EG&G ORTEC 442 Instrukcja obsługi i serwisowania - Strona 12
Przeglądaj online lub pobierz pdf Instrukcja obsługi i serwisowania dla Przyrządy pomiarowe EG&G ORTEC 442. EG&G ORTEC 442 16 stron. Linear gate and stretcher
Drukuj stronę1. Connect ac power to Nuclear-standard Bin and Power
Supply, ORTEC 401/402.
2. Plug module into Bin and check for proper mechanical
alignment.
3. Switch ac power on and check the dc Power Supply
voltages at the test points on the 401 Power Supply control
panel.
Pulse Stretcher
The following procedure wi l l check the
performance of the Pulse Stretcher:
1. Feed the output of the 419 Pulse Generator into the
input of the Amplifier.
2. Set the Amplifier controls for a gain of approximately
200 with equal integration and differentiation time con
stants.
3. Set the 442 Input switch to DC-Couple and the Gate
switch to Normal.
4. Adjust the 419 Pulse Generator for a 100-mV pulse
from the unipolar output of the Amplifier.
5. Feed the 100-mV unipolar output of the Amplifier into
the input of the 442. Load the 442 output with a 100f2
terminator.
13. Increase the input to the 442 to the saturation level of
the amplifier, approximately 12 V; the output of the 442
should be greater than 10.5 V.
14. Connect the amplifier output to the 442 Gate Input
and monitor the Gate Period pulse with an oscilloscope.
The Gate Period should be adjustable from 0.5 to 5 fjsec.
Pulse Pile-Up Test A dual or variable high-frequency pulser
is needed to check the operation of the 442 pile-up
circuit.
1. Connect a dual or variable high-frequency pulser to the
442 input.
2. Monitor the 442 input and output simultaneously with
an oscilloscope.
3. Adjust the output delay and width controls to full
clockwise position.
4. Gradually decrease the time interval between the input
pulses.
5. The second pulse should be blocked by the 442 when the
time interval between the peaks of two consecutive pulses
becomes 8-1 5 fjisec.
6.2. CALIBRATION PROCEDURES
6. Adjust the discriminator trim potentiometer on the front
panel until triggering of the stretcher circuit just occurs, as
evidenced by an output pulse from the 442.
7. Increase the input signal to the 442 (by adjusting the
419 Pulse Generator) to 500 mV.
8. The output of the 442 should have a peak amplitude of
500 ± 25 mV (see "Linear Gate Pedestal Adjustment"
procedure in Section 6.2 if these l imits are exceeded); the
top of the pulse should exhibit a smooth slope of less than
0.5 mV//jsec.
9. Increase the input signal to the 442 to 10 V; the output
should be essentially 10 V.
10. The time at which the output occurs should be ad
justable from 0.3 to 3 jjtsec after the peak of the input
pulse. The duration of the top of the waveform should be
adjustable over the range of 0.5 to 5 jusec.
11. Select the Gated position on the front panel switch and
the Coinc position on the rear panel switch. The 442
output should disappear.
12. Select the Anticoinc position on the rear panel switch
and the 442 output should reappear. (A more complete
check of the 442 Gate can be made if a logic pulse in time
coincidence with the l inear input pulse is available.)
Linear Gate Pedestal Adjustment The input and output
gates are shunt-type gates which clamp the signal l ine to
ground. If the signal line is not at ground potential in the
quiescent condition, then a pedestal is introduced by the
gating action. This can be avoided by adjusting the output
of the Buffer Amplifier (TP1) to zero volts and then
adjusting the output of the Stretch Amplifier (TP2) to
zero volts. Use the following procedure when making this
adjustment:
1. Set the input gate switch to Normal.
2. Set the Input switch to the mode desired. If the DC-
Couple position is used, ensure that the dc level of the
amplifier driving the 442 is set to zero volts.
3. Monitor TP1 with a digital voltmeter and adjust R7, on
the front of the printed circuit board, to obtain zero volts
atTPI .
4. When the Input switch is moved to either of the other
two positions, the voltage at TP1 should remain at 0 V ± 20
mV.
5. Monitor TP2 with the voltmeter and adjust R1(
obtain zero volts at TP2.
to
The 442 is now adjusted for a zero pedestal. These adjust
ments must be made regardless of whether or not the l inear
gating function of the 442 is being used.