18
Checking for Radiated Emission with the 3M
™
ScanEM-EQC
Electromagnetic Near-Field Probe
1. Calibrate the probe by moving it away from the product and setting the
Level dial to light only the green LED. Take precautions to ensure that
no extraneous RF fields are affecting the setting. To do this, compare
the probe level setting at various places within the building. If the probe
level setting is unaffected or only slightly affected, then it is unlikely that
extraneous fields are affecting the probe. If you have any concern that
extraneous RF fields are affecting the probe, the computer system should
be relocated to a different building and the calibration process repeated.
2. Investigate the input/output cables on the computer by placing the
ScanEM-EQC Probe antenna next to the I/O cable(s). Watching the
LED response and listening to the change in audio pitch, move the probe
along the cable to locate the point where the probe response is highest.
The angle of orientation of the rod antenna relative to the cable should be
varied to produce the maximum also. The cable should not be handled at
the time it is being investigated. Recheck the probe Level setting.
3. Chassis seams and openings in the chassis are investigated similarly, by
moving the probe along seams and around openings in the chassis. When
energy is detected the probe rod antenna is manipulated in a manner that
evokes the maximum response. Recheck probe Level setting.
4. This probe (ScanEM-EQC Probe) should not be used to investigate the AC
power cord. The magnetic (ScanEM-HQC Probe) probe is used for this cord.
5. If in any of the above investigations a response of four or five LEDs is found,
then the unit should be considered to be noncompliant. Alternate components
should be substituted or other corrective measures taken until a functional
system that does not produce the requisite probe response is obtained.
