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22
Getting Started
8.
Press [Sensitivity Down] two more times to
select 100 mV.
9.
Press and hold the <CH1 Offset> knob (above
the CH1 BNC) to display the offset keypad.
10. Touch {Auto} in the offset keypad screen.
SR865A DSP Lock-in Amplifier
Note that the trace of X is unchanged. This is
because the value of X is unchanged.
The Sensitivity does not affect the value of the
output, just the way the value is scaled to the
displays and analog output.
The Sensitivity applies to X, Y and R.
The DVM should now read 10 V and X is now
100% of full scale on the bar graph.
It is important to adjust the Sensitivity even if
the analog outputs are not being used. The
Sensitivity determines the resolution of the
numeric readouts and bar graphs.
[Auto Scale] will adjust the Sensitivity
automatically.
X, Y and R may all be offset, ratioed, and
expanded separately.
Since CH1 is set to X (indicated by the
above the [Select] key) the <CH1 Offset> knob
and [Expand] key above the CH1 BNC set the
X offset and expand.
The [CH1 Select] key determines which
quantity (X or R) is offset, ratioed, or expanded,
and output on the BNC.
The ratio function is described later in this
manual, in the Operation chapter. Here we will
explore offset and expand.
Auto Offset automatically adjusts the X offset
(or Y or R) such that X (or Y or R) becomes
zero. In this case, X is offset to zero. The offset
should be about 100%. Offsets are set as a
Chapter 1
X
LED
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