IBM 7220, Instruction Manual

Page: 49 / 155

5-9
Chapter 5, FRONT PANEL OPERATION
MANUAL
In this setting the AC Gain may be manually adjusted from the main display.
AUTOMATIC
In this setting the AC Gain value is automatically selected by the instrument,
depending on the full-scale sensitivity.
TC’s
This control affects the output time constants, and has two settings:-
SYNC
When set to SYNC, the actual time constant used is chosen to be some multiple
of the reference frequency period. In this mode the output will be much more
stable at low frequencies than it would otherwise be. Note: when set to this mode,
output time constants shorter than 100 ms cannot be used.
ASYNC
In this setting, the normal mode, time constants are not related to the reference
frequency period.