Oscillator - Stanford Research Systems SR124 Operation And Service Manual

5 – 4

5.6 Oscillator

Figure 5.2: The front-end JFET (Q1101) socket, un-installed.
cover removed. Be sure to have a second person nearby for
safety, and do not proceed if the metal shroud covering the AC
power entry module has been removed.
7. Place a shorting cap or 50
and turn the instrument on.
REFERENCE knob to show "dEFLt". Press [Recall] a sec-
ond time to restore defaults. Turn the SENSITIVITY knob to
5 mV.
8. Attach the voltmeter test leads to Test Points TP1104 and
TP1105 (see Figure 5.3). Slowly adjust trimmer R1102 to null
the voltage between TP1104 and TP1105. You should be able
to reduce the voltage to
9. Return the top cover and reinstall all the screws.
The Oscillator board contains the quadrature sinewave voltage-
controlled oscillator. This board is mounted vertically, at the right-
hand side of the SR124 chassis.
terminator onto the A I input,
Press [Recall], and turn the
5 mV.
SR124 Analog Lock-In Amplifier
Circuits