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Chapter 5, FRONT PANEL OPERATION
Main Display. There are four auto functions for each of the two harmonic reference
channels, which operate exactly as described for single reference mode in section
5.3.14.
Pressing a key adjacent to the Auto-Default item carries out an Auto-Default
operation and resets the instrument to single reference mode.
5.6.09 Dual Harmonic Configuration Menu
Figure 5-68, Configuration Menu - Dual Harmonic Mode
In dual harmonic mode, the configuration menu appears as above in figure 5-68. To
leave dual harmonic mode and return to single reference mode press the Single
Reference key, to switch to dual reference mode, press the Dual Reference. The
remaining controls, and the Configuration Menu 2 accessed from this menu, operate
as already described in section 5.3.22
This completes the description of the dual harmonic mode menus.
5.7 Typical Lock-in Amplifier Experiment
The model 7270 is a complex instrument that has many controls and the following
basic checklist may be helpful in setting up the instrument for manual operation in
single reference mode.
Auto-Default
Use the Auto-Default function on the Auto Functions menu to set the instrument to a
defined state.
Selection of Signal Input
Use the Signal Channel menu to select voltage (single-ended or differential) or
current input mode, and connect the signal source to the relevant A and/or B (I) input
connector(s).
Selection of Reference Mode
The default setting function will have set the reference mode to internal, which
assumes that the internal oscillator will be used as a source of excitation to your
experiment. Use the Internal Oscillator amplitude and frequency controls to set the
required oscillator output. Then connect the output signal from the OSC OUT
connector on the front panel.
5-89
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