Keithley 640 Service manual

Instruction Manual

Model 640

Electrometer

Keithley Instruments, Inc.

Cleveland, Ohio, U.S.A.

MODEL 640 ELECIROMETER

1. GENERAL OESCRIPTION------------------------------------------------- 1

2. OPERATION----------------------------------------------------------- 5

CONTENTS

3. CIRC”IT DESCRIPTION-------------------------------------------------

4.

5. SER”ICING----------------------------------------------------------- 20

6.

7.

*CCESSORIES--------------------------------------------------------- 1,

CALIBRATION--------------------------------------------------------- 30

REPLACE&&E PARTS---------------------------------------------------

SCHEMATICS---------------------------------------------------------- 51

14

35

0472B

SPECIFICATIONS

MODEL 640 ELECTRO”ETER

AS A MICROVOLTMETER:
RANGE :
ACCURACY: il% of full scale on 30-volt to 300-micro­ZERO DRIFT:

METER NOISE: Less than 0.4 microvolt rm‘m8 (2 microvolts

INPUl’ IMPEDANCE : Greeter than 1016 ohms shunted by

RISE TINS (IO%-90%, with up to 100 megohms source re-

AS AN AMmiTER:
RANGE :

ACCLmcY: 23% of full scale on 3 x 10-5 to 10-11 am-

METER

DAMPING :

30 microvolts full scale to 30 volts in thir-

teen lx and 3x ranges.
volt ranges, decreasing to 25% on 30-microvalt range.

each succeeding 24-hour period after l-hour warm-up.
Less than 35 wVv/‘C.

p-p) with 1 megohm or less input resistance on most

sensitive range.
less than 2 picofarads.

be selected in four steps from 106 to 1012 ohms.

sistance and no external capecitance): Less than 10

milliseconds on 1-mv and higher ranges, increasing

to 6 seconds on the 30-p’! range.

twenty-two lx and 3x ranges using built-in high-

megoh,,, resistors and range switch.

pere ranges using the smallest recommended multi­plier setting; 24% of full scale on 3 x 10-12 to

10-15 ampere ranges. Instrurwnt can be calibrated

to 22% accuracy below IO-9 ampere with external

voltage supply and built-in calibrating circuits.

NOISE:

:;;“li-:&,::,‘:. (5 x lo-16
critically damped.

hour as observed on the 30-millivolt range.

ing with 20 picofarads shunting the high-megohm ra-

seas than 35 6” in the first hour and in

Input reaistsnce may also

10-15 ampere fuL1 scale to 3 x 10-5 ampere in

mess ,rhan 2 x 10-l’ ampere rms (lo-16

-15 ampere range when overdamped
ampere p-p) when

Less than 24 alpha pulses per

Variable from critical damping to overdamp-

sister.

CURRENT STABILITY:

after stabilization.

lative.

MAX. EXTERNAL CAPACITANCE (Feedback c”rrent ranges):

500 pf.

RISE TIME: Seconds, from 10% to 90%.

Recommended Resistor Damped;
Full-Scale Value, no external

Ranges

10-15 to 3x10-11
10-12 to 3x10-9 1010 0.2
10-11 to 3x10-7 108 0.05
10-9 to 3x10-5

AS A CO”LOMS”ETER/C”RRENT INTEGRATOR:
RANGE (recoannended): 2 x lo-14 coulombs full scale to

6 x lo-lo coulombs in ten 2x and 6x ranges.

Setter than 5 x 10-L’ ampere/day

Long-term drift is non-cumu-

ohms

1012

106

Critically Overdamped;

cepeeitenC* capecitance

1.5

0.01

up to

maximum

44

0.5

0.05

0.01

ACCURACY :

+0.25%.

METER NOISE: Less than 3 x Lo-16 coulomb rms (1.5 x

lo-L5 coulomb p-p) on lowest recommended range.
Less than 24 alpha pulses per hour a8 observed on

30-mFllivolt range.
AS AN AMPLIFIER:
RECORDER 0"TPLPl':

scale input.

DOlaritY.
Gain: 6.033 to 3.3 x 104.
Frequency Response (Within 3db): dc to 0.07 cps at
e 9 ain of 3.3 x 104, rising to 35 cps at a gain of

10 or below.
NOiS*:

ified function.
output p-p on the 30-v to lo-mv ranges, increasing

to 10% on the 1-w and lower ranges.

UNITY GAIN ODTPW:

within .Ol% or 10 p’f, excLuaiva of zero drift, for
output C”rre*ts of LOO * or less.

ZERO cHEcx:

low through L kilohm in volt8 position, to feedback

in current or integrate position.

ISOLATION:

than LOgG shunted by 0.05 j.,f. Circuit ground may
be floated up to +LOOV with respect to main case.
Head case is circuit nround. On battery o,,eration,

instrument nay be cc.m;Letely isolated f;om’power

Line and ground.

POIARITY: Meter switch selects Left-zero (wsieive

OK

does not reverse polarity of output.

CONNECTORS : Input: Special type, metes with many

commercially available ion chambers and other ac­cessories (adapter to “SF included). Low: Binding
pst. Recorder output: Amphenol SO-PCZP. “nity­Gain Output and Case Ground: Binding posts.

PCUER:

Line operation: 105-125 or 210-250 volts (switch

selected), 50 or 60 cps, 20 watts.
Battery Operation: Rechargeable nickel-cadmium 6­volt battery pack, S hours full charge to complete
discharge.

ation recomuanded for no more than 6 consecutive
hours before recharge.

DIMENSIONS, WRIGHT:

Power Chassis: 7” high x S-314” wide x LO” deep;
net weight, 14 lbs.
Amplifier Head: 6” high x 5” wide x 6” deep; net
weight, 6 Lbs.

ACCESSORIES SUPPLIED: Connecting Cable: 5’ long, con-

nects head to main chassis. UHF Adapter: adapts

input to UtlF connw.tor. Shield Cap. Mating output
COll”*CtO=.

tery pack and charging circuit.

Integrating capacitance ia 20 picofarads

+l vole at up to 1 ma for full-

output polarity is opposite input

Below 1 cps: same 88 meter noise for spec-

Circuit ground to chassis ground: Greater

W3.StiVa)

Above 1 cps: less than 2% of full

At dc, output ia equal to input

Remote “zero” solenoid shorts input to

or center-zero sce3les. Mete; switch

For maximum battery life, battery oper-

InternaLly mounted nickel-cadmium bat-

LL’LR

GENERAL DESCRIPTION

SECTION 1.

l-l.

GENERAL.

Electrometer is an ultra-stable, solid-state microvolt
electrometer.

a. As a Microvoltmeter.

meter, the Model 640 has an input resistance greeter

than 1016 ohms with thirteen ranges from 30 micravolts

full scale to 30 volts.

b. As a Picoammeter.

high-megohm SHUNT RESISTORS, the instrument has twenty

two ranges from lo-l5 ampere full scale to 3 x 10m5

ampere.

C. As a Coulombmeter.
guarded capacitor in rhe feedback loop the instrument
is useful as a coulombmeter or current integrating

amplifier.
ment has ten ranges Pram 2 x lo-14 coulomb full scale

to 6 x l’~?-~~ coulomb.

d. As an Amplifier.

of the instrument as e very stable, variable gain
amplifier.

The Model 640 Vibrating Capacitor

When used as a microvolt-

When used with the built-in,

By switching en accurate

In the CURRENT INTEGRATE mode the instru-

The analog OUTPUT permits we

GENERAL DESCRIPTION

1-2.

FEATURES.

a. Excellent Stability. A stability specified at
better than 5 x lo-11 ampere/day is useful for mass
spectrometer, resistivity, end ion chamber meesure-

menes.

b. Remote Inwt Head.

amplifier permits convenient set up of en experiment.

C. High Input Impedance. Guarding plus the use of

sapphire insulation provides an input resistance
greater then

farads.

d.

Battery or Line Operation. A choice af beteery
or line operation permits complete isolation (in
battery mode) from power line when required.

e.

Built-In Shunt’Resistors. Four high-megahm
shunt resistors ten be switch selected (Input Head)

for shunt or feedback current measurements.

1016

A compact Remote Input pre-

ohms shunted by less than 2 pico-

1170

GENERAL DESCRIPTION

MODEL 640 ELECTROMETER

TABLE l-l.

Front Panel Controls.

CO”trOl

POWER Switch (5301)
FINCTION Switch (S402)
RANGE Switch (S403)
METER Switch (S404)

Controls the power to the instrument.
Selects the mode of operation.
Selects the meter sensitivity.
Selects meter polarity, center scale, and meter off.

Functional Description

Paragraph

2-3, a
2-3, b
2-3, c
2-3, d

ZERO Controls

KEDIUM (S407)
FINE (R431)

ZERO CHECK Switch (S401)

Adjusts meter zero.

Adjusts meter zero (fine control).

Permits a meter zero check.

2-3, e
2-3, e
2-3, f

!

TABLE 1-2.

Input Head Controls and Terminals.

Control

SHUNT RESISTOR Switch (5102)

Selects P shunt or feedback resistc.r frw 106 to

Functional Description Paragraph

1Ol2 ohms.

ZERO CHECK Switch (SlOl) Permits a meter zero check.

FEEDBACK Terminal (5103) Useful for unity gain or guarded wsauremsnts.

Input Receptacle (5105) Provides connection to Input High
DAMPING Control (RlOS) Adjusts damping for CURRENT INTEGRATE function.

I

2-2, a

2-2, b
2-2, d
2-2, c
2-2, e

2

1170

MODEL 640 ELECTROELETER

FUNCTION

Switch

(5402)

GENERAL DESCRIPTION

POWER
Switch
(S301)

ZERO
Switch
(S407)

METER
Switch

(S404)

FIGURE 2. Front Panel Controls.

FEEDBACK

(5103)

RANGE
Switch
(S403)

ZERO
CHECK

(S401)

SHUNT RESISTOR

1170

FIGURE 3.

Input

(JlO5)

ZERO

CHECK

(SlOl)

Input Head Controls.

3

GENERAL DESCRIPTION

CO”tr01 Functional Description Paragraph

MODEL 640 ELECTROMETER

TABLE l-3.

Rear Panel Controls and Terminals.

REMOTE HEAD Receptacle (5405)
OUTPUT Receptacle (5404)
GND Terminal (5406)
LO Terminal (3402)
FEEDBACK Terminal (5403)
COARSE ZERO Switch (S405)
LINE VOLTAGE Switch (S302)
Line Power Fuse (f301)
Battery Power Fuse (F302)

lV-1MA Switch (S406)

IHA CAL Control (R423)

Provides connection to Input Head.
Provides an analog output.
Connection to Main Chassis ground.
Provides connection to Input LO.
Useful for unity gain or guarded measurementa.

Adjusts meter zero (coarse control).

Sets instrument far either 117 or 234 V power.
Protects line power circuit.

Protects battery power circuit.
Sets OUTPUT for either 1V or 1W..
Adjusts OIJTPLW current for .95-1.05 MA.

2-4, a
2-4, b

2-4, c
2-4, d
2-4, e
2-4, f

2-4,

2-4, h
2-4, i
2-4, j
2-4, k

g

FIGURE 4. Rear Panel Controls and Terminals.

4

1170

MODEL 640 ELECTROMETER

GENERAL DESCRIPTION

SECTION 2.

2-1.

INPUT CONSIDERATIONS.
Input Head Connections.

a.

Remote Cable. A shielded coaxial cable (5

1.

feet long) is supplied to permit remote location of
the Input Head from the Main Chassis. A” accessory
Model 6401 Cable (25 feet long) also can be used
without degradation of specifications.

2. Mounting.

tom mounted as described in paragraph 2-12.

Input Assembly.

3.

of B” insulated input High terminal (center post)
and a machined housing which is input Low. High in-

put resistance (over 10~6

2 picofarads) is maintained by “se of sapphire in-

sulation.

a.) Custom Connections. The input housing has
been designed to easily adapt for use with ion
chambers and other applications where high input

impedance and low capacitance is required. Dimen­sions of the input housing are given in Figure 5.

b.) UHF Adapter. The adapter supplied with the
Model 640 is useful when quick connections must
be made using standard UHF cables, However, this
adapter is limited to measurements above lo-l3

ampere or source resistances below lOI4 ohms.

c.) GRg74 (General Radio) Adapter. This ac­cessory adapter is available for use with G&374

Series coaxial accessories. The limitations of
this adapter are similar to those for the UHF

adapter.

b. ~nsulatio”. Use high

riels such as sapphire, teflon, polyethylene or poly-

styrene for insulation of the input circuit.

The Input Head Chassis can be cus-

This assembly (5105) consists

ohms shunted by less than

resistance,

low-loss mate-

OPERATION

NOTE

The input terminal and sapphire insulator

should be protected from contamination so
that the insulation will not be degraded.

Clean, dry connections and cables are very

important to maintain the value of all in­sulation materials.
tion can be compromised by dust, dirt,

solder, flux, films of oil or water vapor.
A good cleaning agent is methyl alcohol,
which dissolves most common dire without
chemically attacking the insulation.

c. Noise Consideration. The limit of resolution

in voltage and current meaeurements is determined

largely by the noise generated in the source. Stray

low-level noise is present in some form in “early sll

electrical circuits.

guish between stray and signal voltages since it meas­ures the “et voltage.
consider the presence of low-level electrical phenom­ena such as thermocouples (thermoelectric effect),
flexing of coaxial cables (trioelectric effect),
apparent residual charges on capacitors (die-lectric
absorption), and battery action of two terminals

(gslvanic action).

1. Thermal EMFS.

(thermal emfs) are generated by thermal gradients
between two junctions of dissimilar metals. These
can often be large compared to the signal to be
measured.

To

minimize thg drift caused by thermal
emfs, “se pure copper leads wherever possible in
the source circuit.
m*ine*ining c0**t**t ju*cei0* temperatures especially
by using a large heat sink,“ear the connections.
The Keithley accessory Model 1483 Low Thermal Con­nection Kit contains all necessary materials for
making very low thermal copper crimp connections for
minimizing thermal effects.

Even the best insula-

The instrument does “ot dtsttn-

When using the microvolt ranges

Thermoelectric potentials

Drift ca” rlso be mL”immLzed by

1170

FIGURE 5.

Dime”sio”s of Input Housing.

2. AC Electric Fields.

The presence of electric
fields generated by power lines or other source8
can have a” effect on instrument operation. AC
voltages which are very large with respect to the
full-scale range sensitivity could drive the ac
amplifier into saturation, thus producing a” erron­eous dc output. Proper shielding as described in
paragraph 2-1, d can minimize noise pick-up when
the Fastrument Fa in the presence of large ac fields
or when very sensitive me.ssuremBnta are being made.

3. Magnetic Fields. The presence of strong mag­netic fields can be a potential source of BC noise.
Magnetic flux lines which cut a conductor can pro­duce large ac noise especially at power line fre­quencies. The voltage induced due to magnetic flux

is proportional to the area enclosed by the circuit

as well as the rate of change of magnetic flux. Par

5

OPERATION

MODEL

640 ELECTROMETER

example, the motion of a 3-inch diameter loop in the
earth’s magnetic field will induce a signal of sev­eral tenths of a microvolt. One way to minimize
magnetic pickup is to arranSe all wiring so that the

loop area enclosed is as small as possible (such as

twisting input leads). A second way to minimize

magnetic pickup is to use shielding aa described in

paragraph 2-1,

d.

d. Shielding.

Electric Fields. Shielding is usually nec-

1.
essary “he” the instrument is in the presence of
very large ac fields or “hen very sensitive measure-

ments are being

ment

circuit and

made.

The shields of the measure-

leads should be connected together
to Sround at only one point. This provides a “tree”
configuration, which minimizes ground loops.

2. Magnetic Fields. Magnetic shielding is useful

where very large magnetic fields are present. Shield-

ing, which is available in the form of plates, foil
or cables, can be used to shield the measuring cir­cuit, the lead wires, or the instrument itself.

e. Moisture.

The Model 640 Inp;t Head is shipped

with a dessicant bag sealed inside. This bag soaks

up the moisture inside the Input Head to insure opti-

mum operation. The dessicant bag, however, will event-

ually become saturated. At this point the Model 640
offset will increase beyond the specified amount.

When this happens take off the bottom cover of the In-

put Head to remove the desaicant bag. Reactivate it
according to the instructions on the bag.

d. FEEDBACK Terminal (51031. This terminal is

used for unity gain or guarded measurements. _

e. DAMPING Control (RlOSl. (Not Shown). This
control permits adjustment of the damping for
INTEGRATE operation.

When the control is set fully

CURRENT

clockwise to “MAX” damping,the rise time is approxi­mately 44 seconds with a 1012 shunt resistor. When
the control ts set fully counter-clockwise to

“MIN”

damping,the rise time corresponds to the critically
damped or CURRENT FAST condition 88 given in the
specifications.

2-3. FRONT PANEL CONTROLS. The front panel controls
are shown in Figures 1 and 2.

The operation of each

control is described 88 follows:

8.

POWER Switch (5301). This switch has four

positions designated AC, OFF, BATTERY, and BATT TEST.

1. AC Position.

This position permits normal
aperacion of the instrument when the power cord is
connected to line power. (The battery charging

circuit operates in this position.)

2. OFF Position.

This position disables both

AC

and BATTERY power to the electrometer circuits ex­cept for the battery charging circuit which operates
in this position.

3. BATTERY Position.
normal operation of the
battery

pack

is satisfactorily charged.

This position permits

insteument

when the internal

2-2.

INPLT HEAD CONTROLS AND TESMINALS. The Input
Head is shown in Figures 1 and 3. The operation of
each control or terminal is described aa follows:

a. SHUNT RESISTOR Switch (SlOZ1. This switch se­lecte 5 positions corresponding to the shunt resistor
(acro88

ment.

and “OPEN”.

input of feedback) require% by the me~8ure.

The switch positions are 10 , lOa, lOlo, 10lz

The “OPEN” position has no resistor

connected.

by 1000 ohms.

c, Input ReceDeecle (JlOSl. This receptacle pro­vides input connection to the Model 640 Input High
and Input Low.

4. BAIT TESTY Position.

This position permits a

check of the battery voltage as indicated by the

meter.

b. FVNCTION Swtich (S4021. This switch has three

positiona designated VOLTAGE,

C”RRENT

INTEGRATE.

CURRENT

FAST, and

1. VOLTAGE Position. This position co,,,,ects the

electrometer .8 8 very sensitive, high impedance

voltmeter with the

SHLMT RESISTORS

connected in

shunt across the input.

2. CDRRENT

FAST.

This position cannects the
electrometer as a feedback pieoammeter which neu­tralizes the effect of input capacitance and in­cream response speed.

The SHUNT RESISTORS are

connected in the feedback loop of the amplifier.

3.

CDRRENT INTEGRATE.

This Dosition connects
the 20 picofarad warded caPa&or in the feedback
loop of the ampli ier.

c. RANGE Switch (54031. This switch has thirteen
positions corresponding to full scale voltage sensi­tivity from 30 microv01ea to 30 volts.

d. METER Swftch (S4041. This switch has 4 poai­tions designatad OFF, +, -, and CENTER ZERO.

6

1170

SOQEL 640 ELECTROMETER

OPERATION

1. OFF Position.

This position disables the

meter movement to protect against averlaads. This

position has no effect on the OUTPUT voltage when

using a recorder or other instrument.

“i” and ‘I-” Positions. These p0sitiDne select

2.

the polarity af the meter only. The

OUTPUT

voltage

is not affected by these pasitions.

CENTER ZERO. This position sets the meter

3.

circuit so that zero is indicated at center scale

(mid-scale). The deflection of the meter corres­ponds to one-half RANGE setting, The OUTPUT “olt­age is nat affected by this position.

e. ZERO Switch. This switch is a dual-concentric

control.

1. MEDIUM Control (S407). This control is the
cuter knob with eleven pasitions which adjust the
meter-zero.

FINE Confrol (R431). This control is the

2.

inner knob which permits fine meter-zero adjustment.
f. ZERO CHECK (S401). This switch is e normally--

open contact-type switch permitting meter,-zero check.
The ZERO CHECK switch shunts the input HI to input LO

(in voltage function) by 1000 ohms.

ZERO Controls do not provide sufficient range of
CO”tl-01.

g. LINE VOLTAGE Switch (S302). This switch sete
the instrument for either 117 or 234 volt rms line­power. The line-power fuse (F301) should be checked
far proper line voltage rating.

h. Line Power Fuse (F301). This fuse pr~tecee the
power supply circuits when 117-234V line power is
used.

Fuse Racing

117 ”

234 V

1.

Battery Power Fuse (F302). This fuse protects

l/4 smp, 3AG

l/B nmp, 3AG

the power supply circuite when battery power is used.

Fuse rating: 314 amp, 3AG.

j. lv-IMA Switch (5406). This switch sete the

OUTPUT for either 1 volt 0’ 1 mA.

k.

1MA GAL Control (R423). This control permits

adjustment of the

OUTPUT

(with lV-1MA Switch set co

1MA) over the range 0.95 to 1.05 mA.

2-5.

OPERATING CONSIDERATIONS.

REAR PANEL CONTROLS AND TERMINALS. The rear

2-4.

panel controls and terminals sre shown in Figure 4.
The operation of each control or terminal is described
as follows.

a. REMOTE HEAD Receptacle (5405). This receptacle

is a 24-pin cOnnector (Amphenol 57-40240) which mates
with the interconnecting cable between the Main Chas-

is and Input Head (Remote Head). Two “echenical re-

taining clips see provided on the receptacle to Secure

the mating plug (P405).

b.

OUTPUT

Receptacle (5404). This connector pro-

vides en analog output far recording or monitaring

pUrpOSeS. The output is 11 volt at up to 1 “A for

full scale input.

the input palarity.

The output polarity is ~posite

The front panel METER switch has

n0 effect on the polarity of the analog output.

c. GND Terminal (54061. This terminal is connected

to Main Chassis ground and the outside shell of con-

neceor 5405.

With no cOnnection between GND and LO

(shorting link removed), the INPUT LO to Main Chassis

ground isolation is greaterthan 109 : shunted by .05
microfarad,

d. LO Terminal (5402). This terminal is connected

to INPUT LO on INPUT HEAD.

e. FEEDBACK Terminal (5403).

This

terminal is

used for unity gain or guarded measurements. The

terminal (5403) on the Main Chassis is connected to

5103 an the INPuT HEAD by way of the remote cable.

f. COARSE ZERO Switch (5405). This switch hes ten
positions far adjusting the meter-zero circuit. This
switch should only be used when the FINE and MEDIUM

a. Mode of Opereeion.

1. AC Line-Power.

The Model 640 can be operated

using ac line-power at 117V or 234V, 50 .x 60 Hz.

To operete,set LINE VOLTAGE Switch (5302) to 117
or 234, check for proper rated fuse (F301), and
connect the line cord.

Set the POWER Switch (S301)

to “AC” operation.

2. Battery Power.

The Model 640 can be operated

using battery paver supplied by e rechargeable 6-

volt nickel-cadmium battery peck.

a.) To check the battery charge, set the POWER
Switch to “&ATT TEST” position. The meter should
indicate +6V or greeter if charge is sstisfactary.

b.) To recharge the battery pack, connect the
p,yF;z cord to ec power. Set the POWER Switch to

. (The bettery will automatically recharge

when the POWER Switch is in either “AC” or “OFF”

positians).

Battei-y charging-time is approxi­mately 16 hours for full charge after 8 hours of
continuous we.

3. AC Co Battery Switching. The Model 640 ten
be modified so that it will sutomsticallv switch
fro” “AC” operatia t0 “BATTERY” ~peraeibn if the
line power fails.

An explanation of this modifica-

tion is given in paragraph 3-4 in the Circuit Des-

cription section.
b. Warm-UC. If the

instrument

is to be used for
very sensitive measurements,allaw the instrument to
stabilize far an haur or more. The POWER Switch can

be see et either ‘AC” or “BATTERY”.

1170 7

OPERATION

MODEL 640 ELECTROMETER

C. Meter zero.

The meter zero circuit utilizes

three conerols PINE, MEDIUM, and COARSE.

1.

After

warm-up, set the METER Switch to CENTER

ZERO.

2. Adjust the MEDIUM ZERO Control for center-

zero meter position.

(The rear panel COARSE ZERO

Switch can be used tf meter reads off scale).

3. Increase sensitivity using the RANGE Switch

and adjust the

FINE

ZERO Control for center-zero

meter indication.

2-h.

VOLTAGE FUNCTION.

a. General.

When the FUNCTION Switch is set to the

VOLTAGE poaition,the Model 640 operates as a high in-

put-impedance electrometer.

The

b. Input Impedance.16

input resistance (HI to
LO) is greater than 10 ohms shunted by less than 2
picofarads. This specification is valid 2 for the

SHUNT RESISTOR Switch sat to “OPEN” with no depreda-

tion of the input HI to input M insulation. ?‘he in­put resistance can be lowered by se~~ti”gl~lWNUN~RE-

SISTOR

values in four steps from 10 to 10 ,

c. Microvoltmeter Measurements.

1. Theory. The electrometer, when used as a
microvoltmeter, can be illustrated 88 shown in
Figure 6.

In this configuration the instrument is
useful for making sensitive measurements from 30
microvolts full scale to 30 volts. The sensitivity

is adjusted by the RANGE Switch (5403) represented

by RA.
wltage eA is defined by the following expression,

The input voltage is represented by ei.

The

eA = ei (j&)

where K is the amplifier loop gain.

Therefore iA = *A 2 ei where KA is selected by

the RANGE Switch (S403).

XK

2. Voltage “easurement.
a.) High Impedance. Although the electrometer

has a very high input impedance, the useability

of the Model 640 as a micravoltmeter is limited
by the thermal (Johnson) noise generated in the
m impedance.

Refer to paragraph 2-10 for a

complete discussion of thermal notae.

b.) Low Impedance.

The Model 640 can be used
on the more sensitive ranges by setting the SHUNT
RESISTOR Switch to 1012 ohms or lower. The laad-

ing effects should be considered when measuring

high source-impedance.

3. Current Measurement. The Model 640 can be

used for current measurements since the microvolt-

meter measures the volta e ac

resistor selected for 10 , 10 , 1010, or 1012 ohms.

088 a known shunt

k; li

Current can be calculated by the ratio of voltage
reading to shunt resistance. “se this technique

where low noise is important,alehough faster re-

sponse is provided by setting the FUNCTION Switch
to CURRENT FAST as described in paragraph 2-7.

4. Unity Gain Meesurements. The Model 640 can

be used for measuring a potential from B very high

impedance source with .025% accuracy. Connect a
digital voltmeter (or differential) to FEEDBACK and
LO terminals as shown in Figure 7.

SOURCE

VOL’UGE

FEEDBACK -

(INPUT

HEAD)

FIGURE 6. Voltage Function With Shunt Resistor KS

< FEEDBACK

(MAIN CHASSIS)

MODEL 640 ELECTROMETER

-

INPUT

OPERATION

LO

FIGURE 7.

CURRENT FAST FUNCTION.

2-7.

a. General.

CURRENT FAST

“se Of FEEDBACK Connection.

When the FUNCTION Switch is set to the

position,the Model 640 operates es e feed­back ammeter with feedback resistors selected by the
SHUNT RESISTOR Switch in four steps from 106 to 1012

ohms.

b. Feedback Aonoeter Measurements.

1. Theory.

The Model 640,when used 8s e feedback

amm?ter,cen be illustrated 88 shown in Figure 8. In

this configuration the instrument is useful for mek-

ing sensitive meesurements from lo-l5 ampere full
scale. Response speed is greatly improved compared
to the VOLTAGE FUNCTION configuration since the
effect of input capacitance is largely neutralized.
The input voltage drop end effective ameter input

resistance is given for each RANGE setting es in
Table 2- 1.

TABLE 2-1.

Inwt Resiacance in CURRENT FAST Function.

RANGE

Current Input

Resistance

1ov 1x10-11
1V

;;:;I$

1OOmV
1OmV

lmv

:g: ::

108
108
108

108
108 O.lvV

Input

Voltage

lmv
1OO~V
1ovv

4Jv

c

0472B

INPUT HI >-+
INPUT LO >

FEEDBACK >

I

I

5

RF

RM

( OUTPUT

t

a0

I

< LO

FIGURE 8.

Current Feet Function.

OPERATION

MODEL 640 ELECTROMETER

2. Current
e.) Rise Time.

particular meeeuremene depends on the shunt re­sistor end residual capacitance ecroes the feed­beck loop.

is given in the specifications for each resistor
value.
stcondition where no external capacitance is

cannected between the FEEDBACK terminal end u

ix

b.) Guarded Measurements. The Model 640 ten

be used for guarded resistance measurements using

the FEEDBACK Terminal and Input HI connections 89
shown in Figure 9. Since EB and RB develop e

known current IB,then the electrometer will in­dicate the voltege develaped ecrose Rx (un!aowo

resistance).

Rx

CURRRNT INTEGRATE FUNCTION.

2-8.

a. General.
CURRENT INTEGRATE position the Model 640 operates es
e feedback ammeter with damping.

b. Feedback Ammeter Measurements.

1. Theory.

trated es shown in Figure 10. In this configuration

the DAMPING Control is set te WAX” position so thet

a 20 pf cepecitence is connected in the feedback

loop (SHWT RESISTOR Switch set t0 “OPEN”). The
current measured is determined by the following
equation,

Measurement.

The actual rise time for a

The specified rise time (10 to 90%)

These rise times era for a criticallv

, Additional external capacitance ten be

= Eo =

T

When the FUNCTION Switch is eat ta the

The Model 640 operation ten be illus-

%K RB

2-9.

use as en smueter accurate to 20.25%.

10 ) shunt resistors can be accomplished using a
current integrating technique.
voleege eource can be connected in series with the

shunt resistor forming e current source where I =
V/R.

the meter reading EM is e function af cepacitance C
end the integral of the current.

arAEM =

Solving for R,

Where R -

Since the eccuracy of C is +.25% the overall eccurecy
af the calibration will depend on the accurecies of

the voltage swrce V, the meter accuracy EM, end the

time accuracy T.
acy, maesure the enalog OUTPUT using a 0.01% digitel

voltmeter.) Refer to Figure 11 for circuit connec-

tions.

SHUNT RESISTOR CALIBRATION.

8. General. The Model 640 ten be calibrated for

& Theory. Calibration of

With FUNCTION Switch set t0 CURRENT INTEGRATE

c J

$ AT =(!-) AT

shunt resistance, ohms.

V

= eource voltage.

C = integrsting capacitor (20 pf).
E-E0 - chenge in wltage indication.
T-T0 = time ineervel for voltage change.

(To obtain the best possible eccur-

c. Calibretion Procedure.

1. Set the FUNCTION Switch to CURRENT?NTZGRATE.

rhe

high value (lo”,

An

accurately known

where I =

AE

At

2. Variable Damping.

(R108) is adjusted.counter-clockwise,the Model 640
can be used fot current meesuremente with veriable
damping.

10

cm-rent in amperes.

C = feedback capacitance (2 x 10-11).

=

change in the meter resdtng during time

interval

=

time interval of me*aurement.

At.

When the DAMPING Control

2. Set the DAMPING to ‘WAX”.

3. Apply the voltage source between P106 end

input LO. (Remove the Input Heed bottom cover for

access).

4. Zero meter.

5. Select lOlo or 1012 SHUNT RESISTOR.

6. Measure time interval from zero to full scale

an the meter.

7. Calculste the value of R using equation.

Record time interval T-To.

04728

MODEL 640 ELECTROMETER OPERATION

INPUT HI

< OUTPUT OUTPUT

INPUT LO

<

1

e. =

l/C

I

LLO LO

--c

FEEDBACK,

>

!

RI.!

1

I

p+k

E -

-

FEEDSACK~

P106

INPUT HI

FIGURE 10.

Equivalent Current Integrator.

-< OUTPUT

RA,

% *o

t

= l/C J E/R dt

‘< Lo

04728

FIGURE 11. Current Integrate - Shunt Resistor Calibration.

11

OPERATION

MODEL 640 ELECTROMETER

Z-10.

ANALOG OUTPUTS.

a. OlPPPUT

en analog output for recording or monitoring purposes.

eo161”~“,~i?&,,
full scale input. The-polarity of the output is

opposite the input signal.
Gain: 0.033 eo 3.3 x 104
Frequency Response (Within 3 db): dc to 0.07 cps

at a
of 10

Noise: Below lcps: seme es meter noise for spec-

ified function. Above 1 cp8:
output p-p an the 30-v to lo-mv ranges, increasing
co 10% an the 1-w and lower ranges.

dtit~ the o”tp”t is approximately 1X4 for a full
scale input.

b. onio Gain output.

set to VOLTAGE the FEEDBACK terminal can be used for

measuring a potential from a very high impedance

SO”X.2.
in .01X or 10 M”, exclusive of zero drift, for output
current of 100 pA or less.

Terminal

P

ain of 3.3 x 10 , rising to 35 cps at e gain

3

or below.

1MA Output. With the IV-1”A Switch set to

At dc, the output is equal to the input with-

(54041. This terminal provides

With the l”-WA SWitch (S406) set

is + 1 volt corresponding to a

less than 2% of full

When the FUNCTION Switch is

The peak-to-Peak noise is approximately five times the

rms value (from experimental measurements), therefore
the equation can be expressed as follows.

EPP =

If the ambient temPerat”re is 300°K (room ambient)
then the peak-peak noise can be expressed as follows.

EPP =

C. Typical Example. The Peak-peak thermal noise

generated in an ideal so”rce resistance can be illus-

trated as follows.

Given: Amplifier BandwidthAF = 0.08 *

EPP (typically)
KPP =

*AF =

2-12.

8. casting Dimensions.

the Input Head Casting are shown in Figures 12 and

13.

5 x %ms

6.45 x 1O-Lo s

R - 1012 ohms.

RANGE see to 1 MY.

180 vV Peak-Peak

= 6.45 x lo-lo

1

kiK=

MOUNTING DIMENSIONS.

2% lo’& 2 x lo-‘f 2 .OB

The overall dimensions of

2-11. THERMAL NOISE.

e. General. A common limitation of microvoltmeter

measurements from high so”rce impedances is the eherm-

al noise (Johnson noise) generated in the source.

b. Theory. Thermal noise in an w resistance
can be theoretically determined from
noise equation as follows.

%m =

JZXZ

the

Johnson

where

Q-m =

T =

R =
F = amplifier bandwidth, Hz.
K =

rm8 voltage noise generated in the
resistence.

temperature, OK.
ideal resistance, ohms.

soltzmenn CO*Ste”t (1.38 x 10-1ojaulea/4()

b.

Input

loaded with the dimensions from the base 8s shawn in
Figure 12.

c, “auntinn the Base Plate. The Base Plate can be

mounted on a machined surface for custom installation

of the Input Head.
Input Head casting using four type 6-32 x l/4 BCTBWS.
The rubber feet are’attached to the base plate “sing
type 6-32 x l/2 Phillips Heed screws and mating #6

kep nuts.

this hardware).

Casting to e surface Plate.clearance holes must be
drilled in the surface plate as shawn in Figure 14.
The Casting can be fastened to the surface using type

6-32 screwe.

the four 8crews replaced.

ed should provide sufficient clearance for the 6-32

Phillips screw heeds.)

contact. The input COntaCt is spring

The Base Plate is fastened Co the

(The deesicant beg is also attached “sing

In order to mount the Input Head

The rubber feet should be removed and

(Note that the holes drill-

12

04728

MODEL 640 ELECTR‘WSTER

1

.I ._.-._.-.-.

:-.i,-‘-‘-‘-‘-‘-.-’

1 i

i
I
i

I

I

FIGURE 12.

6.28

>ut Head Castins.

I”1

4

L5.13 I

FIGURE 13.

1170

Base Plate Dimensions, FIGURE 14.

Mounting Hole Locations

CIRCUIT DESCRIPTION

MODEL 640 ELECTROMETER

SECTION 3.

3-l. GENERAL.
Head (Remote Preamplifier) end e Main Chassis (Am­plifier end Power Supply).

8. High Impedance Microvoltmeter. When the FLNC­TION Switch is set to VOLTAGE,the Model 640 operates
as e very sensitive, stable voltmeter with very high

input Lmpedance .

b. Vibrating Capacitor Electrometer. When the

FUNCTION

Model 640 operates es a stable current enh charge
measuring instrument.

3-2.
amplifier utilizes e vibrating-capacitor input pre­amplifier end variable-sensitivity emplifier. The
overall amplifier operates es a very sensitive dc
amplifier using e vibrating cepecitor es en input
signal modulator.
amplified end demodulated in the preamplifier circuit.
The dc signal is filtered end amplified further
by the main dc amplifier.

ly to provide gain accuracy end stability, A block

diagram of the overall amplifier is shown in Figure 15.

3-3. INPm HEAD.

Heed contains the input modulator, high-gain ec em­plifier, oscillator end demodulator. The Shunt Re­sistors are connected across the overall amplifier­feedbeck using Switch S102.

Switch is set to either CURRENT position,the

ELECTROMETER AMPLIFIER. The basic electrometer

The Model 640 is composed of an Input

The input signal is modulated,

Feedback is used extensive-

(Remote Preamplifier). The Input

CIRCUIT DESCRIPTION

a. Vibrating Capacitor.
used consisting of two stationary pletes and e vibrat­ing membrane which is excited et e carrier frequency

of approximately 400 kHz. The glass membrane has de-

posited metal surfaces and is sealed in en evacuated
glass “bottle”.

high input-impedance end low drift. When driven et

the carrier frequency (under proper canditions),the

membrane resonates et approximately 6000 Hertz. Since

the carrier (drive) frequency is much higher then the

resonenC

ics does not appreciably effect the amplifier circuit.

b.
to receuescle 5105
is isolated from Main Chassis ground. A 10 megohm
resistor (RIOS) prevents e rapid discharge of the

vibrating capacitor beck ineo the source circuit. The
modulated signal is applied to the first stage ac

amplifier through e guerded, three-terminal air cap­acitor. (Cl05 which is 20 pF 5 0.25%).

c.
a normally-open control which energizes solenoid RlOl.

When KlOl is energized,a cancect connects input High

to FEEDBACK through a 1000 ohm resistor. The input
source end vibrating cspecitor remain connected in
the circuit during zero check. A loading error will
result in the meter zero reading if the source resist­ence (RS) is less then 100 K in accordance with the

following equation.

% Error = 100

frequency, the terrier frequency end harmon-

Input circuit. The input High signal is spplied

Zero Check Circuit. The ZERO CHECK control is

RS’1’

This unique capacitor provides very

on

where KS is expressed in kilohms.

A

special capacitor is

the Inwe Heed. The inout LO

r-

-INPUT HEAD -MAIN CHASSIS -INPUT HEAD -MAIN CHASSIS

FEEDBACK FEEDBACK

INPUT INPUT

FIGURE 15. Block Diagram of Model 640

14

1170

MODEL 640 El.ECTROMETER

CIRCUIT DESCKIPTION

d. AC Amplifier,

The ac amplifier provides very
high gain through the use of a two-stage amplifier
and a phase splitter amplifier. A" FET (QlOl) pro­vides a high input impedance. A" emitter-follower

stage (transistor Ql02) provfdes impedance matching

between QlOl and transistor Q106. Transistors Q103

9104, Q105 and QlOS are switches providing gain ad-

jwtment to prevent oscillation on the higher ranges.

Transistors Q107, Q109 and QllO form a second stage

ac amplifier. A phase splitter circuit is formed by
transistors Qlll and Q112. A tuned circuit composed
of integ. ckt. QAlOl, inductor LlOl and trimmer cap-

acitor Cl24 provide attenuation of carrier frequency

(6000 Hz) second harmonic noise. The ac signal is

synchronously demodulated by transistors 4506 and

Q507 (locatad in the oscillator circuit).

e. Oscillator Circuit. The high frequency drive

(400 kHz) signal is generated by a tuned circuit con­sisting of transformer T501, capacitors c502, c503
and C504 and transistor Q501. Capacitor C502 adjusts
the 400 kHz carrier frequency. Pote"tiometer R506
adjusts the gain of the drive circuit. The drive o"t­put is developed across transformer T502 and capacitor
C509 to excite vibrating capacitor plates (pins 1 and

The actual signal is a modulated "envelope" as

4).
shown in Figure 28 in Section 6. FET Q503 and inte-

grated circuit QA501 form a wave-shaping circuit far
phase and syrranetry control.

Integrated circuit QA502

is part of a phase control circuit for the demodulator
autput. Potentiometer R517 adjusts the phase of the
demodulator drive. Integrated circuit QA503 is part
of a swmletry control circuit.

Potentiometee S.521
adjusts the hemodulator a" and off times (syrmnetry).
Transistor 9505 controls the switching of demodulat-

ing transistors Q506 and Q507.

3-4. MAIN CHASSIS.

The Main Chassis contains a dc
amplifier circuit, meter circuit, sensitivity switch­ing circuit, power supply circuit, and battery charg-

ing circuit 88 shown on Schematic 213833.

a. DC Amplifier.

A differential input stage is

formed by FET's Q401 and Q402 and transistors Q403
and Q404.
balance.

Potentiometer R404 provides dc amplifier

Capacitors C401, C402, and C403 provide
filtering of the demodulator ripple. FET Q405 and
transistors Q406 and Q409 (Darlingto" amplifier) pro-

vide additional gain for driving the meter circuit
and analog O"TPUT.

Transistor Q4OS provides current

limiting when the output is overloaded. Transistor

4407 provides a constant current for biasing purposes.

b. Meter Circuit.

The meter circuit consists of a
meter switch 5404, a 1-W meter movement (M401), and
various meter circuit adjustments. The Meter switch
has a" OFF position (which shorts o"t the meter move­ment), "t" and 11-11

polarity positions (which connect

the meter for either positive 01: negative deflection),

and a ZERO CENTER position (which biases the meter

such that center scale represents zero).

POtf?"tiO­meter R421 is an internal adjustment of the ZERO
CENTER meter bias current. Pote"tiameter R455 is an

internal adjustment of the meter calibration.

c. Zero Controls.

Switch,5405 is B COARSE ZERO

adjustment which can select up to 11 positions a" a
divider string (resistors R432 thtough R442). Switch
S407 is a~MSDILIM ZERO adjustment which can select up

to 11 positions a" a divider strinn (resistors R443

through R452).

Potentiometer R431-is a FINE ZERO

adjustment.

1170

CIRCUIT DESCRIPTION

d. Sensitivity Switching. SANGE Switch 5403 has
13 positions which connect resistors R457 through
R469.

The range resistors determine the voltmeter
gain or sensitivity from 30 microvolts to 30 volts
full scale.

Power Supply, (As shown on Schematic 213823).

a.

The power for the Model 640 is provided by either a
rechargeable 6-volt battery pack or a recitifier cir-

cuit

operated by 50-60 Hz line power.

S301 selects four positions: “AC” (line power),

Power Switch

“OFF”,

“BATT” (battery power) and “SATT TEST” (battery volt­age check).

The power supply utilizes a -6 volt un­regulated voltage from the battery pack or a rectifier
circuit composed of transformer T303 secondary (yellow
end green taps) and diodes X317-D318. A 5-volt regu-

later is composed ofcapacitor C321, transistors Q317-

Q319 (Darlington series regulator), and reference
diode D319. Transistors 9321 and Q322 compoee an out­put sensing amplifier to regulate the series transistor
stage.

Potentiometer R338 is a.” internal adjustment
of the regulated output (approximately -5 volts). The
regulated voltage is applied to an Inverter circuit
consisting of transistors Q301-Q302 end saturable core
transformer T301.

MODEL 640 ELECTROMETER

Line Power to Battery Switching. The Model

5.

640 can be modified so that a failure of line power

(with POWER Switch set to

“AC”)

will ca”se an auto­matic switching to battery operation to occur. A
diode

(0.75A. 5OV,

Keithley Part No. RF-17) can be

connected at the POWER Switch 88 shown in Figure

When line power is present the diode is turned off

and the battery is not used.
f. Battery Charuinp. Circuit. The charging circuit

functions whenever the POWER switch is eet to “AC”
or “OFF”.

Charging c”rrent is provided

by a

rectif­ier circuit conslating of diodes 0315-0316 and re­si*tor 107.9. Fuse F302 is rated for 314 ampere and

used to protect the battery end circuitry during
charging or discharging.

+ 4OV Supply. Power is tapped from B second-

1.
ary winding on Craneformer T302 (brown/yellow,
brown/white, brown). Diodes D301-0304 and capact-

tars C302-C303 provide + 40 volts for the dc ampli-

fier output stage.

- 2ov supply.

2.

This voltage is not used in

the Model 640.

+ 12” supply. Power is tapped from B eecand-

3.
ary winding

on

transformer T302 (red/yellow, yellow/

white, yellow). Diodes 0307-0310, resistor R304,

and capacitor C307 form a rectifier circuit. A
voltage doubling circuit cdnsisting of capacitors
C305-C306, and diodes D30S-D309 forms a bootstrap
voltage).

Transistors Q303-Q304 form a Darlington
series regulator circuit. Feedback is obtained by
sampling the + and - 12 volt outputs at the junction
of resistors R316 and R317. Transistors Q30S and
Q309 form a differential amplifier which senses a
change in either the + or - outputs. Another dif-

ferential pair (transistors Q306-Q307) drives the

base of transistor 9304 to complete the feedback

100p.

Transistor Q305 provides overload-current

protection by sensing the current through resistor

R305.

-12v Supply. Power is tapped from a aecond-

4.
ary winding on transformer T302 (red, blue/ white,
blue). Diodes D311-0312, resistor R318, and cap­acitor form a rectifier circuit. Transistors Q310­Q311 form e Darlington series regulator circuit.
Feedback is obtained by sampling the -12 volt out-

put et the wiper erm of potentiometer R327. This
potentiometer adjusts the output voltage. Transis­tors Q114-Q115 form a differential amplifier with
the base of Q314 referenced to diode D314. Trans­istor 9313 drives the base of Q310 to series regu­late the output. Transistor Q312 provides overload
current protection by sensing the current through

resistar R345.

FROM BATTERY

I

FIGURE 17. Line to Battery Switching.

3-5.

VOLTAGE FUNCTION.
set to “VOLTAGE”, the Model 640 operates as a sensi­tive voltmeter with input “OPEN” or shunted by any
one of four resistors,RlOl through R104.

3-6.

CURRENT FAST FUNCTION.

eet to “CDRRENT FAST”, the Model 640 operates as e

feedback ammeter with a Shunt Resistor connected

acrose the amplifier (from High to Feedback). An
external resistance can be connected ,in place of the
four Shunt Resistors “he,, switch 5102 ie *et to “OPEN”.

This

method minimizes the slowing effect of capacit-

ance across the input.

3-7. CURRENT INTEGRATE
Switch set to “CURRENT INTF.GRATE”,the Model 640

operates ee a feedbaok anmeter or coulomb-meter.

With (1 Shunt Resistor connected,(RlOl through R104)

a 20 pF capacitor (ClO5) shunte the amplifier to
therefore slow the response and filteenoisy signals.

With switch S102 set to “OPEN”,capacitor Cl05 acts

as an integrating capacitor for charge or current

integration measurements. A simplified diagrams of

the current integration amplifier is shown in Figure

11 . When the

INTFJXATE”, switch S4O2 connects -5 volts to

FUNCTION Switch is set to “CURRENT

K102 which in turn closes e contact.

connecte the Damping Control (RlOS) such that Capac-

itor Cl05 is connected in the feedback loop. The
Damping Control adjusts the effective capacitance
connected in the feedback loop and thus controls the
amount of damping. When the Damping Control is ad-

justed fully clockwise the maximum damping (20 pF

+ .25%)

is provided.

With the FUNCTION Switch

With the FUNCTION Switch

FUNCTION.

With the FUNCTION

solenoid

The contact

16

1170

MOOEL 640 ELECTROMETER

ACCESSORIES

SECTION 4. ACCESSORIES

4-1. GENERAL.

The follo"ing Keithlsy accessories

can be used with the Model 640 to provide additional
convenience and versatility.

Model 6401 Remote Cable
Description:
The Model 6401 is a shielded coaxial cable with a

Keithley B-195 (male) connector on each end. The
cable is 25 feet long.

Model
Description:
The Model

6402 is

special adapter which replaces the

UHF adapter supplied with the instrument.

Application:

The Model 6402 adapts the Input Receptacle for GR074
series Of coaxial accessories. (General Radio Co.).

This adapter is limited to measurements above

10

-13

amperes or source resistances belo” 1014 ohms. The
adapter can be connected to the Input Head as shown

in the illustration.

4-2. OPERATING INSTRUCTIONS. A separate Ins~ructio"

Manual is supplied with each accessory giving com-

p1ete operating information.

Application:

The Model

6401 permits remote location

Head up to 25 feet from the Main Chassis with no de­gradation to the specifications.

6402

Adqter

of the Input

Model 399 Isolating Amplifier

Description:
The Model 399 is a unity-gain amplifier which permits

operation with the instrument output floated at up to

1500 volts off ground while the Model 399 output is

grounded or floated up to 100 volts off ground.

1170

Application:

The M,,del 399 can be used for ‘FIFO” operation (float-

ing input, floating output) or when it is necessary
ea break ground loops within a system. The 1 volt at

up to 1 mA output enables use of the Model 399 as a

preamp far driving most analog recorders.

ACCESSORIES

Specifications:

MODEL 640 ELECTROMETER

Model 399 Isolating Amplifier (Cant’d.)

GAIN: XI, adjustable 23%.
GAIN ACCIJRACY :
GAIN LINEARITY:

,o,za (as set ae factory).

Within 3 millivolts for signal levels

below I volt.

FREQUENCY RESPONSE (minimum): Fast: dc to 100 Hz

(-3 dB); Slow: dc to 0.3 He (-3 dB).

NOISE: Less than 5 millivolts p-p, .Ol Hz to lk”z;*

less than 0.5 millivolt p-p, .Ol Hz to 0.35 HZ.*

ZERO STABILITY: Setter than 3 millivolts/24 hours at

reasansblv constant ambient temperature.

106

INPOT RESIS+ANCE:

INPUT OFFSET CURRENT:

FULL-SCALE INPUT:

ohms.
mess than

lo-6

ampere.

11 volt with 100% overrange.

MAXIMUM INPUT OVERLOAD: 100 volts.

INPO’I ISOLATION: Greater than 101’ ohms at 50% rela-

tive humdiity and 2PC shunted by less than 100
picofarads.

MAXIMUM COMMON MODE VOLTAGE: 1500 volts peak, dc or

ac.

CMRR: Greater than 120 dS at dc, greater than 100 dB

up to 1 kHz.

OOTPUT :

+l volt at up to 1 milliampere, 100% over-

range.

OUTPUT ISOl.4TION:

Greater than lo* ohms shunted by

less than 0.001 microfarad.

POWER :

105-125 ar 210-250 volts (switch selected),

SO-60 Hz, 5 watts.

DIMENSIONS, WEIGHT:

4-112” high x 4-112” wide x 7”

deep (11 cm x 11 cm x 18 cm); “et weight, 3 pounds

(1.3 kg).

ACCESSORIES PURNISHED:

Model 3991 Input Cable

(to

safely mate Model 399

to most Keithley instruments).

xModulation suikes a few hundredths of B volt D-D

at a IO-kliz. ;ep-rate may be observed with widebind

SyStmS*

Model 370 Recorder

rlescription:
The Model 370

is compatible

is a compact, paper chart recorder which

with most Keithley instruments having a

1 volt; 1 milliampere output.

Application:

The

Model 370 can be used for analog recording appli­cations with inputs floated at up to 500 volts off
ground.

The Model 3701 Input Cable supplied permits

convenient connections to the instrument.

18

1170

MODEL 640 ELECTROMETER

ACCESSORIES

Model 4006 Reck Mounting Kit
Description:
The Model 4006 is a rack mounting kit with overall

dimensions, 7 inches high x 19 inches wide. Two top

covers are provided for use with either 10 inch or

13 inch deep instruments.

Application:

The Model 4006 converts the lnetrur,,ent from bench

mounting to rack mounting.

It is suitable for mount-

ing one instrument in one-half of a standard 19-inch

rack.

Pares List:

Item

NO.

OescripCion

1 Top Cover, 10”
2 Panel Adapter Plate
3 Angle Support
4 screw, 1110 x 3/S”
5 connecting Plate
6 screw, ii10 x l/2”
7 Angle
8 Top Cover, 13”

Qcy. Per

Assembly

1
1

1
4
1
4

1
1

Keithley
Pare NO.

200168

19158A
19157A

--­19154A

___
191478

200158

Model 4007 Rack Mounting Kit
Description:
The Model 4007 is a rack mounting kit with overall

dimensions, 7 inches high x 19 inches wide. Two top
covers are provided for use with either 10 inch or

13 inch deep instruments.

Application:

The Model 4007 con”erts the instrument from bench
mounting to rack mounting.

It is suitable for mount-

ing two instruments in a standard 19-inch rack.

1170

Parts List:
Item

NO.

Oe.SCriptiO” Assembly Part NO.

1 Top cwer, 10”

screw, n10 x l/2”

4
5 COnneceing Plats

6 screw, ii10 x l/Z”

7 Angle
8 Top Cover, 13”

9 Zee Bracket

10 Plate

Qty. Per

2 200168
s
1 19154A

4 --­2 141478

2 200158
1 19167A

1 19700‘4

Keithley

_--

19

SERVICING

MODEL 640 ELECTROMETER

SECTION 5.

GENERAL. This section contains procedures for

5-l.
checkout and servicing the instrument.

step-by-step procedures for complete servicing.

SERVICING SCHEDULE. This instrument requires

5-2.

no periodic msintenance

beyond the normal care re-

quired for high-quality electronic equipment.

PARTS KEPLACmT. Refer to the Replaceable

5-3.
parts diet, Section 7, for information regarding corn-

ponent specifications end part numbers.

ponents as indicated using replacement parts which

meet the listed specifications.

Code
etter Instrument Type

Follow the

Replace com-

TABLE 5-l.

Test Equipment.

Specificetion

SEWICiNG

5-4. TROWLESHOOTING.

Test Equipment.

a..

mended test equipment for servicing end calibrating
this instrument.

b. Troubleshootina Guide. Refer to Table 5-2 for

e brief outline of troubleshooting hints. The Table

identifies the Symptoms or Trouble, the Probable

Cause, and the suggested Solution.

If the instrument problem cannot be readily
located or repaired, contact a Keithley rep­resentative or the Sales Service Department,
Cleveland, Ohio.

Manufacturer
and Model No.

Refer to Table 5-l for recom-

NOTE

“Se

A

High Voltage Supply

B Nanovolt Source
c
D

E
F

Picoampere Source 10-4 to lo-14A

Megohnrmeter

Differential Voltmeter 1OOmV - 5OOV, .Ol%
Digital Voltmeter

G Function Generator

H

I

J

Oscilloscope

Probes; 1O:l & 1:l

Capacitance Bridge

K “eriable Transformer

& Power Line Meter

L Recorder

o-lOOOV, .01-V steps,

10-10 to 1v

, .25 to .75% accuracy.

.05% accuracy.

, .25 to .l% accuracy.

lo7 to lo13 ohms 220% accuracy.

1wv to lOOOV, 0.1%

1mA sensitivity: .05 8 Rise Time
lo-90%

Keithley, Model 241
Keithley, Model 260
Keithley, Model 261
Keiehley, Model 500

Accuracy checks.
Accuracy checks.
Accuracy checks.

ISOlatio” Resist

ante Check.
Keithley, Model 662
Keithley, Model 163
Wavecek, Type 110

Accuracy checks.

Trouble-shooting

Frequency Respon

Check.
Tektronix 503/5blA

Trouble-shooting

Calibration.
Tektronix

Use with Oscillo

scope.
Generel Radio 1blbA
Variac/RCA

Capacitor checks
Power Supply

Calibration.

Keiehley, Model 370 Drift end Noise

Checks.

20

1170

MODEL 640 ELECTROMETER

symptom or Trouble

Probable Cause

TABLE 5-2.

Troubleshaming Guide

SOlUti.3”

SERVICING

Sub-

Assembly Figure

kcessive Voltage Drift

ixcessive Noise at
~UTPIJT or Meter

!xcessive current ­>ffset or drift

eter Pegs Off-Scale

(all ranges)

DC Amplifier
Vibrating Capacitor
Input PET (QlOl)

Vibrating Capacitor
Defective Insulaeio”
Excessive Humidity

Vibrating capacitor

Power Supplies
AC Amplifier
Oacillatar Circuit

Power Supplies

Replace V.C. (C121).

Check diodes 0405-6 and potentio­meter R431.

Replace V.C. (C121).
Replace PET (QlOl).
Replace V.C. (C121).
Check sapphire insulation.
Allow instrument to warm-up. Re-

activate the dessicanc in the
INPUT HEAD.

Calibrate drive circuit as in

para. 6-3.
Check voltages in the INPUT HEAD.
Check for proper gain.
Check drive voltages. Calibrate

as in para. 6-3.

Check voltages on the Main Chassis.

INPUT HEhO

PC-149

PC-150
INPUT

HEAD

PC-151
INPUT HEAD
INPUT HEAD
INPUT HEAD

INPUT HEAD
PC-151
PC-247

23

‘5

24

24
27

(one range only)

1170

DC AmpLifier
Vibrating c*pacieor
RANGE Resistor

Check meter circuit.

Replace V.C. (C121).

Check RANGE switch. Replace RANGE

resistors.

PC-150
INPUT HEAD
S403

25

21

SERVICING

MODEL 640 ELECTROMETER

FIGURE 18.

Test Points, PC-148.

22

FIGURE 19.

Test Points,

PC-149.

MODEL 640 ELECTROMETER

SERVICING

FIGURE 20.

Chassis, Top view.

23

SERVICING

MODEL 640 ELECTROMETER

24

FIGURE 21.

Chassis, mp view.

1170

MODEL 640 ELECTROMETER

SERVICING

1170

FIGURE 23.

component layout, PC-149.

25

SERVICING

MODEL 640

ELECTROMETER

FIGURE 24.

component Layour, PC-151

FIGURE

component Layout,

25.

PC-150,

1170

MODEL 640 ELETROMRTER

SERVICING

1170

FIGURE 26.

Component Layout, ~~-153.

SERVICING

MODEL 640 ELECTROElETER

FIGURE 27.

Component Layout, PC-247.

1170

MODEL 640 ELECTROMETER

SERVICING

CHECKOUT PROCEDURE.

j-5.

Refer to Table 5-3 for

seep-by-step procedures for instrument checkout.

Use care when troubleshooting an instru-

NOTE

"tent connected to line power and/or with
Power switch an.

Before a step-by-step checkout is started,

inspect the circuits visually to detect
problems such as broken wire, loose parts,
dirty or oily switch contacts, etc.

checks are made, remove all power to

Fnstrument and discharge power supply

capacitors through a law value resistor

(loon).

TABLE 5-3.

Checkout Procedure.

LTS.
.5

Connect the shorting link between GND and LO on

a.

Description

Sub-

Aseembly

Main Chassis

rear panel of Model 640.
Place Dust Cover (20911A) over Input receptacle INPUT HEAD

b.

(To prevent contamination and stray noise pickup)
Check retaining screws on all PC boards in the

c.

INPUT

HEAD

INPUT HEAD. (The LO to case connection is made
through these screws).

d. Check the unregulated voltage an PC-148. Volt- PC-148 18

age should be nominal-11 volts dc with 3 volts
p-p ripple.

"se Oscilloscope (H).

WARNING

whenever resistsme

Tese

FQ"lX POi"?

4

Rear

Panel

-1lV "Iwe*.

CirC"it

Descriptic

Para. 3-4e

Check the regulated voltage on PC-148. Voltage

e.

PC-148 18 -5”

should be nominal -5 volts.

f. Check inverter voltage on X-148. Voltage should PC-148 18 I""erter

be 5V p-p square wave at 1100 Hz.
Check the +4OV unregulated voltages an PC-149.

8.
Check the unregulated voltage at collector of

h.

Q303.

Voltage should be nominal 15 volts dc.

i. Check regulated c12V cm PC-149.

Check regulated -12V on K-149.

j.

PC-149 19
PC-149

PC-149

PC-149

19

19

19 -12v

i4OV pera. 3-4c

+15v ""reg. eara. 3-k

c12v Fara. 3-4e

k. If all power supply voltages are nominal proceed -

to oscillator check.

1.

Check Vibrating Capacitor drive signal an PC-

247.

In.

Check demodulator drive signal on PC-247.

n. Check the dc amplifier circuit on PC-150.

Check meter circuit on PC-149, PC-150.

P.

PC-247

PC-247
PC-150
PC-149,

PC-150

27

27
25
23 eara. 3-4b

25

Pare. 3-4e

ears. 3-k

Pars. 3-48

ears. 3-3e

ears. 3-s
eara. 3-48

1170

29

CALIBRATION

MODEL 640 ELECTROMETER

SECTlON 6. CALIBRATION

6-1.

GENERAL.

This section contains procedures for

checking the instrument in order to verify operation

wfrhin specifications.

6-2. TEST EQUIPMENT.

Refer to +able 5-l for recom-

mended teec equipment for servicing and calibrating

this instrument.

CALIBRATION PROCEDURE.

6-3.

Refer to Table 6-1 for

step-by-step procedures for calibrating this instru-

ment.

Calibration Procedures.

eara.

6-3

a.

Specification

or AdjustInent

LO to GND Isolation

Description Measurement

Set Power to “OFF”. Remove shorting LO to GND should Main

link between GND -and Lo an rear be SreaCer than Chassis
pane 1. Measure LO to GND resistance log&
using Megohmeter (D).

Mechanical Zero see meter zero.

b.

Adjust

TABLE 6-1.

NOTE

If proper facilities and equipment are not
available, contact a Keirhley representative
or the Sales Service Department, Cleveland,

Ohio.

Keithley Instruments, Inc. maintains

a compleee repair and calibration facility

with equipment traceable to

the National

Bureau of Standards.

Sub- Test

Assembly Figure PoFnt

4

LO to GND

Hair!

2

Meter

Chassis

Line Voltage Setting Connect Variac and set line voltage

C.

for 115v.

d. -5v Reg. VoltaRe

e.

_ _

Ripple Voltage hleaaure ripple on -5v supply using

Set Power to “AC” Measure -5V Supply Adjust wtentio­on PC-148 using Diff. Voltmeter ii,;

Oscilloscope (Ii).

Voltage Checks Check remaining voltages.

f.

SUPPlY.

(Ripple should not exceed

5mv p-p).
+12v Supply. (Ripple should not

exceed 15mV p-p).

-40V Supply, (Ripple should not

exceed 50mV p-p).

+4ov Supply.

(Ripple should not

exceed 5OmV p-p).

!3.

Zero circuit

Check zener voltage an PC-149

using Diff. Voltmeter (E).

Check zener voltage on PC-149 using

Diff. Voltmeter (E).

-12v

115v nominal.

PC-148

meter RI338

-5v +5mv.

for

Ripple to be less PC-148

than

5OOmV

p-p.

Adjust potentio-

meter R327 far

-12v +5mv.
.-

t12v +5oom" PC-149

-40v +2v

+4ov +2v PC-148

D405

voltage

PC-148

PC-149

should be +9V 25%

Noise less

than 0.3mV.

0406

voltage PC-149

should

be -9,

+5%.

Noise less

5han 0.3mV.

22

18,
22

L9,
23

18,
22

18,
22

23

23

30

0472R

TABLE 6-1. (cont’d)

Calibration Procedures.

CALIBRATION

Pam.
6-3

h.

Speciftcaeio”
or Adjustment

Battery Charging

circuit

Description

Set Parer to ‘OFP”. With line cord
connected measure the charging

voltage *t K329.

i.

Battery Check Set PWER Switch to “BAT’f TEST”.

Oscillator check

1.

Check waveform on PC-247 using

Oscilloscope (H).
NOTE : Use P 1O:l Probe for the
Oscilloscope in*ut. “se 1:l

Probe

for & T&GER and c~naect

to R521 (wiper).

k. Oscillaeor Recovery

Set Payer to ‘WF” for 10 seconds.
When Power is eet to “‘AC” the

Oecfllator signal should recover.

1.

Oscfllator

Mjustsnt

Adjust variable capacitor C502 to

“start” oecilletor if neceaasry.

Set the Gain Adjust potentimeter

X506 to obtain B stable waveform.

m.

symmtry Adjustint

Set the Sym. Adjust potentiometer

S521 for equal demodulator “ON”

and “ORF” times.

Voltage should be

-22V with less

than 2N p-p

ripple.

Meter should in-

dicate greater
than 6V.

see *igum 28
for desired

Wavefom.

se* Figure 29.

Sub-

Assembly

Main

Chassis

Main

Chessis

PC-247

PC-247

PC-247

FigUCe

27,

28

27

27

8

20

Test

Point

R329

Meter

Oscillator
Waveform

5104
n521

lls21

n.

Phase Adjustment Set Fuse Adjust potenticmeter

ll517 for proper phasins 88 shmm

in Pi& 30. Not*: The amplifier
must be driven into eaturetia, to

obtain e phase petter,,.

lhdty Gain Check

P.

Set FLNCl’IOII to VOLTAGE

FANG?3 to LVOLT
titer

to

Hwga

"+"

to AC

sm RKSISTOR to 106

Connect the Nenovolt Source (II) to

the Model 640 Input using UHF

adapter. Connect the Differenciel
Voltmeter to read the difference

potential between the Input hi@ end

PEKDBACK

terminala of the “ode1 640.

With the Nanwolt Source set to O-O-

0, adjust the Model 640 zero controls

for null on the Diff. Voltmeter
(+lwJ).

and check the Diff.

Apply +L.OOOV to Model 640

The Diff. Voltmeter should indicate

vithin +lOO microvolts.

Voltmeter null.

see Figure 30

for phasir.&

PC-247

INPUT

HKAB

27.

29

R517

- FBEDSACR
TeminaL

on INPUT
HEAD

04728

31

CALIBRATION

MODEL 640 ELECTROMETER

TABLE 6-1. (cont’d)

Calibration Procedures.

Meter Cal. for

q.

r.

Full Scale

Meter Cal. far

center Scale

Voltage Range

8.
Accuracy Check

e.

Meter Noise

“*

OUTPUT Noise

Set front panel controls as in 6-3~.

Apply +1 volt using Nanovolt Source Input +1.ooov

(8).

Observe the Model 640 OUTPUT using OUTPUT should
Diff. Voltmeter. be Cl.OOOV +

1omv.

Adjust Meter Cal potentiometer R455

far full scale deflection.

Without readjusting the Zero controls

set the

Meter

for Center Scale. Ad-

just the Center Zero potentiometer

R421 far zero while in ZERO CHECK

mode.

Set front panel controls as in 6-3

p. Check all voltage ranges far
full scale accuracy. “se the Neno-

volt source as input reference.

Accuracy to be +l%

of full scale on
3ov-30o~v ranges.
15% on the 3O,,V

range.

Set front panel controls as in 6-3

Place Dust Cap over the Input.

P.

Observe Meter Noise an the 30 ,,”
Range.

Observe OUTPUT Noise using Oscillo-

scope (H).

Meter Noise to be -

less than 2 pV p-p,

OUTPUT noise to be -

less than 1OOmV
p-p, however occa­sianal spikes may
exceed 1OOmV.

PC-147

PC-147

-

20

20

R455

R42 1

V.

current Range

w.

current Range

32

Accuracy

(1060 Shunt)

Accuracy

(10&l Shunt)

Set RANGE to 1OV

FUNCTION to CURRENT FAST
METER to “+”
POWER to “AC”
SHUNT RESISTOR eo

106

Check the OUTPUT accuracy with the

Picoampere Source (C) used as In­put current reference.

e CURRENT

1ov TT

1v lo-6A

1oonlv 10-7A

1 Om”

lo-BA

1mv lo-PA

Verify OUTPDT accuracy as in 6-a

v.wieh SHUNT RESISTOR set to 10

and RANGE to 1V.

Accuracy

should be -

i3% Of full scale.

Accuracy should be -

+3% of lo-SA full

&ale.

0472R

MODEL 640 ELECTROMETER

CALIBRATION

TABLE 6-l. (cont’d)

Calibration Procedures.

Para. Specification

6-3

X.

or Adjustment Description MeamremenC

Current Range

Accuracy

( lOloo Shunt)

Current Range

Y.

Accuracy

( 1012fl Shunt)

Current Rise Time

Z.

as. Frequency Response

Verify 0LrrP”T accuracy with SHUNT
RESISTOR set to 10~~ and RANGE te

1v.

Repeat above using 1hnV RANGE.
(lo-12A).

Verify OoTPUT accuracy with SHUNT
RESISTOR see to 1012 and RANGE to

1v.

See RANGE to 1V

FUNCTION to CURRENT INTEGRATE
METER to OFF
POWER to AC
SHUNT RESISTORS to 1012

Set Damping to MAX: Apply +10-12A

input current using PFcoampere
source. Observe lo-90% rise time
“sing oscilloscope.

Set RANGE t” 1OmV

FUNCTION to VOLTAGE

METER to OFF

POWER to

AC

SHUNT RESISTOR to 106

Accuracy should be
23% of full scale.

Accuracy should be
24% of full scale.

Accuracy should be
24% of full scale.

lo-PO% Rise

Time

to be less then
44 sec.

Sub-

Assembly Figure

-

-

-

Test

Point

bb. Drift Check

Apply 10 Hz sinewave to Input “sing

Function Generator (C). Adjust

signal for 1.6V p-p as observed at

OUTPUT using Oscilloscape (Ii).

Set Function Generator (G) far
1HZ.

Increase the frequency of Function
Generator until OKfP1pp 1s reduced

D l.lV p-p. (3 dB down).

NOTE :

The Model 640 power must be

off far at least 2 hours prior to

this check.

Connect Recorder (L)

co the Model 640 OUTPUT. With o”et
Cover in place allaw a 60 minute
warm-up.
Set RANGE to 100 MICROVOLTS

FUNCTION to VOLTAGE

SHUNT

to 106

NOTE :

Maintain a constant ambient

temperature if passible. Otherwise
monibx temperature change to COW
pensate for 35 PVV/~C drift.

After weno-up period the drift

should not exceed 35 UV per 24
hours.

OUTPUT should re­main at 1.6V p-p.

Frequency et 3 dB

down should be 35
Hz or higher.

Drift less then
35 @V per 24
hours.

-

-

0172R

33

CALIBRATION

MODEL 640 ELECTROMETER

lYP!CAL WAVEFORM

FIGURE 28. Typical Oscillator Waveform.

34

FIGURE 29.

FIGURE 30.

Proper Symmetry Adjustment

CORRECT

PHASE

INCORRECT

Proper Phase Adjustment.

1170

MODEL 640 ELECTROMETER

RBPLACEABLE PARTS

SECTION 7.

7-1. REPULCEABLE PARTS LIST: This section contains
a list of components used in this instrument for
user reference. The Replaceable Parte List describes
the individual pares giving Circuit Designation,
Description, Suggested Manufacturer (Cade Number),

Abbreviations end Symbols

A ampere

CbVar
CerD Ceramic Disc
Cer Trimmer

ComP

DCb
Desig.

PAL
ETB
ETT

Carbon Variable
Ceramic Trimmer

Composition
Deposited Carbon

Designation
Electrolytic, Aluminum

Electrolytic, tubular
Electrolytic, tantalum

F
Fig

GCb
k

11

M
Mfr.
MtF

MY

REPLACEABLE

Manufacturer’s Pert Number, and the Keithley Part

Number.
where applicable. The complete “eme end address of
each Manufacturer is listed in the CODE-TO-NAME
Listing following the parts list.

TABLE 7-1.

farad

Figure
Glass enclosed Carbon
kilo (10 3)
micro (10-6)

Meg (106)
Manufacturer
Metal Film

Mylar

Number

PARTS

Also included is a Figure Reference Number

n

P

PC

Poly
Ref
TC”
V

w
ww
WW”WL

ohm
pica (10-12)

Printed Circuit
Polystyrene

Reference
Tinner Copperweld
volt
watt

Wirewaund
WirewOund Variable

ELECTRICAL SCHEMATICS AND DIAGRAMS. Schematics

7-2.
and diagrams are included to describe the electrical or your nearest Keithley representative.
circuits ee discussed in Section 3. Table 7-2

identifies all schematic pert numbers included. h. When ordering parts, include the following

HO” TO oSE THF. REPLACeABLE PARTS LIST. This

7-3.

Perts List is arranged such that the individual types
of components ere listed in alphabetical order. Main
Chassis perte are listed followed by printed circuit
boards and other subassemblies.

7-4. HOW TO ORDER PARTS.

a. Replaceable pews .may be ordered through the

TABLE 7-2.

Description

Remote Head

Pwer Supply
Switching (Main Chassis)

Circuit Designation
PC-151, W-153, PC-247, PC-249
W-147, PC-148, PC149

PC-150

Sales Service

information.

1. Instrument Model Number.

2. Instrument Serial Number.

3. pert Description.

4. Schematic Circuit Designation.

5. Keithlay Pert Number.

C. All perte listed are maintained in Keithley
Spare Parts Stock. Any pert net listed ce” be made
available upon request. Parts identified by the
Keithley Manufacturing Code Number 80164 should be

ordered directly fram Keithley Instruments, Inc.

Department,

Keithley instruments, Inc.

Schematic Part No.

213818
213823
21383E

1070

3s

REPLACEABLE PARTS

MODEL 640 ELECTROMETER

circuit Designation series.

TABLE 7-3.

series

LOO
200

300
400
500

Remote Head, Amplifier

Main Chassis

Description

Pawee supply

Remote Head, Oscillator

circuit oesig.

K-151, PC-153, PC-249

Page NO.

44
PC-153
K-147, K-148, PC-149 41
PC-150 38
PC-247 47

t

TABLE 7-4.

Mechanical Parts List.

F

O~SC~iptiL7ll Per Assembly Part No.

Q”aIltity Keithley

Fig.

NO.

1) Chassis 1 20727C 32

11) Front Panel 1 20725B 31, 32
Top Cover Assembly

12) Cover, Sheet Metal 1
L3) screws 4
Handle Assembly

14) Handle 1

15) Screws #b-32x3/8” R.H. Slotted 2

--_

___

20906C

31

20905C
___

--- 31

HH-18

-__

Bottom Cover Assembly --- 19298C 32

2) ccwer 1 193408

3) Fastener 2 FA-54

Feet Assembly --- --- 32

4) Feet

5) Ball

6)

Screws #8-32x3/8” Phillips. Pan Head 4

Tile Bail Assembly

4 FE-5

4

FE-6

--_

--_ --_

32

7) Bail 1 171478

36

8) Right Assembly 1 192068

9) Left Assembly 1 192058

10) Screws #6-32x1/4” Phillips, Pan Head

2

---

04728

MODEL 640 ELECTROMETER

REPLACEABLE PARTS

FIGOF@. 31. Top Cowr Assembly.

1170

FIGURE 32.

Bottom Cover Assembly.

37

REPLACEABLE PARTS

MODEL 640 ELECTROMETER

Circuit
oesig.

c401
C402
c403
C404
c405

*NOmilld

Circuit
Desig.

D401
D402

0403
D404
D405

0406

D407

(Refer to Schematic 21383E for circuit designations).

MAIN CHASSIS PARTS LIST

Value Rati"g Type

.a2 p.~ 20 v ETT

4.7 LlF 20 v WI

4.7 WF 20 v ETT
.1 irF 200 v MY
.05 p.F 600 V MY

CAPACITORS

Mfr.
Code

05397 KOR27JZOK CBO-.82M
05397 K4R7JZOK CBO-4.7M
05397 K4R7J20K C80-4.7M
02777 PlZM-C C47-.lM
56289 6PS-S50 C62-.05M

DIODES

Mfr.

Code Part NO. Part No.
12954 IN709 DZ-21 25

01295 lNb45 RF-14 25
01295 113645 RF-14 25
12954 lN715 DZ-22 20
04713 18936 02-5 23
04713 lN936 02-s 23
12954 lN706 DZ-1

Mfr.

Parr NO. Part No.

Mfr.

Keithley

Keithley

Fig.

Ref.

25
25
25

20

Fig.
Ref.

25

3401

5402

5403
5404

-__

J405
P402
5406

-__

S401

___

S402

--_

s403

--_

---

s404

-__

S405

--_

_-_

MISCELLANEOUS FARTS

Conne~eor, 9 pin card-edge

Binding Post

Binding Post, FEEDBACK

Receptacle, Micrcqhone, OUTPUT

Plug, Microphone, mate of 5404
connector, Receptacle
con*ector, mate of 3405

Binding Past, GND
Shorting Link

Push Button Switch, ZERO CHECK
Knob Assembly, Zero Check
Rotary Switch less com~onenta, FUNCTION

Dial Assembly, Function Switch

Rotary Switch less components, RANGE
Rotary Switch with components, Range
Dial Assembly, Range Switch

Rotary Switch leas components, METER
Dial Assembly, Meter Switch

Rotary Switch less components, COARSE

ZERO

Rotary Switch with components, Coarse

Zero

Knob Assembly, Coarse Zero Switch
FINE ZERO Control (R431)

Knob Assembly, Fine Zero

Mfr.
Code Part No.

03612 PSCLSS9
05474 DFZlB~
58474 DFZlBLU
02660 80PCZF
02660 80PCZM
02660 5740240

02660 --­58474 DFZlG

24655 938L
80164 _--

80164 ---

80164 ---

80164 --­80164 ---

80164 _--

80164 ---

80164 --­80164 _-_

80164 _-­80164 --­80164 _-­80164 62JA-IK-2W

80164 _--

Mfr.

Keirhley

Part No. Ref.

cs-175-9

BP-118

BP-11BLU
CS-32
cs-33
CS-196
cs-195

BP-11G

BP-6
SW-223

16373A

SW-227

14838A

SW-228

213368

21200A

SW-225

14838A

SW-224

213618

163738

RP42-1K

16994A

Fig.

20
20
20

4
4

20

4
2
2
2

2
2

2
2

2
2

4
4
4
2

2

38

0472R

MODEL 640

ELECTROMETER

REPlACEABLE PARTS

MAIN CHASSIS (cont’d)

MISCELLANEOUS (cont’d)

circuit
Desip;.

5406

s407

_-_

--_

-__

---

M401

circuit

Desig.

R401 500

R402
R403

R404 2
R405 50

R406
R407 12
R408 560
R409 12

R410

Description

Code Pa-t NO.
Slide Switch, LV-LMA 80164
Rotary Switch less components, MEDIUM 80164

ZERO

Rotary Switch with components, Medium 80164

Zero

Dial Assembly, Medium Zero Switch 80164

Mfr. Mfr. Keithley

1 MA CAL Control (R423)

71450 A”-2OK-5” RP34-20K

Knob Assembly, 1 Ma Cal Control 80164

Meter 80164

RESISTORS

Mfr. Mfr.

Value

kfl

68

k0

68

kn

k0
kn

10 kn

k0
kn
k0

27

kO

Rating
lo%, l/2 W

l%, l/2 w

l%, l/2 w

l/4 w

1%. l/2 w
l%, l/2 w

LO%, l/2 w
lO%, l/2 W
lO%, l/2 W
LO%, l/2 W

Type
DCb

DCb

DCb
Cb
DCb

DCb

COIW

corn;

Comp

Code

00327
00327
00327
09569
00327

00327

01121 EB
01121 EB
01121 EB
01121 EB

Part No.

---

-__

--_

---

___

--_

SW-45

SW-209

213358

16993A

16373A

ME-71 20

Keithley

Part NO. Part No.

NllA

812-5OOK
NllA RlZ-68K
NllA

RLZ-b8K
MTC23Ll RP59-2K
NllA RlZ-50K

NllA

RLZ-10K

Rl-12K

Rl-560
Xl-12K
Rl-27K

Fig.
Ref.

4
4
4
4
4

4

FLS.
Ref.

25
25

25
25
25

25
25
25
25
25

R411 100 kfi
R412 1 R413

R414 150
R415 120

R416
R417

R418 3

R419

R420

39

35
820

20
15

:::

n

kn
k0

Cl
kil
k$,

kfl

R42 1 10 ks,
R422 910 R

R423 20

R424

8.6

kfi

kn

R425 1.5 kll
R426 1.5 kn

R427 11 ki-,

R428

11 ki7

R429 80 kn

R430 80

R431

k0

1

kn

R432 1.11 kn

R433
R434

1.11 k0

1.11 kR

R435 1.11 ki,

lO%, l/2 W
lo%, l/2 W
lO%, l/2 W
lO%, l/2 w
LO%, l/2 w

l%, l/2 w
LO%, l/2 W
l%, l/2 w
l%, 1/2 W

l%, l/2 w

20%, 2

0.5%. l/2"

w

10%. 5 w
l%, l/2 w
l%, l/2 w

1%. l/2 w
1%. l/2 w
l%, l/2 W

l%, l/2 w

l%, l/2 w

5%,2

w
l/4%, l/3”
l/4%, 1/3w

l/4%, l/3”
l/4%, 1/3W

camp 01121 EB

Rl-100K

camp 01121 EB Rl-LM

C0Ulp 01121 EB Rl-39K
camp 01121 EB Rl-150
ccmp 01121

DCb

00327

EB RL-12OK
NllA

RlZ-35K
camp 01121 EB Rl-820
DCb
DCb

DCb

ww
MFF
wwvar

DCb

ww
ww

ww
ww
ww
ww

wwvar
WWenc
WWenc

00327
00327
00327

71450

07716

71450
00327
01686 E-30 R58-1.5K

01686

01686
01686
01686
01686

12697
01686
01686

WWenc 01686
WWenc 01686

NllA
NllA
NllA

R12-3K 25
R12-20K 20

RlZ-15K

LNS 115 RPSO-1OK
CEC R61-910
A”
NllA

E-30
E-30
E-30
E-30 R58-80
E-30 R58-80

b2JA

7010

7010

7010

7010

RP34-20K

RLZ-8.6K

R58-1.5K
R58-llK 23

R5S-1lK

RP42-1K

R105-l.llK
R105-l.llK
R105-l.llK
R105-l.llK

25
25
25
25
25

25
25

20
20
20

20
23

23
23

20
20

20
20
20
20
20

0472R

39

REPIACFABLE PARTS

MODEL 640 ELECTROMETER

MAIN CHASSIS (conc'd)

RESISTORS (cont'd)

CiX”it

IkSiR.

R436

R437
R438
R439

R441

Value

1.11 kR

1.11 kc2

1.11 kfl

1.11 k0

1.11 kR

Rating
l/4%, l/3 w

l/4%, l/3 w
l/4%, l/3 w
l/4%, l/3 w

114%. l/3 w
R442 1.11 kR L/4%, l/3 w
I1443 320 0 O.l%, l/Z w
R444 320 fl O.l%, l/2 w
R445 320 a o.L%, L/2 w

R446
R447
R448
R449
R450

R451
R452
R453
R454
R455

R456
R457
R45S 9.1 kfi

320 Cl 0.1%. l/2 w wl
320 0
320 0
320 n
320 R

320 I?
320 n
320 n

9.7 kfl
2

k0

500 n

27.3 k0

O.l%, l/2 w ww

0.1%. l/2 w WI
O.l%, l/2 " ww
O.l%, l/2 w ww

0.1%. l/2 w w
O.l%, l/2 w ww
O.l%, l/2 w ww

l%, L/2 w

20%, 2 w ww
l%, l/2 w

0.5%, l/2 w

0.5%, l/2 w

Type Code

Mfr.

Mfr.

Part NO.

Keithley
Part No.

Fig.
Ref.

wwenc 01686 7010 RlOS-l.llK 20
wwenc 01686 7010 R105-l.llK 20
WWC2"C 01686 7010 R105-l.llK 20
wwenc 01686 7010 R105-l.llK 20

wwenc 01686 7010 R105-l.llK 20

wwenc 01686 7010

ww 15905 1142
ww 15909 1142

ww 15909 1142

15909 1142

DCb

DCb
MtF
MtF

15909
15909

15909
15909

15909
15909
15909

00327

71450

00327
07716
07716

1142
1142
1142
1142

1142
1142
1142 R67-320

NllA

1NS 115

NllA

CEC
CEC R61-9.1K

R105-l.llK

R67-320
R67-320
R67-320

R67-320
R67-320
R67-320
R67-320
R67-320

R67-320

R67-320

RlZ-9.7K

RP50-2K
R12-500

R61-27.3K

20

20

TRANSISTORS

Circuif
IJesig.

Q401 N-Channel FET, Case TO-92
Q402 N-Channel FET, Case TO-92
Q403 PNP, Case R-110

Mfr.

Code

01295

Mfr.

Part NO.
SF5043

Keithley
Part No.

TG-40

01295 SF5043 TG-40 }* 2

07263 S17638 x-33 25
Q404 PNP, Case R-110 07263 517638 x-33 25
Q405 N-Channel FET, Case TO-92

Q406 NPN

Q407 NPN

Q408 PNP
Q409 NPN

04713 MB' 103 TG-41 25

73445 A1380 TG-32 25

80164 -_- 21676A 25
02735 2N398A TG-13 25
80164 -_- 21676A 25

*Matched pair, order TG-40 for @r.

Fig.
Ref.

40

0472B

MODEL 640 ELECTROMETER

REPL4CEABLE PARTS

(Refer to Schematic No. 21382E for circuit designations).

POWER SUPPLY PARTS

c301
C302
c303
c304
c305

C306
c307
C3OS
C309
c310

.Ol p

50 WF
50 UF

Not Used

100 &lF

50 UF
100 p

Not Used

330 pF

2.2 fl

c311 .02 @
C312 .0022 (LF
c313 .Ol p 600 V
c314 100 @

200 v
50 v
50 v

MY

ETT
ETT

25 V
50 v

25 V

1ooov

50 v

1ooov
1ooov

ETT 37942
EAL 56289 89D226

ce L-D 71590 DD331-10% C22-330P 23

ETB

&k-II
CerD 72982 811000X5F0222 C22-.0022M
CerD

25 V EAL

c315 100 fl 25 V EAL

C316
c317
C318
c319
C320

Not Used
Not Used

.02 p.F
.Ol @
100 pF

1ooov
1ooov

25 V

Get-D

CerD 56289

EAL

Mfr.

Mfr.

Keirhley Fig.

Code Part NO. Parr NO. Ref.
13050

37942

SMlA
TC39

C47-.OlM
c39-5OM

22
22

37942 TC39 C39-50M 22

56289 890226

TC39

C94-100M

C39-SOM

CV4-100"

23
23

23

05397 J2R2J50S C149-2.2M 23
56289 loss-szcl

C22-.02" 23

23

56289 loss-SlO

C22-.OlM 23
56289 890226 c94-1OOM 23
56289 89D226 C94-1OOM 23

56289
56289

loss-s20
loss-SlO
89D226 C94-100M 23

C22-.02M 23
C22-.OlM 23

C321 500 p
C322

.0033 p

C323 500 p

25 V

1ooov

25 V

C324 *loo fl 40 v

EAL
EAL

EAL

24309
56289
56289

73445

JCS10025SP
loss-D33

JCS10025SP

C437ARlGlOO

C211-500M
C22-.0033M
CZll-500M
C150-1OOM

*Nominal

DIODES

CilTUit

rusi*.

D301

Mfr. Mfr. Keithley Fig.

Code Part No. Part NO. Ref.
01295 lN645 RF-14 22

0302 Silicon 01295 lN645 RF-14 22
0303 Silicon 01295 lN645 RF-14 22
0304

SilkOIl

01295 lN645 RF-14 22

0305 Not Used
0306 Not Used

D307 SiliCOll 01295 110645 RF-14 22
D308 Silicon 01295 lN645 RF-14 23
D309

SilkOIl

01295 lN645 RF-14 23

0310 SiliCOlI 01294 lN645 RF-14 23
0311 SFlk0n 01295 18645 w-14 23

0312 Silicon 01295 lN645 RF-14 23
D313 Silicon 01295 lN645 RF-14 23
D314 zener 04713 lN935 DZ-7 23
0315 Silicon 01295 lN645 RF-14 22

D316 Silicon
0317 Silicon

0318

SilkOIl

0319 zener
D320
D321

Silicon

Silicon
D322 zener
0323 SiLiCCSl

01295 lN645 RF-14 22
02735 lN3256 RF-22 22
02735 lN3256 RF-22 22
12954 lN709 DZ-21 22
01295 113645 w-14 22
01295 lN645 RF-14 22
12954 lN709 DZ-21 22
01295 lN645 RF-14 20

22
22
22

04728

41

KEPU.CEABLE PARTS MODEL 640 ELECTROMETER

POWER SUPPLY (cont’d)

MISCELLANEOUS PARTS

CirC”it

llesig. Description

ST301 Battery

Assembly

Mfr.

Code
SO164

Mfr. Keithley
Part No. Part NO. Ref.

_--

23731A
F301 (117V) F”SB, .25A, 3 AG 75915 313.250 FU-17
F301 (234V) Fuse, 1*5*, Slow blow

71400 MDL

PU-20

F302 Fuse, Battery, lA, 3 AC 75915 312001 F"-7

--- Fuse Holder 75915 34201 m-3

--_
P301 Cord Set SO164

s301 Rotary Switch less

-_-

---

Fuse Holder 759L5 346001

-_-

Rotary Switch with components, POWER 80164

components,

Dial Assembly, POWER Switch 80164

POWER 80164 --- SW-226

_-­_--

m-9

co-5

213378

lS393A

5302 Slide Switch, 117-234 ” 80164 -_- SW-151 4
5301 Connector, PC board 148 03612 PSC4SS2212 cs-m-9 20

5302 connect0 PC board 149 03612 PSC4SS2212 cs-182-Z 20

T301 Transformer SO164

---

TR-102
T302 Transformer 80164 __- TR-101 20
T303 Transformer 80164 --- TR-110 20

RESISTORS

Value

Rating Type

Mfr.
Code Parr No.

Mfr. Keithley

Part

No.

Fig.

20

4
2

Fig.
Ref.

R301
R302

R303

Is.304
R305

R306
R307
R308

R310
R311

R312

R313

R314
Ii315

R316

P.317
R318
R319
R320

R321
R322
R323
R324
R325

R326
R327

R32S

R329

47 n
470 n
10 kn

10 0

4.7 n

4.7 k0
NOC Used
47 kfl

Not Used

100 kn

27 kn
47 kn
47 k0

100 k0
82 kfl

100 kn
100 ka
10 kR

Not Used

4.7 kfi

Not Used

100 n

2.7 k.0
100 ki2
47 kn

22 k0
10 kfl
91 kn
56 iI

2.7 kfi

lO%, l/2 W
lO%, l/2 w
lO%, l/2 w

l%, l/2 w

lO%, l/2 w
lo%, l/2 w
IO%, l/2 w
1%. 112 w
lO%, l/2 W

lO%, l/2 W
lO%, l/2 w

lO%, l/2 w

lO%, l/2 w
I%, l/2 w

l%, l/2 w
l%, l/Z w

lO%, l/2 w

lO%, L/2 w
l%, l/2 w
lO%, l/2 w
lo%, l/2 W

l%, l/2 w
20%, 2 w
l%, l/2 w

10 w

lO%, l/2 W

COTUp
C0lllp
Comp
DCb
C0lllp

ClXlp
camp
DCb

COKtp
DCb

DCb
DCb

camp

DCb

DCb

wwvar

DCb

01121
01121 EB
01121 EB
00327 NllA
01121 ES

01121 EB
01121 EB
00327 NllA
01121 ES

01121 EB
01121 EB
01121 EB

01121 EB

00327 N11A

00327 NllA
00327 NllA

01121 EB

01121 EB

EB

a-47
Rl-470
Rl-1OK
R12-10

u-4.7
u-4.x
Rl-47K

R12-100K

Rl-27K

Rl-47K

Rl-47K

Rl-100K

Rl-SZK

R12-100K

RlZ-100K

R12-10

RI.-4.x

RI-100

00327 NllA R12-2.7K
01121 EB Rl-100K
01121 EB Rl-47K

00327 NllA RlZ-22K

71450 1NS 115 RPSO-1OK

00327 NllA

R12~-91K
91637 HLM-10 R13S-56
01121 EB Rl-2.7K

22
22
23
23
23

23
23
23
23

23
23
23
23

23
23
23

23

23
23
23
23

23
23
23
23
23

42

n472u

MODEL 640 ELECTROMETER

REPI&XASLE PARTS

POWER SUPPLY (cont'd)

RESISTORS (cant'd)

R331

R332

R333
R334
R335

R336
R337
R338
R339
R340

R341
R342
R343
R344
R345

Desiz.

Q301
Q302
Q303
Q304

Q305

Value Rating
600 0 I%, l/2 w

1.8 kS?
1

kR l%, l/2 w

2.7 k0

1.8 kfi

2.73 kR

390 n

1

kfl

1.4 k$l

2.2 kfi

3.3 kfl
20 kfl
20 k0.
33 n

4.7 R

l%, l/2 w
lo%, l/2 w

lO%, l/2 w
I%, l/2 w

lo'/,, l/2 w
20,2 w
l%, l/2 w
lO%, l/2 w

lO%, l/2 w
l%, l/2 w

I%, l/2 w
lO%, 1 w
10%. l/2 w

PNP

PNP
NPN, Case TO-5
NPN, Case TO-106
NPN, Case TO-106

Type

Code

DCb 00327
"Cb 00327
DCb 00327
camp 01121
COtlIP 01121

DCb 00327
camp 01121
WW"ar 71450
DCb 00327
camp 01121

COUIP 01121

Mfr.

DCb
DCb
CLXlp

00327
00327
01121

COIlID 01121

TRANSISTORS

Mfr.
Code

02735
02735
02734
07263
07263

Mfr.

Part NO.
NllA

NllA
NllA
EB
EB

NllA
EB

INS 115

NllA

ES
NllA
NllA
GB
EB

Mfr.

Pa'rt No.
2NllS3A

2NllS3A
40317
2N3565
2N3565

Keithley
Part No.

RlZ-600
R12-l.SK
RlZ-1K
Rl-2.7K
Rl-l.SK

RL2-2.73K
Kl-390
RPSO-1K
Rl-1.4K
Kl-2.2K

Kl-3.3K
R12-30K

Rl2-20K

m-33
Rl-4.7

Keithley

Pare No.

TG-31
TG-31
TC-43
TG-39

TC-39

Pig.
Ref.

22

22

22
22
22

22
22
22
22
22

22
22
22
20
23

Fig.

Ref.

22
22
23
23
23

Q306

Q307
Q308
Q309
Q310

Q311
Q312
Q313

Q314
Q315

Q316

Q317
4318

Q319

Q320
Q321

Q322

NPN, Case TO-106
NPN, Case TO-106
NPN, Case TO-106
NPN, Case TO-106
NPN, Case TO-106

NPN, Case TO-5
NPN, Case TO-106
NPN, Caee TO-106
NPN, Case TO-106
NPN, Case TO-106

PNP
PNP

PNP
PNP

PNP, Case R-110
PNP, Case

PNP, Case

R-110
R-110

07263
07263
07263
07263

07263

02734
07263

07263
07263
07263

01295 2N1381
04713

01295
01295

07263

07263
07263

2N3565
2N3565
2N3565
2N3565

2N3565

40317
2N3565

2N3565

2N3565

2N3565

2N1535

2N13Sl

2N13Sl
S17638 TG-33

517638
517638

TG-39
TG-39
TG-39

TG-39

TG-39
w-43

TG-39
TG-39
TG-39
TG-39

X-8

lx-7

TG-8
TG-8

TG-33
TG-33

23
23
23

23

23

23
23
23
23
23

22

20

22
22
22

22
22

0472R 43

REPIACEABLE PARTS

MODEL 640 ELECTROMETER

REMOTE HEAD PARTS

(Refer to Schematic 21381E for circuit designations).

Amplifier, PC-151, PC-153, PC-249

CAPACITORS

Value Ratin*

*Cl01
*cl02 6.5 pF
*cl03

Cl04
Cl05 20 pF

150 pF 500 v

--_

___
___

10 pF 20 v

___

CL06 Not Used
Cl07
Cl08
Cl09 2.2 +F
Cl10

2.2 p 20 v
5

PF

1000"

20 v

Not Used

Cl11 .1 UF 50 "
Cl12
Cl13
Cl14 5
Cl15 Not Used

Cl16
Cl17
Cl18
Cl19 .02 pF
Cl20

10 b 20 v

2.2 pF 20 v
PF

1000"

2.2 UF 20 v

.1 'b 50 v

llF 20 v

10

1000"

.02 p

1000"

Cl21 "ibraeine Ca~acieor
Cl22 .OOl fl - : 1ooov
Cl23
Cl24
Cl25

.OOl @

1000"
15-60pF 500 v
100 pF 600 V

Mfr.

Mfr. Keithley

Code Part NO.

Paly 71590
_-_

_--

80164
80164

ETT 05397
_--

ETT

CerD

80164

05397

71590

ETT 05397 KZR2J20K

MY

ETT

84411 601PE
05397

CPR-15OJ

___

--_

KlOJ20K
215578

K2R2JZOK
DD-050-10%

KlOJZOK
ETT 05397 K2RZJZOK
CerD

ETT

MY

ETT
CerD
ce i-D

71590

05397

84411

05397
56289
56289

80164

72982
72982
72902
72982

PD-050-10%

KZR2JZOK

6OlPE

KlOJZOK
10ss-S20

loSs-s2o

-__

801000X5F0102K C22-.O(JlM
801000X5F0102K C22-.OOlM

538-Oil-P3PO-112R

ED-100

Parr NO.

Ref.

C138-15OP
C31-5PhC77-1.5P -

13410A

Fig.

c*o-1OM

26

215578

CEO-2.2M
C22-5P
CEO-2.2M

C41-.lM
CEO-1OM
CEO-2.2M
C22-5P

CEO-2.2M
C41-.lM

CEO-1OM

C22-.02M
c22-.02M

24
24
24

24
24
24
24

24

24
24
24

24

"C-2

C158-15/6OP
c22-1OOP

Cl26
Cl27 100 pF

10 P

Cl28 0.1 @
Cl29

.OOl fl
Cl30 Not Used
Cl31 1.5 pF

* Nominal Value.

l3esi.g.

0101
D102

TVW

Silicon
Sil.ican

D201 Silicon
0202
0203

Siltcon
SilFCOIl

600 V

1000"

50 v

1000"

600 "

71590

71590

84411
72982

TCZ C77-1OM

DD-lOl-10%

601 PE C41-.lM
801000X5F0102K C22-.ODlM

80164 C123-1.5P C123-1.5P

DIODES

Mfr.

Mfr. Keithley Fig.

cock Part NO.

01295 113645
01295 lN645

73445

lN3182

01295 lN914

01295 lN914

c22-1OOP

Part No.
RF-14

RF-14
RF-31

W-28
RF-28

Ref.

26
26

44

0472R

MDDEL 640 ELECTROMETER

REPLACEABLE PARTS

RWOTE HEAD (cont’d)

MISCELLANEOUS PARTS

CirCUit

Desig.

JlOl
P401

5102
PI02
5103

5104
J105

--_

---

5106
P106
5107
P107
5108
P108

J109

P109

SlOl

___

Description

Code

Connector, Receptacle (Mfg. No.57-40240) 02660

Mfr.

Connector, Plug, mate of JlOl (Mfg. No.

02660

57-30240)
connector, PlUP. PC-153
connector; Pi”;.mate of .I102
Test Jack, FEEDBACK
Test Jack Connector Pin

Input Connector Contact Assembly

80164
SO164
80164
80164

80164

Input Cup, Adapter Assembly consisting SO164

of an adapter cap, (20569A) a contact
cap (2056SA) and a UHF connector

(U-64)
DUBC cover

connector, Plug
connector Pill, mate of 5106
connector, Plug
Connector Pin, mate of 5107
connector, SlOl

80164
80164

80164

80164
80164
SO164

Connector Pin, mate of 5108 SO164
CantleCtOr, SlOl

Connector Pin, mate of J109

Push Button Switch, ZERO

CHECK

SO164
80164

80164

(input head)

Knob Assembly, Zero Check

80164

Mfr.

Part No.

5740240
5730240

---

-__

--­_-_

-__
_-_

---

-_-

-_­__­_-_
___

---

-__
___

___

Keithley

Part No.

CS-196
cs-195

cs-197
cs-198
TJ-1

cs-198
20613A

21146B

20911A

cs-197
cs-19s
cs-197
cs-198
cs-197
cs-198
cs-197
cs-19s

SW-223
16373A

Fig.
Ref.

s102

___

Rotary Switch lass components, SHUNT

RESISTOR

Rotary Switch with components, Shunt

Resistor

QAlOl Integrated Circuit
KlOl

Solenoid Assembly
KlO2 Reed Relay
LlOl Choke

Value

RlOl 1

MO

R102 108 n
R103

1010 n
R104 1012 ”

Ratill*

l%, l/2 w
1%

---

---

R105 10 M&-i 10%. l/4 w
RI06

R107 108 R
RlOS
R109 108 n
RllO

Fall
R112 47 kn
R113 12 kn
R114

RI15

1

Ml?

lO%, l/4 w

20%, l/2 w

7.5 Mll

40x, 0.3 w
20%, l/2 w

68.lki7

1.5 kn

l%, l/8 w
lo%, l/4 w

lO%, l/4 w
lO%, l/4 w

5.6 kn lO%, l/4 w
60 kn

IO%, l/4 w

MtF

ComP
GCb

GCb
camp

COBI;
Cb

MtF’

CODb
ComP

80164
80164

12040 IX201
SO164
27682 GPlA650MW RL-31
80164

RESISTORS

Mfr.

Code
07716

03888 HR 1000
63060 Rx-1
63060 Rx-1
44655

44655
75042

71450
75042
07716

44655
44655

01121

44655

01121

--_
___

___

--_

Mfr.

Part No.

CEC

RC07

GBT

SERIES 70

GBT

CEA

RC07
RCO 7
CB
RC07
CB

SW-237

211438

x-2
215538

lx-13

Keithley

Fig.

Part NO. Ref.

R113-1M
R144-10S

RZO-lOlo
R20-1012

R76-1OM

R76-1M
R37-lO*
RP71-7.5M
R37-10B

RBB-6S.lK
R76-1.5K

R76-47K
R76-12K
R76-5.6K

R76-68K

24
24
24
24
24

24
24
24
24
24

04728 45

REPtACFABLE PARTS

MODEL 640 ELECTROMETER

REMOTE HEAD (cont'd)

RESISTORS (cont'd)

R116
a117
R118
a119
R120

Rl21
R122
R123
8124

R125
R126

R127
R128
R129
RL30

RI31

R132
Rl33
RI34

R135

R136
R137
R138

R139
R140

Value Rating

12 kn

2.2 k0

8.2 k!,
100 kfi
100 ki?

12 k0
68 k0
68 kSl
68 kn
68 kil

10 MS-2
12 kfl

1 kn
68 kfl
47 kn

270 kG

150 kR

1.5 kR

8.2 kn
100 n

4.7 kn
18 ks,
18 kfi
390 n
10 kn

lO%, l/4 w

10%. l/4 w

lO%, l/4 w
lo%, l/4 w
lO%, l/4 w

10%. 114 w
LO%, l/4 w
IO%, l/4"
lO%, l/4 w
lO%, l/4 w

lO%, l/4 w
lO%, l/4 w
lO%, l/4 w
lo%, l/4 w
IO%, l/4 w

lO%, l/4 w
lO%, l/4 w
10%. l/4 w
lo%, II4 w
lO%, l/4 w

lO%, l/4 w
lO%, l/4 w
lO%, l/4 w
lO%, l/4 "
lO%, l/4 w

Type
camp

ccmp
camp
COUlp
camp

camp
camp
camp
camp
CW+

COTlIP
camp
camp
camp
camp

Code Part No.
01121

44655
44655
44655
44655

01121
01121
01121
01121
01121

44655
01121
01121
44655
44655

COUIP 44655

Mfr. Mfr.

camp

01121
COtlIp 44655
COtUP 44655
camp 44655

camp 44655
camp 44655
camp 44655
camp 44655
Comp 44655

Keithley
Part No.

CB

R76-12K
RC07 R76-2.2R
RC07 R76-8.2K
RC07
RC07

a76-100K

R76-100
CB R76-12K

CB

R76-68K
CB R76-68K

CB
CB

RC07

a76-6BK

R76-6BK

R76-10M
CB R76-12K

CB

R76-1K
RC07 R76-68K
RCO7 R76-47K

RC07

R76-270K
CB R76-150K
hC07 R76-1.5K
RC07 R76-8.2K
RC07

R76-100
RC07 R76-4.7K

RC07 R76-18K
RCO7 R76-1SK
RC07 R76-390
aco7

a76-10K

Fig.
Ref.

24
24

24

24

24
24

24
24
24
24

24
24
24
24
24

24
24
24
24
24

24
24
24
24
24

a141
Rl42

R143

RI44

R145

R146
R147

R148
R149
R150

10 kfl

4.7 kR
100 kO
100 k0

22 kR
180 kll

100 kR
150 kn

390 n

100 kQ

lO%, l/4 w
10%. l/4 w
lO%, l/4 w
10%. l/4 w
lO%, l/4 w

lO%, l/4 w
lO%, l/4 w
10%. l/4 w
10%. 114 w
lO%, l/4 w

COXllp

camp

camp

COiT8P

camp
camp

CCXlP

COtlIP

camp
camp

01121

44655
44655

44655

44655
01121

CB
RCO7 R76-4.7K
RC07 R76-100K
RC07 R76-100K

RC07

CB
44655 RC07
44655
44655

ac07

RC07 R76-390

44655 RC07

a76-1OK

a76-22K
R76-180K

R76-IOOK
a76-150K

R76-100K

TaANSISTOas

circuit
maig.

Mfr.

Code

Mfr. Keithley Fig.

Part No. Part No. Ref.

QlOl N-Channel FET 04713 2N4220 TG-42 21

Q102
Q103
Q104
Q105

Q106
Q107
QlO8
Q109
QllO
Qlll
Qll2 PNP. Case R-110 07263 517638 TG-33 21

NPN, Case TO-92
NPN, Case TO-92
NPN, Case To-92
NPN, Case TO-92

PNP, Case TO-92
N-Channel FET, Case TO-92

NPN, case TO-92
NPN, Case TO-92
PNP, csse TO-92
PNP, Case R-110

04713
04713 2N5089

04713 2N5089

04713

04713
04713
04713 2N5089 TG-62
04713

04713 2N5087

07263

2N5089

2N5089 TG-62

2N5087 TG-61

MPF103 TG-41

2N5089 TG-62
S17638 TG-33

TG-62
TG-62 21

TG-62

TG-61

24
24
24
24
24

24
24

24
24

24

21
21

21
21

21
21
21
21
21

46

04728

MODEL 640 ELECTROMETER

RF.PL4CBABl.B PARTS

REMOTE HEAD (cont'd)

08cilletor, PC-247

CAPACITORS

Cik-C"it
Desk+

C501
c502

*c503

c504
c505

Value

10 @
7-25 pF
100 pF
10 pF

5 PF

Rating

35 v
350 v
200 "
500 v
200 v

Type
ETT

T~iU@il~~

Poly
POly
Poly

Mfr.

Code

Mfr. Keithley
Part NO, Part NO.

05397 KlOE35 C170-10M 27

72982 538-011-938 cs9-7-2s 27
84171 ZPJ-10x C108-1OOP 27
71590 cm-1OJ C138-1OP 27
00686 E1013-1 c31-5P 27

C506 47 pF 500 v Poly 71590 CPR-47J C138-47P 27
c507 47 pF 1ooov CerD 71590 DD-470-10% CZZ-47P 27
C5OS l!B 35 v ETT 05397 KlE35 C170-1M 27

*c509 100 GF 200 v Paly 84171 2PJ-10x C108-1OOP 27

c510 .OOl fl

1ooov

CerD 72982

801000X5F0102K C22-.OOlM

c511 10 Is 35 v ETT 05397 KlOE35 c170-1OM 27
C512 .Ol irp

1ooov

ce l-D

56289 loss-SlO

CZZ-.OlM
c513 10 llF 35 v ETT 05397 KlOE35 C170-10M 27
c514 .0047@
c515

C516 10

.Ol p

$ 1ooov &i-D 71590 DD-100-10X c22-1OP 27

c517 .Ol

1ooov
1ooov

200 v MY 13050 SMlA C47-.OlM 27
C518 100 pF 1oooV CerD 71590 c22-1OOP 27
c519 ,047 lip 200 v MY 13050

&k-D
CerD

56289 loss-D47
56289

loss-SlO

z21-10x

C22-.0047M
C22-.OlM

c47-.047M 27

c520 10 @ 35 v ETT 05397 KlOE35 C170-10M 27

CitXUft

Desk?.

Type

Mfr.

Code

Mfr.
Part No.

Keithley

Part No.

Fig.
Ref.

27

27
27

27

Fig.
Ref.

D501
D502
0503
D504

Silicon

SiliCOlI

Silicon
SiliCLX

circuit
Desig.

QA501
QA502

QA503

CirCUit

Desig.

R501
R502
a503
R504
R505

Type

Integrated Circuit
Integrated Circuit
Integrated Circuit

Value ltatingq

10 n 10%. l/4 w
1

l-l*

l%, l/2 w MtF 07716

32.4 KR l%, 1/a w MtF

32.4 KC

9.31 KR

l%, l/8 w MtF 07716
l%, l/S w MtF 07716

*Nominal Value, Selected during calibration.

01295

01295
01295

01295

INTEGRATED CIRCUITS

Mfr.
Code

07263
07263
07263

RESISTORS

Mfr.

Type

ComP

Code

44655 KC07 876-10
07716 CEA ma-475

lN914
lN914
lN914
lN914

Mfr.
Part No.

lJ5B770939X
USB770939X
U5B770939X

Mfr.

w-28
RF-28
KF-28
RF-28

Keithley
Part No.

IC-1
IC-1

IC-1

Keithley

Part No. P&-t No.

CEC R94-1M
WA

RSS-32.4K

CSA RBB-9.31K

27
27
27
27

Fig.
Ref.

27

27

27

Fig.

Ref.

27
27
27
27
27

0472B

47

P.RPL4CEASLR PARTS

MODEL 640 ELECTROMETER

REMOTE HFAD (cont'd)

OSCILLATOR

RESISTORS (cont'd)

Mfr.
Code

73138

R506

Value

1 kn

20%, .75 w

l%tYllet

*a507 301 kn l%, l/S w MtF 07716

R508
R509
a510

R511
R512
R513
R514
R515

R516
a517
a51s
R519
R520

a521

R522

R523
R524

R525
R526

R527
R528
a529
a530

10 kC l%, l/8 w MtF 07716
10 a
1

Mi? lO%, l/4 w COIDP

5.62 kn 1%. l/8 w

1.5 kn l%, l/8 W
442 kG l%, l/S w

22.1 kn

2.21 kn l%, l/8 w
22 kfl

10 kn

402 n
442 kn

14.7 kn
10 kn

10 kfl

100 kn
10 kfi

10 k0

49.9 n

1

kC

10%. l/4 w Camp 44655

44655

MtF 07716

l%, l/8 w

MtF

MtF

MtF 07716

07716
07716

MtF 07716

1%. l/8 w
20%, 2 W

1%. l/8 w
l%, l/8 w

l%, 1/a w
20%. 2 w

l%, l/S w
l%, l/8 w
lO%, l/4 w
lO%, l/4 w

MtF 07716

--- 10582
MtF 07716
MtF 07716
MtF 07716

-_- 10582
MtF 07716
MtF 07716

camp 44655
Camp 44655

l%, l/S w MW 07716
l%, l/8 W

Mt.F 07716

10 kn lO%, l/4 w Camp 44655
10 n
10 kn lO%, l/4 w

lO%, l/4 w camp 44655

COIUP 44655

Mfr. Keithley
Part

77 PR

CEA

CEA
ac07
ac07

No.

Part NO.

RP64-1K
RSB-301K
RS&lOK
R76-10
R76-1M

CEA R8S-5.62K
CEA

CEA

R&3-1.5K

RSS-442K
CBA R88-22.1K
CEA RSB-2.21K

CEA

115-117

CEA
CEA
CE4

115-117
CEA
CEA
aco7
RC07

R88-22K
RP58-10K
R88-402
RSB-442K
RBS-14.7K

RP58-10K
a&3-1OK
RSS-100K
R76-10K
R76-10K

CEA R88-49.9
CEA
aco7
ac07

RSS-1K
R76-10K
R76-10
R76-10K

Fig.

Ref.

27
27
27
27
27

27
27

27
27
27

27
27

27
27
27

27
27

27
27
27

27
27

27

27
27

“BSIP;.

T501
T502

CiXUIt,

DBSill.

Q501
4502

9503
9504
Q505
9506
9507

Type

--­_-_

Type
Silicon, NPB, Case TO-92

SilLc.on, NPN, Case TO-92
N-Channel FET, Case TO-92
PNP, case R-110
PNP, Case R-110
PNP
PNP

"Nominal Value, Selected during calibration,

TRANSFORMERS

Mfr. Mfr. Keithley
CO&

SO164 TR-132 TR-132
80164 TR-132 TR-132

TRANSISTORS

Mfr. Mfr. Keithley

Code Part No. Part NO. Ref.

04713 2135089

04713 2N5089
04713 MPF103
07263 S17638
07263 517638
01295 2Nl381
01295 2Nl381

Part No. Part No.

X-62 27
TG-62 27
TG-41 27
TO-33 27

TG-33

TG-8 27
E-8 27

Fig.
Ref.

27
27

Fig.

27

48

0472R

63060

70309

70903

71002

“ictoreen Instrumant co.

5806 Hough Ave.

Cleveland, Ohio 44103
Allied Control Co., Inc.

2 East End Ave.

New York, N.Y.

Belds” Mfg. Co.
415 so. K‘lpsfrisk
Chicago, Ill. 60644

Sirnbaeh Radio Co., Inc.
147 Hudson St.

NB” York, N.Y.

75042

75915

76055

76493

1P.c 1°C.

401 Worth Broad SC.
Philadelphia, PS. 1910s

86684

8,216

90201

90303

PhihO col‘p.

Lansdals Div., Church Rd.
Lensdale, Pa. 19446

11279

71400

71450

71468

71590

71785

72619

72653

,2699

CTS Corp.

1142 W. Besrdsley Aver
Elkhart, I”d.

ITT Cannon lclaetric, Inc.

37.08 H”lnhOlC se.

LOS *ngs1*s, Calif. 90031

Cinch Mfg. co. and

Howard 8. Jones Div.
Chicago, Ill. 60624

76545

77764

79127

60164

SO294

81073

81483

62389

83125

Keiehley I”srr”!m”t*, 1°C.

28775 hurora Road

Clewlend, Ohio 44139

BD”r”S , IDE.

6135 “agnolia Ave.
Riverside. Calif. 92306

91637

91662

9173,

91802

91929

93332

93656

94144

94154

Gremsr Mfg. co., 1°C.

7 Norrh me,

Wakefield, l&w..

72982

73690

74W6

83330

63594

83701

64171

64411

84970

serre* Tarz*e”, Inc.

E. “illefde Dr.

Slohmi”~to”, Tnd.

0670

94310

94696

95346

95712

9,933

99120

:
i

6
”

1

I t

-

.+--.

15 I

------__-_-_-_­I,

I I I I I I