Stanford Research Systems SR865A, Operation Manual

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192 Performance Tests Appendix G
SR865A DSP Lock-in Amplifier
Phase Accuracy
This test measures the phase accuracy of the lock-in. The phase accuracy is determined by measuring the
phase of the internal oscillator Sine Out.
Setup
Connect the Sine Out+ to the Voltage A input of the SR865A using a 24-inch BNC cable, with the
precision 50
Ω
feedthrough terminator at the A input BNC. This test only uses ONE Sine Out BNC.
Please note that the phase calibration is performed at the factory relative to a 24-inch RG-58 BNC cable,
with approximately 3 ns of propagation delay. Results will be show a significant dependence on cable
length. For example, using a 2 m long cable instead of the specified 24-inch cable will introduce an
additional 6.9 ns of propagation delay between sine output and signal input: at 4 MHz, this corresponds to
10° of additional phase delay.
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.
Touch {Ampl} to display the sine out amplitude keypad
Enter an amplitude of 100 mV.
Press Filter [Slope/ adv ] multiple times
Select 24 dB/oct.
Press [Time Constant Up]
Select 300 ms
Press [Input Range Down]
Select 300 mV
Press [Couple]
Select DC coupling.
3) The value of R (yellow) should be 0.050 V (±2%) and the va lue of θ (orange) should 0° (±1°).
4) Phase accuracy is checked at various frequencies. The test frequencies are listed below.
Test Frequencies
10 Hz
100 Hz
1 kHz
10 kHz
100 kHz
1.0 MHz