4.5.1 General Keypad Operation
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4.6 Display Setup
The Display Setup allows you to set the display brightness. The vacuum fluorescent
(VF) display on the Model 648 has four brightness settings between 25% and 100%
that can be changed from the front panel. The brightness setting changes the entire
VF display, but it does not affect the LED annunciators to the right of the display. Con-
tinuous use of the instrument at 100% brightness will reduce the operating life of the
display; therefore, brightness of 25%, the default setting, is recommended for most
applications. To change the display brightness, press
Display Setup
and the bright-
ness setup will appear.
Menu Navigation:
Display Setup
Q
(
25%, 50%, 75%, 100%
)
Default: 25%
Interface Command:
DISP
4.7 Setting Output
Current
The main purpose of the Model 648 electromagnet power supply is to supply a very
precise and stable current to a magnet load. Before setting output current, make sure
that the instrument is properly setup for the magnet system that is being used. This
includes setting up the maximum output current (section 4.12.1) and maximum
ramp rate (section 4.12.2). When a new output current setting is entered, the supply
will ramp to the new setting at the current ramp rate, unless limited by the fixed com-
pliance voltage. The ramping LED will be lit while the output current is ramping.
When the output current setting is entered, it will be limited in magnitude by the
maximum current setting. Refer to section 4.12.2 to setup the maximum settings.
The output current setting value can be set as high as ±135.1000 A. This can be used to
compensate for variances in calibration. The output current is guaranteed to reach a min-
imum of 135 A into a 0.5
)
load but may not be able to reach 135.1 A in all circumstances.
The output current setting is not allowed to change if the instrument is set up so that
the output current is programmed solely by an external voltage. The screen will read
“change not allowed while in external current program mode.” Refer to section 4.16
to setup the external current program mode.
Menu Navigation:
Output Setting
Q
(
-135.000 to +135.000
)
Default: 0.0000 A
Interface Command:
SETI
4.8 Output
Current Ramp Rate
The output current of the Model 648 will always ramp from one current setting to
another. There is no way to turn off the current ramping function, but if a very fast
ramp rate is desired, a ramp rate as high as 50.000 A/s can be entered.
Menu Navigation:
Ramp Rate
Q
(
0.0001 to 50.000
)
Default: 50.0000 A/s
Interface Command:
RATE
