2. Pole/zero adjustment using a square wave and preamp test input. See note 2
on page 12.
Driving the preamp test input with a square wave, will allow a more precise
adjustment of the amplifier pole/zero.
a. The Amplifier’s controls should be basically set for its intended
application: COARSE GAIN, shaping, INPUT POLARITY.
b. Adjust the square wave generator for a frequency of approximately 1
kHz.
c. Connect the square wave generator’s output to the preamp’s TEST
INPUT.
d. Remove all radioactive sources from the vicinity of the detector.
e. Set the scope’s channel 1 vertical sensitivity to 5 volts/cm, and adjust the
main time base to 0.2 ms/cm. Monitor the 2015A’s AMP OUTPUT and
adjust the square wave generator’s amplitude control (attenuator) for
output signals of ± 10 volts.
Note Both positive and negative near-Gaussian linear pulses will be observed at
the output.
f. Reduce the scope vertical sensitivity to 50 mV/cm. See Note 1 on page
11.
Figure 9 shows the correct setting of the pole/zero control. Figures 10
and 11 show under and over compensation, respectively for the
preamplifier decay time constant. As illustrated in Figure 9, the AMP
OUTPUT signal should have a clean return to the baseline with no
bumps, overshoots or undershoots.
10
Operating Instructions
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