1. Front Panel
TD 8620 front panel key are defined as follows.
1) ON/OFF: Turns power to the unit on/off.
2) Hold: Turn Max Hold feature on and off. Max Hold captures and displays the highest field reading.
3) Turn backlight feature on and off. Backlight lighten up the LCD for reading.
4) NULL: Used to zero or null effects of ambient low level fields from the probe. When user pushes the NULL key ,”0000.0 G or 000.00 mT”displayed. The unit then automatically accepts whatever residual field it reads as a zero offset .
5) mT/G : Changes units from mT to gauss .Gauss is used in the cgs system :1 G=0.1 mT,mT is used in the SI system :1 mT =10 G
2.. Rear Panel
3. Axial and Transverse Probe
CAUTION :Care must be taken when handing the probe .The tip of the probe is very fragile .Pressure the Hall sensor can alter its calibration. Don’t apply more force than is required to hold probe in place. So there is no excessive pressure which will tend to bend or depress the sensor substrate and will destroy the Hall element inside.
5.1 Turn on meter
Push the On/Off key. The LCD displays parameters as range, polarity, value, unit ,battery indicator, percent of range and so on.
Press the Gauss/mT key to toggles the display between the two units.
5.3 Handing probe
The tip of the probe is very fragile. Stressing the Hall senor alter its calibration. Any excess force can easily break the sensor. Broken sensor are not repairable. The axial sensor is exposed on the end of the probe. A collision with a hard surface can damage the sensor or wear away its protective coating. The transverse sensor is somewhat susceptible to bending stress and erosion of the protective coating.
5.4 Probe operation
For best results , the instrument and probe should warm up for at least 10 minutes before operation.
When magnetic field forward vertical cross the Hall sensor ,the polarity is positive(N) or negative (S)
Probe readings are dependent on the angle of the sensor in relation to the magnetic field. The magnetic field should Vertical cross the sensor. Maximum output occurs when the flux vector is perpendicular to the plane of the sensor. The greater the deviation from vertical orientation, the larger error of reading.
The Hold function display the largest field magnitude measured .When the Hold key is pressed, the maximum value is captured and shown in the display.Press the Hold key again, Hold function will be turn off ,the “Hold” is disappear .The meter is real-time measurement of magnetic field.