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Z33048_00_01
Getting Started
1.9 Setting the Magnet to the Correct Field
The magnet is designed to be operated at 300.18 MHz, with the current in the H0 field
coil of the shim system set to zero. At this frequency the synthesizers are “cleanest” and
least likely to create spurious problems.
When the lock is powered up from a cold start, the field DAC is not automatically set.
In order to make sure the current in the field coil is set to zero:
1. Open the BSMS panel.
2. Set the field value to 2048.
3. Switch the lock to “ON” once, then switch it off again while the magnet is being
charged to the correct field and the cryo-shims are adjusted.
1.10 Setting the Spin Safety Threshold
The spin has a safety function that shuts the spin off as soon as the Lift is turned on,
either manually, or during the initialization of the sample changer. In order to do this, the
analog sensor that monitors the spinner has to be calibrated. The sensor has three volt-
ages for the three possible states:
No spinner (typically 0.1 to 0.6V)
Black (typically 0.6 to 1.5V)
White (typically 2.5 to 4.5 V)
Since the values vary between shim stacks, and also depend somewhat on the spinner
type, it is necessary to calibrate this value. Usually this only has to be done once at
installation.
1. Open the Web server of the VTU and go to -> peripheral control -> spin
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