ETS-Lindgren 7606 Coil Antenna/Shielded Coil - Manual (Page 27)

A BOUT THE M EASURING I NSTRUMENTS
The measuring instruments can be radio-noise or EMI meters, calibrated
receivers, spectrum analyzers, or other tunable (narrowband) voltmeters. These
instruments must be accurately calibrated with appropriate correction factors
available across the frequency range. A number of possible instruments are
available. Some instruments, for example, certain automatic spectrum analyzers,
may require no correction factors, since they self-calibrate and internally
generate and apply a correction factor at each frequency.
A single instrument can be used for both Measuring Instrument A and
Measuring Instrument B indicated in the illustration on page 25. If this is done:
• The Model 7606 should be loaded by a 50 Ω dummy load while the
output of the current probe is being measured.
• More importantly, the output of the current probe must be loaded by a
50 Ω dummy load when the output of the Model 7606 is being
measured.
Failure to load the current probe in 50 Ω while the measuring
instrument is not connected to it may result in unpredictable changes
in the impedance inserted into the line by the current probe. This may
then cause an unknown change in the current flowing in the
Model 7605.
For convenience during the susceptibility testing of the EUT, a spectrum analyzer
with a tracking generator may be used for measuring instrument A.
A BOUT THE C URRENT P ROBE
The current probe may be a low-frequency EMI measuring clamp-on
current probe designed to cover the frequency range from 30 Hz to 100 kHz;
several manufacturers offer this type of probe. The accuracy of the individual
calibration is important because it is a key element in setting the test current
during EMI measurements.
The transfer admittance (or impedance) should be individually calibrated over the
frequency range. Usually, the probe calibration by the manufacturer is adequate,
but do not rely on a probe that has a calibration reported at a single frequency or
has a single conversion factor that is to be applied across the entire frequency
range.
MIL-STD-462D Method RS101 Testing | 27