Stanford Research Systems SR865A, Operation Manual

Page: 91 / 221

Chapter 3 Operation 73
SR865A DSP Lock-in Amplifier
Output <Offset>
Press this knob briefly to toggle the X or R offset (CH1) or the Y offset (CH2) on and off.
Use the [Select] key to select either X or R
(CH1) and Y or θ (CH2). The value of θ
cannot be offset. Use Auto Phase to offset phase to zero.
This allows the offset to be turned on and off without adjusting the actual offset
percentage.
The OFFSET LED is on when the offset is being applied.
Press and hold the <Offset> knob to display an offset keypad as shown below.
Touch {Auto} Offset to automatically adjust the X offset (or Y or R) such that X (or Y or
R) becomes zero. Offsets can also be set using the keypad or by turning the <Offset>
knob. Turning the knob ALWAYS adjusts the offset, even if the offset is toggled off and
the keypad is not shown.
Offsets are set as a percentage of the Sensitivity up to ±999% (10×). The offset
percentage is not changed with the sensitivity
— it is an output function.
Touch {Close} to dismiss the keypad.
Touch {Ratio} to cycle between Off (no ratio) and an Aux Input. The RATIO LED is on
when a ratio is being applied.
Output Overload
Outputs which would exceed ±10 V generate an Output Overload and the red Overload
LED will light. Any corresponding displayed numeric value/bar graph will indicate
‘Scale’ in the display.
The actual measurement is unaffected since it is done in floating
point and has no overload. Data displayed in the strip chart will still be accurate.