5. 3 Mon it o r O ut p ut 41
| www.lakeshore.com
5.3 Monitor
Output
The Model 425 provides a monitor output that can be connected to an oscilloscope or
data acquisition system. The monitor output function provides a voltage proportional
to the measured field, where ±3.5 V equals ±full scale for the selected range. It is cor-
rected for nominal probe sensitivity and probe offset, but it is not corrected for probe
non-linearities. The monitor output function is always enabled. To use it, connect
your measurement device to the monitor output terminals on the rear panel as
defined in FIGURE 8-1.
The monitor output has two different frequency responses, depending on how the
instrument is set up. In DC mode and RMS narrow band mode, the monitor output has
the frequency response shown in FIGURE 5-3. The output will work down to DC levels
but rolls off above 400 Hz due to the product detector filter. This filter exists to reduce
high frequency noise generated by the 5.4 kHz carrier. Refer to section 2.2 for a sys-
tem block diagram.
In RMS wide band mode, the monitor output has a frequency response shown in
FIGURE 5-4. Here the frequency responds up to 10 kHz, but rolls off below 50 Hz
because the input is AC coupled.
5.4 Probe
Management
The Model 425 has several capabilities that allow the best possible measurements
with Lake Shore probes. These firmware-based features work in tandem with probe
calibration and programming to ensure accurate, repeatable measurements and
ease of setup. Many of the features require probe characteristics stored in non-vola-
tile memory during calibration that are located in the probe connector.
FIGURE 5-3 Monitor output DC and
narrow band mode frequency response
FIGURE 5-4 Monitor output wide band mode frequency response
Frequency (Hz)
1 10 100 400 1000
Error (%)
-60
-50
-40
-30
-20
-10
0
-2.4%
Frequency (Hz)
10 10050 1000 10000
Error (%)
-3.5
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
-0.1%
-0.5%
To Next Page
Loading...
