Triaxial Cable Preparation; Figure - Keithley 7174A Instruction Manual

Service Information
(A) Cut off insulation with knife.
Cut off outer shield.
(B) Strip insulation off inner shield.
(C) Twist inner shield then strip inner conductor.
Twister inner shield and center conductor together,
slip on plastic cover.
(D) Insert wires into hole and wrap around body.
(E) Screw on plastic cover.

Figure 4-5

Triaxial cable preparation

NOTE
The following procedure must be per-
formed at an ambient temperature of 23°C
and at a relative humidity of less than
60%.
4-8
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Cut
Cut
1"
Insulation Over
Inner Shields
3/4"
1. Turn on the Model 617 and allow it to warm up for two
hours for rated accuracy.
2. With the mainframe power turned off, plug the Model
7174A into slot 1 of the mainframe. Remove all other
cards from the mainframe, and install the slot covers.
3. After the prescribed warm up period, select the Model
617 amps function, and enable zero check. Select the
2pA range, and zero correct the instrument.
4. Connect the Model 617 to rows A and B of the matrix
card, as shown in Figure 4-4.
5. Program the Model 617 voltage source for a value of
+100V, but do not yet turn on the voltage source output.
6. Close crosspoints A1 and B2 by using the switching ma-
trix front panel controls.
7. With the Model 617 in amps, enable suppress after the
reading has settled.
8. Turn on the Model 617 voltage source output, and en-
able the V/I ohms function on the electrometer.
9. After the reading has settled, verify that the resistance is
>67T Ω (6.7 × 10 Ω ).
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10. Turn off the voltage source, and enable zero check.
Disable suppress, and select the amps function on the
electrometer.
11. Open crosspoints A1 and B2, and close crosspoints A3
and B4.
12. Repeat steps 7 through 11 for A3 and B4.
13. Repeat steps 7 through 12 for crosspoint pairs A5 and
B6, A7 and B8, A9 and B10, and A11 and B12.
14. Disconnect the electrometer from rows A and B, and
connect it instead to rows C and D.
15. Repeat steps 7 through 13 for rows C and D. The path
isolation for these rows should be 67T Ω (6.7 × 10
16. Repeat steps 7 through 14 for row pairs E and F, and G
and H. For each row pair, step through the crosspoint
pairs 1 and 2, 3 and 4, 5 and 6, 7 and 8, 9 and 10, and 11
and 12. The complete procedure outlined in steps 7
through 11 should be repeated for each crosspoint pair.
Each resistance measurement for rows E through H
should be 67T Ω (6.7 × 10
Ω ).
3
Ω ).
13