And R - Stanford Research Systems SR810 Manual

X, Y, R and q
This measurement is designed to use the internal oscillator and an external signal source to explore some of
the display types. You will need a synthesized function generator capable of providing a 100 mVrms sine
wave at 1.000 kHz (the DS335 from SRS will suffice), BNC cables and a terminator appropriate for the
generator function output.
Specifically, you will display the lock-in outputs when measuring a signal close to, but not equal to, the
internal reference frequency. This setup ensures changing outputs which are more illustrative than steady
outputs. The displays will be configured to show X and R.
1. Disconnect all cables from the lock-in. Turn
the power on while holding down the [Setup]
key. Wait until the power-on tests are
completed
2. Turn on the function generator, set the
frequency to 1.0000 kHz (exactly) and the
amplitude to 500 mVrms.
Connect the function output (sine wave)
from the synthesized function generator to
the A input using a BNC cable and
appropriate terminator.
3. Press [Freq]
Use the knob to change the frequency to
999.8 Hz.
4. Press [Channel 1 Display] to select R.
When the power is turned on with the [Setup] key
pressed, the lock-in returns to its standard settings.
See the Standard Settings list in the Operation section
for a complete listing of the settings.
The Channel 1 display shows X.
The input impedance of the lock-in is 10 MΩ. The
generator may require a terminator. Many generators
have either a 50 Ω or 600 Ω output impedance. Use
the appropriate feed through or T termination if
necessary. In general, not using a terminator means
that the function output amplitude will not agree with
the generator setting.
The lock-in defaults to the internal oscillator reference
set at 1.000 kHz. The reference mode is indicated by
the INTERNAL led. In this mode, the internal oscillator
sets the detection frequency.
The internal oscillator is crystal synthesized so that the
actual reference frequency should be very close to the
actual generator frequency. The X display should read
values which change very slowly. The lock-in and the
generator are not phase locked but they are at the
same frequency with some slowly changing phase.
Show the internal oscillator frequency on the
Reference display.
By setting the lock-in reference 0.2 Hz away from the
signal frequency, the X and Y outputs are 0.2 Hz sine
waves (frequency difference between reference and
signal). The X output display should now oscillate at
about 0.2 Hz (the accuracy is determined by the
crystals of the generator and the lock-in).
The default Channel 1 display is X. Change the display
to show R. R is phase independent so it shows a
steady value (close to 0.500 V).
2-5
X and R