ETS-Lindgren HI-3603 VLF Survey Meter - Manual (Page 10)

HI-3603 VDT/VLF Survey Meter
© ETS-Lindgren, August, 2005
Revision E, Part # H-600042
10
sensor has been resistively loaded to produce a relatively flat
response over the frequency range of interest for VDT emissions
and an output that is proportional to the magnitude of the
magnetic field. Thus, the HI-3603 is capable of accurately
measuring the strength of magnetic fields from all kinds of
VDT's, regardless of their frequency of operation.
VDT's, because of their circuitry, produce several kinds of
electromagnetic emissions. These include 60 Hz AC fields
associated with the power supply, ELF (Extremely Low
Frequency) fields produced by the vertical deflection of the
electron beam, DC fields produced by the high DC voltages
applied to the CRT to accelerate the electron beam toward the
CRT screen (this DC field possesses a 60 Hz modulation), and
RF fields caused mainly by the flyback circuitry (that circuitry
associated with the horizontal deflection of the electron beam
and its return to one side of the screen-the flyback). The HI-3603
is designed to be responsive to these RF emissions of VDT's. It
has been designed to minimize response to other emissions.
NOTE: When using the ¼-20 UNC mounting holes,
the maximum length of screw thread is 10 mm (0.4
inches). If longer threads are used they may extend into
the instrument case and cause damage to the internal
circuit board.