443B101/443B102
3
Manual 19854 Rev. D
ECN 50523
high temperature transient sensitivity are used, the
high pass filter of the amplifier can be changed from
0.2 Hz to 2 Hz, reducing the influence from
temperature-induced signals. The overall gain of the
amplifier is the ratio of the output sensitivity to the
sensor sensitivity.
Low Pass Filters
Six selectable upper cutoff frequencies are provided
by the low pass filter, located just after the input
amplifier to filter out unwanted signal components
before further amplification. The filters are of the
two-pole configuration, giving a 12 dB/octave cutoff.
The low pass filter section may be turned off giving a
frequency response of >200 kHz.
Integrator Amplifiers
The integrator amplifiers provide single integration
for velocity and double integration for displacement.
Two low-frequency cutoff settings of 1 or 10 Hz are
provided in the velocity and displacement modes to
suppress low-frequency noise.
Output Amplifier
The output amplifier provides the signal to the con-
tinuous gain stage and then to the BNC output
connector on the front panel. It provides a fixed gain
of x1 or x10.
Typical frequency response as a function of
capacitive load of the output of the 443B dual mode
amplifier is shown in Figure 7 of Appendix B. Note
that for a frequency range up to 10kHz, a capacitive
load of up to 50 nF may be applied. For standard
cable with a shunt capacitance of 100pF/m, up to
500 m of output cable can be used to cover this
frequency range.
Overload Detector
The overload detector monitors the output of the
charge amplifier, the low pass filter, and the output,
so overload in various parts of the circuitry are not
masked by filtering. The overload indicator is located
on the front panel. In ICP® mode, the sensor output
is also monitored for overloads.
Reference Oscillator
The Model 443B has a built-in reference signal
source, providing a signal of 100 pC RMS at 159.2 Hz
in charge mode. In ICP
®
mode, the reference signal is
1 V RMS. These signals can be used as a reference
when using portable DAT recorders.
Operation
Set-Up and Measurement
1.
Connect the Model 443B to a suitable power
source. Switch the unit on and let it stabilize for
30 seconds.
2.
Connect the output of the 443B to a suitable
indicating instrument, voltmeter, scope or
frequency analyzer.
3.
Select a suitable accelerometer to be used for
the measurement and observe the correct
mounting and installation instructions. Connect
it to the input connector of the Model 443B.
4.
Refer to the acc
elerometer’s calibration chart to
select the sensitivity.
Setting the Operational Mode
1.
Press the MENU button on the Model 443B. The
main menu appears on the screen of the Model
443B.
2.
Select the MODE position with the down button.
3.
Press the MENU button again. The display now
shows the following text:
Charge
Ref. On
ICP
Ref. Off
4.
Select the mode by moving the cursor to Charge
or ICP® depending upon which type of sensor is
being used. Note that in ICP® mode, zero
current can be selected, which will put the unit
in voltage mode.
5.
The internal sinusoidal reference may be turned
on by moving the cursor to Ref. On and pressing
the MENU button. To turn off the reference,
move the cursor to Ref. Off in the MODE menu
and press MENU.
Setting the Sensor Sensitivity
1.
Press the MENU button again and select SEN
Содержание 441A101
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