ETS-Lindgren HI-3603 VLF Survey Meter User Manual
Page 39
HI-3603 VDT/VLF Survey Meter
© ETS-Lindgren, August, 2005
Revision E, Part #H-600042
39
frequency counter to this jack allows immediate measurement of
the flyback frequency of a VDT. Figure 12 illustrates the use of a
portable digital multimeter (DVM) capable of measuring
frequency to observe the flyback frequency of a VDT. To perform
this measurement, an analog signal sufficient to drive some
frequency counters may require that the HI-3603 be placed
relatively close to the surface of the VDT.
Measuring the Time Rate of Change of the Magnetic Field
(dB/dt)
In some applications it may be of interest to determine the time
derivative of the magnetic field (see for example MPR, 1987). In
this case the use of an oscilloscope is required. The oscilloscope
is connected to the waveform output jack on the bottom of the
HI-3603 and adjusted to observe the waveform of the magnetic
field emission. This analog output signal is directly related to the
instantaneous value of the magnetic field strength where a 1
millivolt peak-to-peak output voltage corresponds to 1 mA/m
peak-to-peak measured field. This relation holds true regardless
of the range setting of the HI-3603.
Figure 12: Use of a portable DVM with frequency measuring
capability to determine the flyback frequency of a VDT.