Ametek 7270 Instruction Manual page 115

Figure 5-50, Dual Reference Output Filters Menu 1
The Dual Reference Output Filters Menu 1 has four controls affecting the
instrument's output low-pass filters, and a key to access the Output Filters Menu 2.
Changes to the setting of these controls can be made by using the adjacent
keys.
The controls operate as follows:-
TIME CONSTANT 1
This control, which duplicates the Main Display control of the same name, is used to
set the time constant of each of the output filters.
SLOPE 1
The roll-off of the outputs filters can be set, using this control, to either 6 dB or
12 dB per octave (Fast time constant mode) or 6 dB, 12 dB, 18 dB or 24 dB per
octave (Normal time constant mode).
SYNC TIME CONSTANT
This control has three settings, as follows:-
OFF
In this setting, which is the normal mode, time constants are not related to the
reference frequency period.
ON
In this setting, the actual time constant used is chosen to be some multiple of the
reference frequency period, giving a much more stable output at reference
frequencies below 10 Hz for the Normal time constant mode (below 1 kHz for
the Fast time constant mode) than would otherwise be the case. In this setting,
the actual time constant will not change if the reference changes. Note that,
depending on the reference frequency, output time constants shorter than 100 ms
cannot be used.
AUTO
This is the same as the ON setting except that if the reference changes the time
constant will be recalculate to the nearest legal synchronous setting.
TIME CONSTANT MODE
This control has two settings, as follows:-
Chapter 5, FRONT PANEL OPERATION
5-67