Stanford Research Systems SR844, User Manual

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3-4 Overview
SR844 RF Lock-In Amplifier
Keys
The keys are grouped and labeled according to function. In the manual, keys are referred
to in
This Font
. A complete description of the keys follows later in this chapter.
Legends printed in blue below some keys are shift key functions. Just like on a calculator,
the
Shift
key combinations are sequential, e.g. press
Shift
followed by
Recall
to
PRESET the instrument to its factory default setup. Sequential keypresses are
designated with a
–
sign, e.g.
Shift–Recall
.
Simultaneous keypresses are reserved for a few test functions and are designated with a +
sign, e.g.
Local+Setup
.
Invalid keypresses cause the SR844 to produce an audible error tone.
Key-Click On/Off
Press TimeTimeConstDown (both keys simultaneously) to toggle the key-
click on and off.
Keypad Test
To test the keypad, press the Ref Z-In+Source keys together. The CH1 and CH2
displays will read
Pad Code
, and a number of LED indicators will be turned on. The
LED’s indicate which keys have not yet been pressed. Press all of the keys on the front
panel, one at a time. As each key is pressed, the key code is displayed on the
REFERENCE display, and the LED nearest that key turns off. When all of the keys have
been pressed, the display will return to normal. To return to normal operation without
pressing all the keys, simply turn the knob.
Knob
The knob is used to adjust parameters in the Reference Display. The following
parameters may be adjusted:
•
Reference Frequency (Internal Reference Mode)
•
Reference Phase
•
Auxiliary Output Voltages
•
Interface parameters (GPIB or RS-232)
•
Active Remote Interface
•
All Offsets
•
Manual Scan parameters
•
Save/Recall memory location
•
Scrolling the Remote Interface Queue display