Ametek 7280 Instruction Manual page 56

Chapter 5, FRONT PANEL OPERATION
5-10
-B
The signal channel input is an inverting single-ended voltage input to the BNC
connector on the front panel marked B/I.
A-B
In this setting the signal channel input is a differential voltage input connected to
the BNC connectors on the front panel marked A and B/I.
NONE
The input is disconnected in this setting.
In current input mode, shown in figure 5-6, this control has three settings:-
WIDE (Wide Bandwidth Converter)
In this setting the signal channel input is a single-ended current input connected
to the BNC connector on the front panel marked B/I, and uses the wide
bandwidth current-to-voltage converter.
NORM (Normal Converter)
In this setting the signal channel input is a single-ended current input connected
to the BNC connector on the front panel marked B/I, and uses the normal
current-to-voltage converter.
LO-NOISE (Low Noise Converter)
In this setting the signal channel input is a single-ended current input connected
to the BNC connector on the front panel marked B/I, and uses the low-noise
current-to-voltage converter.
LINE NOTCH FILTER
This control selects the mode of operation of the line frequency rejection filter and
offers four possible settings out of the seven described in the following table:-
Legend Function
OFF
Line filter inactive
50
Enable 50 Hz notch filter
60
Enable 60 Hz notch filter
100
Enable 100 Hz notch filter
120
Enable 120 Hz notch filter
50/100
Enable 50 and 100 Hz notch filters
60/120
Enable 60 and 120 Hz notch filters
The filter frequencies available (i.e. 50/100 Hz or 60/120 Hz) depend on the setting
of the LINE FREQUENCY control on the Configuration Menu - see section 5.3.13
AUTO AC GAIN
The final control on the Signal Channel menu selects whether or not the Automatic
AC Gain function is active. As discussed in section 3.3.04, the correct adjustment of
the AC Gain in a DSP lock-in amplifier is necessary to achieve the best results. This
control allows the user to select whether this adjustment is carried out automatically
or remains under manual control.