Stanford Research Systems SR865 Operation Manual page 206

188 Performance Tests
Amplitude Accuracy and Flatness
This test measures the amplitude accuracy and frequency response.
Setup
We will use the internal sine output to provide an accurate sine wave for testing the signal input function.
This test requires the preceding Sine Output Amplitude Accuracy and Flatness test results to verify
specified performance.
Connect the Sine Out+ to the Voltage A input of the SR865 using a 1 meter BNC cable, with the
precision 50Ω terminator at the A input BNC. This test only uses ONE Sine Out BNC. This means that
each measurement will nominally be 50% of the programmed sine amplitude.
Preliminary calculations
i) Refer to the Reading values recorded for the Sine Output Amplitude and Flatness test.
ii) Results labeled (A) through (J) are used to set performance Lower Limits and Upper Limits for
Amplitude Accuracy and Flatness
iii) On the Performance Test Record, for Lower and Upper limits, perform the multiplication
indicated with the referenced value of Sine Output Amplitude and Flatness. For example:
Assume result (A) is recorded as 0.4966 V
The Lower Limit at 1V will be 0.99×(
The Upper Limit at 1V will be 1.01×(
Procedure
1) {PRESET} (press [Save Recall], then touch {Recall default}. Touch {Confirm})
2) Use the front panel to make the following adjustments
Touch {Fint} to display the internal frequency keypad
Enter a frequency of 1.0 kHz.
Press Filter [Slope/adv] multiple times
Select 24 dB/oct.
3) Amplitude accuracy is verified at 1 kHz and various sensitivities. For each input range setting in
the table below, perform steps 3a through 3c.
Sine Out Amplitude
1.0000 Vrms
300.00 mVrms
100.000 mVrms
30.000 mVrms
10.000 mVrms
SR865 DSP Lock-in Amplifier
)= 0.99×0.4966 V = 0.4916 V
A
)= 1.01×0.4966 V = 0.5016 V
A
Input Range Sensitivity
1 V 1 V
300 mV 200 mV
100 mV 100 mV
30 mV 50 mV
10 mV 10 mV
Appendix G