Shift Functions - Stanford Research Systems SR844 User Manual

3-42 Shift Functions

Shift Functions
Some keys have shift functions labeled in blue below the key.
SETTLE... Shift–Time
Constant Up
PRESET Shift–Recall
–90° [Shift– +90°]
I.F. [Shift– AuxOut]
PRECISE [Shift– Freq]
FREQ
Null [Shift–Shift]
OFF [Shift–
Scan Set]
CLEAR ALL [Shift–Rel
Mode]
SR844 RF Lock-In Amplifier
This key sequence causes the Reference Display to show the elapsed
time (in units of the current Time Constant).
This key sequence restores the instrument to its factory defaults (see
earlier in this chapter).
This key sequence changes the reference phase by –90°.
This key sequence shows the IF frequency on the Reference Display.
See Chapter 2, Sources of Error, for more information about the IF
(chop frequency). This display is provided as a user convenience.
The instrument has weak spurious responses at offsets of
± ×
4 IF, etc. from the reference frequency. Some users may wish to set
up their experiments to avoid specific IF frequencies.
When the reference is in internal mode and the IF frequency is
displayed, the knob may be used to adjust the internal reference
frequency while showing the IF frequency.
Important!
The SR844 covers the operating frequency range in octave bands.
Users can check the IF frequency to determine whether the instrument
is at the high end of an octave band or the low end of the next band.
At the high end of an octave, the IF frequency will be close to 3 kHz
(12 kHz for time constants
close to 2 kHz (8 kHz for time constants
affects the output update rate for the analog CH1/CH2 OUTPUTs.
The fastest update rates occur at the high end of each octave band
(where the IF is the highest).
This key sequence shows the reference frequency with 6 or 7 digits
resolution using the CH2 and Reference displays together. Read the
two displays as if they were one single display. While the internal
reference frequency is set to 3 digits resolution, the actual frequency
generated in internal mode may be slightly different (within
4th digit).
To cancel this display mode, choose another reference display (Freq
or Phase for example).
A second keypress cancels the first Shift if it is pressed by mistake.
This key sequence terminates Scan Mode. It has no effect if SCAN
MODE is off.
This key sequence discards all stored Rel Configurations and Values.
≤ µ
300 s), while at the low end it will be
≤ µ
300 s). The IF frequency
± ×
2 IF,
±
1 in the