NARDA 8718B, User Manual

Page: 85 / 137

84 Operating the Meter
Shielding the Probe
The probe must be shielded from significant RF fields whenever
it is zeroed with the meter. This is to establish a zero reference
for the field.
There are four ways to shield the probe during zeroing:
•
Use the Model 8713B Electric Field Attenuator supplied
with the meter. This conductive fabric is the same
material that is used in RF protective clothing. The
attenuator should be put over the head of the probe and
closed off around the neck of the probe above the
handle using the hook-and-loop fastener band.
•
Use the shielded storage case. Place the probe in the
case and close the lid carefully on the cable with the
meter outside the case. Be careful not to move the
probe while zeroing takes place (On probes with low
frequency test points you can create static which will
give inaccurate results, although this is less of a concern
with the new 8700D series probes).
•
Use aluminum foil to shield the head of the probe. Fully
wrap the head of the probe and close it around the neck
of the probe about half way down. If the probe has
metallic low frequency test points, these must be
insulated from the aluminum foil. One way to do this is
to use electrical tape to cover the test points. The other
solution is to use a wide elastic band around the head of
the probe over the test points. The elastic band can
easily be moved to use the 8718B’s built-in low
frequency RF test source. Alternately, use an aluminum
can.
•
Use your body to shield the probe from the source of
energy.
N
ote
The Electric Field At-
tenuator can not be
used to zero mag-
netic field probes.