ORTEC 572A, Руководство по эксплуатации и обслуживанию

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Fig. 6.1. Circuit Used to Measure Nonlinearity.
d.
Vary the DC Adj control on the front panel while
monitoring the Unipolar output. Ensure that the
baseline can be adjusted through a range of +0.1
to -0.1 V. Readjust the control for zero.
e.
Recheck the output pulse amplitude and adjust
if necessary to set it at +10 V with maximum gain.
DecreasetheCoarseGainswitchstepwisefrom1K
to20andensurethattheoutputamplitudechanges
by the appropriate amount for each step. Return
the Coarse Gain switch to 1K.
f.
Decrease the Gain control from l.5 to 0.5 and
check to see that the output amplitude decreases
by a factor of 3. Return the Gain control to
maximum at 1.5.
g.
With the Shaping switch set for lµs, measure the
time to the peak on the unipolar output pulse; this
should be 2.2 µs, for 2.2τ. Measure the time to
baselinecrossoverofthebipolaroutput;thisshould
be 2.8 µs for 2.8τ.
h.
Change the Shaping switch to 0.5 through 10 µs
in turn. At each setting, check to see that the time
to the unipolar peak is 2.2τ and the time to the
bipolar crossover is 2.8τ. Return the switch to 1 µs.
OVERLOAD TESTS
Start with maximum gain,
τ
=2µs, and a +10 V output amplitude. Increase the
pulser output amplitude by X200 and observe that
the unipolar output returns to within 200 mV of the
baseline within 24 µs after the application of a
single pulse from the pulser. It will probably be
necessary to vary the PZ Adj control on the front
panel in order to cancel the pulser pole and
minimize the time required for return to the
baseline.
Increase the pulser output amplitude to 1000 times
the setting that provided the or10 V output
amplitude from the 572A. Observe that the bipolar
output returns to within 200 mV of the baseline
within 26 µs after the application of a single pulse
from the pulser. It may be necessary to use
external control on the pulser to obtain the 6.6-V
output required for this test.
LINEARITY
The integral nonlinearity of the 572A
can be measured by the technique shown in
Fig. 6.1. In effect, the negative pulser output is
subtracted from the positive amplifier output to
cause a null point that can be measured with
excellent sensitivity. The pulser output must be
varied between 0 and 10V, which usually requires
an external control source for the pulser. The
amplifier gain and the pulser attenuator must be
adjusted to measure 0 V at the null point when the
pulser output is 10 V. The variation in the null point
as the pulser is reduced gradually from 10 V to 0 V
is a measure of the nonlinearity. Since the
subtraction network also acts as a voltage divider,
this variation must be less than
(10 V full scale) x (±0.05% maximum nonlinearity)
x (1/2 for divider network) = ±2.5 mV
for the maximum null-point variation.
OUTPUT LOADING
Use the test setup of Fig. 6.1.
Adjust the amplifier output to 10 V and observe the
null point when the front panel output is terminated
in 100
Ω
. The change should be less than 5 mV.