Main Controls: Reference 1 - Ametek 7230 Instruction Manual

Chapter 5, WEB CONTROL PANEL OPERATION

5.3.04 Main Controls: Reference 1

5-18
60Hz
Enable 60 Hz notch filter
120Hz
Enable 120 Hz notch filter
60Hz + 120Hz
Enable 60 and 120 Hz notch filters
Demod2 source
When the demodulators are configured for dual reference operation, this control
selects the signal source for the second set of demodulators
Sig Chan ADC
In this setting the signal input to the second set of demodulators is taken from the
main signal channel ADC. This is the normal mode of operation. In dual
reference or dual harmonic mode this means that the two signals being measured
are applied to the same input connector and share a common path through the
main ADC.
Rear ADC1
In this setting the signal input to the second set of demodulators is taken from the
rear panel auxiliary input ADC1. The full-scale sensitivity is adjustable over the
normal range of 1 V to 2 nV, but because there is no AC Gain, the effective
maximum sensitivity is 1 mV.
Demod1 output (Tandem demodulator mode)
In this setting the signal input to the second set of demodulators is taken from the
X-channel output of the first set of demodulators
Figure 5-21, Main Controls: Reference 1
The Reference 1 controls, figure 5-21, affect the reference channel of the first set of
demodulators.
Source
This control allows selection of the source of reference signal used to drive the
reference 1 circuitry, and has four settings:-
Internal
The lock-in amplifier's reference is taken from the instrument's internal
oscillator. Note that this setting gives the best phase and gain measurement
accuracy under all operating conditions, and it is always to be preferred, if
possible, to design the experiment so that the lock-in amplifier acts as the source
of the reference signal.
External digital
In this setting the reference channel is configured to accept a TTL reference
source applied to the front panel REF IN input connector, except if using the
Dual Demodulator mode and the Reference 2 input selection is set to External