Table of Contents
Advertisement
FRONT PANEL OPERATING SUMMARY
The operation of the SR570 Low-Noise
Preamplifier has been designed to be as simple
and intuitive as possible. The effect of each
keypress on the front panel is reflected in the
change of a nearby LED. All front panel
functions, except power, can be controlled
through the rear-panel RS-232 interface.
Power
The SR570 is turned on by depressing the
POWER switch. When disconnected from AC
power, the unit will operate for approximately
15 hours on internal sealed lead-acid batteries.
Up to 200 mA of unregulated battery power is
available at the rear panel banana jacks as long
as the power switch is in the ON position.
Battery life will be reduced when the unit is
providing external power through the rear panel
jacks. When operating on batteries, the front
panel LINE indicator will not be lit. As the
batteries near depletion, the LOW BATT LED
will light, indicating that the unit should be
connected to AC power to charge the batteries.
When connected to an AC power source,
amplifier power is derived from regulated line
power, and the internal batteries are
automatically charged. When operating on AC
power, the front panel LINE indicator is on to
indicate the source of amplifier power.
Figure 2: SR570 Front Panel
Charging status is indicated on the rear panel by the
CHARGE and MAINTAIN LED indicators.
Input
An insulated BNC is provided to connect the signal
of interest to the amplifier. Care should be taken in
choosing a cable to connect to the amplifier input.
Both cable capacitance and dielectric quality will
affect sensitive measurements. Whenever possible,
use low noise coaxial cable and always use the
shortest possible cable length. Above the input BNC
is the FREQ COMP adjustment potentiometer. This
feature allows the user to compensate for any input
capacitance by varying the capacitance across the
front-end amplifier feedback resistor. In this way,
the amplifier bandwidth can be easily adjusted to
compensate for source capacitance by measuring a
square wave signal from the source of interest and
using FREQ COMP to optimize the output
waveform. See Appendix C for further discussion of
the effects of source capacitance.
Defaults
Any changes made to the front panel settings of the
SR570 will be stored even when power is turned off,
as long as the batteries are hooked up. To reset the
SR570 to its default settings, simply turn the power
off, and while depressing the FILTER RESET
button, turn the power on. Alternatively, removing
3
Operation and Controls
Hide quick links:
Advertisement
Table of Contents
