Keithley 6521, Инструкция по эксплуатации, Страница: 44 / 65

Service Information
4-2
4.3.1 Environmental conditions
All performance verification measurements should be made
under the following environmental conditions:
• Offset current and isolation measurements: 23°C,
<60% relative humidity.
• All other measurements: 18°C to 28°C, <70% relative
humidity.
4.3.2 Recommended verification equipment
Table 4-1 summarizes the equipment necessary for perfor-
mance verification, along with an application for each item
NOTE
Various coax/triax cables, adapters, and
wires (not shown) are also required. Use
only high-quality low-noise coax/triax
cables and adapters, and Teflon-insulate
wires where required. (See paragraph 1.9
in Section 1 for cable recommendations.)
Make sure that connector and adapter
insulators are clean and free of
contamination.
4.3.3 Scanner card connections
Various cables should be connected to the input/output jacks
before the card is installed in the electrometer. Also, a num-
ber of triax/BNC adapters are required. See the pertinent
drawings for each procedure and the detailed connection in-
formation provided in Section 2.
Table 4-1
Recommended verification equipmen
Description
Manufacturer/
Model
Specifications
1
Application
Electrometer
Digital Multimeter
Keithley 6517
Keithley 2001
20pA, 1%
20G Ω , 20T Ω , 1%
20 Ω , 79ppm
200mV, 44ppm
Control card, measure offset cur-
rent, isolation
Contact resistance
1
Full-range input specifications
2
Various coax/triax cables, adapters, and wires (not shown) are also required. Use only high-quality low-noise coax/triax
cables and adapters, and Teflon insulated wires where required. make sure that connector and adapter insulators are clean
and free of contamination.
• Once the flux has been removed, swab only the repaired
area with methanol, then blow dry the board with dry
nitrogen gas.
• After cleaning, the card should be allowed to dry in a
50°C low-humidity environment for several hours be-
fore use.
4.3 Performance verification
The following paragraphs discuss performance verificatio
procedures for the Model 6521/22, including offset current,
channel and input isolation, contact resistance, and contact
potential.
CAUTION
Contamination will degrade the perfor-
mance of the card. To avoid contamina-
tion, always grasp the card by the side
edges. Do not touch connector insula-
tors, board surfaces, or components.
NOTE
Failure of any performance verificatio
test may indicate that the scanner card or
its input/output connectors are contami-
nated. See paragraph 4.2 for information
on cleaning the card.