Keithley 604 Service manual

INSTRUCTION MANUAL

MODEL

DIFFERENTIAL ELECTROMETER AMPLIFIER

604

KEITHLEY INSTRUMENTS, INC.

PRINTED JANUARY 1977, CLEVELAND, OHIO U.S.A.

CONTENTS

MODEL 604

CONTENTS

Section

Page

SPECIFICATIONS ................................. iv

1. GENERAL DISCRIPTION.

2. OPERATION

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

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

1
3

3. CIRCUIT DESCRIPTION. ............................ 11

4.

MAINTENANCE.................................1 3

5.

ACCESSORIES. ................................ 25

6. REPLACEABLE PARTS. ............................. 27

SCHEMATICS...................................3 6

ii

0177

MODEL 604

ILLUSTRATIONS

ILLUSTRATIONS

Fig. No.

1 Model604FrontPanelControls
2

Model 604 Rear Panel Controls .................... 3

Title

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

3 Model 6041 Front Panel. ....................... 4

4

TypicalExperiment

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

5 Error Due to Ammeter Resistance ................... 8

6 Internal View of Model 301 Amplifier.
7 Model 604 Block Diagram

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

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

Ripple Obtained for the 26 Volt Supply. ............... 14

:

Ripple Obtained for the 15 Volt Supply. ............... 15

10 Ripple Obtained for the 21 Volt Supply. ............... 15

11 Location of Voltage Supplies Test Points. .............. 15

12 Null Obtained with the Signal Generator at 5H.z. ........... 17

13
14 Top View Model 604.
15

Null Obtained with the Signal Generator at 1kHz ........... 17

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

Bottom View Model 604

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

16 Component Layout of PC-165. ..................... 23

17
18

19

Resistor Locations on PC-165. .................... 24

Top Cover Assembly.

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

Bottom Cover Assembly ........................ 35

Page

3

5
9

11

21
22

35

0177

iii

SPECIFICATIONS

MODEL 604

SPECIFICATIONS

iv

0177

SECTION 1.

GENERAL DESCRIPTION

h. When used in conjunction with the Model 6041
Differential Current Shmt the Model 604 hecome* a
single-ended or differential picoameter. Single­endp and differential current measurement* from
lo- to 10-14
Also, high megohm resistors may be installed within
the Model 604 to allow shunt picoammeter operation.

AS an amplifier, the Model 604 will operate

a.
over a bandwidth from dc to 50 km or greater with
six select&l* 3-dB points from 30 kHz to 100 Hz.
Thus, the signal-to-noise ratio may-be optimized for
a particular application. The amplifier output fur­nishes 210 volts at 5 milliamperes single-ended.

The Electrometer Amplifier has an input re-

b.
sistance of greater than lOI4 ohms shunted by less
than 5 picofarads in the unguarded position, that
allows high impedance measurement to be made easily.

When in the guarded position the input impedance is

shunted by less than 1 picofarad.

LOW OffSet Current - 1855 than 2 x m-14 ampere

- tkimiaes zero offset with high source resistance
and permits maximum resolution when measuring cur-

rent.

A choice of outputs which can he used simul-

d.

taneously or *ingly is available. Each input of

the Model 604 has' a unity gain output, which has
*so omn acc"rac". This alloWS the Model 604 to be

used-& a prea&ifier with differential or digital
voltmeters for precise measurements. Also, these
outputs can he fed into an X-Y recorder for recording
data from high impedance sources. When desired, the
unity-gain outputs can be monitored for absolute
values while recordings are made from the amplifier

output.

e. All outputs are short-circuit proof, and out­put noise referred to the input is nearly constant
regardless of the gain.

The guarding capability of the Model 604 al-

f.
lows fast masurements from high resistance sources,

by eliminating the effects of cable capacitance and

leakaoe. TO convenientlv facilitate these measure-

ments, the Model 6301 Gu&ded Probe can be used to

connect the eonroe to the Model 604 in the guarded
mode. the guard feature is switch seleotable.

ampere can be made with this setup.

Mo%l 604 is its zero stability. signals can be
monitored over weeks without constant rezeroing.

volts per week; zero offset due to temperature chan­ges is less than 300 microvolts per OC. Zero shift

A unique circuit provides protection while main-

&ides a very stable tl volt suppression on any

eliminated from the Model 604 output.

ent Shunt is an accessory specifically designed to

Noise will be as low as 2 x 10-15 anumre usins a

method limits the current span to only four decades,

Another outstanding feature of the Keitbler

Zero drift of the Amplifier is leas than 4 milli-

due to mechanical shock or vibration is negligible.

Overloads up to +4OO volts will not damage

h.

the 604 Amplifier, and recovery is almost immediate.
taining the favorable features of the MOS PET input.

AS another convenience feature, the Model 604

range.
l-volt signal can be displayed full scale.

volts cauee no apparent change even on the most sen­sitive range. Line frequency noise is practically

l-3.
convert the Model 504 Amplifier into a single-ended

or differential multi-range picometer.

fier and the Model 6041 Shunt combination to obtain
fast response in c*rrent measurexnente. Input capac­itance at the end of a IO-foot cable is maintained
at 1 picofarad in the guarded mode. As a result,
risaltimes of 0.5 millisecond are possible with
lo- ampere input signals.
through the Model 6041 by the use of triaxial input
conneotors and total auardina within the Shunt
itself.

h.
to-noise ratio is more desirable than fast response,
the Model 604 can be used in its unguarded mode.

lOI ohm resistor.

longer than when the Model 604 is in its guarded
mode. Regardless of mode, the high frequency cut­off can be used to reduce noise at the higher fre­quencies .

is to he monitored, a pair of high megohm resis-

tors, available as the Model 6033, can be mounted
internally within the Model 604. Although this

it does slightly improve both the noise and the
rise time characteristics over that obtainabLe with
the multi-range Model 6041 Current Shunt.
promise between noise and rise time still must be
made by choosing the guarded or unguarded mode.

high source resistance, permitting maximum resolu-

tion when measuring current.

variations a5 small as 1 millivolt in a

j. Variations in line valtagee from 105 to 125

MODEL 6041. The Model 6041 Differential cur-

a. The driven guard enables the Model 604 Ampli-

Guarding is maintained

For those applicarions where maximum signal-

Hcwever, rise t&es are m&h

For those cases where a limited current span

C.

The cam-

d. Low offset cn~lent minimizes zem offset with

0373

Varies the high frequency rolloff of the Model 604 and
selects the maximum bandwidth to be measured. When the
Switch is in the OFF Position the full handwidth of the
Model 604 is available.

Turns instrument off and on; disconnects meter; selects
meter polarity: sets instrument for center zero operation.

Indicates instrument is on.

2-2

2-8
2-6

t+, and c-, INPUT

Receptacles.

Control
UNITY GAIN O"TP"l3:

FROM c-j TNP"Ti FROM (+I
INPUT

GROUND Post

I

FUSE

I

shunts respective INPUT Receptacle. Locking either one
allows single ended use.
Opening both allows differential measurements,

connect inputs to sources. May be wed either singularly
or conjointly for single ended or differential measure­ments respectively.

triaxia1 COnrLectOTs.

Functional Description

For use as an extremely linear preamplifier. Outputs 2-11
are equal to respective inputs within *0.005% at dc,
exclusive of offset, noise and drift.

Connected to ground of all the outp"ts and the ground ---

wire of the power cord.

3x slow Blow.

117 volt operation: -l/8 ampere.
234 ""It nnaration: -,~/I~6 amnerc.

Locking both zeroes the meter.

Receptacles are Teflon-insulated

2-2

2-2

2-l

Paragraph

2-8

INPUT :

lo 604 INPUTS:
+ and -

GND

2

+ and -

Functional Description

switches shunt resistor at input of the amplifier
for the Model 604 +INPUT Receptacle, thus determining
full scale current range Model 604 is to measure.

Switches shunt resistor at input of the amplifier

for the Model 604 -INPUT Receptacle, thus determining
full scale current range Model 604 is to measure.

~0th switches are used in differential current measure-

Connects Model 6041 inputs to BOUTCBS. May be used either 2-2
singularly or conjointly for single-ended or differential

measurements respectively.

insulated triaxial connectors.
Connects Model 6041 to respective Model 604 Input Recep-

tac1es.
connected to ground of Models 604 and 6041

Receptacles are Teflon-

Paragraph
2-2

2-2

2-2

0373

SECTION 2.

OPERATION

2-l. INPUT CONNECTIONS.
put connectors, the +1NFUT receptacle and the -IN­PUT Receptacle, for use either single-endedly or

for measuring the difference between two input
signals.

a. The Model 604 INPUT Receptacles are Teflon­insulated triaxial connectors.
is the high impedance terminal; the inner shield is
either guard or ground; the outer shield is ground.
The inner shield of the INPUT Receptacle may he
used as a driven guard with the GUARD-OFF Switch in
the GUARD Position.

h. There arc Keithley Accessories available which

are designed to lnclease accuracy and co""e"ie"ce

of input connections.

C.

The Model 6011 Input Cable facilitates input
connections. Table 5 indicates the color coding
of the alligator clips. The center terminal is
shielded by the inner braid of the triaxial cable up
to the miniature alligator clip.
clip causes pickup from nearby electric fields, re-

move it and connect the shielded lead directly to

the source.

I

Lead

heavy wire with

red clip cover

thin wire with Inner Shield

black clip cover guard

thin wire with Outer Shield

"7%-P" rlin rn.lP?

The Model 604 has two in-

The center terminal

If the unshielded

circuit Terminal

center

high

d. When working with a high impedance source
carefully shield the input connection and the source
since any variation in the electrostatic field near
the input may cause definite meter disturbances.

Use high resistance, low-loss materials -­s":h as Teflon (recommended,, polyethylene or poly­styrene -- for insulation. The insulation leakage

resistance of test fixtures and leads should be

several orders of magnitude higher than the inter-

nal resistance of the source. Excessive leakage

reduces the accuracy of reading from high impedance
sources. Triaxial or coaxial cables used should be
a low noise type which employs a graphite or other

conductive coating between the dielectric and the
surrounding shield braid. Amphenol-Borg Electronics
Corporation, Microdot, Inc., and Simplex Wire and
Cable Company make satisfactory types. use of the
Model 6011 Input Cable insures good input connec­tions.

NOTI?

Clean, dry connections and cables are very
important to maintain the value of all in­sulation materials. Even the best insulation
will be compromised by dust, dirt, solder
flux, films of oil 01 water vapor. A good
cleaning agent is methyl alcohol, which dis­solves most commm dirt without chemically
attacking the insulation. Air dry the cables

I

or connections after washing with alcohol or
use dry nitrogen if available. Or, if it
is available, Freon is an excellent cleaning
agent.

f.

With the GUARD-OFF Switch in GUARD Position
the Model 604 may have at least ten feet of triaxial
cable on its input without adding capacitance to the

FI

0373

3

input (input capacitance is specified at 1 pF).
Note, hwever, that guarding can only eliminate in­put cable capacitance effects.
ial case, see subparagraph S-Ii, guarding cannot be

Except in one spec-

used to eliminate effects due to source capacitance.
DO not connect the guard circuit to the source.

--__-

__--.~

NOTE

For a complete discussion on guarding with
the Model 604 refer to paragraphs 2-3 and
2-4.

When working with a high impedance source any

4.
change in the shunt capacitance of the input cir­cuit will cause disturbances in the reading. Make
the measuring setup as rigid as possible, and tie
down connecting cables to prevent their movement.

A continuous vibration may appear at the output as

a sinusoidal signal, and other precautions may be

necessary to isolate the instrument and the connec­ting cable from the vibration.

For low impedance measuremen~s~-- measurements

h.
that are above 10-8 ampere -- ""shielded leads may
ae usea.

The Model 6012 Triaxial-to-Coaxial Adapter
enkles using coaxial cables and accessories with
the Model 604 by adapting the triaxiol INPUT ~ecep­tacles to the UHF coaxial type.

The Adapter connects the Model 604 inner

1.
shield to ground defeating the guard capability
that the triaxial receptacles make possible. EX­cept for the special case spelled out in the fol­lowing subparagraph 2, the GUARD-OFF Switch must
be in the OFF position for the instrument to func­tion

2. If the Model 6012 Adapter is used with the
Model 6041 Shunt in front of the Model 604 and
the current souroe can be floated off ground, then
a feedback picoameter connection is possible.
In this situation the coaxial shield is guard

with the GUARD-OFF Switch in the GUARD position.
TO make possible a guarded circuit, connect guard,
the coaxial shield, to the low of the current

SOUlCe. Remember, however, if the current source
low is grounded, the GUARD-OFF Switch must be in

the OFF position for the instrument to operate,
and no guarded circuit is possible this way.

a. The Model 604 + INPUT Receptacle is the input

to the non-inverting amplifier.

This means that
for a single-ended positive input to this Receptacle
the output is positive and for a negative input the
output is negative. The polarity can also be inter­preted with the METER Switch and displayed on the

meter.

b. The Model 604 - INPUT Receptacle is the input
to the inverting amplifier.
ended positive input signal to this Receptacle the

Thus for a single-

output is negative and for a negative input the
output is positive.

For single-ended measurements just lock the

C.
ZERO CHECK Button for the Input Receptacle that you
do not intend to me, and apply the signal to the
other Receptacle. When locked, the ZERO CHECK But-

ton will connect its Input Receptacle to ground pre­senting an open circuit to the respective amplifier.
The Model 604 always measures the signal differen­tially.
difference between the applied signal and the ref-

In the single-ended mode it measures the

erence signal (ground).

L

F: LG”Rr! 3.

d.
CHECK Buttons and apply one signal to one of the In­put Receptacles and the other sianal to the other
Kecepta&.
accepts the high or low signal.
the -INPUT Receptacle is positive with respect to

Model 6041 Front Panel Controls and

For differential measurements unlock both ZERO

It does not matter ;hich Receptacle

If the signal to

the signal to the +INPUT Receptacle, then the output,
and the meter, will read negative.
to the +IINPUT Receptacle is positive with respect
to the signal to the -INPUT Receptacle, then the

If the signal

output will be positive.

whpch, when used in conjunction with the Model 604,
enables the Model 604 to become either a single­ended or differential shunt ammeter.

The Model 6041 'is a Differential Current Shunt

ceptacles on the Model 6041 are nominally labeled.

The INPUT ne-

That is, it is not essential that, single-endedly,

a positive signal be applied to the C+) Receptacle
and a negative to the (-) Receptacle or, differen­tially, the high signal to the (+I and the low to
the (-).

1.

The Model 6041 outputs (labeled: TO 604
INPUTS; + and -,,
the Model 604, are directly tied to their corres­pending Input Receptacle.
the +INPUT Receptacle will be accepted at the +

which connect the Model 6041 to

That is, a signal to

output and a signal to the -TNPUT Receptacle will

be accepted at the - output.

2. Though it is not absolutely necessary, it
is recommended that upon connecting the Model
6041 to the Model 604, the corresponding output

receptacle of the Model 6041 be connected to the

corresponding Input Receptacle on the Model 604.

Otherwise, the user may become utterly confused

at what the polarity at the Model 604 output
corresponds to.

3. Note that the +INPUT Switch on the Model
6041 applies to the Model 6041 +INPUT Receptacle

only and the -INPUT switch applies to the -INPUT
Receptacle only, regardless of the relative or

absolute polarities of the signals at the inputs.

4

0373

2-3. GUARDING.

a. There are several factors which contribute to

the bandwidth of an experiment.

1. The amplifier bandwidth;

2. The so"rce resistance and capacitance;

3.

The capacitance of the cable connecting
amplifier to the source.

f3dB =

So, in this example, connecting the source to the
amplifier with a 3 foot cable, withcut guarding,

would cause a IO:1 reduction in bandwidth.

The Model 604 is designed to eliminate (guard)

thz'cable capacitance when used in the guard mode.

The Model 604 will reduce the apparent capacity at

the end of an up to 10 foot long triaxial cable to
approximately 1 picofarad by driving the inner
shield of the cable.

10~~10+90) (10-l')

.16

= 1.6 iiz

Model 604

GLw.E 4.
g the Amplifier, Cable and Source.

is the capacitance due to the connecting cable,
is the source capacitance,

stance and ES is the source voltage.

b. In the typical setup shown in Figure 4, if a

perfect amplifier were placed at the source,the 3 dD

frequency of the so"rce would be

f3dB =

where f3du is the 3dB bandwidth of the source in HZ:

1. If, to take an example, Rs is equal to lo9

ohms and Cs is equal to 10 picofarads, then

2. NOW, if a cable is used to connect the so"rce
to the amplifier, a new bandwidth is encountered
because of the addition of the cable capacitance
and equation 1 becomes

f3dB =

where $$B

An average cable adds approximately 30 picofarads

per foot to the circuit. Th"s, a 3-foot cable

would add 90 picofarads and

Figure Depicts a Typical Experiment Show-

KS is the source re-

&I$ cs = .M& cs

R, is the ~o"rce resistance in ohms.
and Cs is the so"rce capacitance in farads.

.16 equation 2

Rs (c,+c,)
is the 3d0 bandwidth of the system in

R,'is the source resistance in ohms;
Cs is the source capacitance in farads;

=*d Cc is the cable CaDacitance in farads.

In the figure

equation 1.

The capacity from the center conductor of a
triaxial cable to the inner shield is about

30 picofarads per foot. From the inner shield
to the outer shield it is about 70 picofarads
per foot, The signal source, however, only
sees the capacity from the center conductor
to the inner shield. The guard circuit,
though, drives the entire capacity, about
100 picofarads per foot. The yodel 604 guard
circuit effectively drives up to 1000 pico­farads; th"s the 10 foot cable limitation.

1.

ture of the Model 604 allows the user to achieve
almost the entire bandwidth of the so"rce circuit.

does not increase the bandwidth of the so"rce, but
$xf.y;ically eliminates the effect of cable cap-

d.

limitations.

picofarads. Thus, no more than 1000 picofarads

should be guarded from either input for optimum

response.

common mode voltage swing (tll volts dc to 1 kliz
and approximately 22 volts at 5 !a~).

5 kllz because of internal phase shifts.
shifts cause peaking to occur above 5 kHz, but
the system still remains stable.

e.
own separate guard circuit which is completely in­dependent of the other. Note, also, that guard and
the unity-gain 0"tp"ts are electronically identical

(see schematic diagram 228201: in Section5 ).

2-4.

a. This Switch when in the GUARD Position reduces
the effect of input cable capacity and provides

high speed measurements from high resistance so"rces

at the end of a cable by driving the cable capaci­tance and the inner shield of the INPUT Rece~ta­cle(s) (refer to paragraph 2-3). h guarded ckuit
is possible in this way.

b. With the Switch in the GUARD Position input
capacity is decreased (to approximately 1 pi even

with "p to 10 feet of cable on the input) and rise

time is decreased. Note, however, that the noise
is increased.

In the above example, then, the guard fea-

f

3dB =

2. Notice that, in the above case, guarding

The guard feature does, however, have several

1.

2. The guard voltage swing is limited by the

3.

Note that each input of the Model 604 has its

GUARD-OFF SWITCH.

lo~(lo+l) (lolr)

It is effective driving only up to 1000

The guard feature is not effective beyond

.16 = 14.1 LIZ.

These

0373

5

the input capaoity is increased to 5 pF with no

cable

on the input.

are decreased.

d. Therefore, although guarding increases speed,
it also increases noise as well and a oompromise
between speed and noise will have to be made.

a. This Switch allows the user to select the most

amenable bandwidth to achieve optimum rise time and

noise

the S&itch determines fhe meGured bandwidth of the
amplifier and cuts off higher f&quenc~ea a+ the 3
dEi point. For example, if the Switch is set to 1
kHz the~bahdwidth~of the Model 604 is 1 ~HZ and all
higher frequencies are cut off. Setting the Switch
to OFF gives the rated frequency response.

b.
select the optimum bandwidth for his measurement by
cutting off higher frequency noise components, ring­ing and overshoot.
bandwidth the longer the rise time.

will have to use the reguirements of his experiment

and the method of trial and error to select the
proper setting of the Switch for optimum achieve-

ment.

2-6.

ME,";,ld
Controls are eight position switches. The MEDIUM
control interpolates between the setting of the
COARSE Control.
turn potentiometer that interpolates between the

settings of the MEDIUM Control.
either be used for suppression or for zeroing the
Model 604.

b. The zero suppress circuit cancels any constant
dc voltage in order to use a more sensitive range to
observe a superimposed signal. There is up to 11
volt available for zero suppression. This means
that on the most sensitive ranges up to 1000 times

full scale may be suppressed.
604 can measure changes of 1 millivolt full scale in
a 1 volt steady signal on its .OO1 wit range.

C. operation.

c,:,;~ the closest to a full scale meter deflec-

the direotion opposite meter deflection (counter­clookwise for positive deflections and clockwise
for negative deflections).

meter needle passes through zero.

IUM Control until the needle passes back through

zero and then adjust the FINE ADJ. Control for
zero deflection.

the input and 100 pF with 3 feet of cable

The speed of response and the noise

When using the Model 6041 with the GUARD­OFF Switch in the GUARD position the total

system is guarded. Also, less than 3 pF
will be present at the Madel,~ input
with 3 feet of cable on the Input:

The amplifier ro+ off at 6 dB/octave and

The user oan use the HIGH CUT HZ Switch to

Note, however, the lower the

SUPPRESS CONTROLS. METER Switch
There are three SUPPRESS Controls:

and COARSE.

1. Adjust the VOLTS Switch to the range that

Turn the SUPPRESS Controls completely in

2.

turn the COARSE Control setting until the

3.

The COARSE and MEDIUM SUPPRESS

The FINE ADJ. Control is a ten-

For example, the Model

So the "ser

Fnm ALU.,

These controls may

Turn the MED-

With the GUARD-OFF switch in the OFF position

C.

4. Set the VOLTS Switch to a more sensitive

range and readjust for zero, if necessary.

a. A good differential amplifier is character­ized by Its common mode rejection and also its
common mode voltage range.

atively well in both these areas.

b. The specifications in Table 1 read greater
than 90 dB from dc to 120 HZ decreasing to 80 dB
at 1 kHz.
greater than this.
the nonlinear distortion caused by swinging the
amplifier between i-11 volts comon mode.

damental is almost completely removed and all

appears at the output is predominately second bar-

manic of the cornon mode input signal. This dist­ortion inoreases with frequency and the specifica-

tion is degraded acoordinyly. At lower ~mnmn

mode levels, lets say 2 volts peak-to-peak, it is
practically impossible to see any output change
due to the common mode signal up to 1 kHz at any
gain setting on the Model 604.

a. Check the Fuse and the LINE VOLTAGE Switch
for the proper line voltage. Connect the power
cord to the power source.

GUARD-OFF Switch OFF

C. Turn the METER Switch to CENTER ZERO. The

Meter Pilot Light should turn an. Within a few

seconds the meter needle should come to the

position.
FINE AN. and MEDIUM SUPPRESS Controls. Normall".
there is no need to use the COARSE Control.

Using the center zero scales decreases accu­raoy because the scale span is reduced.

d. After a few moments increase the voltage sen­sitivity by advancing the VOLTS Switch to .3, .1,
etc.

e. After long periods of storage or after an
overload, the Model 604 may drift excessively.

input transistors are insensitive to mechanical
shock; however, a severe input overload may cause

a zero offset.
Controls.
ho"rS

2-Y. VOLTAGE MEASUREMENTS.

tW:'WayS.

guarded or the unguarded mode (refer to ,,aragraphs

2-3 and 2-4).

1. In the single-ended method the unknown volt-

age is connected to one of the Input Receptacles.

The other Receptacle is locked in Zero Check Po-

sition Irefer to paragraph 2-2).

Actually, the comm mode rejection is

The specification is based on

If not, adjust the meter zero with the

Continue zeroing with the FINE ADJ Control.

This is corrected with the SUPPRESS

Drifting, though, can occur far several

The Model 604 can be used to measure voltages

Both ways may be used in either the

The Model 604 rates re1-

POWER OFF.

NOTE

The fun-

that

center

.

The

6

0373

NOTE

The ZERO CHECK Buttons are tr”e transfer

type switches.
the input will be briefly connected to

lo9

ohms to ground.
are further depressed toward LOCK posi­tion the input is open circuited and will

remain so until the B"tto" is released.
I" the LOCK position the Model 504 input
is internally connected to ground.
note that for certain very high impedance

sources it may be necessary t" "ever con-

nect the i"p"t to ground, eve" through
109 ohms.

and release the ZERO CHECK Button as
fast as possible and the source will see
109 ohms for only a few milliseconds.

In the differential method one ""know" "olt-

2.

age is connected to one of the Input Receptacles
and the other voltage is connected to the other
Input Receptacle.

ButtonS are unlocked.

ACC~SSCX-y probes extend the Model 604's

3.

range to 10 kilovolts. (Use either single-endedly

or differentially only with the GUARD-OFF Switch

in the OFF position).

b. Single-Ended Method Voltage Measurements.
This method should be used when an unknown voltage
from a single source is to be measured.
paragraph 2-2 also).

set the Model 604 front pane1 Controls as

1.

follo"s:

connect the unknown voltage to one of the

2.
Input Receptacles.
and ""lock the ZERO CHECK Button pertaining to
tile used Input Receptacle.

CHECK Button in the LOCK position.

witch to + or -, as necessary. Increase sensi­tivity with the VOLTS switch until the greatest
on-scale meter deflection is obtained.
zero setting after increasing sensitivity.

fer to paragraph 2-2 also).

For guarded, fast r"easure,"e"ts, set the

3.
GUARD-OFF Switch to GUARD.
the effects of input cable capacity with very
high impedance sources and allouis guarded voltage
measurements (Refer to paragraphs 2-3 and Z-4).

set the HIGH CUT HZ Switch to the desired

4.
position to obtain optimun response.
paragraph Z-5).

Differential Method Voltage Measurements.
T.;, method should be used to ",eas"re the difference
between two ""know" voltages "either of which has
to be at ground potential, and either of which may
be as much as 211 volts off ground.
graph 2-Z).

Set the Model 604 front panel controls as

1.

show" in subparagraph bl above.

connect one unknown voltage to one Of the

2.
input receptacles and the &her "oltage to the
other 1npLlt Receptacle.

When they are depressed,

Then as the L3uttons

Please

1f this is the case, depress

I" this mode both ZERO CHECK

(Refer to paragraph Z-2).

Zero the meter (paragraph 2-6,

Keep the other ZERO

Set the METER

This method reduces

(Refer to

(Refer to para-

zero the meter and the"

(Refer to

Recheck

CR*-

""lock both ZERO CAECK Buttons.
Switch to + or -, as necessary. Increase sensi­tivity with the VOLTS Switch until the greatest
o" scale meter deflection is obtained.

7.ero settina after increasinil sensitivitv. me
difference Gig"& is equal to the perce";age of
full scale that the mete* reads times the VOYPS
switch setting. (Refer to paragraph 2-2 also).

3. For guarded, fast IneasureInents, set the
GUARD-OFF Switch to GUARD.
2-3 and 2-4).

4. Set the HIGA CUT HZ switch to the desired
position to obtain "ptimum response.
paragraph 2-5)

TO tneaS"re sollrces greater than 1 Volt, use

d.

one of two divider probes.
Divider Pr*be extends the Model 604's range to 10
volts' overall accuracy is i48 and input resistance
is 1Oio ohms. The Model 6103. 1OOO:l Divider Probe
extends the ?.,odel 604's range to 1 kilovolt; over­all accuracy is 26% and input resistance is 1012
ohms. Follow the same operating procedures with
the dividers as in subparagraph b.
Triaxial-to-coaxial Adapter must be used with the
~"dels 6102A and 6103A Divider Probes.
ever, "sing the Adapter connects the inner shield
to ground, defeating the g"ardi"g capability of
the Model 604. Th*r*fOre,
rnu~t be in the OFF position for the instrument to
operate. The full-scale voltage range is the di­vider ratio times the VOLTS Switch setting.

If the Models 6102~ and 6103A Divider Probes
are used with the Model 604 in the differen­tial mode, the comm"" mode rejection is lim­ited by the probe matching and typically weld
be about 30 dU. Thus,
mode voltage would cause a full scale indica
tion.

Z-10. CURRENT MEASURl?MENTS.

an ammeter when used in conjunction with the Model

6041 Differential C"rre"t Shunt or when resistors
are installed within the cases of the Model 301 (see
Figure 61. When using the Model 6041, resistors

are switched across the inputs of the Model 301
Amplifiers in the Model 604 with the + and - INPUT
Switches on the Model 6041.
range is equal to reciprocal of the INPUT Switch

setting on the Model 6041 times the setting of the
VOLTS Switch on the Model 604.
the INPUT Switch is set to lOa and the VOLTS switch

is set to .Ol, the" the full scale cwrent range

is equal to l/108 x .Ol = 10-B x .Ol = 10-10 amp-

eres.

The Model 301 Instruction Manual, SUpplied The Model 301 Instruction Manual, SUpplied
with the Model 604, gives complete informa- with the Model 604, gives complete informa-

tion on Model 301 operation, circuit descrip- tion on Model 301 operation, circuit descrip­tion, troubleshooting, calibration, parts tion, troubleshooting, calibration, parts
lists and schematic diagrams. There are lists and schematic diagrams. There are
two Model 301 Operational Amplifiers used two Model 301 Operational Amplifiers used
as plug-i" ""its in the Model 604. as plug-i" ""its in the Model 604.

a. the Model 604 can measure curlent~ several

ways. each of which may be used either in the guard-

ed or ""guarded mode.

1. I" the single-ended method the ""know" cur­rent is connected to one of the 1"p"t Receptacles
03 the Model 6041. The other I"p"t Receptacle on
the Model 6041 is locked in Zero Check position

The Model 6102A 10:1

the GUARD-OFF Switch

NOTE

30 Volts of common

set the rnTER

Recheck

(Refer to paragraphs

(Refer to

The Model 6012

Note, how-

The Model 604 becomes

The full scale current

For example, if

0373

7

by its corresponding ZERO CllECK Button on the
Model 604 front panel.

I" the differential method one unknown cur-

2.
rent is connected to one of the Input Receptacles
on the Model 6041 and the other current is con­nected to the other Input Receptacle. In this
mode both ZERO CHECK Buttons are ""locked.
fer to paragraph Z-2).

With the shunt resistors mounted inside the

3.
cases of the Model 301 Amplifiers in the Model 604
the Model 604 may be used as an anuneter either
single-endedly or differentially. This method,
however, limits versatility and gives only four

decades of response.
tions apply with this method as spelled out in

,,aragraph 2-2.

When resistors are mounted internally, the

input is open circuited when in zer" check.
This presents a" open circuit to the cur­rent source, stopping CUrrent flow. I"

some cases this could be harmful to the
current source and possibly to the Model

604 itself when high complicance voltages
are encountered.

(Refer to paragraph 2-2).

CR*-

The same input considera-

CAUTION

range, the input capacity and the method used

(guarded or unguarded). See specifications, Table
1, page ii. On all ranges, the rise time in the
guarded method is less than one second with the spe­cified capacity across the input. Even with much
larger capacities on the input the negative feedback
maintains a relatively short rise time. Given a
choice, it is better to place the Model 6041 nearer
to the CUrrent source than to the data readinq in­strulnent. Transmitting the input signal through

long cables decreases the responses speed and in-

creases noise.

MC&l 6041. This method is used to measure an "n­known current from a single source (Refer to para­graph 2-2).

Single-Ended Method Current Measurements with

Connect the Model 6041 Outputs, labeled TO

1.
604 INPUT + and -, to the corresponding Input
Receptacles on the Model 604 with the supplied

mating cable.
pane1 controls as follows:

Set the Model 604 and 6041 front

when making measurements from high impedance
sources or low current sources usinq the

guarding feature, it may be desireable to

set the HIGH CUT HZ Switch to the lowest

setting, 100 HZ, to limit the noise band­width in some ca6es'.
when guarding, increases linearity with

the bandwidth increase and the noise may

eventually overload the amplifier. This
would cause a" error in a meter reading,
but the error would go undetected ""less

the o"tp"t was monitored o" an oscilloscope.

Rise time varies primarily with the c"rre"t

b.

The noise increase.

LB------------

2. Connect the unknown current to one of the
input Receptacles on the Model 6041.
meter and unlock the ZERO CHECK Button that CDT­responds to the Input Receptacle being used. Set
the METER switch to + or -, as necessary. In­create sensitivity with the VOLTS Switch and the
Input Switch that corresponds to the Input Recep­tacle beinq used until the qreatest on-scale
meter deflection is obtained. Recheck zero set­ting after increasing sensitivity.
paragraph 2-2 also).

The full-scale c"rrent range is the VOLTS

3.

measuring point

‘70 error in reading due to circuit loading = -100

it Rin (< R, I a I meter and 9b error E 0

zero the

(Refer to

it!,

FIGURE 5. Error due to Ammeter Resistance. Current sources may be considered a voltage (E) in series with
a resistance (R). The current with the ammeter short circuited is I = E/R. With the Short circuit removed,

the effective i"p"t resistance of the ammeter (Ri") is in series with the source resistance (R). The cur­rent of the complete circ"it is reduced and Imeter = E/(R+Ri").
is small compared to R, Imeter

8

N I and the error introduced by circuit loading is negligible.

If the effective ammeter input resistance

0373

Switch setting times the reciprocal of the In­put Switch setting. use the Smallest VOLTS
Switch setting possible to minimize input volt­age drop and thus obtain the best accuracy. The

full scale input voltage drop is equal to the

VOLTS Switch setting.

(Far example: If a currenf2sourae has a
300 Volt compliance and 10 ohms OutpUt
resistance, then I = 300/101z = 3 x 10m10
ampere. Using a lo9 ohms shunt resistor
and a 300 millivolt full scale voltage
range would display this current full
scale. The loading error would he only
O.l%, which is 40 times less than the
accuracy of the system. The signal-to-

noise ratio would be 100 times better

than if a 107 ohms shunt resistor and
a 3 millivolt full scale range were

used, .

d. Differential. Method Current Measurements with
the Model 6041. This meth*d is used to measure the
difference between two unknown currents neither of

Which has to he at ground. (Refer to paragraph 2-2 Each Mode:

also).

1.

Connect the Model 6041 outputs, labe?lad TO

604 DWJTS + and -, to the respective Input R&­ceptacles on the Model 604 with the supplied mat- -INPUT Receptac:

ing cable. set the Models 604 and 6041 front pan­el COntrOlS as follows:

toe, Model 301 c
single-ended COI
panding to the
verting mode ant

34 Input Receptacle is connected
rational Amplifier hooked up in
pration.
XJT Receptacle is in a non-in­ne Amplifier corresponding
is in an inverting mode. If so

The Amplifier corres-

to

the

0373

IGURE 6.
01 Amplifier Showing Location
31 Installing Internal Resistor.
or complete and comprehensive
nfomation on the Model 301. re­?I?

to

nstruction

internal View of Model

the supplied Model 3oi

Manual.

9

TWLE 6.

shunt Resistors ~"ternally Mounted.

permissable to obtain the rise times.

to the signal bandwidth.

Shunt
Resistor

(ohms,

:$
1010
1011

Typical Rise Times and Noise of the Model 604 As A" Ammeter With a Single Pair of Model 6033

current
span

,fUll scale)

~__

10-6 to lo-9 A
10-S to 10-11 A
10-10 to 10-13 A

10-11 to 10-14 A

This table was compiled using the smallest HIGS CUT LIZ Switch setting

Thus, the noise bandwidth of the system is kept as close as possible

100 pF Guarded
Rise Time
lo%-90%

0.00003 set

0.0003 set

0.03 set

0.3 set

Noise

P-P

10-9 A
10-10 A

100 pF ""guarded

~~~"-,~p"

0.0003 se=

0.03 s-y

3.0 set

30.0 set

Noise
P-P

10-F A
10-U A

desired, the Model 604 may be used as a" ammeter
by installing shunt resistors within the cases of
either or both Model 301 Amplifiers.
the positions in which the internal resistors may
be mounted.

NOTE

When measuring current with the internally
mounted Keithley Model 6033
the Model 604 has slightly shorter rise times

and lower noise for corresponding Model 6041
ranges.

1. I" this configuration, therefore, the Model
6041 Current Shunt does not have to be used with
the Model 604 to make current "wasurements.

however. that installing the resistor* within the
Model 301 asses is a time consuming operation.
Note, also that using the Model 604 in such a ma"­"er severely limits the versatility and capahil-

ity of the Model 604.

meter in such a way allows only four decades of

current measuring capability.

The Mcdel 604 may be used to measure voltages

with the resistors installed within the

Amplifier*.
tude of the input impedance would the" be
equal to the value of the installed resis­tor. This could lead to significant errore
in voltage measurements if the source resis­tance is on the order of magnithde of the
installed resistor.

2. The Model 604 may be used aa either a

single-ended or differential current measuring

device in this configuration.

tions given in paragraph c and d above, less the

Model 6041 instructions, apply here for the
single-ended and differential modes respectively.
The full scale current range, or difference sig­"al, is equal Co the reciprocal of the shunt

resistcr times the setting of the VOLTS Switch.

(Refer to paragraph 2-2 also,.

Pay special attention to the caution of

paragraph 2-10.3, sub-paragraph 3.

f. Use the GUARD-OFF Switch for Guarded or un­g"arded Measurements. Guarded or ""guarded meas­urements can be made in each of the preceeding
modes.

g. Use the HIGS CUT HZ Switch in each of the

current moded as desired to obtain optimum response.

(Refer to paragraph 2-5).

Please refer to Table 6.

&lso, using it as a" am-

Note, however, that the magni-

CAUTION

(Refer to w.ragra@,s 2-3 and 2-4 also,

Shunt

Figure 6 shows

Resistors,

Note,

The same instruc-

two UNITY GAIN OUTPUTS each corresponding to its
respective Input Receptacle, Providing signals
equal to each input-to-ground voltage to within

10.005% at dc; a" AMPLIFIER OUTPUT for recordina
the amplified or difference signal.

may be used to drive recorders, oscilloscopes and

X and Y recorders to record amplified signals, dif-

ference signals and absolute signals.

NOTE

The front panel SUPPRESS Controls will zero
only the FROM +INP"T GAIN OUTPUT: that

is the output for the non-inverting input.

Al*o, the tl volt suppression may only be

applied at this output. The FROM -INPUT UNITY
GAIN OUTPUT may be zeroed internally by ad­justing the zero control in the Amplifier

for the -INPUT.

301 Instructian Manual,. ThUS, when the
AMPLIFIER OUTPUT is zeroed, it is highly
unlikely that both UNTW CARIN OUTPUTS will
be zeroed and several millivolts offset may
be present. ~160, it is very improbable &at
both the UNITY GAIN OUTPUTS and the AMPLIFIER
OUTPUT will all be exactly zero at the same

time, but any two of the three can be.

a. The AMPLTFIER OUTPUT is 310 volts at 5 milli­amperes to amplify sign@ within 1% for recorders.
osoillo9copes and similar i"strume"ts. This out­put can be used for recording single-ended signal3
or differential, relative signals. The RMPLTIPXER
OUTPUT Receptacle is a microphone receptacle Amphen­;i,;y 80MC2F and mates with a" Amphenol type

output and pin "wnber 2 is ground when the GUARD-OFF
Switch is in the OFF Position.

GAIN Receptacles may be used in conjunction; the
AMPLIFIER OUTPUT for recording the relative differ­enoe signal and a UNITY GAIN for recording the ab­solute signal of its input.

ea% input-to-ground voltage within 10
They can be used for impedance matching to mini­mize circuit loading error8 or convenient oonnec-

tions to a racorder when the GUARD-OFF Switch is in

the GUARD position. Also, these two outputs may be
used to record with a" XY recorder; I output to
drive the X channel and one the Y.

. Pi" NO. 1 of the output terminal LS the

b. The AMPLIFIER OUTPOT Receptacle and the UNITY

All Outp"ts of the Model 604 are short
circuit proof.

The UNfTY GAIN Outputs provide si nals to

(Refer to the supplied Model

NOTE

These &P&s

.205% at dC.

Z-11.

10

OUTPUTS. The Model 604 has three outputs:

0373

SECTION 3. ClRCl JIT DESCRIPTION

3-1. GGNERAL.

st%ment that uses as its basic circuit components
two Keithlev Model 301 Ooerational Amolifiers.

these two &@ifiers, hobked-up in unity-gain con-

figuration, are the input amplifiers for the Model

604. Three other major blocks of the Model 604 cir­cuit are composed of three integrated circuit ampli­fiers that serve the functions of differential amp-

respectively. The let major block to be considered
is the power supplies. Peripheral circuits result
in zero suppression, frequency attenuation and amp­lifier gain through switched in resistors end cap­acitors.

basic sections of the circuit of the Model 604. The
schematic diagram, 22820$, is a detailed diagram
showing the complete circuit of the Model 604 and
the circuit deeignations. Refer to these to better
understand the description given in the following
paragraphs.

Elktrometer operational Amplifiers, designated
AR101 and AR102, are used in the inout: one for

The Model 604 is an entirely solid-state in-

lifier, auxiliary amplifier end an output amplifier,

b. The block diagram in Figure 7 illustrates the

NOTE

The circuit description of the Model 301
Amplifiers, circuit designations AR101 and
AK102, are not given in this particular

section. However, the complete circuit
description of these Amplifiers is in the
supplied Model 301 Instruction Manual.

TWO standard Keithley Model 301 Solid-State

each input.
such a fashion that an input resistance of greater
than 1014 ohms for the Model 604 is achieved.
is done by using the inverting input Of the Model
301 es the input, connecting its output to ground
and using the common as the output with the non-in-

verting input connected to common.

uration the gain accuracy is the reciprocal of the

open loop gain of the Model 301 Amplifier.

b.

verting input and the common in the Model 301 Ampli-

fier which is used in the Model 604 + input.
panel oontrols 5106 and S107 switch in resistors
R122 through 1x144 to achieve this suppression.

3-3.
QAlOl is a linear integrated circuit connected as
a differential amplifier.
of the Model 604 is obtained by adjusting this
amplifier, through capacitor Cl14 and resistor
R148, both at low and high frequency.

3-4. AUXILIARY AMPLIFIER.

QA102 isalinear integrated circuit connected for
a non-inverting gain of 30.
highest three gains,
Table 7,.

3-5. OUTPUT AMPLIFIER.

is a linear integrated circuit connected as an in­verting amplifier.
and 33.3 (See Table 7).

Zero suppression is added between the non-in-

refer to ~ahld 7 for the gains of each amp­lifier in the Model 604 corresponding to
each total gain of the Model 604.

DIFFERENTIAL AMmIFIER.

They are connected for unity gain in

This

In this config-

Front

Circuit designation

The common mode rejection

Circuit designation

1000 to 10,000 (refer to

Gain is adjustable between 1

It is used only on the

Circuit designation QA103

The high frequency rolloff

FIGURE 7. Model 604 flock "iitnram~

The Table gives the total gain of the Model 604 Electrometer Amplifier in one column, and the gain of each
component amplifier within the Model 604 corresponding to each total gain.
shows the basic amplifiers composing the Model 604 circuit.

Total

Model 604

Gain

10

33.3

100

333
1000
3333

10,000

t

of these high cuts is 6 dB pe; octave. The output
of QA103 goes to output connector .JlO3 and drives
the meter, mol.
in the alitput amplifier, the noise bandwidth is
always the same as the signal bandwidth.

3-6.

POWER SUPPLIES.

volt power supplies in the Model 604. One set is

located an the main board and drives the three lin­ear integrated circuit amplifiers, w.101, QUO2 and
on103. There is one set of sutmlies for each of the

By putting the HIGH CUT HZ Switch

Input Differential

Amplifier Amplifier

Gain

1
:

1
1 10
1

1

There are three sets of il5

TABLE 7. Model 604 Gain Chart

Gain

10 1
10 3.33
10 10
10

10
10

3-7. MODEL 6041 DIFFERENTIAL CURRENT SHUNT. The
Model 6041 basically consists of two differentially
connected, shielded,
either or both switches, high megohm resistors are
shunted across the inputs of the respective ~lodel

301 Amplifiers to make the Model 604 a differential
or single-ended ammeter.

Refer also to Figure 7 which

Auxiliary OUtpUt
Amplifier

Gain Gain

30
30
30

high megohm switches. "Sing

NOTE

Amplifier

33.3

3.33

11.11

33.3

lipment Recommended for Models 604 and 6041 Maintenance. Use these instruments or their equivalent.

TABLE 8.

SECTION 4.

4-l. GENERAL.

me function Of the maintenance section is LO

pr%ide a method of checking the Models 604 and 6041

to make sure that they operate properly and within
the specifications given in 'Table 1 on page ii.

MAINTENANCE

+15v Ad;.

-15" Mj.
common Mode nrii

commr
Full Scale Adj: R161 4-6

position, at which time the reading should in­create to greater than 10 x 109 ohms.

is the make with the input contact when the 10')

ohm3 resistance shaft moves away from the wiper.

to slow the readin

ton until a 1 x 10 ohms reading is achieved.
This is the position at which the shaft of the
Hutton touches the wiper. note the distance that

the shaft must be dearessed to reach this point.

I

Depress the ZERO CHECK mt-

3

'This point

13

With the Switch in the GUARD position the ohm-

meter should read greater than 30 kilohms and typ-

ically from 50 to 70 kilohms.

Repeat t:he above tests with the Model 7050

2.

connected between ground and inter-shield of the

- INPUT Fezept:ac1e.

If the instrument is inoperative, that is,

2.
if the meter pegs or indicates a large positive
or negative up-scale reading, then set the +li
and -15 volt supplies per subparagraph g below.
Do this before troubleshooting far other than an
obvious problem.

We yodel 301 Amplifiers may be defective.

1.
If this is so, then either they should be repaired
or a new operational set must be substituted.

the Model 604 suppression may be defective.

2.
Check this out per paragraph 4-6.

3. The 21 volt regulated supplies may be defec­tive. Refer to paragraph 4-3 to check the sup­plies.

If none of the above localizes the problem,

4.

then perform the zero Balance and Unity Gain

checks as shown in paragraphs 4-4 and 4-5.

b. Check the plus and minus 26 volt supplies.

(During this check, the Model 604 should be connect-

ed to a 117 or 234 Volt ac power source).

We voltage for this check should be 26

1.

"OlkS 13 volts.

me ripple must be less than 3 Volts peed-

7..

to-pea!%.

Figure 8 shows a typical ripple obtained

3.

for the 26 volt supply.

NOTE

The voltage across these capacitors with

the Model 301s installed Will be approx­imately 29 volts.

Hence, they are re-

ferred to as unregulated 29 volt supplies.

Set the Model 604 GUARD-OFF Switch to GUARD.

1.

Check for continuity between the inter-shield of

the + INPUT Receptacle and the center pin Of the

UNITY GAIN OUTPUT, PROM + INPUT.

In like manner

check for continuity between the inter-shield of

the - INPUT Receptacle and the center pin Of the

"NlTY GAIN OUTPUT, FROM - INPUT.

If there is no continuity, check the respec-

2.
tive Model 301 Amplifier for continuity between
pin 2 and pin 15.

set the Model 604 front pane1 controls as

j.

follows:

I ’

FIGURE 8. Typical Ripple Obtained for the 26 Volt

S"PPlY~
and 5 milliseconds per division horizontal.

C.

the Model 604 connected to a 117 or 234 Volt ac

The scale is 1 "olt per division vertical,

Check the plus and minus 15 "olt supplies with

power line.

1. Adjust Cl% Adj. Potentiometer, RllZ, for

+15 "olts *30 millivolts. (Figure 17 shows R112).

2. Adjust -15" Adj. Potentiometer, RlZO, for

-15 volts 130 millivolts. (Figure 17 shows RlZO).
'rhe ripple in each case must be less than 2

3.

milli"olts peak-to-peak.

Figure 9 ShDWS typical

ripple for the 15 "olt supplies.

4. Monitor the plus and minus 15 "olt supplies
as the line voltage is changed from 105 to 125
volts ac far a 117 "olt line or 210 to 250 "olts

for a 234 volt line.

"olt supplies should be less tnan 100 millivolts.

The voltage change in the 15

5. Return the line to 117 or 234 "olts ac.
Check the regulated pl"s,a"d minus 21 volt

d.
supplies of both Model 301s. Pin 6 and pin 10 of
the Model 301s on the underside of the PC board are

I

14

0373

FIGURE 9. Typical Ripple Obtained for the 15 Volt

SUPPlY.
tical, and 10 milliseconds per division horizontal.

the test points for the -21 Volt supply and t21 volt
supply respectively. Figure 1.5 shows the location
Of these test points.

test points should be +21 and -21 volts i* VOltS
respectively.

The scale is 1 millivolt per division ver-

1. The voltage at the positive and negative

AR102 Unregulated

+29V Test Points

AR101

Unregulated

+29v

Test Points

I

FIGURE 10. Typical Nipple Obtained for the 21 "01
S"PPlY.

vertical, and 5 milliseconds per division horizon­tal.

The stale is 10 millivolts per division

Unregulated

*2@.7

Test Points

0373

-15v

Test Point

AR101

Common Mode

Adj. (Cl14)

I

A~102

I

Common Mode Adj.

(R148)

.15V Adj

(R120)

+15v

Test Point

+15v Adj.

(R112)

Zero Center

Adj. (R158)

Full Scale

.

\-Adj. (~161)

15

On the underside of R-195, jumper the sup-

b.
pression voltage to law as shown in Figure 14. The
suppression voltage is available at one input of
the AR101 Model 301.

Voltmeter to the Model 604 UNITY GAIN OUTPUT,

FROM + INPUT.

Repeat the procedures in subparagraph 1 a-

2.

bove using the UNITY GAIN OUTPUT, FROM - INPUT

‘Miust the AR101 Model 301 zero

Connect a Keithley Model 662 Differential

1.

and the AR102 Model 301.

Remove the jumper attached in subparagraph

3.

il-4b above.

set the Model 604 VOLTS Switch to

.OOl and zero the Meter with the Model 604 SUP­PRESS Controls. when completed retUrn the VOLTS
Switch Setting to 1.

Connect the UNITY GAIN OUTPUT, FROM + INPUT
tn"im ac counled Model 561 Oscilloscooe and set it
on the 1 millivolt per division vertical scale.

Observe the oscilloscope far high frequency oscil-

lations as the Model 604 VOLTS Switch is stepped
from 1 through .OOl settings.

observed, it can be corrected by replacing the 1.2

If oscillations are

microfarad capacitor Cl03 in the Model 301.

Set the Model 662 dials to zero and the null

3.

switch to 10 millivolts. The Model 662 Should in-

dicate at or near zero.

A large transient generated when the Model

241 output switch is charged from stand-by
to an causes a zero shift which results in
erroneous readings.

me correct method to

use is to de.1 out zero Volts the" turn the

output switch to on.

b. With the Model 241 at zero volts, release the

Model 604 ZERO CHECK Button *or the + INPUT Recap-

tack and note that the Model 662 ""11 remains the
same.

1. Rpply a positive 10 volts with the Model

241. The Model 662 null indication should not
chancre more than 0.5 millivolts and tvDicallv is
1es~~tte.n 0.2 millivolts. A change 0:'0.5 milli-

volts indicates a unity gain of 50 pp.

2. Return the Model 241 to zeqo Volts. me

Model 662 null should return to the original read-

ing.

Repeat the procedures in above paragraphs a

anz'b with the Model 241 connected to the Model 604

- INPUT Receptacle and the Model 604 UNITY GAIN OUT­PUT, FROM - INPUT Terminal connected to the high
terminal Of the Model 662.

‘I-6. S"PPRESSION AND METER CALIBRATION.

set the Model 604 front pane1 contacts as

fGi0ws:

Do not mistake normal output noise for
oscillation.

Normal output noise is

approximately 1 millivolt of grass and

I*0 cycle ripple.

Connect the UNITY GAIN OUTPUT, FROM - INPUT

d.

to the Oscilloscope and repeat the procedures of

paragraph 4-4~ above.

UNITY GAIN CHECK

4-5.

set the Plcde1 604 front pane1 COntrOlS as

a.

follows :

connect a Keithley Model 241 Voltage Supply

1.

to the yodel 604 + INPUT Receptacle and to the

low terminal of the Keithley Model 662 Differen­tial Voltmeter. Make sure, upon connection, that
the Model 241 is dialed for zero volts and that
the output is on.
the yodel 662 is not attached between low and

ground of the Differential Voltmeter.

Connect the Model 604 UNITY GAIN OUTPUT,

2.

FROM + INPUT Terminal to the high terminal of the

Ensure, also, that the link on

Model 662.

b.

Model

connect the Model 604 AMPLIFIER OUTPUT to the

7050 Digital Voltmeter.

Check to make sure that the Model 604 SUPPRESS

Controls are able to adjust the output far greater

than plus and minus, 10 volts.
for exactly 10.000 volts (10.000 volts is achieved

when the yodel ,050 alternates between 9.99 and

men set the output

10.00).
Adjust the Full Scale Potentiometer, RI61

(F;gure 17) , for full scale meter indication.

Set the VOLTS Switch to .OOl and zero the

..:,1 604 output and. meter.

1. Set the VOLTS Switch to 1 and adjust the
FINE ADJ SUPPRESS Control for exactly 0.000 Volts
at the output, if necessary.

16

0373

me output voltage nl”5t he less than 6 volts

2.
peak-to-peak (this is 90 dB of rejection at the
amplifier gain of 104). Typically the minimum
output will be less than 3 volts peak-to-peak and

will be composed basically of second harmonic.

When completed with the above tests, zero

3.

check both Model 604 INPUT Receptacles.

FIGURE 13.
at 1 kHZ. me scn1c is 2 volts per division verti­Cd, and 1 millisecond per division horizontal.

Null Obtained with the Signal Generator

I I I

2. The output voltage m"St he less than 20

volts peak-to-peak (this is 80 dB of rejection at

the amplifier gain of 1041. Typically the mini-

mum output Will be less than 8 YOltS peak-to-peak

and will be composed basically Of second harmonic.

When completed with the above tests, zero

3.
Check both Model 604 INPUT Receptacles.

e. If, in either or both of the preceding checks
of paragraphs c and d, the minimum output exceeds
the stated limits, then the probable cause is high
second harmonic generated by intfqrated circuit

amplifier aAl01 (Figure 14).

If this is so, re-

I

4.

‘UNITY GAIN OUTPUT Terminals with the Oscilloscope,

The signal at the input, monitored at the

should be 100 millivolts peak-to-peak or greater.

0373

Abe meter noise, excluding drift, should

),

a)

be less than 80 millivolts peak-to-peak.

b) The output noise, excluding drift, must

be less than 200 millivolts RMS.

set the HIGH CUT iiz Switch to 0FP and observe

C.

the output noise.

It should be less than 600 mill.i-

"OlJcS RMS.

OBFSET CURRENT CHECK.

4-9.

This check requires a

special, easy-to-construct, fixture. The fixture

consists of a triaxial connector Keith& part
number cS-141, and a shielded 10
that connects the center pin of W-141 to ground.

12

ohm resistor

The fixture must be shielded to eliminate excessive
noise pickup.

connect the Current Offset Pixture to the

b.

Model 604 + INPUT Receptacle and zero the meter

with the 1012 ohm resistor in the Fixture, this
results in lo-l3

Release the + ZERO CHECK Button and note

2.

the offset cuxn?nt.

ampere (this is within 2 major divisions of

10-14
zero).

C.

The offset may be positive or negative.

Repeat the procedure Of above paragraph b

ampere full scale.

It should be less than 2 x

Set the VOLTS Switch to .l.

1.

In conjunction

with the Fixture on the - INPUT Receptacle.

4-10.

234 VOLT AC OPERATION CHECK. (For 117" units)

tion is now 10 millivolts full scale either side of

zero.

After a one hour warm-up, the Model 604 m"St

C.

not drift more than 4 millivolts per week or more

than 0.3 millivolts per W.

While the drift specifications is in terms Of

d.

a week, it may be possible to determine the drift
within 24, 48 or 72 hours rather than run the full
week.

drift due to temperature, the drift may be calcu-

After the one hour warm-up and excluding

lated as shown in the subparagraphs below.

1. After 24 hours, if the drift is less than

0.55 millivolt, the instrument meets specifica­tions. 1

After 48 hou?s, if the drift during the

2.
last 24 hours is multiplied by six and is added
to the drift during the first 24 hours and the
total is 4 millivolts or less, then the Model 604
meets specifications.

3. after 72 hours, if the drift during the last
24 hours multiplied by 5 is added to the drift of
the first and second 24 hours and the total is 4
millivolts or less, then the unit meets the week's
drift specifications.

Since temperature can be a major contributor

e.

to drift (up to 0.3 millivolt per W allowable),
the temperature should be recorded along with the

drift.

f. 1f the drift of the Model 604 is excessive,

age the instrument and redrift.

If it is still ex-

cessive, then a probable cause of poor Model 604
drift is excessive Model 301 Amplifier drift. One
or both of the Model 301s may have excessive drift.
or, it may be that the drift of that particular
pair of Model 301s is additive, in which case re­placing one Model 301 might ml"e the problem.

set the Model 604 front panel controls as

a.

follows:

i

set the LINE VOLTAGE Switch on the rear panel

a.

of the Model 604 to 234" and plug the unit into a

234 "Olt ac 50 or 60 HZ power sO"rce.

set the VOLTS Switch to ,001 and Zero the

b.

meter with the SUPPRESS Controls.

zero on this range is sufficient indication that
the instrument is operative at 234 Volts ac.

Being able to

Unplug the instrument from the 234 "olt ac

y+ source and return the LINE VOLTAGE switch to

4-11.

DRIFT VERIFICATION.

set the Model 604 fro"t panel controls as

a.

f0ll0VS:

LOCK

LOCK
VOLTS Switch
HIGH CUT HZ Switch
cxmD-OFF Switch
METER Switch

connect the Model 604 AMPLIFIER OUTPUT Recep-

!a.
tacle to the Keithley Model 370 Recorder.
Recorder attenuator to 10 Volts.

Recorder calibra-

01
OFF
OFF
OFF

18

set the

connect the Keithley Model 260 Nanmolt Source

b.

to the Model 604 + INPUT Receptacle. Monitor the

Model 604 AMPLlFlER OUTPUT Receptacle with the Model

7050 D"M.

Starting with setting of 1, check all the set­t&s of the VOLTS Switch down to .OO1 for 10 volts
h18 at the 0utplIt.

This is an indication of from

9.90 Volts to 10.10 volts on the Model 7050.

0373

;'

ca.1.

C.

Set the IIIGH CUT HZ Switch to the settings

d.

indicated in Table 10.

dB clown from the 2 Volts RMS leference at some fre­quency within the frequency limits listed for each

setting.

If the output does not roll Off at 3 dB With-

ineihe frequency limits listed, the applicable high
cut capacitor is out of tolerance.

connect the Model 260 NanO”Olt source tc’ the

b.

Model 604 + INPUT Receptacle and the kxlel 7050 D”M

to the AMPLIFIER OUTPUT Receptacle.

Apply + 1 Volt to the + INPUT Receptacle.

1.

'The output voltage should he 10 Volts ?18 (9.90

to 10.10 Volts).

Connect a Keithley Model 5155 High Megohm

stLard 1012 ohms resistor in series between the

Model 260 and the + INPUT Receptacle.

Apply + 1 Volt to the + INPUT Receptacle.

3.

me output voltage must come to within 100 milli­volts of the voltage noted in subparagraph 1 a­hove.
ohms or greater.
quire a few minutes for the reading to come in

and stabilize.
c.

Volt an'3 the - INPUT Receptacle.

onaChe

actual output voltage and use this as a reference to

determine the accuracy of the Model 6041 ranges.

This indicates an input impedance of 1014

Repeat the procedure in paragraph b using -1

Check the full Scale accuracy Of the Model 604

1 Volt range per paragraph d-12.

Check that the output is 3

Note, however, that it may re-

Note the

set the equipment up in feedback picommeter

b.
configuration as specified in the following sub­paragraphs.

set the Model 6041 + INPUT and - INPUT

1.
S.vitches to the 106 position. Attach the TO 604
INPUTS + and - Connectors to their respective

Model 604 INPUT Receptacles.

set the Model 504 front pane1 contrOlS as

2.

folloWS :

Connect a Model 7050 D”M to the Model 604

3.

AMPLIFIER OUTPUT Receptacle.

Remove the link from between low and ground

4.

on the rear of the Keithley Model 261 Picoampere

source. connect the Model 261 to the MO&l 6041
+ INPUT Receptacle through a Keithley Model 6012
coaxial-to-Triaxial Adapter.

Check the

&",h 1011
Model 261
All ranges must be within f2% of the Model 604 full

scale accuracy (actual OUtpUt voltage eo.20 volt,.

After checking the accuracy set the Model

1.
6041 + INFUT s,litcll to 1011 and the Model 604 +
mm csmx mtton to mcK and the GUARD-OFF switch

to OFF.
ammeter configuration.

Release the + ZERO CIIECK BUtto" and note

2.
that the meter reading climbs slowly to approxi­mately l/2 scale indication.

When completed, set the + ZERO CHECK Button

3.

to mm and the GUARD-OFF Switch to GUARD.

Repeat the procedure of paragraph c above with

d.
the Model 261 connected to the Model 6041 - INPUT
Receptacle.

full Scale accuracy Of the 106

settings of the + INPUT Switc~lwith the

set for 1 x 10-S through 1 x lo-

This places the equipment in shunt pico-

ampere.

0373

FIGURE 14.

Top View Model 604 Chassis. Front pane1 faces up.

nents, PC boards, and switches. For Bottom View. see Figure 15.

Figure shows location of compo-

0373

21

Rl08 -

R116--

R107 -

RI06 -

RlO9

RI10

Rlll

Rll2

1 R113 1 ~158 i

R159

161
~148

~152

-RR151

-RI47

-RR149

R117 -

Rll9-

RIO2

R103-

R104-

R105-

Rl'20

1 R141

R143 R144

-R145

-R146

-RllE

-R142

FIGURE 17. Resistor Locations on x-195.

24

For Other component locations, see Figure 16.

0373

MODEL 604

ACCESSORTES

SECTION 5. ACCESSORIES

Model 6011 Input Cable

oescription: ‘rhe 6011 is a low-noise triaxial cable,
30” long, terminaeed by three color-coded alligator
clips. This cable mates directly wirh the triaxial

input.
no. CS-141 connector and part no. SC-22 low-noise cable.

Description: The 6301 is a guarded triaxial cable,
3 ft. long, terminated by a probe for making point-to­point measurements.

The cable is fabricated using a Keithley part

Model 6301 Guarded Probe

~->sc-22-ipJ&g

Model 1531 Gripping Probe

Application: The 6011 may be used for measurements

which require a rriaxial connection, especially when

the input LO is floated above CASE ground. The cable
permits full use af the Model 615:capabilities.

Application: The 6301 may be used for measurements

which require a triaxial cable with a guarded pfzbEhms
having an insulation resistance greater rhan 10

cs-141

Description: The 1531 is a triaxial cable, 3 ft. long,
terminated by a special gripping-type probe.

insulation resistance is greater than 10~0 ohms.

probe is rated for off ground measurements up t0 500 ”

The 1531

The

Hi

Lo Lead

Model 6012 Triax-to-Coax Adapter

Description: The 6012 is an adapter for mating the
triaxial input and UHF (caax) type c~nnecmrs. This
adapter can be used with Models 6101A, 61018, 6103A,
6102A, etc.

~~~licatio,,: the 1531 may be used for measurements
which require a triaxial cable. The probe permits

convenient connections to the circuie under test due

to the gripping feature.

0373

25

ACCESSORIES

Description:

MODEL 604

Model 4006 Rack Mounting Kit

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 instrument from bench

mounting to rack mounting. It is suitable for mount-

ing one instrument in one-half of a standard l9-inch
rack.

Itern

NO. Description

1 Top Cover, 10" 1 200168

2 Panel Adapter Plate 1 191588
3

Angle

4 Screw, 810 x 3/E" 4 ___
5 Connectina Plate 1 19154A

6 Screw, NT, x l/Z" 4

7
8 Top Cover, 13" 1 200158

Support 1 19157A

Angle 1

Qty. Per

Assembly Part NO.

Keithley

___
19147B

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 far use with either 10 inch or

13 inch deep instruments.

Application:

The Model 4007 converts the instrument from bench
mounting to rack mounting.

ing two instruments in a standard l9-inch rack.

26

It is suitable for mount-

Parts List:

Itern

No.

1

Top Cover, 10"

screw, $10 x l/2"

4
5

Co""eceF"g Plate
Screw, 810 x l/2"
Angle

8

Tap CoYer., 13"
Zee Bracket

9

10

Plate

WY. Per
Assembly Pare No.

2 20016B
8
1 19154A
‘

1

2 200158

1 19167A
1 197OOA

lceithley

___
__-

141478

0373

MODEL 604 REPLACEABLE PARTS

SECTION 6. REPLACEABLE PARTS

6-l. REPIACEASLE PARTS LIST: This section containe
a list of components used in this instrument for
user reference. The Replaceable Parte Ll~t describes

the individual parts giving Circuit Designation,

Description, Suggeeted Manufacturer (Code Number),

Abbreviations and Symbols

A A

Cb”ar Cb”ar
CerO CerO
Cer Trimmer Cer Trimmer
COmp COmp

DCb DCb
oesig. oesig.

EAL EAL
ETB ETB
ETT ETT

ampere
Carbon Variable

Ceramic Disc
Ceramic Trimmer
Composition

Deposited Carbon
Designation

Electrolyeic, Aluminum
Electrolytic, eubular
Electrolytic, tantalum

C

6-2. ELECTRICAL SCHEMATICS AND DIAGRAMS.
and diagrams are included to describe the electrical
circuits as discussed in Section 3.

Schematics

TABLE

F
we%

GCb
k

li

M
Mfr.
MtF

MY
NO.

Manufacturer’s Part Number, and the Keithley Part
Number. Also included is a Figure Reference Number
where applicable. The complete name and address af

each Manufacturer is listed in the CODE-TO-NAME
Listing following the parte list.

6-l.

farad

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

Meg (106)
Manufacturer
Metal Film
Mylar

Number

Sales Service Department, Keifhley Instruments, 1nc.
or your nearest Keithley representative.

b. When ordering parts, include the following

information.

n

I&
P0ly

Ref.

TC”
”
w

ww
ww”ar

ohm
pica (10-12)

Printed Circuit
Polystyrene

Reference

Tinner Copperweld
volt
watt

Wirewound
Wirewound Variable

6-3. HOW TO USE THE REPLACEABLE PARTS LIST. This
Parts List is arranged such that the individual types
of components are listed in alphabetical order. Main
Chassis parte are liated followed by printed circuit

boards and oeher subassemblies.

6-4. HOW TO ORDER PARTS.

a. Replaceable parts may be ordered through the

0373 27

1.

Instrument Model Number.

2.

Instrument Serial Number.

3. Part Oescripeion.

4. Schematic Circuit Designation.

5. Keiehley Part Number.

c. All parts listed ere maintained in Keithley
Spare Pate Stack. Any part not listed can be made
available upon request. Parts identified by the

Keichley Manufacturing Code Number 80164 should be

ordered directly from Keithley Instruments, Inc.

(Refer to schematic Diagram 228203 for circuit designations)

MODEL 604 REPLACEABLI? PARTS LIST

CAPACITORS

40 ”
40 ”
40 ”

Type

Mfg.
Code

Mfg. Keithley
Part NO. Part Ncl.

NG106A
C437AR/GlOO
C437AR,GlOO
C437AR,G100
C437AR/GlOO

40 v
40 v
600 v
20 v
40 v

40 ”
600 ”
20 v
200-300 ”
600 v

600 v
600 ”

600 ”
600 ”

600 ”
600 v

600 v
600 ”
200 v

75 ”
600 ”

Poly

ceru

73445
72982
05397
72982
72982

72982

77.982
72982

72982
72982

72982
72982
72982
56289

56289
72982

C437AR,G100
ED-.001
KlR2JZOK

538-037

ED-10
ED-5

ED-22

C182-10M
CEO-100M
C150-10OM
C150-100M

C150-100M
C150-100M

C150-100M
C22-.oom
C80-1.2M
C150-100M

CEO-100M
C22-.OOlM
CSO-1.m
c175-7-2%
CZZ-1OP

a*-5P
c22-22P

c*2-1OP
cz*-33P

Dfsig. Description

Receptacle, triaxial, +mPUT
Receptacle, triaxial, -INPUT
Plug, triaxial, mate of of JlOl
and J102 (2 n?q'dl

J105 Receptacle, NC, FROM +INP"T UNITY

GAIN OUTPUT o"lil. NO. "G-1094,",
Plug, BNC, mate Of 5104 an.3 J105, 2
req'd (Mil. No. K-88/U)

J106
,710,

PlOZ

__-

Card edge Connector to AR101
car-3 edge connector to AR102

Plug, coaxial, +Input of AR101
Hwded hield for P102
coaxial Receptacle, mate of p102

P103

___
___

Plug, coaxial,
Hooded Shield for P103
Coaxial Receptacle, mate of PI03

-Input Of AR102

*Nommal Value, factory set.

Mfg.
Code

95712
95712

95712

02560
02660

02660
02660
09922

09922
02660

02660
02660

02660
02660
02660

02660
02660

02660

Yarc NO.

33050-NT-34
33050-w-34

30197-l

SO-PCZF
so-MC2M

31-221

FXR30775
FXR2275
FXR217-5

Keithley
rart NO.

CT-32

c-33

Fig.
Ref.

:

2

__

2

2

__
__
__

_­__

28

0373

Fig.
nof

-­__

--

Description

Mfg. Mfg. Keithley
CO& Part NO. Part NO. Ref.

Fig.

DS-101
FlOl (117")

FlOl (234V)

Pilot Light (Mfg. NO. 2100)
Fuse, slow Blow, l/8 A (Mfg. Type HDL)

FUBB, slow mow, l/16 A wq. Type HDL)
Fuse Holder (Mfg. NO. 3420121

14

2

16

Circuit
Desig.

"dUl?

Rating

lO%, l/Z w
10%. l/2 w

lo%, l/2 w

108, l/2 w
108, l/2 w

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

IO%, l/2 w

l/4 w
108, l/2 w
108, l/2 w
lo%, l/2 w

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

lo%, l/2 w

I.,4 w

lO%, l/2 w

258, 2 w

l/2 w
:i: l/2 w
18, l/2 w

l%, l/2 w

l/2 w

18,
l%, l/2 w
l%, l/2 w

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

l/2 w

=a,
l%, l/2 w

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

l/2 w
:;: l/Z w
18, l/Z w

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

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

l/Z w

=*,
1%. l/Z w

O.l%, l/2 w

TYP

Mfg.
Code

Mfg.
Part NO.

EB

EB
EB
EB
WIT-I.4

EB
series 62
CEC
CEC
CEC

CEC
CEC
CEC
CEC

CEC
CEC
CEC

CEC
CEC

CEC
CEC
cm
CEC
CEC T-l

Keithley
Part NO.

Rl-1K
Rl-1K
Rl-1K
Rl-1K

Rl-*.a
Rl-2.2K
Rl-1K
Rl-15
RI-N

Rl-1K
ill-15
Rl-1K
Rl-4.x
RP67-2K

Rl-5.m
w-lo-1OK
R94-4.02K
R94-4.02K
R94-4.OZK

R94-4.02K

R94-4.02K

R94-4.02K
R94-4.OZK
R94-4.OZK

R94-4.02K

R94-1%
R94-15K

gr::::
R94-1%

R94-15K
R94-1%
R94-15K

R94-1%

R94-402K
R94-40iK
R94-801
R94-801
R135-10K

Fig.
Ref.

17
17
17

::

::
17

17
17

17

17

17

17

Circuit
"eslg. Value Rating

R146
R147
R148
H149
RliO

P.156
K157
Ii158
K159
R160

R161
R162
R163
K164

MU 07716 CEC T-l
MU 07716 CEC T-l

Cb
MtF 07716 CEC T-l
MW

37942

07716

MTC-L4
CEC T-l

CEC T’-1
CEC T-l
CEC T-l
CEC T-l
CBC T-l

R135-3K
R135-10K
RP67-2K
R88-28.X
R88-9.76K

RP67-1K
RI-47

R37-109
R37-109

Circuit

Circuit
oesig.

Mfg.
Code

Desxiption

Potentiometer, FINE AN. (P.122)
Knob, Fine Adj.

Rotary Switch with components, Medim and
coarse
Knob Assembly, Medium Switch
Knob Assembly, Coarse switch

Rotary Switch less components, VOLTS
Rotary Switch with components, Volts
Knob Assembly, Volts Switch

Rotary Switch less components, HIGH CUT HZ

Rotary switch with components, High Cut Hz
Knob Assembly, High Cut HZ Switch

Mfg.
Part NO.

Keithley
Part NO.

209068
19298C
FE-5
FE-6

Mfg.
Code

80164
80164

80164
80164

80164
80164
80164

80164
12697

80164

Keithley
Part NO.

14376A

14376A

14376A

14376A
SW-45
SW-151
SW-165

14838A

80164 SW-267
80164

80164
80164

229738
16993A
16995A

SW-266

229740
1483811

Fig.
Ref.

Fig.
Ref.

1
1

1
1

1

-­1

1
1
1
1

__

1

31

CiZCC”ik
oesig.

Number

Mfg.

Code

Keithley
Part NO.

Fig.
Ref.

Circuit
msig.

JlOl Rweptacle, triaxial, +INPUT 95712

___

Plug, triaxial, mate of JlOl 95712

Description

Mfg.
Code

cap, +INP"T Receptacle 02660

5102
__-

___

Receptacle, triaxial, -UWUT
Plug, triaxial, mate of .slO*

-INPUT Receptacle

CaP,
J103 Binding Post, Gm 08811
PlOl

___
PlOZ Connector, triaxial, TO 604 INPUT:-

Connector, triaxial, To 604 nut:+ 95712

Connector Assembly with cable

connector ASsembly with cable 80164

80164

95712

RESISTORS**

Circuit
Desig .

RlOl
RlOZ

R103

R104
FL105

R106

R107
R108
R109
RllO

Rlll
Rll2

Rating

+3-o%, l/R w GCb 63060
+3-o%, l/R w
+3-o*, l/R w

18, 2w
18, 1/m DCb

18, 1/m DCb
+3-o%, l/R w
+3-o%, l/R w
+3-o%, l/R w

1%. 2w
18, 1/m

l%, 1/m

Type Code

GCb
GCb 63060 RX-1 RZO-109
DCb

GCb 63060 Rx-1
GCb 63060 RX-1
GCb 63060 RX-1 SO-109

DCb

DCb
DCb

Mfg.

63060 RX-1
91637

91637

91637

91637
91637

91637

Mfg.
Pa?-+ N"

Keithley

Part NO.

33050-w-34 cs-181
30197-l m-141
31-007 CAP-18

x3050-NT-34 cs-181

30197-l CS-141
31-007 CAP-18

33-286 BP-15

30197-l CS-141

30197-l a-141

Mfg. Keithley

Part NO. Part NO.
RX-1

DC-2
DCF-l/2

DCF-l/2

;;;I:$
R14-100M

R12-10M
R12-1Mll

;;;:;;10

DC-2
DCF-l/2

DCF-l/2

R14-100M
RlZ-1OM

R12-1M

Fig.
Ref.

-­__

-_
__

--

-_

-­__

__

-­T.t.

Fip .

rce ;

3

3

__

3

--

3

__

Ci7X"it
oesig.

sl.01
_--

5102

Description

Rotary Switch, +INP"T

Knob Assembly, +Input Switch

Rotary Switch, -INPUT

Knob Assembly, -Input Switch

Mfg. Keithley
Code

Part NO.

80164 Model 3011 3
80164 16338A

80164
80164 16338A

Model 3011

Fig.
iwf

-_

__

3

** A complete set of resistor for the Model 6041 may be purchased from Keithley Instruments under the Model

Number Of 6033. The Model 6033 contains resistor pairs matched to within ?2%.
ordering resistors for the Model 6041 the user purchase matched pairs to assure accura-~y,

32

It is advised that upon

0373

(Based on Federal Supply Code far Manufacturers, Cataloging mndbook 114-1).

01121 Allen-Bradley Corp.

1201 So"th 2nd Street

Milwaukee, wis.

01295 Texas Instruments, Inc.

semiconductor-Components Division
13500 North Central Expressway
Dallas, Texas 75231

02660 Amphenol Corp.

2801 South 25th *Yenlie
Broadview, Ill. 60153

02734 Radio Corp. of merica

Defense Electronic Products
Camden, N. J.

04713 Motorola Semiconductor Products 1nc

5005 East hICkwe Road
Phoenix, Adz. 85008

TABLE 14.

53204

Code List of Suggested manufacturers.

28520 Heyman Mfg. co.

3,942 Mallory, P. R. and Co., Inc

56289 Sprague Electric co.

63060 Victoreen Instruments co.

71400 Bu~mann Mfg. Div. of

147 N. Michigan Avenue
Kenilworth, N. 3.

3029 E. Washington Street
Indianapolis, Ind. 46206

North Adams, Mass.

5806 Ho"gh AYenue
Cleveland, Ohio 44103

McGraw-Edison Co.

2538 w. University street
St. LOUiS, MO.

Cleveland, Ohio 4410,

0,263 Fairchild Camera & Instru. Corp.

0,716 IRC, Inc.

I

08811 GI, Electronics Division of

12040

1269,

12954

Semiconductor Division
313 Frontage Road

Mountain View, Cal.

2850 Mt. Pleasant

Burlington, Iowa 52601

GL Industries Inc.
300 mrvard Avenue

iiestville, N. J. 08093

National Semiconductor Corp.

Commerce Drive
Post Office BOX 443
Danbury, corm. 06813

Clarostat Mfg. CO., Inc.
Lower washington Street
DOYer, N. H. 03820

Dickson Electronics Corp.

302 s. Wells Fargo Avenue

Scottsdale, Arizona

73445 Amperex Electronic Co., Div. of

75042 IRC, Inc.

75915 Littlefuse, Inc.

80164 Keithley Instruments, Inc.

93656 Electric Cord co.

95712 Dage Electric Co., Inc.

North American Philips Co., Inc.
Hicksville, N. Y.

401 North Broad Street

Philadelphia, PA. 19108

800 E. Northwest my.

Des Plaines, 111. 50016

28775 Aurora Road

Cleveland, Ohio

1275 Bloomfield Avenue

Caldwell, N. J.

Hurricane Road
Franklin, Indiana

44139

MODEL 604

DSCript*O*

1) Chassis

11) Front Panel
To* Co"er Bssembly

12) Cmx, Sheet Metal

13) screws
Handle Assembly

14) Handle

15) screws #6-32 x 3/P R.H. Slotted
Bottom cover Assembly

2) Cover

3) Fastener

Feet Assembly

4) Feet

5) Ball

6) Screws f/8-32 x 3/8" Philli,m, Pan Head

Tilt Bail Assembly

quantity

Per fLasemLJ1y

1
1

__

1 24561D
4

_- __

1 HH-18
2

1 17149c
2

_- __

4
4 FE-6
4

_-

K‘Zithley
Part NO.

22636B
22306C
20906B

__

_-

1929%

PA-54

FE-5

-­_-

7) Bail

8) Right Assembly

9) Left Assembly

10) Screws //6-32 x l/4" Phillips, Pan Head

34 0373

1 17147B

1
1
2

19206B
19205B

_-

MODEL 604

REPLACEABLE PARTS

FIGURE 18.

Top Cover Assmbly.

0373

FKURE 19. Bottom Cover Assembly.

35

r

r------

I

11

-02

./

I

I I

.3

,

r---­I

I

---7--

I -2

'~pLy,, +

h

OFF0 0

I

(I -

I

u

I

I
I

A A

0

C

I (1 -

Y

I IL t-l- ..,

I I

CN604-2
Applies to Manual Printed

January, 1977.

MODEL 604 ELECTROMETER AMPLIFIER

Sheet I of I

INSTRUCTION MANUAL

CHANGE NOTICE

INTRODUCTION:

duct performance and reliability, it is often necessary to make changes
to Instruction Manuals to reflect these improvements.

Instruction Manuals occasionally occur that require changes.

due to printing lead time and shipping requirements, we can't get these

changes immediately into printed Manuals. The following new change in­formation is supplied as a supplement to this Manual in order to provide

the user with the latest improvements and corrections in the shortest

possible time. Many users will transfer this change information directly

to a Manual to minimize user error. All changes or additions are indi-

cated in ita2ics.

CHANGES:

Cl14 1.9pF-15.7pI

Since Keithley Instruments is continually improving pro-

Also, errors in

Sometimes,

200-300 v

13050

C-284-l.QP-15.7P 16

KEITHLEY INSTRUMENTS, INC.

28775 AURORA ROAD

CLEVELAND, OHIO 44139

SERVICE FORM

MODEL NO.
NAME

COMPANY
ADDRESS CITY

Describe problem and symptoms using quantitative data whenever possible (enclose

El :

readings, chart recordings, etc.)

Show a block diagram of your measurement system including all instruments connected

El

(whether power is turned on or not). Also describe signal source.

SERIAL NO. P.O. NO. DATE

(Attach additional sheets as necessary).

PHONE

STATE

ZIP

List the positions of &l controls and switches on both front and rear panels of

' the instrument.

Describe input signal source levels, frequencies, etc.

El

j-g List and describe all cables used in the experiment (length, shielding, etc.).

List and describe all other equipment used in the experiment. Give control settings

' for each.

Environment:

El

pg Additional Information. (If special modifications have been made by the user,

Where is the measurement being performed? (Factory, controlled laboratory,
out-of-doors, etc.)
What power line voltage is used?
Ambient temperature?
Other

please describe below.)

OF.

Variation?

Variation? Frequency?

"F. Rel. Humidity?

REV 0774