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1.8 Reference oscillator external input
1.8 Reference oscillator external input
SR124 Analog Lock-In Amplifier
2. Press [Ampl] in the Reference section, and turn the
REFERENCE knob counterclockwise until the numeric dis-
play shows 95.0 mV.
3. Turn SENSITIVITY 2 clicks counterclockwise, to 100 mV. The
meter should read near 95% deflection
4. Enable the output o set by pressing [On O ] in the OFFSET
block. Perform an auto-o set adjustment by pressing [O set]
in the AUTO block. After the pause, the o set should show a
value near 95% o set. The panel meter should read near zero.
5. Turn SENSITIVITY 2 more clicks counterclockwise, to 20 mV.
The panel meter should still read near zero, while the REFER-
ENCE display shows a value near 475%.
6. Turn SENSITIVITY 1 click counterclockwise, to 10 mV. The
REFERENCE display should read near 950%, and the panel
meter should still be near null.
7. Turn SENSITIVITY 1 click further counterclockwise. The dis-
play should show the message "Attn OFFSt", and the OFFSET
annunciator in the REFERENCE display block should blink.
The sensitivity does not change.
8. Press the [Ampl] button, and reduce the amplitude to 90.0 mV.
The panel meter should show around 50% full scale deflec-
tion.
9. Press the [O set] button in the AUTO block again, to automati-
cally re-adjust the o set. The REFERENCE display should now
show near 900%, and the panel meter should be nulled.
1. Restore
default
REFERENCE if necessary to display "deFLt", and then
press [Recall] again.
2. Set the function generator to produce a 1 Vrms, 2 kHz sine wave.
Connect the function generator output to the SR124 "Ext. In"
BNC, in the REFERENCE section.
3. Turn the Mode knob in the REFERENCE section one click
clockwise, to the f External setting. The Unlocked indicator
should illuminate for between 5 and 20 seconds, and then the
SR124 should lock to the external signal.
4. Press [Freq] in the REFERENCE section to perform an oscillator
frequency measurement. After a brief delay, the REFERENCE
settings
by
pressing
1 – 7
[Recall];
turn
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