.02 VAC RMS. Record the result.
4) Set the frequency to 1 kHz. Set the voltage to 0.25 V and 0.10 V. The meter should read within 2.0%
of the nominal values (between .245 and .255 and between .098 and .102 respectively). Record the
result.
5) Set the AC/DC volt meter to DC volts. Set the SR715/720 to C+D, 100 kHz, 0.10 Drive Voltage,
Internal Bias on. Verify that the DC voltage is 2.0 VDC ± 2%.
3. Impedance Accuracy
These tests confirm that the SR715/720 meets its impedance measurement accuracy specification.
Precision impedance standards are required. The minimum and maximum acceptable values are
determined by adding the tolerance of the SR715/720 and that of the standard. For example, at 1.000 kΩ
the tolerance of the SR720 is ±0.05%, the tolerance of the resistance standard is ±0.02% and thus the
total tolerance is ±0.07% or ±0.7 Ω. So the range of acceptable values is 999.3 Ω to 1000.7 Ω. If
standards with different tolerances are used, the acceptable limits will have to be adjusted.
Resistance Accuracy
1) Connect the SR728 Fixture Adapter to the SR715/720. Install a BNC to stacking banana plug adapter
on the end of each BNC cable. Tape over (or cut off) the ground leads of the plugs connected to the
orange (Vh) and purple (Vl) cables. Connect the ground leads of the red (Ih) and blue (Il) cables to the
case ground of the decade box.
Plug the orange and purple signal leads to the "+" and "-" terminals on the decade box. Plug the red
signal lead into the orange signal lead and plug the blue signal lead into the purple signal lead.
Set the SR715/720 to its default conditions ( [recall] 0 ), then press [R+Q] and 1 kHz.
2) Unplug the red/orange lead pair from the "+" terminal of the decade box and plug them into the
blue/purple lead pair. Perform short circuit cal. Remove the red/orange lead pair from blue/purple lead
pair and locate them at the same separation from the blue/purple pair as they will be during operation.
Perform open circuit cal.
3) Connect the red/orange lead pair to the "+" terminal of the decade box. Set the dials to all zeros.
4) Note the resistance value the SR715/720 measures. This is the resistance of the switch contacts and
connectors. Enter this as a relative value in the entry display. Set the SR715/720 to the DEV display
mode.
5) Set the decade resistor and the SR715/720 according to the values in the Resistance Accuracy Table
below. Verify that the readings fall within the acceptable values. Record the results.
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