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Mounting the Cryogenic Probe
The probe can be mounted by bonding, using a minimal mount epoxy adhesive, or by
loosely supporting the probe within a tube.
Proximity Effects
No two Mag cryogenic probes should be operated within 10mm of each other if
interaction is to be avoided. If the probes are mutually orthogonal they may be placed in
contact with no adverse effects.
3.4.
Conventions
The sensing direction for the probes is the direction for which conventional flux will
produce a positive value to be recorded.
Definition
Conventional flux direction is said to be "out-of-the-page" when produced by a
conventional current (+ve to -ve) circulating counter-clockwise in a conducting loop
"parallel-to-the-page".
4.0
OPERATING INSTRUCTIONS - See figures 2, 5 and 6
Switching On
Connect the probe selected to the 6-way probe socket and switch on the magnetometer.
Note that the plug locking mechanism requires that the outer shell of the plug is retracted
(towards cable) during insertion and removal.
For the first 2-5 seconds following switch-on the battery voltage will be displayed on the
LCD. If the battery voltage is below 5V the instrument must be put on charge
immediately. An audible alarm will also signal when the battery requires recharging.
The instrument should never be left in a discharged state as the capacity of the battery
will be adversely affected.
Some increase in noise can be expected during the first few minutes of charging. The
charging circuit is temperature compensated and the instrument may be left on charge
indefinitely without harm to the battery.
The optimum stability of the magnetometer will be achieved in approximately 10 seconds
following switch on. Check that the instrument is working by subjecting the probe to a
slowly varying magnetic field. This is best done for a free probe by rotating it in the
earth's magnetic field and observing the change in values. The geomagnetic field will be
between 30μT and 90μT. If used within a steel framed building the shunting effect of the
steel could reduce the field below the outdoor value.
Using the offset control (Mag-01H only)
To obtain the maximum resolution on the autoranging LCD or to bring measurements
within the range of a chart recorder, a back-off value can be added arithmetically to the
OM0382 ISSUE 8 PAGE 8 OF 14
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