Keithley 2002 Page 26 Calibration Manual Download

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Performance Verification

1-15

2. Characterize the 1G

Ω

resistor to within ±1,000ppm or

better using an accurate megohm bridge or similar
equipment. Record the characterized value where indi-
cated in Table 1-9. Also compute the limits based on the
value of R using the formula at the bottom of the table.

NOTE

The actual value of the 1G

Ω

resistor

should not exceed 1.05G

Ω

3. Set Model 2002 operating modes as follows:

A. From normal display, press CONFIG then

Ω

B. Select SPEED, then press ENTER.
C. Select HIACCURACY, then press ENTER.
D. Select FILTER, then press ENTER.
E. Select AVERAGING, then press ENTER.
F. Using the cursor and range keys, set the averaging

parameter to 10 readings, then press ENTER.

G. Press EXIT to return to normal display.

4. Select the 2-wire ohms function (

Ω

2) and the 1G

Ω

range on the Model 2002. (If the FILT annunciator is off,
press the FILTER key to enable the filter.)

5. Connect the 1G

Ω

resistor test box (from steps 1 and 2)

to the INPUT HI and LO terminals of the Model 2002.
(Be sure that the box shield is connected to INPUT LO.)
Allow the reading to settle.

6. Verify that the Model 2002 reading is within the limits

you calculated and recorded in Table 1-9.

1.8.6 Frequency accuracy verification

Frequency accuracy verification is performed by connecting
an accurate frequency source to Model 2002 inputs, and then
verifying that the frequency readings are within stated limits.

Use the procedure below to verify the frequency measure-
ment accuracy of the Model 2002.

1. Connect the frequency synthesizer to the Model 2002

INPUT terminals, as shown in Figure 1-9.

2. Turn on both instruments, and allow a one-hour warm-

up period before measurement.

Table 1-9

Limits for resistance verification (1G

Ω

range)

Characterized
resistor (R)

Reading limits
(1 year, 18°C to 28°C)

_________ G

Ω

_________ G

Ω

to _________ G

Ω

* 1 year limits = R ± (0.0 15,000)

Ω

Where R = characterized value of 1G

Ω

resistor in ohms.

Ω

range verification

1. Mount the 1G

Ω

resistor and the banana plugs to the test

box, as shown in Figure 1-8. Be sure to mount the
banana plugs with the correct spacing. The resistor
should be completely enclosed in and shielded by the
metal test box. The resistor LO lead should be electri-
cally connected to the test box to provide adequate
shielding.

Table 1-8

Limits for resistance verification (20

Ω

-200M

Ω

ranges)

2002

Ω

range

Nominal
applied
resistance

Reading limits
(1 year, 18°C to 28°C)

Ω

18.9985025

Ω

to 19.0014975

Ω

200

Ω

190

Ω

189.991277

Ω

to 190.008723

Ω

1.9k

Ω

1.89994714k

Ω

to 1.90005286k

Ω

20k

Ω

19k

Ω

18.9994638k

Ω

to 19.0005362k

Ω

200k

Ω

190k

Ω

189.989313k

Ω

to 190.010687k

Ω

1.9M

Ω

1.89981109M

Ω

to 1.90018891M

Ω

20M

Ω

19M

Ω

18.9940619M

Ω

to 19.0059381M

Ω

200M

Ω

100M

Ω

99.930910M

Ω

to 100.069090M

Ω

Notes:

1. Limits shown include total absolute calibrator uncertainty (see Table

1-1) and factory calibration uncertainty (see specifications), and are
based on nominal calibration values shown. Recalculate limits using
Model 2002 relative accuracy specifications, factory calibration uncer-
tainty, and calibrator absolute uncertainty if calibrator resistance val-
ues differ from nominal values shown.

2. Use 4-wire connections and function for 20

Ω

-2M

Ω

ranges. Use 2-

wire connections and function for 20M

Ω

and 200M

Ω

ranges.

Figure 1-8

Ω