3
Section 3
INSTALLATION
A. Portable Operation:
The Model 257D Portable Electrostatic Fieldmeter is designed primarily for portable
operation. Since electrostatic field measurements are made with respect to ground
be sure to connect the ground cable to a known good ground.
B. Power Line Operation:
An AC power adapter is supplied with each Model 257D. When the adapter is
plugged into the receptacle on the rear of the instrument and an appropriate power
source, the instrument will resort to line operation and the battery will automatically
be charged as necessary. The ground cable must still be used as in (
A
).
C. Installation of Probe:
The probe is normally connected directly to the instrument via the DB-9 connector
recessed into the rear panel.
Probe mounting requirements for electrostatic field determinations vary with the
nature of the desired measurement. In general, it is best to mount the probe 1 cm
from the material under test – so long as the input signal remains less than
20kV/cm. The Model 1036F-5 is calibrated for 20kV/cm at 1cm spacing.
The backside of the probe assembly is electrically isolated from the rest of the
probe. A pair of #4-40 threaded inserts are provided for attaching the probe to a
user provided mount. It is recommended that, if possible, the probe be mounted
“looking” downward to minimize the possibility of contamination entering the
aperture.
The probe may also be hand held at its base for survey measurements. At full scale
reading, the operator should take care when making measurements as the probe
may arc to the surface under test.
D. Output:
A BNC connector is provided for an analog output. This output is 2 volts for full-
scale reading (1/10,000
th
of 20,000 volts). The output impedance is less than 10
and is capable of driving capacitive loads
E. Grounding:
A standard banana jack is provided at the rear of the instrument for grounding
purposes. A wire cable (supplied) must be connected to a known good ground for
accurate measurements.
Summary of Contents for 257D
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