Tektronix 600A Instruction Manual

Model 600A

Electrometer

Instruction Manual

Contains Operating and Servicing Information

WARRANTY

Keithley Instruments, Inc. warrants this product to be free from defects in material and workmanship for a period of 1 year from
date of shipment.

Keithley Instruments, Inc. warrants the following items for 90 days from the date of shipment: probes, cables, rechargeable batter­ies, diskettes, and documentation.

During the warranty period, we will, at our option, either repair or replace any product that proves to be defective.

To exercise this warranty, write or call your local Keithley representative, or contact Keithley headquarters in Cleveland, Ohio. You
will be given prompt assistance and return instructions. Send the product, vansportation prepaid, to the indicated service facility.
Repairs will be made and the product returned, transportation prepaid. Repaired or replaced products are warranted for the balance
of the original warranty period, or at least 90 days.

LIMITATION OF WARRANTY

This warranty does not apply to defects resulting from product modification without Keithley’s express written consent, or misuse
of any product or part. This warranty also does not apply to fuses, software, non-rechargeable batteries, damage from battery leak­age, or problems arising from normal wear or failure to fallow instructions.

THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING ANY IMPLIED

WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. THE REMEDIES PROVIDED HEREIN
ARE BUYER’S SOLE AND EXCLUSIVE REMEDIES.

NEITHER KEITHLEY INSTRUMENTS, INC. NOR ANY OF ITS EMPLOYEES SHALL BE LIABLE FOR ANY DIRECT,
INDIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF ITS INSTRU­MENTS AND SOFTWARE EVEN IF KEITHLEY INSTRUMENTS, INC., HAS BEEN ADVISED IN ADVANCE OF THE POS­SIBILITY OF SUCH DAMAGES. SUCH EXCLUDED DAMAGES SHALL INCLUDE, BUT ARE NOT LIMITED TO: COSTS
OF REMOVAL AND INSTALLATION, LOSSES SUSTAINED AS THE RESULT OF INJURY TO ANY PERSON, OR DAM­AGE TO PROPERTY.

Safety Precautions

The following safety precautions should be observed before using
this product and any associated instrumentation. Although some in­struments and accessories would normally be used with “on-haz­ardous voltages, there are situations where hazardous conditions
may be present.

This product is intended for use by qualified personnel who recog­nize shock hazards and are familiar with the safety precautions re­quired to avoid possible injury. Read the operating information
carefully before using the product.

The types of product users are:
Responsible body is the individual or group responsible for the use

and maintenance of equipment, for ensuring that the equipment is
operated within its specifications and operating limits, and for en-

suring that operators are adequately trained.
Operators use the product for its intended function. They must be

trained in electrical safety procedures and proper use of the instm­ment. They mut be protected from electric shock and contact with

hazardous Iive circuits.

Maintenance personnel perform routine procedures on the product
to keep it operating, for example, setting the line voltage or replac­ing consumable materials. Maintenance procedures are described in
the manual. The procedures explicitly state if the operator may per­form them. Otherwise, they should be performed only by service
personnel.

Service personnel are trained to work on live circuits, and perform
safe installations and repairs of products. Only properly trained ser­vice personnel may perform installation and service procedures.

Users of this product must be protected from electric shock at all
times. The responsible body must ensue that users are prevented
access and/or insulated from every connection point. In some cases,
connections must be exposed to potential human contact. Product
users in these circumstances must be trained to protect themselves
from the risk of electric shock. If the circuit is capable of operating
at or above 1000 volts, no conductive part of the circuit may be
exposed.

As described in the International Electrotechnical Commission
(IEC) Standard IEC 664, digital multimeter measuring circuits

(e.g., Keithley Models 175A, 199,2000,2001,2002, and 2010) are
Installation Category II. All other instruments’ signal terminals are
Installation C&gory I and must not be connected to mains.

Do not connect switchjng cards directly to unlimited power circuits.
They are intended to be used with impedance limited sources.

NEVER connect switching cards directly to AC mains. When co”-

netting sources to switching cards, install protective devices to lim­it fault current and voltage to the card.

Before operating an instrument, make sure the line cord is connect-

ed to a properly grounded power receptacle. Inspect the connecting

cables, test leads. and jumpers for possible wear, cracks, or breaks
before each use.

For maximum safety, do not touch the product, test cables, or any

other instruments while power is applied to the circuit under test.

ALWAYS remove power from the entire test system and discharge

any capacitors before: connecting or disconnecting cables or jump-

ers, installing or removing switching cards, or making internal

changes, such as installing or removing jumpers.

Exercise extreme caution when a shock hazard is present. Lethal
voltage may be present on cable connector jacks 01 test fixtures. The
American National Standards Institute (ANSI) states that a shock
hazard exists when voltage levels greater than 30V RMS, 42.4V
peak, or 60VDC are present. A good safety practice is to expect
that hazardous voltage is present in any ““known circuit before

measuring.

Do not touch any object that could provide a current path to the

common side of the circuit under test or power line (earth) ground.
Always make measurements with dry hands while standing on a

dry. insulated surface capable of withstanding the voltage being

measured.

The instrument and accessories must be used in accordance with its

specifications and operating instructions or the safety of the equip­ment may be impaired.

The WARNING heading in a manual explains dangers that might
result in personal injury or death. Always read the associated infor­mation very carefully before performing the indicated procedure.

Do not exceed the maximum signal levels of the instruments and ac­cessories, as defined in the specifications and operating informa­tion, and as shown on the instrument or test fixture panels, or
switching card.

When fuses arc used in a product, replace with same type and rating
for continued protection against fire hazard.

Chassis connections must only be used as shield connections for

measuring circuits, NOT as safety earth ground connections.

IF you are using a test fixture, keep the lid closed while power is ap
plied to the device under test. Safe operation requires the use of a
lid interlock.

Ifa@

wire recommended in the user documentation.

Then

fer to the operating instructions located in the manual.

Then
sure IO00 volts or more, including the combined effect of normal
and common mode voltages. Use standard safety precautions to

screw is present, connect it to safety eanh ground using the

symbol on an instrument indicates that the user should re-

symbol on an instrument shows that it can source or mea-

avoid personal contact with these voltages.

The CAUTION heading in a manual explains hazards that could

damage the instrument. Such damage may invalidate the warranty.

Instrumentation and accessories shall not be connected to humans.
Before performing any maintenance, disconnect the line cord and

all test cables.
To maintain protection from electric shock and fire, replacement

components in mains circuits. including the power transformer, test

leads, and input jacks, must be purchased from Keithley Instru­ments. Standard fuses, with applicable national safety approvals,
may be used if the rating and type are the same. Other components
that are not safety related may be purchased From other suppliers as
long as they are equivalent to the original component. (Note that se­lected pans should be purchased only through Keithley Instruments
to maintain a.ccuracy and functionality of the product.) IF you are
unsure about the applicability of a replacement component, call a

Keithley Instruments office for information.

To clean an instrument, use a damp cloth or mild, water based

cleaner. Clean the exterior of the instrument only. Do not apply
cleaner directly to the instrument 01 allow liquids to enter or spill
on the instrument. Products that consist of a circuit board with no
case or chassis (e.g., data acquisition board For installation into a

computer) should never require cleaning if handled according to in­structions. If the board becomes contaminated and operation is af­fected, the board should be returned to the factory for proper
cleaning/servicing.

Rev. ?.I99

MODEL 6OOA ELEKX'ROMFt73R

TABLE OF CONTEmTs

Title
section I.
Section II. - Specifications

- Introduction. ........................

....................... 2-1

Section III. - Operation .........................

Controls andTerminals

A.

Preparing the Instrment for Operation

B.

Measuring Voltage. .........................

C.

.......................

D. Measuring Current. .........................

E. MeasuringOhms ...........................

BatteryCheck. ...........................

F.

G. Using Extenal Indicators.

Misce.Ll.aneous Applications

R.

Zero Center Operation.

I.

Section IV.

Voltmeter ..............................

A.

- Circuit Discussion

.....................

..................... 3-5

.......................

..................... 4-l

B. Ammeter.. .............................

C. Ohmmeter ..............................

Section V.

- Accessories .........................

Section VI. -Maintenance. ........................

Pa3

1-l

3-1
3-l

............... 3-2

3-2
3-2
3-3

3-4
3-5

3-6

4-l
4-2
4-3

5-l
6-1

section VII.

Voltage-Resistance Diagram

- Replaceable Parts List.

....................... 7-3

Schematic Diagram. ...........................

rChangeNot.ice .............................

.................. 7-l

7-5

La&Page

?+l'he yellow Change Notice sheet is included only if the instrument contains mod-

ifications which affect the

0962~

instruction

manual.

i

MODEL 6OOdELFcl'RGhfg!FgB

INTFDIUCTION

SECTION I - INTRODUCTION

The Keithley Model 600A Electrometer is an ultra-high impedance voltmeter

with full-scale ranges of 0.01, 0.03, 0.10, 0.30, 1.0, 3.0 and 10 volts.

The maximum input resistance is greater than 10lh ohms; in addition, the

input resistance may be varied in decade steps from one ohm to 1011 ohms
by means of the shunt resistors built into the instrument. Thus, the
600A is not ,only appropriate for measurement in high-impedance circuits,
but also can be used where a high input impedance would merely introduce

unwanted pickup.

The 6OOA may be used as a direct-reading ammeter from 3 amperes to lo-l3
ampere full scale.
and 10x scales.

This &decade range is covered in overlapping 3x

Two current measuring methods are available to the user

of the 6OOA. Normally, current is determined by measuring the voltage

g,"",;"';"t"~ ;,33

input of the voltmeter through the current measuring resistor.

istor shunted from input to ground. Alternately, on

ampere ranges, negative feedback can be applied to the

This
largely eliminates the input drop and increases measuring speed, particu­larly on the,more sensitive ranges.

The 600A measures 10K to 1012 ohms full scale wit P a two-terminal input.
With a guarded input, its range is extended to 10 3 ohms. Unlike con­ventional ohmmeters, information is presented on the

linear scales

used

for current and voltage readings.
As a dc preamplifier, the 600A has gains of 0.1, 0.3, 1, 3, 10, 30 and

100.

The continuing stability of the gain is assured bv a feedback

factor in excess of 100 on any range.
The output is minus 1 volt, open circuit, with an internal resistance

of

17K.

Thus, the outputmay be used for driving oscilloscopes or

pen recorder amplifiers, or the output may be shunted down to provide

lo- or SO-mv outputs for servo-rebalance recorders.

NOTE

When the Model 600A is shipped from the factory, an angle
bracket (Keithley Part No. 13766A) sapports the printed

circuit board (PC-29).

rear panel with a #I6 x S/16 sheet metal screw.

The bracket is fastened to the

The bracket

and screw may be removed after the Model 600A is received.

WHEN SHIPPING THE INSTRUMENT TO ANOTHER DESTINATION, RE-

PLACE THE BRACKET TO FIRMLY SUPPORT THE PRIBTED CIRCUIT BOARD.

D704R

1-l

INTROlWCl'ION

MODEL 6OOA ELECTROMETER

1-2

MODEL 600A ELECTROMETER

& A VOLTMETER:

SPECIFICATIONS

SECTION II - SPECIFICATIONS

RANGE:

ACCURACY:

ZERO DRIFT:
INPUT IMPEDANCE:

0.01 volt full scale to 10 volts in seven lx and 3x ranges.
'r2% of full scale on all ranges exclusive of drift.

Less than 2 millivolts per hour after l-hour warm-up.

Greater than 1014

ohms shunted by 30 picofarads.

be selected in decade steps from 1 ohm to 101~ ohms.

& & AMMETER:

RANGE: LO-l3

ACCURACY:
MLJLTIPLIER Switch setting;

GRID CURRENT:

ampere full scale to 3 amperes in twenty-eight lx and 3x ranges.

23% of full scale on 3-ampere to lo-lo

+5% cf full scale on 3 x 10

ampef~lr::g;;~13 ampere ranges.

Less than ~5 x LO-l4 ampere.

fi & OHMMETER:

RANGE:

LO4 ohms full scale to 1013

ACCURACY:

23% of full scale on lo4

ohms in nineteen linear lx and 3x ranges.
to 1010 ohm ranges, using largest available MULTIPLIER

Switch setting; ?5% of full scale on 3 x 10~' to 1013 ohm ranges.

Input resistance may

using smallest available

& & AMPLIFIER:

GAIN:
FREQUENCY RESPONSE (Within 3 db):

0.1, 0.3, etc., to 100.
dc to 100 cps at a gain of 100, rising to 1.5 kc at a

gain of 0.1.
NOISE:

INPUT IMPEDANCE:

Less than 3% peak-to-peak of full scale.

Greater than 1014 ohms shunted by 30 picofarads.

be selected in decade steps from 1 ohm to 1011 ohms.

OUTPUT:

+-1 volt for full-scale input. Internal resistance is 17 kilohms.

ity is opposite input polarity.

GENERAL:

POLARITY:

METER Switch selects left-zero (positive or negative) or center-zero scales.

Output polarity is not reversed.

CONNECTORS: Input:

uhf type; ground binding post.

Input resistance may

Output polar-

output: Amphenol 80-PC~F.

0565R

2-1

SPECIFICATIONS MODEL 600A ELECTROMETER

BATTERIES:

minimum battery life.

DIMBNSIONS, WEIGHT:

weight, ?-l/2 pounds.
ACCESSORIES SUPPLIED: Mating input and output connectors; binding post adapter,

Two 413 (30 volts), four El46 (8.4 volts), two RM42R (1.34 volts). 500 hours

10-l/4 inches high x 6-l/2 inches wide x 6-l/2 inches deep; net

2-2 0565R