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INSTRUCTION MANUAL
MODELS 15OA, 150AR
MICROVOLT-AMMETERS
WARRANTY
We warrant each of our products to. be free
from defects in material and workmanship. Our
obligation under this warranty is to repair or
replace any instrument or part thereof (except
tubes and batteries) which, within a year after
shipment, proves defective upon examination.
To exercise this warranty, contact your Keithley
field engineering representative. You will be
given assistance and shipping instructions.
REPAIRS AND RECALIBRATION
Keithley Instruments and its international dis-
tributors maintain complete repair facilities.
To insure prompt repair or recalibration service,
please contact your Keithley field representative
before returning the instrument.
Estimates for repairs, normal recalibrations, and
calibrations traceable to the National Bureau of
Standards are available upon request.
MODEL 150A CONTEXTS
TABLE OF CONTENTS
section Page Section Page
I. INTRODUCTION. . . 1-l D. Zero Suppression. . . . . . 4-2
E. Other Controls. . . . . 4-2
II. SPECIFICATIONS . 2-l F. Power Supply. . . . . . . 4-2
III. OPERATION . . 3-l V. MAINTENANCE. . . . . . 5-l
A. Operating Controls. 3-l Trouble-Shooting. . . . 5-l
B. Preliminary Set-up. 3-l Excessive Output Noise. . 5-l
C. General Precautions 3-2 Output Not Zero . 5-2
D. Measuring Voltages. 3-3 220-Volt Operation. . . 5-2
E. Measuring Current . 3-3
F. Other Applications. 3-3 VI. REPLACEABLE PARTS . . . . 6-1
IV. CIRCUIT DESCRIPTION 4-l Models 150A, 150AR Replaceable
Parts List . . . . 6-2
A. Input Circuit , . . 4-l Model 1501 Replaceable Parts
B. AC Amplifier. . . 4-l List............ 6-7
C. DC Amplifier. . . . 4-l Model 1502 Replaceable Parts
List............ 6-7
Voltage Resistance Chart. . 6-9
Schematic Diagram 12188D. 6-11
9~ Change Notice
* Yellow Change Notice sheet is included only for instrument modifications
affecting the Instruction Manual.
0764R i
MODEL 150A 1NTR0lxlc!rI0n
SECTION I - INTRODUCTION
The Model 150A Microvolt-Ammeter is a stable, versatile instrument
for measuring extremely low level DC signals. It functions as a
voltmeter from one microvolt to one volt full scale, and as an
ammeter from one milliampere to one hundred micro-microamperes
full scale. It also operates as a DC amplifier with gains up to
ten million for driving recorders.
The very low noise level of the Model 150A, together with its long
term stability make it ideal for many measurements requiring ex-
treme power sensitivity.
Typical applications include measuring the output from strain gages,
thermopiles, thermocouples, bolometers, phototubes, ionization chambers,
scintillation counters, and barrier layer cells. Other apnlications
are found in cell studies, measurement of electrochemical potentials,
electrolytic corrosion studies, molecular weight analysis and Hall
effect studies.
In addition to its use as a direct indicator of minute potentials
and currents, the Model 150A may also be used as a null detector in
Wheatstone or Mueller bridges, or with an external voltage source as
a meg-megohmmeter.
An important feature of the instrument is zero supnression up to
100 times full scale, in place of the usual more limited meter zero.
This permits measurements of small signals in the presence of large
thermal EMF's or other masking DC signals.
l-l
MDLRL15OA SPECIFICATIONS
SECTIONII - SPECIFICATIONS
VOLllvIETw sF%xxlxcATIoRS
RANCE.: Thirteen overlapping ranges in lx and p steps from one micrcvolt
to one volt full scale on a zero-center meter.
ZEROAccuRAcy: 2% of full scale on all ranges.
STABILITY: After one hour, +O.lmicrovolt +2 x 1O-5 R microvolt drift per
day, where R is the source resistance in ohms.
NOISE: With the input shorted, less than 0.03 microvolt peak-to-peak (0.006
nlicmvo1t m3). At various cmrce r&sistances, she noise peak-to-peak in
microvolts is given by E = 6.5 x lo- (R + ZOoO)~, since the Input resist-
ance is added to R, the source resistance.
INFUT RHISTANCE: Tabulated below; if input shunting resistors are requested,
the Input resistance is loo kilohms on MICROVOLT ranges and one megohmon
MILLIVOIiT rages. maximum murce resistancea specified on the l- and 3-
microvolt ranges also hold with shunting input resistors.
RAliOE Input Resistance Max. Source Resistance
lmicrovolt 1 megohm 10 kilohms
3 micrcvolts 3 megohms 30Mlom
10 microvolts 10 megohms 100 kilohms
30 micrcvolts 30 megohms 300 kilohms
loo microvolts and 90 megohms 1 megohm
above
RESPONSE SPEE!D (1% to VC$ of final value): Depends on ~0urc.e resistance.
With maximumspecified source resistance, less than one second on all ranges
except the l-microvolt range, where it is within two seconds.
With source resistance less than l@ of the maximum, response is within 0.5
second, except on the l-microvolt range, where It is within one second.
VOLTAOE ZEROSUPPRE!SS:Ranges of lo, 100, loo0 and 10,OoO micmvoltS; and
0.1, 1, 10 and loo millivolts, corresponding to the MICROVOLTS MILLIVOLlB
and
positions on the FUNCTION switch. Accuracy of the buckout ranges Is about
2% and stability is such that 100 times full scale may be suppressed.
RANLIES: Fi een overlapping rangee in IX and p steps from 0.1 SIIIJA-~~C~-
ampere (10' in smpere) to loo0 microamperes (10'3 ampere) on a zero-center
meter.
STABILTPY: After one hour', 22 x lO-ll ampere per day.
0763 2-l
sPFCLF1cATI0NS MODEL15OA
NOISE: Less than 2 x 10-12 ampere peak-to-peak.
ACCURACY:Within 3% of full scale on all ranges.
VOLTAGE DROP: 100 microvolts on the MILLI-MICROAlmZRESranges, one millivolt
on the MICROAMFERESranges.
INFVT RESISTANCE: On the MICRCAMPERES ranges the input resistance is equal
to 10-3 divided bx&the range in amperes. On the MILLI-MICROAMPERES ranges
it is equal. to 10 divided by the range in amperes.
RESPONSE SPEED: One second maximum, except on the 0.1~milli-microampere
range, where it Is two seconds maximum.
CURRENT ZEROswpREss: Up to 100 full scales on any range. Accuracy and
stability are the same as for the voltage zero suppress.
GENERAL
SPECIFICATIONS
ouTHl* + volts at five milliemper s for full-scale
-I.0 deflection on any range.
Gain of dc amplifier is from 10 to lG 7 .
RmT.sTANcE: Less than 10 dms within
OUTPUT the emplifierpassbend.
60 CFS REJ-EZTION: Greater than 50: 1.
-LNHJl!ISOLATION: Neg8tiVe terminal may be grounded or floating up to +&JO
volts with respect to the case. A link is provided for grounding the negative
terminal to the case.
CONNECTORS:
Input: Special receptacle.
Rear Output: Amphenol 8GPC2Freceptacle.
Front Output (Model15OAR): Binding posts.
'IUBE COMPLEMENT:TWO~~86, one 0~2, one l2~T'7, two 12~x7, one 12&A, one 5651,
one 6~~6, one 6084.
TOWER: Lo5-125 v0lt.s OP 210-250 Mlts, 50 watts, 60 CPS. 50-CPS models on
special order.
AccEssoRIEs SUPPLIED: Model 1501 Low Thensal Test Leads; a length of low-
thermal solder; mating output plug.
AVAILABLE: Model 1502 Low Thermal Connector Pair.
ACCESSORIES
DIMENSIONS: Model 15OA: U.-l/6 inches high x 7$ inches wide x ,13* inches deep.
Model 15OAR: 7 inches high x 19 inches wide x 13 inches deep.
NET WEIGRTz Model 150A: 20 pounds.
Model 15OAR: 22 pounds.
2-2 0763~
I&XIEL15OA OFTRAl'ION
SECTIONIII - OPElRATION
A. o- c0mR0J.s
The controls of the Modell5OA exe simple and conveniently placed.
Their functions are as follows:
ON switch is located to the right of the panel meter.
l?UICTION stitch selects the fkuction which is to be used: MILLI-
vom, MIcmvoLm, MICRO- or MILLI-MICROAMPERES.
RANGE switch selects the full scale multiplier of the function
selected by the IBJNUTION switch. Note that the .3 and .l posi-
tions are to be used for CURRENT measurements only.
ZEIiU SUPPRESScontrols consist of the zero RA!K$E switch, which
selects the coarse range of suppressing voltage in discreet steps
and the zero SET potentiometer, which gives continuously variable
fine control, including settings through zero.
B. PBELrnY SET-UP
Connect the instrument to the power line. Unless otherwise marked the
unit may be used on IL7 volt, 60 cps line. To convert to 220-volt
operation, refer to the MAINTENANCE section. Athree-wire line cord
is furnished, which grouuds the cabiuet. If a three-wire receptacle
is not available, use the two-pin adapter furuished, and ground the
third lead to e.n external ground.
Set controls as follows:
FlJfEIIION: MILLIVOLTS
RANGE: loo0
.zEm s-s: OFF
Inptl~ Short the input leads together.
0763~ 3-l
MDDEL 150A
C. GENERAL PRECAUTIONS
1. Source Resistance - In SECTION II - SPECIFICATIONS un-
der INRJT RESISTANCE, the maximum source resistance for use with
each voltage range is specified. Reasonable operation is possible
with source resistance up to ten times greater than those specified;
however, the measurement will suffer from a considerable decrease in
speed of response, and measuring accuracy. If the instrument is
left completely open-circuited, the meter will generally drift off
scale on any voltage range. On current ranges this does not happen
because of the input shunting resistors.
2. Shielding - Since the instrument operates with a modulator fre-
quency of 120 cps, it is no% generally sensitive to 60 cps pickup
unless it is large enough to overload the amplifier. The pickup
may be a source of difficulty when using the amplifier with high
impedances on the more sensitive voltage ranges and on the two or
three most sensitive current ranges. In these cases it is desirable
to shield the leads and the sources as completely as possible. In
some cases a simple low-pass filter at the input to eliminate fre-
quencies of about 1 cps and above will be helpful. No use is made
of an input filter in this instrument, since any input series impe-
dance due to the filter will increase the input noise and the thermal
drift. When operating above ground, the case of the instrument must
be grounded.
3. Thermal E&iF - Extreme precautions have been taken in the input
circuit to minimize thermal EMF's so that the residual EMF is less
than 0.6 microvolt. 'Ihe material used in the input circuit is pure
copper. Any other metal will generate a thermocouple potential.
Lead solder is particularly troublesome. Where thermal EMF's are
a problem, soldering should be done with the cadmium-tin solder
supplied with the instrument.
Ir. Input Noise: The noise at the input is a function of input
resistance and is approximately given by
E q 1.29 x lo-lo (R+2000)$
where E is the rms noise, and R is the source resistance. It is
assumed that the bandwidth of the instrument is about 1 cps and the
temperature is SOoF. If noise is observed, calculate the theoretica
noise and compare results. Also bear in mind that only wire-wound
resistors approach the ideal resistor. However, if Evanohm or
manganin resistors are used,a considerable thermal EMF of the re-
sistor material against copper will be observed.
5. Checking the Zero Point - At low levels, spurious E&W's may be
generated simply by contact between the input leads and the terminals
under test. If possible, always leave the instrument connected and
adjust the zero after establishing a zero reference in the apparatus
under test. For example, in bridge measurements, disconnect the
bridge exciting voltage; or with a phototube, shield the tube from
light.
3-2 0763~
MODEL 150A OPERATION
6. Overloads - The current applied to the input circuit should be less
than one milliampere dc steady state, 10 milliamperes dc short-term.
When the FUNCTION switch is on the MILLIVOLTS position, the off-scale
impedance can be as low as 10 kilohms. On the MICROVOLTS position, it
may approach 10 ohms.
D. MEASURING VOLTAGE
1. Direct Voltage Measurements - Place the FUNCTION switch at
MILLIVOLTS or MICROVOLTS as necessary for the measurement to be taken
Then turn the RANGE switch to more sensitive ranges until the meter
gives a usable deflection.
2. Measuring Voltage Variations - Set the FUNCTION switch and RANGE
switch to obtain the best deflection of the meter. Use the ZERO SUP-
PRESS controls as described in IV-D to increase the sensitivity of
the meter. Then small changes in a relatively large steady signal may
be displayed with a large scale deflection.
3. Measuring Differential Voltages - When measurements are to be made
in a circuit where the LOW connection is above ground potential, re-
move the DISCONNECT LINK from one of its posts. This disconnects the
instrument circuit ground from chassis ground. DO NOT attempt to make
such measurements where the low side of the circuit being measured is
more than 400 volts above external ground potential.
If a recorder is being used with the instrument in this arrangement,
the recorder ground must not be connected to the output ground of the
instrument, since the low side of the output would no longer be grounded.
E. MEASURING UNRENT
Direct Current Reading - Turn the FUNCTION switch to MICROAMPERESor
MILLI-MICROAMPERES, and the RANGE to 1000. Connect the instrument to
the current source and set the RANGE to the range which gives the
best deflection of the meter.
Measuring Current Variations - Proceed as above for direct current
readings, and then use the ZERO SUPPRESS and SET as described under
IV-D.
F. OTHER APPLICATIONS
1. Null Indicator - The Model 510A makes an extremely sensitive null
indicator which may be used in a Wheatstone or Mueller Bridge.
In a Wheatstone Bridge, the Model 150A is connected between the two
resistor arms. With the FUNCTION on MILLIVOLTS, and the RANGE on 1000,
the bridge can be adjusted to give a zero reading on the meter. The
instrument can then be set on more sensitive ranges for finer adjustments
of the bridge,*
*If the bridge is arranged so that one terminal of the detector is
grounded, the Model 150A may be used as described in E. If the
detector must be used floating, remove the DISCONNECT LINK at the
rear and observe the same precautions as in D.3.for measuring
differential voltages.
0764R 3-3
OPERATION MODEL 150A
2. Megohmmeter - The Model 510A may be used to measure resistances,
utilizing an external voltage source and measuring the current which
flows in the unknown.
3-4 0764R
MODEL
I.5OA CIRCUPP DY&CRIppIoIi
SECTION IV - CIRCUIT DESCRIPTION
The Model 150A is basically a narrow-band chopper amplifier employing
negative feedback to stabilize the gain and increase the input impedance.
A. Input Circuit
Zero Stability: The effect of thermal W's generated in the input
circuitry is reduced to nearly the vanishing point by the use of only
copper or silver materials in the input circuit. All solder joints
are made with a low thermal cadmium-tin solder. The chopper and
chopper transformer employ copper leads. All switching in the input
circuit is accomplished with a solid copper switch. Critical re-
sistors in the input circuit are wound of copper wire. The input
connector has solid copper spring-loaded contacts.
The input voltage is applied to the moving arm of a 120-cps mechan-
ical chopper. The feedback voltage is connected to the primary
center tap of the input transformer. '%us, the difference voltage
is applied first across one half of the primary and then, +th phase
reversal, to the other half. This full wave error signal is stepped
up 16 to 1 by the input transformer and applied to the grid of VI., a
608h low-noise pentode.
B. AC Amplifier
In parallel with the plate load resistor of Vl is a relatively high
Q, 120 cps resonant circuit which narrows the bantiidth and reduces
spurious signals.
V2 and V3, EF86 pentodes, further amplify the chopped error sipnal
which is then demodulated synchronously by selenium diodes DlOlend
Dl.02.
To obtain the 120 cps demodulator driving sianal, use is made of the
ripple frequency from a bridge rectifier circuit operating from the
line voltage. The ripple Js connected to the primary of the de-
modulator driver transformer.
C. tC Amplifier
The demodulated signal is applied to the grid of VL. Vii, V5, and
~6 form the dc amplifier and output cathode follower which add
further forward gair. to the system and supply output power. Feed-
back around VL, V5 and V6 multiplies the effective capacitance of
demodulator filter capacitor Cl13 by about 1000. This yields the
large equivalent capacitance necessary to smcoth the demodulated
error signal. Because of the feedback, spurious noise in the dc
stages outside the pass band of the whole amplifier are effectively
degenerated.
0763~ 4-l
CIRCUll' WBXIFTION MIDELL
150A
D. Zero Suppression
A low-current *lo volt supply is derived from the main dc supply
using lo-volt sener diodes. Potentiometer Rl7h may be set at any
voltage from -10 to +lO volts, this voltage being applied through ap-
propriate dropping resistors to the feedback point to achieve sero
suppression. The potentiometer is the front panel control marked
SET, while switch S3, which detemAnes the portion fed back, is
Labeled RANGE.
E. Other Controls
Three controls are set at the factory and should require only infre-
quent attention by the user.
R118 is an internal control marked DC AMP BAL. It is used to zero the
IX amplifier, i.e., to set the output voltage to sero when the de-
modulator output is zero. This is not very critical since any unbal-
ance will simply be fed back to the inout to produce a small error signal
to correct itself. RlS7is markedME!WR:CAt. This is the variable
portion of the meter multiplier resistance to allow for meter-to-meter
sensitivity differneces.
FCL77,
marked CURRENTBALAE!CE, may be set at some voltage which will
cause a current to flow through Rl75 to the chopper am. This current
is used to compensate for a small generated "chopper current" which
would otherwise flow in the input circuit. This "chopper current"
differs from chopper to chopper,but is fairly stable for long periods
of time. Its effect on any current range could be removed with the
ZERO SUPPRESS controls, but the Current Balance method used here gives
an effective aero input current for all ranges.
F. Power Supply
A standard half-wave rectifier followed by an R-C filter is used to
supply unregulated B+ and B- to the output cathode follower.
The unregulated B- is regulated to -150 volts in V7, OA2, and is used
for the negative returns for the dc amplifier.
Unregulated B+ is fed to the plate of V8, 12BU, the series tube in a
225-volt electronic regulator. The output voltage from this regulator
is divided by R510 and P.511 and compared to reference tube V9, a 5651.
The difference signal is amplified by cascade amplifier VlO, a 12AX7,
and applied to the grid-cathode circuit of the series tube. This
regulated 225 volts supplies Bc directly to the dc amplifier, through
a decoupling filter (R176, CllO) to the second and third ac amplifier
stages, and through another decoupling filter (R103, ClOh) to the
first ac amplifier stage.
Regulated B+ and B- also supply currents to the 10 volt sener diodes
which are used for xero suppression. This gives two-stage regula-
tion for these very critical voltages.
The first two ac amplifier filaments and the first dc amplifier fila-
ments are driven by a bridge-rectified 6-volt d.c. supply. The R-C
filter, R512, C507, and ~5~8, insure lowripple.
4-2 0763
Mom 15oA MAIAPENAIOCE
SECTION V - MAINTENANCE
Except for occasional tube or chopper replacement, very little maintenance
is required by the Models 150A and 15OAR. Components are operated well
below rating and solid-state devices are employed where possible to achieve
long, trouble-free service.
Certain portions of the input circuit are wired using copper wire and special
cadmium-tin solder. These special joints are painted red. If, for any
reason, these joints must be unsoldered or re-soldered, USE ONLY CADMIUM-
TIN SOLDER AND A COPPER-TIPPED SOLD!iRING IRON !'bMICH HAS NEVER BEEN USED WITH
ORDINARY LEAD-TIN SOLDER. A small spool of cadmium-tin solder is supplied
with each instrument.
What may seem to be circuit failure in the Micro Volt-Ammeter is quite often
found to be an unusual condition in the entire test set-up. Therefore, be-
fore trouble-shooting the instrument, check to see whether it operates cor-
rectly with:
1. All other circuitry disconnected.
2. Input shorted (with copper leads).
3. Power line voltage and frequency correct.
If the difficulty persists, the following systematic procedure may be em-
ployed to determine the fault.
TROUBLE-SHOOTING
Reference is made to the Schematic Diagram, lZl@8D, and the Voltage-
Resistance Diagram enclosed at the rear of the manual.
To begin trouble-shooting, short the input terminals, strap chassis ground to IO
withthe link pmvided(Model15OAB only), and switchRANGE to OFF.& zero off-
set of a few tenths of a microvolt is noml. On current functions with the
input terminals open but shielded, it should be possible to set aero current
with the CURRENTBALANCE control.
EXCESSIVE OUTPUT NOISE (INPUT TmINALS SHORTED)
Short the input grid of the dc amplifier, pin 7 of Vk, to ground. If this
stops the noise, it is being generated in the ac amplifier. Unfortunately,
because of the very low signal levels involved, noise in the ac amplifier
is difficult to trace by other than the substitution method. Most logical
noise sources are Vl or the chopper. To replace the chopper, unplug the
cap at the top, and unscrew the three thumb-screw nuts which clamp the chop-
per leads. Unscrew the four chopper mounting screws and lift out the chopper.
When inserting the new chopper, make sure that the chopper leads are pressed
against the copper terminals and that the insulating washers are between
the leads and the thumb-screw nuts. ,Observe wiring so as to rewire exactly
the same as the original.
5-l
-CE M)DEL 15OA
If the noise persists after shorti.ng the dc amplifier input, the noise is
being generated in the dc amplifier or power supply. A stage-by-stage
search should reveal the source.
OUTPUT NOT ZERO (INPUT TERMINALS SHORTED)
Be sure that RAIWE is set to OFF. Short the clc amplifier input grid,
pin 7 of Vh, to ground. Use the DC AMP BAL control to set the output to
zero. If this cannot be done, the dc amplifier or power supply are at
fault. If it can be set to zero, the trouble may be in the ac amplifier
or demodulator circuit.
- B+ should be about +225 on pin 1 of ~8 and B-
Zoui~ pins 2, h or 7 of v7. If v7 is not fir&
correct the fault in the unregulated B-. If +225 is not pre;ent,
check for unregulated B4 (about 3LO vclts) at the plate pin 9 of
va. If the unregulated Ik is all right, check the tube pin voltages
of ~8, V9, and VlO to locate the faulty tube or part.
b. AC Amplifier - Remove the output tube (~6) and clip pir 1 of
the output connector to ground. Place the FlJBCTION switch on
MlLLIVOLTS, and turn the SJECand RANGE controls full
clockwise. This puts a large dc error signal across the chopper
and input transformer. Use an oscilloscope to check for the
presence of 120 cps at the primary of the input trsnsformers (the
two outside terminals on the chopper terminal block). Absence of
signal means chopper failure (or much less likely, shorted input
transformer). Listen for audible chopper action and check chopper
drive, if necessary.
If the 120 cps signal is present, check stage-by-stage throughout
the ac amplifier, reducing the input signal as desired by backing
off the RANGE and/or SET controls, until the failure is
discovered.
d. Demodulator Circuit - Check for presence of about 80 volts -
at the secondary of the demodulator transformer (at the ends of R113
and Rllh).
The tests outlined above will not suffice to pin-point every fault
which may exist. They should, however, lead to the correction of
common failures. In the event that troubles cannot be corrected
by these means, or the user finds it more expedient, the unit may
be returned to the factory for repair and recalibration at a
nominal cost.
220-VOLT OPERATION
For 220~volt operation the power transformer primary connections must be
changed. The jumpers connecting black and black-white together and blue
and blue-white should be removed. The blue and black-white leads should
be tied together. Replaos the 1.5 tuapere fuse (Keith&y part m-8) with
a 0.75 ampere fuse (Kaithley part W-14).
5-B
MODELS 150A, 15OAR MICROVOLT-AMMETERS REPLACEABLE PARTS
SECTION 6. REPLACEABLE PARTS
6-1. REPLACEABLE PARTS LIST. The Replaceable Parts List describes the com-
ponents of the Models 150A and 15OAR Microvolt-Ammeters and their accessories.
The List gives the circuit designation, the part description, a suggested
manufacturer, the manufacturer's part number and the Keithley Part Number.
The name and address of the manufacturers listed in the "Mfg. Code" column
are contained in Table 2.
6-2. HOWTO ORDER PARTS.
a. For parts orders, include the instrument's model and serial number, the
Keithley Part Number, the circuit designation and a description of the part.
All structural parts and those parts coded for Keithley manufacture (80164)
must be ordered from Keithley Instruments, Inc. In ordering a part not
listed in the Replaceable Parts List, completely describe the part, its
function and its location.
b. Order parts through your nearest Keithley distributor or the Sales
Service Department, Keithley Instruments, Inc.
aP ampere n Ohm
CbVar Carbon Variable FMC Paper, metal cased
CerD Ceramic, Disc Poly Polystyrene
camp composition P pica (10-12)
DCb Deposited Carbon Spec Special
ETB Electrolytic, tubular w micro (10-6)
f farad v volt
Var Variable
k kilo (103)
w watt
M or meg mega (106) or megohms ww Wirewound
m milli (10-3) WWVar Wirewound Variable
Mfg. Manufacturer
MtF Metal Film
Mil. No. Military Type Number
rs Mylar
TABLE 1. Abbreviations and Symbols.
0764R 6-l
REPLACEABLE PARTS MODELS 150A, 15OAR MICROVOLT-AMMETERS
MODELS 150A, 15OAR REPLACEABLE PARTS LIST
(Refer to Schematic Diagram 12188D for circuit designations.)
CAPACITORS
Circuit Mfg. Mfg. Keithley
Desig. Value Rating Type Code Part No. Part No.
Cl01 ".047-.33 pf 200 v MY 00656 V84C-V161 C29-$<
Cl02 4.7 IJf 10 v ETB 05397 K4R7-JlOS C71-4.7M
Cl03 .1 pf 200 v PMC 00656 P82-Z C18-.lM
Cl04 20 IJ.f 450 v ETB 56289 TVA1709 C8-20L
Cl05 .l pf 400 v MY 00656 V84C-V161' C30-.lM
Cl06 (60 cps) .0082 pf 100 v Poly 84171 PE C45-.0082M
Cl06 (50 cps) .0122 pf 100 " Poly 84171 PE C45-.0122M
Cl07 4.7 wf 10 " ETB 05397 K4R7-JlOS C71-4.7M
Cl08 .Ol pf 600 v CerD 72982 811Z5VlO3P C22-.OlM
Cl09 .l pf 200 " PMC 00656 P82-Z Cl%.lM
Cl10 20 pf 450 v ETB 56289 TVA-1709 C8-20L
Cl11 4.7 pf 10 " ETB 05397 K4R7-JlOS C71-4.7M
Cl12 .l pf 400 v MY 00656 V84C-V161 C30-.lM
Cl13 333 If 200 " MY 00656 V84C-V161 C29-.333M
Cl14 :001 pf 600 v CerD 72982 80125V102P CZZ-.OOlM
Cl15 .0047 Kf 600 v CerD 72982 811Z5V472P C22-.0047M
Cl16 .OOl bf 600 v CerD 72982 80125VlO2P C22-.OOlM
Cl17 (50 cps) .0047 I*f 600 v CerD 72982 811Z5V472P C22-.0047M
c501 20 pf 600 v ETB 00656 PRS-1890 C35-20M
C502 20 pf 450 v ETB 56289 TVA1709 C8-20L
c503 20 vf 600 v ETB 00656 PRS-1890 C35-20M
c504 .Ol wf 600 v CerD 72982 811Z5VlO3P C22-.OlM
c505 20 pf 450 " ETB 56289 TVA1709 C8-20L
C506 "0.5 I*f 600 v MY 14655 PM-65P C92-0.5M
c507 1000 pf 12 v ETB 83125 TDlOOO-15 Cll-1000M
C508 1000 pf 12 v ETB 83125 TDlOOO-15 Cll-1000M
c509 .1 I.lf 400 v MY 14655 PM-65P C30-.lM
DIODES
Circuit Mfg. Keithley
Desig. Type Number Code Part No.
DlOl Selenium 5Ul 81483 RF-15
D102 Selenium 5Ul 81483 RF-15
D103 Zener lN71p; 12954 DZ-2.1
D104 Zener lN71,W 12954 DZ-2,X
D105 Selenium PT065 81483 RF-18
Nominal value, factory selected.
6-2 0764R
MODELS 150A, 15OAR MICROVOLT-AMMETERS REPLACEABLE PARTS
DIODES (Cont'd)
Circuit Mfg. Keithley
Desig. Type Number Code Part No.
D106 Selenium PT065 81483 RF-18
D107 Sf?leIliUm PT065 81483 RF-18
D108 Selenium PT065 81483 RF-18
D109 Selenium PT065 81483 RF-18
DllO Selenium PT065 81483 RF-18
Dill Selenium Bridge ClB 81483 RF-7
MTSCELLANEOUSPARTS
Circuit Mfg. Keithley
Desig. Description Code Part No.
Fl (117 v) Fuse, 1.5 amp, 3 AG 75915 FU-8
Fl (234 v) Fuse, 0.75 amp, 3 AG 75915 FU-14
--- Fuse Holder (Mfg:No. 34201) 75914 FH-3
Gl (60 cps) Chopper 80164 cv-2
Gl (50 cps) Chopper 80164 cv-3
Jl Receptacle Assembly, Input 80164 12450B
--_ Plug, Special, Mate of Jl 80164 13011B
s2 Receptacle, Microphone, OUTPUT
mfg. NO. 80P~2~) 02660 CS-32
--- Plug, Microphone, Mate of 52
(Mfg. NO. 80~~2.0 02660 cs-33
--(r) Binding Post OUTPUT (Mfg. No.
DF21RC) 58474 BP-11R
--(r) Binding Post, LO (Mfg. No.
DFZlBC) 58474 BP-11B
--CT) Binding Post, G (Mfg. No.
DFZlBC) 58474 BP-11B
--(r) Shorting Link (Mfg. No. 938-L) 24655 BP-6
Ll Choke, 200 hy 80164 m-1
M Meter 80164 ME-14
--- Meter Lamp (Mfg. No. 323) 08804 PL-1
Pl Power Cord, 6 feet (Mfg. No.
4638-13) 82879 co-2
--- Cable Clamp 80164 cc-7
Sl Rotary Switch less components,
FUh'CTION 80164 SW-56A
(r) Used only on Model 15OAR.
0764R 6-3
REPLACEABLE PARTS MODELS 150A, 150AR MICROVOLT-AMMETERS
MISCELLANEOUS PARTS (Cont'd)
Circuit Mfg. Keithley
Desig. Description Code Part No.
--- Rotary Switch with components, FUNCTION 80164 12914B
--- Skirted Knob, Function Switch 80164 m-11
s2 Rotary Switch less components, RANGE 80164 SW-54
Rotary Switch with components, Range 80164 12310B
--- Skirted Knob, Range Switch 80164 l-w-10
53 Rotary Switch less components, ZERO
SUPPRESS Range 80164 SW-58
--- Rotary Switch with components, Zero
Suppress, Range 80164 12311B
--- Skirted Knob, Zero Suppress Range Switch 80164 la- 10
--- Skirted Knob, Zero Suppress Set Poten-
tiometer 80164 KN-17
s4 Toggle Switch, DPDT, ON (Mfg. No.
20905-FR) 04009 SW-14
Tl Power Transformer 80164 TR-27
T2 Demodulator Transformer 80164 'IX-26
T3 Input Transformer 80164 TR-28
RESISTORS
Circuit Mfg. Mfg. Keithley
Desig. Value Rating 5Pe Code Part No. Part No.
RlOl 33 k-l lO%, l/2 w Comp 01121 EB Rl-33K
R102 2m l%, 1 w MtF 75042 MEF R44-2M
R103 47 kn lO%, l/2 w camp 01121 EB Rl-47K
R104 l?%l l%, l/2 w DCb 79727 CFE-15 RlZ-1M
R105 3.3 a-l lO%, l/2 w camp 01121 EB Rl-3.3M
R106 1m l%, l/2 w DCb 79727 CFE-15 RlZ-1M
R107 22 krl lO%, l/2 w Comp 01121 EB Rl-22K
R108 3.3 im lO%, l/2 w Comp 01121 EB Rl-3.3M
R109 1m lO%, l/2 w Comp 01121 EB Rl-1M
RllO 22 kn lO%, l/2 w camp 01121 EB Rl-22K
Rlll ll% l%, l/2 w DCb 79727 CFE-15 RLZ-1M
R112 x200 k!J. l%, l/2 w DCb 79727 CFE-15 RLZ-200K
R113 100 Ilc2 l%, l/2 w DCb 79727 CFE-15 RLZ-100K
R114 100 kn l%, l/2 w DCb 79727 CFE-15 RlZ-100K
R115 1.2 m l%, l/2 w DCb 79727 CFE-15 R12-1.2M
R116 470 kn l%, l/2 w DCb 79727 CFE-15 Rl2-470K
R117 333 kn l%, l/2 w DCb 79727 CFE-15 RlZ-333K
R118 500 kfl lO%, 2 w CbVar 01121 553034 RP5-500K
R119 680 kn l%, 112 w DCb 79727 CFE-15 RLZ-680K
R120 3.3 8-l l%, l/2 w DCb 79727 CFE-15 RlZ-3.3M
timnina value, factory selected.
6-4 0764R
MODELS 150A, 15OAR MICROVOLT-AMMETERS REPLACEABLE PARTS
RESISTORS (Cont'd)
Circuit Mfg. Mfg. Keithley
Desig. Value Rating TYPO Code Part No. Part No.
R121 2.2 T-m l%, l/2 w 79727 CFE-15 R12-2.2M
R122 62 kn l%, 1 " DCb 91637 DCF-1 R13-62K
R123 100 kfi l%, l/2 " DCb 79727 CFE-15 RlZ-100K
R124 1m l%, l/2 w DCb 79727 CFE-15 RlZ-1M
R125 1Kl l%, l/2 " DCb 79727 CFE-15 RlZ-1M
R126 30 kc? 5%, 10 w ww 63743 10F R5-30K
R127 10 kn lO%, 2 w War 71450 WPIOK RP9-1OK
R128 95.3 kn l%, 1 " MtF 75042 CEC R94-95.3K
R129 Not Used
R130 Not Used
R131 Not Used
R132 Not Used
R133 '1220 kn lO%, l/2 w camp 01121 EB Rl-220K
R134 ~~10 n 1% wspec 80164 Rl8-18-10
R135 Ml0 kn 1% wwspec 80164 R18-18-10K
R136 1.11 kn l%, l/2 " DCbSpec 80164 R38-l.llK
R137 100 kn l%, 112 " DCbSpec 80164 R38-100K
R138 10 h-l 5%, wwspec 80164 R18-19-10K
R139 Not Used
R140 10 kn l%, l/2 w DCb 79727 CFE-15 RlZ-10K
R141 3.33 kc2 l%, l/2 " DCb 79727 CFE-15 RlZ-3.33K
R142 lk0 l%, l/2 " DCb 79727 CFE-15 RlZ-1K
R143 333 cl l%, l/2 " ww 01686 7020 R48-333
R144 100 n l%, l/2 " ww 01686 7020 R48-100
R145 33.3 n l%, l/2 w DCb 79727 CFE-15 RlZ-33.3
R146 10 n l%, l/2 w DCb 79727 CFE-15 R12-10
R147 "3.3311 l%, l/2 " DCb 79727 CFE-15 Rl2-3.33
R148 x1.0 n l%, l/2 " DCb 79727 CFE-15 R12-1.0
R149 1Wl l%, l/2 w DCb 79727 CFE-15 RlZ-1M
R150 333 kQ l%, l/2 " DCb 79727 CFE-15 RlZ-333K
R151 100 kc) l%, l/2 w DCb 79727 CFE-15 RlZ-100K
Rl52 33.3 ka l%, l/2 " DCb 79727 CFE-15 RlZ-33.3K
R153 500 R l%, l/2 w DCb 79727 CFE-15 RlZ-500
R154 500 n l%, l/2 " DCb 79727 CFE-15 RlZ-500
R155 10 m l%, 1 w DCb 91637 DCF-1 R13-10M
R156 3.3 wl lO%, l/2 w camp 01121 EB Rl-3.3M
R157 1Wl l%, l/2 " DCb 79727 CFE-15 RlZ-1M
R158 333 kn l%, l/2 " DCb 79727 CFE-15 RlZ-333K
Rl59 99 kcl l%, l/2 w DCb 79727 CFE-15 RlZ-99K
R160 32.3 kn l%, l/2 " DCb 79727 CFE-15 Rl2-32.3K
*Nominal value, factory selected.
**Resistors R134 and R135 are matched to l/2%. Order only as a pair.
0764R 6-5
REPLACEABLE PARTS MODELS 150A, 150AR MICROVOLT-AMMETERS
RESISTORS (Cont'd)
Circuit Mfg. Mfg. Keithley
Desig. Value Rating TYPO Code Part No. Part No.
R161 9kQ l%, II2 w DCb 79727 CFE-15 RlZ-9K
R162 100 krl lO%, l/2 w Comp 01121 EB Rl-ZOOK
R163 390 kn lO%, 112 w camp 01121 EB Rl-390K
R164 100 kn lO%, l/2 w camp 01121 EB Rl-100K
R165 47 kfl lO%, 112 w camp 01121 EB N-4X
R166 15 krl lO%, l/2 w camp 01121 EB Rl-15K
R167 4.7 ksl lO%, l/2 w Comp 01121 EB Rl-4.7K
RL68 5.6 ksl LO%, I.12 w camp 01121 EB Rl-5.6K
R169 2.2 kn lO%, l/2 w camp 01121 EB Rl-2.2K
R170 llcn l%, 112 w DCb 79727 CFE-15 RlZ-1K
R171 1m l%, l/2 w DCb 79727 CFE-15 RlZ-1M
R172 100 kcl l%, 112 w DCb 79727 CFE-15 R12-100K
R173 9 kn l%, l/2 w DCb 79727 CFE-15 RlZ-9K
R174 10 kn 3%, 5 w WWVar 73138 A-RlOK- RP4-1OK
125
R175 100 I-Q l%, 2 w DCb 91637 DC- 2 R14-1OOM
R176 10 k lO%, l/2 w camp 01121 EB Rl-1OK
R177 10 kfl lO%, 2 w WWVar 71450 WPLOK RP9-1OK
R178 75 ko l%, l/2 w DCb 79727 CFE-15 R12-75K
R179 75 ksl l%, l/2 w DCb 79727 CFE-15 R12-75K
R180 30 kn 5%, 10 w ww 63743 10F R5-30K
R181 **100 kn l%, 1/4 w ww 80164 RlB-21-100K
R182 Ml I$ l%, II2 w DCb 79727 CFE-15 RI?.-1M
R183 *1 M lO%, l/2 w Comp 01121 EB Rl- 1M
R184 *82 n l%, I./2 w DCb 79727 CFE-15 RlZ-82
R501 100 n lO%, 2 w Comp 01121 HB R3- 100
R502 100 R lO%, 2 w camp 01121 HB R3- 100
R503 5 kn 5%, 10 w ww 44655 BLUME RS-5K
R504 5kil 5%, 10 w ww 44655 BLUME R5-5K
R505 22 kQ lO%, 2 w camp 01121 HB R3- 22K
R.506 10 m lO%, 1/z w Comp 01121 EB Rl- 10M
R507 220 ko l%, l/2 w DCb 79727 CFE-15 R12-220K
R508 33 kn lO%, l/2 w Comp 01121 EB RI-33K
R509 33 kG lO%, l/2 w camp 01121 EB RI-33K
R.510 1m l%, l/2 w DCb 79727 CFE-15 RlZ-1M
R511 600 kn l%, II2 w DCb 79727 CFE-15 RlZ-600K
R512 6n lO%, 5 w ww 44655 4654 R4-6
+c Nominal value, factory selected.
ek Not usually in instrument but supplied upon request
6-6 0764R
-MODELS 150A, &SOAR MICROVOLT-AMMETER REPLACEABLE PARTS
VACUUM TUBES
Circuit Mfg. Keithley
Desig. NUmber Code Part No.
Vl 6084 73445 EV-6084/E80F
V2 BF86 73445 EV-EF86/6267
v3 EF86 73445 Ev-EF86/6267
V4 12Ax7 73445 EV-12Ax7
v5 12AT7 73445 EV-12AT7
V6 6~~6 00011 m- 6~~6
V7 *WA2 80164 BV-OA2
V8 12B4A 85599 EV-12B4A
v9 **5651 80164 m-5651
VlO 12AX7 73445 EV-12AX7
MODEL 1501 REPLACEABLE PARTS LIST
Mfg. Keithley
Description Code Part No.
Plug Assembly 80164 13011B
Cable, 48 inches, Vinyl, shielded 86696 SC-5
Alligator Clamps, (2), (Mfg. No. 6OC5) 76545 AC-8
MODEL 1502 REPLACEABLE PARTS LIST
Mfg. Keithley
Description Code Part No.
Plug Assembly 80164 13011B
Cable, 10 feet, Vinyl, shielded 86696 SC-5
* Specially aged tubes.
00011 Sylvania Electric Products, Inc. 02660 Amphenol-Borg Electronics Corp.
Buffalo Operations of Sylvania Broadview Chicago, Illinois
Electronic Systems
Buffalo, N. Y. 04009 Arrow-Hart and Hegeman Elec-
tric Co.
00656 Aerovox Corp. Hartford, Corm.
New Bedford, Mass.
05397 Kemet Co.
01121 Allen-Bradley Corp. Cleveland, Ohio
Milwaukee, Wis.
08804 Lamp Metals and Components
01686 RCL Electronics, Inc. Department G. E. Co.
Riverside. N. J. Cleveland, Ohio
TABLE 2 (Sheet 1). Code List of Suggested Manufacturers. (Based on
Federal Supply Code for Manufacturers, Cataloging Handbook H4-1.)
0764R 6-7,
REPLACEABLE PARTS MODELS 150A, 15OAR MICROVOLT-AMMETERS
12954 Dickson Electronics Corp. 75915 Littelfuse, Inc.
Scottsdale, Ariz. Des Plaines, Ill.
14655 Cornell-Dubilier Electric Corp. 76545 M.zeller Electric Co.
Newark, N. J. Cleveland, Ohio
24655 General Radio Co. 79727 Continental-Wirt Electronics Coq
West Concord, Mass. Philadelphia, Pa.
44655 Ohmite Mfg. Co. 80164 Keithley Instruments, Inc.
Skokie, Ill. Cleveland, Ohio
56289 Sprague Electric Co. 81483 International Rectifier Corp.
North Adams, Mass. El Segundo, Calif.
58474 Superior Electric Co., The 82879 Royal Electric Corp.
Bristol, Corm. Pawtucket, R. I.
63743 Ward Leonard Electric Co. 83125 General Instrument Corp.
Mount Vernon, N. Y. Capacitor Division
Darlington, S. C.
71450 CTS Corp.
Elkhart, Ind. 84171 Arm Electronics, Inc.
Great Neck, N. Y.
72982 Erie Technological Products, Inc.
Erie, Pa. 85599 Tube Department G. E. Co.
Schenectady, N. Y.
73138 Helipot Division of
Beckman Instruments, Inc. 86696 Radix Wire Co.
Fullerton, Calif, Cleveland, Ohio
73445 Amperex Electronic Co. Division of 91637 Dale Electronics, Inc.
North American Philips Co., Inc. Columbus, Nebr.
Hicksville, N. Y.
75042 International Resistance Co.
Philadelphia, Pa.
TABLE 2 (Sheet 2). Code List of Suggested Manufacturers. (Based on Federal
Supply Code for Manufacturers, Cataloging Handbook H4-1.)
6-8 0764R