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using the Select Control key is therefore extended to include those relating to both
harmonics of the reference, as follows:-
SENSITIVITY 1 and SENSITIVITY 2
When set to voltage input mode, using the Signal Channel menu, the instrument's
full-scale voltage sensitivity may be set to any value between 10 nV and 1 V in a
1-2-5 sequence.
When set to current input mode, using the Signal Channel menu, the instrument's
full-scale current sensitivity may be set to any value between 1 pA and 100 µA (wide
bandwidth mode, or 10 fA and 10 nA (low-noise mode), in a 1-2-5 sequence.
The number reported after the letters DR is the instrument's Dynamic Reserve,
expressed in decibels, as calculated by the following equation:-
DR
20
log
10
SEN
Example:-
If AC Gain = 12 dB and SEN = 2 mV then
DR
20 log
10
0.002
DR = 46 dB
TIME CONSTANT 1 and TIME CONSTANT 2
The time constant of the output filters is set using this control, in the range 10 µs to
100 ks in a 1-2-5 sequence. Settings of 1 ms and below restrict the choice of
instrument outputs to X, Y and Magnitude.
HARMONIC 1 PHASE and HARMONIC 2 PHASE
These controls allows the reference phase of each detection channel to be adjusted
over the range -180° to +180° in 1 m° steps. Adjustment is faster using the Keypad
or Active Cursor controls - see section 4.1.04.
HARMONIC 1 PHASE ±90° and HARMONIC 2 PHASE ±90°
These controls allow the relevant reference phase to be adjusted in steps of ±90°.
X1 OFFSET, Y1 OFFSET, X2 OFFSET and Y2 OFFSET
These are the manual X1/X2 channel and Y1/Y2 channel output offset controls. The
offset levels set by these controls, which can be any value between -300% and
+300% in 0.01% steps, are added to the X1, X2, Y1 or Y2 channel outputs when the
relevant channel offsets are switched on using the Output Channels menu.
Adjustment is faster using the Keypad or Active Cursor controls - see section 4.1.04.
The values are set automatically by the Auto-Offset function. Note that the Auto-
Offset function automatically switches on all output offsets
HARMONIC 1 and HARMONIC 2
These controls set the harmonic of the applied reference frequency, either internal or
external, at which the lock-in amplifier's two reference channels operate, in the range
1 st (fundamental mode) to 127 th. For example, if a reference frequency of 1 kHz is
applied, Harmonic 1 is set to 3 and Harmonic 2 to 5, the instrument will measure
signals at both 3 kHz and 5 kHz.
Chapter 5, FRONT PANEL OPERATION
2
ACGain (in dB)
2
14
5-81
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