Service Information; Introduction; Calibration; Environmental Conditions - Keithley 1801 Instruction Manual

5.1

Introduction

This section contains information necessary to service the
Model 1801 Nanovolt Preamplifier.
WARNING
The information in this section is
intended only for qualified service
personnel. Do not attempt these pro-
cedures unless you are qualified to do
so.
Information is arranged as follows:
5.2 Calibration: Covers the equipment and procedures
necessary to calibrate the Model 1801.
5.3 Principles of operation: Briefly discusses circuit
operation.
5.4 Special handling of static-sensitive devices:
Reviews precautions necessary when handling
static-sensitive devices.
5.5 Troubleshooting: Presents some troubleshooting
tips for the Model 1801.
5.2

Calibration

This section gives detailed procedures for calibrating the
Model 1801. Basically, there are two types of calibration
procedures:

Service Information

• Normal calibration, where the Model 1801 preampli-
fier, power supply card, and Model 2001 are cali-
brated together as a unit. The normal calibration
method should be used in most cases.
• Gain constants calibration, where preamplifier gain
constants are manually entered into the Model 2001.
This method can be used to transfer gain constants
from one power supply card to another when a
preamplifier module is to be used with a power
supply card other than the one with which it was
calibrated.

5.2.1 Environmental conditions

Normal calibration procedures should be performed at an
ambient temperature of 23° ±1°C, and at a relative humid-
ity of less than 80% unless otherwise noted.

5.2.2 Warm-up period

The Model 1801 must be allowed to warm up for at least
two hours before calibration. If the preamplifier has been
subjected to temperature extremes (outside the range
stated in paragraph 5.2.1), allow additional time for inter-
nal temperatures to stabilize. Typically, it takes one addi-
tional hour to stabilize a unit that is 10°C (18°F) outside
the specified temperature range.
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