Ametek 7230 Instruction Manual page 59

bandwidth current-to-voltage converter (10E6 V/A transimpedance).
B (current^8)
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 (10E8 V/A transimpedance).
Off
In this setting, used for test purposes, the signal channel input is disconnected.
Input coupling
The input coupling can be set as follows:-
AC
The signal channel is AC coupled at the input with a lower-frequency –3 dB
cut-off of < 0.2 Hz, although it is recommend to use DC coupling at frequencies
< 1.0 Hz for best results. If phase (as opposed to magnitude) readings are
important then DC coupling should be used at higher frequencies, since no
correction is made for amplitude or phase changes caused by the AC coupling
capacitor. Bipolar mode cannot be AC coupled.
DC
The signal channel is DC coupled
Input device
This control selects the type of input device used for the signal channel connections
in voltage mode input settings.
FET
Uses a FET as the input device, for which case the input impedance is 10 M.
This is the usual setting.
Bipolar
Uses a bipolar device in the input stage, for the lowest possible voltage input
noise. In this case the input impedance is 10 k. Note that this selection is not
possible when using the AC-coupled input modes.
Input shield
The input connector shells can optionally be floated or connected to chassis ground
as follows:-
Float
The shells of the A and B (I) connectors are connected to chassis ground via a
1 k resistor.
Ground
The shells of the A and B (I) connectors are connected directly to chassis
ground.
Line filter
This control selects the mode of operation of the line frequency rejection filter and
offers the following settings:-
Selection Function
50 Hz
Enable 50 Hz notch filter
100 Hz
Enable 100 Hz notch filter
50Hz + 100Hz
Enable 50 and 100 Hz notch filters
Chapter 5, WEB CONTROL PANEL OPERATION
5-17