EG&G ORTEC 414A Manuale operativo e di servizio - Pagina 11

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8.
Set the In/Out Control switches as follows: A and B,
In; C and D, Out.
9.
Set the Resolving Time control to 1 TOO.
10.. With the equipment connected as shown in Fig. 6.1,
two pulses (the Calibrated 420A output and the 414A
output) should be visible on the oscilloscope. Set the
horizontal time base to 20 nsec/cm. It may be necessary to
use the Delayed Sweep function on the oscilloscope in
order to observe both pulses at this horizontal sweep speed.
11. Decrease the output delay control on the Calibrated
420A until the 414A output pulse disappears.
12. Increase the output delay control on the Calibrated
420A, and the 414A output pulse should reappear and
disappear again as the delay is increased. Measure the
change in delay of the Calibrated 420A pulse from the time
that the 414A output pulse reappears until it disappears
again. This time can be accurately measured looking at the
oscilloscope. The time measured represents the 2t resolving
time of the 414A with the Resolving Time control set at
1100 and should be 110-150 nsec.
13. Connect the Calibrated 420A output to Input C on
the 414A.
14. Set the In/Out control switches as follows: A and C,
In; B and D, Out.
15. Repeat steps .9 through 12.
16. Connect the Reference 420A output to Input B on the
414A.
17. Set the In/Out control switches as follows: A and D,
Out; B and C, In.
18. Repeat steps 9 through 12.
19. Repeat steps 9 through 16 with the following
exceptions:
a. In step 9 set the Resolving Time control to 100.
b. In step 10 set the oscilloscope horizontal time base
to 10 nsec/cm.
c. In step 12 the 2t resolving time should be less than
10 nsec with the Resolving Time control set at 100.
20. Set the output delay control on the Calibrated 420A
so that its output occurs approximately 100 nsec prior to
the Reference 420A output.
21. Connect the Reference 420A output to the 414A
Input A.
22. Connect the Calibrated 420A output to the 414A
Input D.
23. Set the Resolving Time control to 1100.
24. Set the In/Out control switches as follows: A, In; B, C,
and D, Out.
25. A pulse should be present at the output of the 414A.
Place In/Out control switch D to the In position, and the
414A output pulse should disappear.
6.2. ALIGNMENT OF RESOLVING TIME
TRIMMER CAPACITORS
If the resolving time readings (Section 6.1) were not
satisfactory, the trimmer capacitors in each resolving
network may be adjusted to optimize the resolving time in
each channel:
1. , Connect and adjust the equipment as stated in Section
6.1, steps 6 and 7.
2.
Set the In/Out control switches as follows: A, In; B, C,
and D, Out.
3.
Set the Resolving Time control to 100.
4.
Observe the 414A output with an oscilloscope.
5.
Using an insulated screwdriver, adjust capacitor C4
until the output pulse disappears. Continue to rotate C4
adjustment until the output reappears. Stop the adjustment
of C4 as soon as an output pulse appears for each input
pulse.
6.
Set the In/Out control switches as follows: A, C, and
D, Out; B, In.
7.
Adjust C23 as explained in step 5.
8.
Connect Reference 420A to Input C.
9.
Set the In/Out control switches as follows: A, B, and
D, Out; C, In.
10. Adjust C18 as explained in step 5.
11. Perform the tests outlined in Section 6.1, steps 1 —
25, to check the instrument performance.
6.3. SUGGESTIONS FOR TROUBLESHOOTING
In situations where the 414A is suspected of malfunction, it
is essential to verify such malfunction in terms of simple
pulse generator impulses at the input and output. The 414A