2 – 16
Introduction
If the DC output signal is overloaded, the red
OVLD
indicator (just
above the time constant control) is lit.
2.3.2.2
Offset
The output o
ff
set function is enabled and disabled by pressing the
[On
/
O
ff
] button within the OFFSET block. (
OFSE
, 4 – 14 )
Pressing [Modify] within the OFFSET block switches the focus of the
REFERENCE block to the o
ff
set value; turning the
REFERENCE
knob will then adjust the o
ff
set between
−
1000% and
+
1000% of full
scale. (
OFST
, 4 – 15 )
2.3.2.3
Output
The overall functional mode of the SR124 is controlled by the [Mode]
button within the OUTPUT block. Pressing [Mode] toggles between
Lock-In
and
AC Volt
modes. (
OMOD
, 4 – 14 )
The output signal from the SR124 is available on the BNC output
connector within the OUTPUT block. Full scale at the output is
±
10 V.
2.3.3
Setup section
The next section of the instrument is “Setup”. See Figure 2.5 for
detail.
2.3.3.1
Automatic functions
Four built-in automatic functions are available in this block.
Pressing [Phase] within AUTO starts an auto-phase cycle, which
adjusts the oscillator phase to maximize the output signal. Auto-
phase is disabled when output o
ff
set is enabled. (
APHS
, 4 – 16 )
Pressing [Gain] starts an auto-gain cycle, which will increase the gain
(decrease the sensitivity) step by step to maximize the output without
causing a signal overload. (
AGAN
, 4 – 16 )
Pressing [O
ff
set] starts an auto-o
ff
set cycle, which will adjust the
OFFSET setting to null the output signal. Note that the auto-o
ff
set
cycle does not change the enabled
/
disabled state for OFFSET. Run-
ning auto-o
ff
set with o
ff
set disabled will set and report the o
ff
set
parameter that would null the output if o
ff
set were enabled, but the
output is una
ff
ected. (
AOFF
, 4 – 16 )
Pressing [Lock Assist] starts a measurement cycle for the Reference
oscillator Ext. In, to speed the locking to a user’s reference when
operating in external mode. (
ASST
, 4 – 17 )
SR124
Analog Lock-In Amplifier
