Reference Channel Menu - Ametek 7280 Instruction Manual

Chapter 5, FRONT PANEL OPERATION

5.5.03 Reference Channel Menu

5-62
selection is made via the computer interface. The Curve Select menu only allows
selection of the same sixteen data types as in single reference mode.
When in dual reference mode, the user-defined equations, specified on the Output
Equations menu, allow the selection of the additional outputs as variables. For
example, it is possible to calculate a value proportional to the ratio of the X
output to that of the X
2
the CH1 or CH2 connectors on the rear panel as an analog voltage.
Naturally, the signals at the two frequencies that are being measured share a common
signal path and hence controls affecting the signal channel, such as AC Gain and the
line filter controls, apply to both reference frequencies. Although the full-scale
sensitivity setting can be independently set for both references, the maximum AC
Gain that is possible is defined by the least sensitive setting of the two.
In standard instruments, the maximum detection frequency for either regference
reference is 20 kHz; units fitted with the 7280/99 option allow operation to 800 kHz
2
and those with the 7280/98 option allow operation to 2.0 MHz
In dual reference mode, the reference channel is controlled by the Dual Reference
Channel menu, which differs from the Reference Channel menu used in the other
three modes. In addition, controls are needed for the corresponding output channels,
and so the Output Filters and Output Offset sub-menus also change. The relationship
of all these menus to Main Menu 1 is shown in figure 5-40. Note that as with the
main menu structure, shown in figure 5-1, it is possible to return to the Main Display
from any menu by pressing the Previous Menu key, but this has been omitted from
figure 5-40 for the sake of clarity.
Figure 5-40, Dual Reference Mode Menu Structure
In dual reference mode, pressing a key adjacent to the Reference Channel item on
channel output. With suitable scaling, this can be output to
channel
1
or
1