Ametek 7124 Instruction Manual page 117

SENSITIVITY 1 and SENSITIVITY 2
When set to voltage input mode, using the Signal Channel menu, the instrument's
full-scale voltage sensitivity may be set to any value between 10 nV and 1 V in a
1-2-5 sequence.
When set to current input mode, using the Signal Channel menu, the instrument's
full-scale current sensitivity may be set to any value between 1 pA and 100 µA (wide
bandwidth mode, or 10 fA and 10 nA (low-noise mode), in a 1-2-5 sequence.
The number reported after the letters DR is the instrument's Dynamic Reserve,
expressed in decibels, as calculated by the following equation:-

  
DR 20 log

10
SEN
Example:-
If AC Gain = 12 dB and SEN = 2 mV then

 

DR 20 log
10

0.002
DR = 46 dB
TIME CONSTANT 1 and TIME CONSTANT 2
The time constants of the output filters are set using this control. When the Time
Constant Mode on the Output Filters Menu 1 (see section 5.5.04) is set to Fast, the
range is 10 µs to 100 ks in a 1-2-5 sequence; when the Time Constant Mode is set to
Normal the minimum time constant is 5 ms.
REF1 PHASE and REF2 PHASE
These controls allow the reference phase of each detection channel to be adjusted
over the range -180° to +180° in 1 m° steps. Adjustment is faster using the Keypad
or Active Cursor controls - see section 4.1.04.
REF1 PHASE ±90° and REF1 PHASE ±90°
These controls allow the relevant reference phase to be adjusted in steps of ±90°.
X1 OFFSET, Y1 OFFSET, X2 OFFSET and Y2 OFFSET
These are the manual X1/X2 channel and Y1/Y2 channel output offset controls. The
offset levels set by these controls, which can be any value between -300% and
+300% in 0.01% steps, are added to the X1, X2, Y1 or Y2 channel outputs when the
relevant channel offsets are switched on using the Output Channels menu.
Adjustment is faster using the Keypad or Active Cursor controls - see section 4.1.04.
The values are set automatically by the Auto-Offset function. Note that the Auto-
Offset function automatically switches on all output offsets
REF1 HARMONIC
This control sets the harmonic of the reference frequency at which the lock-in
amplifier's reference 1 channel operates, in the range 1 st (fundamental mode) to
127 th.
RELOCK EXT. REFERENCE
The 7124 includes frequency-dependent calibration parameters. In Dual reference
mode the correct parameters can be chosen for the internal reference channel because
its frequency is equal to the specified oscillator frequency. The parameters for the
Chapter 5, FRONT PANEL OPERATION

2
 
ACGain (in dB)


2


14

5-63