Figure 2-4 Triaxial Cable Preparation - Keithley 7072 Instruction Manual

OPERATION
Table 2-2. Parts for Special Triaxial Cable 2.5.4 General Instrument Connections
Keithley Part or
Model Number
7078-TRX-3 triax
CIA
cot
r
I
le- l"4
(A) Cut off insulation with knife.
Cut off outer shield.
/-
Insulation Over
Inner Shield
(B) Strip insulation off Inner shield.
(C) Twist inner shield then strip Inner conductor.
Twist 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 2-4. Triaxial Cable Preparation
The following paragraphs discuss connecting the
Model 7072 to various general classes of instrumentation
such as DMMs, electrometers, sources, and source/measure
units. Because these configurations arc generic in nature,
some modification of the connecting schemes may be nec-
essary for your particular instrumentation. Also, special
cables or adapters may be necessary. In all cases, 3-lug triax
cables must be used to make the connections.
WARNING
Do not use coaxial cables and adapters
because hazardous voltage from guard
sources may be present on the cable shields.
Figure 2-5 shows the general instrument connections for the
discussions below. Note that DUT guarding or shielding are
not indicated here; see Figures 2-21 and 2-24 for shielding
and guarding information. Also, 2-pole switching for rows
A-F is shown in the figures; GUARD is not switched on
rows G and H. As shown, all figures assume instruments are
connected to rows, and the DUT is connected to columns.
DMM Connections
General DMM connections are shown in Figure 2-5(A),
(B), and (C). Floating connections are shown in (A), with
LO and HI routed to two separate jacks on the Model 7072.
The common LO connections in (B) should be used only for
non-critical applications because the performance of the
GUARD pathway is not specified.
WARNING
Hazardous voltage from other guard sources
may be present on LO or the DUT if other
crosspoints are closed.
4-wire DMM connections are shown in Figure 2-5(C). In
this case, a total of fourjacks are required; HI, LO, SENSE
HI, and SENSE LO.
Electrometer Connections
Typical electrometer connections are shown in Figure
2-5(D) through (G). The unguarded volts connections in(D)
show the HI signal path routed through one jack, and the LO
path goes through the other connector. Both GUARD path-
ways are connected to electrometer LO. For guarded volt-
age (E), Model 7072 GUARD is connected to electrometer
GUARD.
2-5