Keithley 147 Service manual

INSTRUCTION MANUAL

MODEL

NANOVOLT NULL DETECTOR

147

OCOPYRIGHT

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

1972,

KEITHLEY INSTRUMENTS, INC.

CONTENTS

MODEL 147

CONTENTS

Section

GENERAL DESCRIPTZON---------------------------------------------- 1

1.

OPERATION-------------------------------------------------------- 5

2.

APPLICATIONS----------------------------------------------------- 21

3.

C1I<CUIT DESCRIPTION----------------------------------------------

4.

MhINTENANCE------------------------------------------------------ 31

5.

REPLACEABLE PARTS------------------------------------------------ 51

6.

Page

25

SCHE~T~CS------------------------------------------------__-----__-- 65

0477

ii

MODEL 147

igure

NO. la.

lb.

2.

a:

5.

6.

7. a.

9.

10.

11.

12.

13.

14.

15.

16.

17.

18.

19.

20.

21.

22.

23.

24.

25.

26.

27.

28.

29.

30.

31.

32.

33.

34.

35.

36.

37.

38.

39.

40.

ILLUSTMTIONS

ILLUSTNATIONS

Title FrontPanel..

______-

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

Pag:e

1

Front Panel with Cable ......................... 3

Front Panel Controls .......................... 4

Model 147 Rear Pmel Controls & Connections. .............. 6

Model 1481 Low-Thermal Input Cable ................... 10

Model 1483 Low-Thermal Connection Kit. ................. 10

Bus System for Model 147 ........................ 12

Thermal Sink Construction.

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

15

Normal Wave Form at Demodulator with Input Shorted ........... 17

Wave Form at Demodulator Shown with Some Pickup. ............ 17

Wave Form at Demodulator when Amplifier is Saturated .......... 17

8-cps Filter Circuit for Recorder Output ................ 18

Using Model 147 with 4-Terminal Connections. .............. 18

Exploded View for Rack Mounting .................... 19

Circuit UsingGuildline9144 with Model 147 Null Detector ........ 21

Circuit Using Guildline 4363DL with Model 147 Null Detector. ...... 22

Circuit Using Guildline 9120 with Model 147 Null Detector. ....... 22

Circuit Using Biddle 605001 with Model 147 Null Detector ........ 23

Circuit Using Leeds & Northrup 7556. .................. 23

Circuit Using Model 147 Null Detector with ES1 240, 8OOR and KS 925. .. 24

Block Diagram of Model 147 Amplifier Circuits. ............. 25

Model 1.47 Tnput Circuit. ........................ 26

Diagranl of Power Supplies & Battery Charging Circuit .......... 29

Model 147 Input Compartment. ......................

32

Correct Wave Form in dc-to-dc Inverter ................. 36

Correct Wave Form in Oscillator Circuit. ................ 38

Improper Wave Forms in Oscillator Circuit. ............... 38

Correct Wave Form at Demodulator Test Jack ............... 41

Out-of-Phase Wave Form at Demodulator Test Jack. ............ 41

Top View of Model 147 Chassis ..................... 44

Bottom View of Model 1~47 Chassis .................... 45

Transistor Locations on Printed Circuit 76 ............... 46

Capacitor & Diode Locations on Printed Circuit 76. ........... 46

Resistor Locations on Printed Circuit 76 , ............... 47

Resistor 6 Test Point

Locations

on Printed Circuit 76. ......... 47

Resistor b Test Point Locations on Printed Circuit 74, Bottom Face ... 48

Component Locations on Printed Circuit 74, Top Face. .......... 48

Resistor & Test Point Location on Printed Circuit 75 Capacitor & 'Transistor Locations on Printed Circuit 75

Resistor Locations on RANGE Switch (5102). ...............

..........

.........

49 49

50

Resistor Locations on RANGE Switch (S102). ............... 50

i

0477

iii

SPECIFICATIONS

MODEL 147

SPECIFICATIONS

iv

0477

MODEL 147 NULL DETECTOR

GE:NLSAL DESCRIPTIOX

SECTION 1. GENERAL DESCRIPTION

l-1.

electronic null detector. x source resistance and 10 nanovolts with a a power sensitivity of 3 x lo-21 watt.

GENERAL. The Keithley Model 147 is designed specificaLly RS a col,vcnicnt self-contained dc

a.

Its sensitivity is 0.6 x LOT3 microvolt per mi.llimrter or 0.03

10-e

microampere per millimeter.

Its resolution is better tllnn 3 nanovolts with a LO-oll:il

300-ohm

source resistance.

This corresponds Lo

Zero shift is less than 15 nanovolts for sourcf resistance changes from 0 to 300 ohms. Line frequency r~!jcction is better than 5OOO:l 011 its most sensitive range.

The Model 147 has 16 ranges from 30 nanovolts full scale to 1.00 millivolts on a

b.

zero-center meter. Meter accuracy is f2% of full scale on ~11 ranges.

For reliable and versatile use, the Null Detector is of solid-state design, cxccpi

c. for the first two input stages. It has high line isolation - lOl(J ohms - and battery or ac power line operation.

0572

FIGUPJ? La.

Front ,>anel,.

I

GENERAL DESCRIPTION

MODEL 147

l-2.

grounding problems.

FEATURFS, Battery operation permits complete isolation from ac power lines, eliminating many

a.

Battery operation also allows flexibility and convenience in use.

The Model 147 automatically recharges the battery if needed when the powercord is connected.

As an electronic null detector,

b.

the Model 147 is immune to mechanical vibrations. It will also recover from a Z-volt overload on its inost sensitive range in less than 20 seconds.

c. Besides performing as a null detector, the Model 147 can also be used as a 2% direct-

reading nanovoltmeter.

The Null Detector has an output of ;tl volt at up to 1 milliampere for full-scale

d.

meter deflections to drive a recorder or oscilloscope. Output accuracy is ;tl% of full

SCSlS.

e. A zero suppression circuit,

furnishing up to 100 microvolts, permits measuring small

changes in a larger dc signal or compensating for thermal emf's. l-3.

APPLICATIONS. (Also see Section 3.)

The Model 147 is designed specifically as a null detector. It has sufficient sensi-

a.

tivity to be used in most applications with all commercially available potentiometers, in-

cluding 6-dial models, ratio sets and resistance bridges, including Wenner, Wheatstone and Kelvin Double Bridges. It can be used to make 4-terminal measurements.

Keithley's Model 147 is more sensitive than the finest galvanometer systems. It is

b.

also immune to mechanical vibrations,

thus eliminating the need for shock-free mountings.

Additional advantages over galvanometer systems'include the ability to recover from 2-volt overloads in 20 seconds,

much less off-null loading, plus considerably faster speed of

response.

0572

MODEL 147

CKNERAL DESCKIPTION

0572

GENERAL DESCRIPTION MODEL 147

FIGURE 2. Front Panel Controls.

0572

MODEL 147 NULL DlXI:C'l'OR

SECTION 2.

2-l.

line and the POWER SUPPLY Switch is in tile AC or OFF position,

charge current determines its brightness. charged.

FRONT PANEL CONTROLS.

a. AC CONNECTI?D Lamp. l:hc Lamp is lit whcncvcr the unit is connected t0 i.lll xi. pwur

BATTERY CHARGING Lamp. When lit,

b.

POGJIZR SUPPLY Switch.

c.

AC position: The Null Detector will opcratc from the nc power Lint.

1.

battery will be charged if needed; then,

(See Figure 2.)

this Lanq indicates the ibattery ins clrnr:ini:.

Ihe Switch controls tlrc mode of opcratiori for tile powel- suppI!:.

OPERATION

NOTE

If the lamp is noi l~it,

the BATTEQY CIIARGINC Lamp will lil:ht.

tllc" LllC lbilCLtdl.\ ii

'TIIC

p1,:

OFF position:

2.

charged,

3.

power line is internally disconnected, whether or nut tile power cord is coluieclcd;

the AC CONNECTiXD Lamp is off; the battery cannot be charged.

4. the Model I.47 shows the state of the battery charge directly on its mctcr. circuits within the instrument are the same as for battery operation exccpl at Lllc

meter terminals.

POWER SUPPLY

Switch Setting Connected

if nccdcd and if the power cord is connected.

BATI'ERY position: The Null Detector is operating from its battery.

BATT. TEST position:

AC

OFF BATTERY

BATT TEST

The Model 147 is not operating. Howcvcr ,

When the POWER SUPPLY Switch is held in this posil:ioii,

Power Cord AC CONNKTED

I

Yes YCS NO Yes NO Yes NO

Lamp

0” On Oil Off Off Off Off Off

I

tlic battery wil~l lbc

'I‘liC ni'

Al I

BATTERY CIIARGINC La"{'

(If battery is charging)

on

Battery CllnnOt bc cli;lr::c!d Battfry cannot IbC char;:ed Battery cannot hc chnr~cd Battery can,,ot bc cllar~:cd LIattcry cannot be charged

TABLE 1.

relationship between the front panel lamps,

Switch setting.

0365

Indicating Lamps and POWER SUPPLY Switch Settings.

The Table SllOWS tile

the power cord and the I'Oli'ER SUl'1~'I.Y

OPERATION

MODEL 147 NULL DETECTOR

RANGE Switch.

d.

The RANGE Switch selects the full-scale meter sensitivity (either

microvolts or millivolts) for one of eight ranges, from 0.03

FUNCTION Switch.

e.

The FUNCTION Switch selects the function - MICROVOLTS or HILLI-

VOLTS - which is to be measured.

ZERO SUPPRESS Controls.

f.

The COARSE Control disconnects the suppression circuit (in OFF position) or

1.

Two controls determine

the

amount of zero suppression.

selects one of four suppression voltages in decade steps.

The FINE Control is a continuously variable adjustment for the suppression

2.

voltage set by the COARSE Control.

It adjusts the range between the positive and

negative values of the maximum voltage set by the COARSE Control.

INPUT Receptacle. The INPUT Receptacle is of a special low-thermal design.

g.

only the Models 14.81, 1482, 1486 and 1488 for mating connectors.

to

100.

Refer to Table 3.

Use

FIGURE 3.

Model 147 Rear Panel Controls and

to Replaceable Parts List and schematic diagrams.

2-2.

RTtiR PANEL CONTROLS AND CONNECTIONS. Line Voltage Switch. The screwdriver-operated slide switch sets the Model 147 for

a.

117 or 234-volt ac power lines.

Fuse.

b.

For 117-volt operation, use a 3 AG or MDL Slow-Blow l/@ampere fuse.

2. For 234-volt operation,

2.

Power Cord. The 3-wire power cord with the NEMA approved 3-prong plug provides a

c.

ground connection for the cabinet.

use only a MDL Slow-Blow l/16-ampere fuse.

An adapter for operation from Z-terminal outlets is

provided.

6

Connections.

Circuit designations refer

0365

MODEL 1~47 NULL DETCC'TOR

A note above the power cord shows the ac power line i:rcqucncy for which the rejection filter is ad.justcd. 'The instrument will work at any line frequency from 50 t" 1000 cps, at the indicated frequency.

filter circuit.

NOTE

but ac rejection is bcsc

Paragraph 2-18 dcscribcs adjustirl~; lilf

DEMODULATOR TEST Jack.

d.

A phone jack provides access to LllE denl"dLll~ator ior ti.5:

purposes.

f.

OUTPUT.

'The OUTPUT Rcceptaclc provides

iL

volt at

one! mill.iampcrc f:or a

iilll.-scale

meter deflection on any range.

GND and LO Tcrmiasls.

f.

third wire of the power cord.

'The ground terminal. (GND) i.s conncctcd to tllc chassis ;~II)~! ! 1)~.

The low terminal is connected t" circui.t ground and cl!&:

low side of the input connection. 2-3.

MODE 01: OPERATION.

battery. b-or illost "SfS,

the ac power line will create ground loop or isolation problems.

The Model 147 operates cithfr irom an ac power line or irom iis

it functions well from ac. Use battary operation, llo~ifver, i~1~

1solnfi"n irun low to ground is complete for battery operation when tllc power cord is disconnccl:cd; i,t is greater than lOlo ohms wit11 the power cord connected.

Al.so use battery operntiiln it>

reduce the 8-cps ripple which may appear at the output with i-11" input shorted in i&c

operation.

See paragraph Z-16.

NOTE

Before using the battery operation, tll"r"ugllly read paragraph 2-4. Improper battery "pcration can damage the battery pack and lead to inaccurate measurements.

2-4. UXTERY OPERATION.

The Model 1.47 is supplied with a rcchargcablc h-volt,

ba:tery pack (Model 1489).

Recommended:

secutive hours without recharging.

Do n"t usf the battery more tlliln cigirt COII-

At this discharge rate,

4 ampere-ilour Iliclr~l-~~l(llnilIr!l the battery sl10u1d last abOUt

1000 recharge cycles.

NOTE

Permanent damage to the battery pack occurs if it is used for more

than 16 consecutive hours without recharging. rate, the recharge cycles are greatly reduced. Model 147,

Cheek the battery charge before making a measurement.

b.

in the BATT. TEST position.

check the state of the battery charge.

The minimum acceptable charge is a meter indi.cntion oi ,8;

full. charge is shown by the BATTERY CHARGING Lamp not being lit.

At this discharge

Bflorf usi~ng tile

Hold the POWER SUPl'LY Switch

Recharge il needed.

Otherwise, battery operation is the same as for the ac power line operating mode; rcI:cr

to paragraph 2-5.

0365

OPERATION

When the battery is used beyond its capacity, two effects aye seen.

There is a shift in zero offset from ac to battery operation. the power supplies do not regulate and high ripple voltages appear at the supply outputs.

MODEL 147 NULL DETECTOR

Also,

(See paragraph 5-8.)

To recharge the battery,

c.

POWER SUPPLY Switch to AC or OFF.

be charged only if needed, and the circuit automatically prevents it from being overcharged.

It is suggested that the battery be used during the day and be recharged at night.

d.

Leave the instrument always connected to the ac power line; then turn the POWEK SUPPLY

Switch to OFF at night. After a fully charged battery is used for eight consecutive hours ) it will recharge within 16 hours. effect on the isolation: 1010 ohms with the POWER SUPPLY Switch in BATTERY position and

the shorting link between GND and LO Te?.minals disconnected.

2-5. OPERATING PROCEDURES,

Set the front panel controls as follows:

a.

POWER SUPPLY Switch

FUNCTION Switch

RANGE Switch ZERO SUPPRESS COARSE Control

Make sure the ZERO SUPPRESS COARSE Control if OFF. If it is not, a

suppression voltage is introduced, causing an error in measurements.

connect the power cord to an ac power line.

The BATTERY CHARGING Lamp will light.

Leaving the power cord connected has little

OFF

MILLIVOLTS

100 OFF

NOTE

Turn the

The battery will

Connect the voltage swrce or null circuit to the INPUT Receptacle.

b.

graph 2-6 for suggestions.

Check the voltage shown on the rear panel Line Voltage Switch; connect the Model 147

c. to the ac pcwer line. Make sure the frequency shown above the power cord is the frequency of the ac power line. At this point, the AC CONNECTED Lamp will light, asp will the BATTERY CHARGING Lamp if the battery is being charged. If the circuit low is to be at ground, put the shorting link between the LO and GND posts on the rear panel.

Turn the POWER SUPPLY Switch to the desired mode of operation, AC or BATTERY.

d.

Increase the Model 147 sensitivity until the meter shows the greatest on-scale de-

e.

flection.

1. Check the source resistance to make sure it is within the maximum value specified for the range being used. sitive ranges is exceeded, the Model 147 may not measure within its specifications.

2. Zero offsets seen when the Zero Suppress Controls are off will vary with the quality of the circuit's thermal construction, Shorting Plug is connected to the Model 147 INPUT Receptacle, offset should be less than 0.3 microvolt.

8

(See Table 2.)

If the maximum resistance for the more sen-

See paragraph Z-14. When a Model 1488

Refer tO para-

046613

OP1:llATION MODEL I,47 NULL I1lYl'ECTOR

Make sure the signal is greater than Johnson noise in the source resistance (par-

1, ,

agraph 2-12 ).

2. Use materials which generate a low thermal emL (paragraph 2-14).

3. Mini.mize temperature changes and thermal gradients (paragraph Z-14).

4 Reduce magnetically induced signals by proper shielding and minimizing experimen-

tal layout area (paragraph 2-15).

5. Eliminate ground loops through proper grounding and connection to the signal cir-

cuit (paragraph 2-16).

2-6.

14~7 input is with the Model 1481 Low-Thermal Input Cable, mcnt Use tile Cable for temporary setups,

for measurements at several points, and

when fast connections are needed. del 148~1 connects directly to the INPUT 1~eceptacl.e.

sible or where very Sow thermal connections FIGUKC 4. Model 1481 Low-Thermal Input arc needed, use the Model 1482 Low-Thermal Cable.

Input Cable. 1481 ,

stead of nl,ligator clips. Clean the bare

wire! width a non-metallic abrasive, such as

Scotch Isrite, before making the connection.

illc> Model 1483 Kit, is best.

iron used is clean and that it has not been used with regular solder before.

LOW-THEIMAL INPUT CONNECTIONS.

a Tlie easiest connection to the Model

supplied with the instru-

The Mo-

b. Where more permanent setups are pos-

'The Model 11+82 Low-Thermal Input

It is similar to the Model

except it leas bare copper leads in- leads instead of alligator clips.

('. Si cadmium solder (Model 1503) is used for a connection, make sure the soldering

Cable is similar except it has bare copper

Making crimp connections, as possible with

USC only rosin solder flux. If possible, heat sink all cadmium-soldered joints together to reduce generated thermal emf's. techniques will keep thermal emf's below

0.1 microvolt.

Careful

I'LCUIW 5 . K in t .

lieTcr to Section 6 for contents.

Model 1483 Low-Thermal Connecti

d. Use crimp connections with copper

wire and lugs for the best low-thermal

joints. 10 nanovolts or less using the copper wire, sleeves and Lugs found in the Model 1483

Low-Thermal Connection Kit. tains a crimp tool, shielded cable, an assortment of copper lugs, copper wire, cad-

mium solder and nylon bolts and nuts.

is a complete kit for making very low ther-

mal measuring circuits.

the user 011 the Model 147 to maintain the

Thermal emf's can be reduced to

The Kit con-

It

The Kit enables

0466K

OPERATION

MODEL 14,7 NULL DETECTOR

2-8.

line ground.

2-9.

range is $1 volt at 1 milliampere.

less than 5 ohms within the amplifier pass band.. Output may be used during both ac and battery operation. If the Model 147 is used for differential measurements, do not ground the recorder connected to the output.

FMATING OPERATION. The Model 147 can be connected between two potentials,

a.

It can be floated up to ?4,00 volts off ground.

CAUTION

The front panel controls are electrically connected to the case.

power cord is unplugged,

ground voltage. use necessary e precautions.

For best results with floating operation, follow the steps below:

b.

Remove the shorting link from the LO or GND Post on the rear panel.

1. Connect the input circuit to the Null Detector.

2.

2-5.

wfth this operation, since the low of the Model 14,7 output is no longer grounded.

better results.

The zero suppress controls may also be used.

If power line frequency pickup is a problem,

3.

KECORDER OUTPUT.

-

The Null Detector output for a full-scale meter deflection on any

the case may be at a voltage equal

Do not ground any recorders used

battery operation usually provides

Accuracy is ?I% of full scale. Output resistance is

neither of which is at power

If the

to

the off-

Operate as described in paragraph

Model 147

P

FlGURF 6. Synchronized Buss System for Model 14,7. used in one system, an oscillator beat may occur; see paragraph 2-10.

instruments by connecting them as shown.

12

Model 147

V

Model 147 Model 147

v

LOW

When two or m"re Null Detectors are

See Figure 29 for point II.

b

4

Synchronize the

P

4

1

04,67R

MODEL 1.47 NULL DETECTOR

2-10. USING MOIW THAN ONE MODEL 147 IN A SYSTEM.

The Model 1.47 oscillator is adjusted for a nominal freqnency ol 94 cps. ,,Oi.!i~VC~1 ~

a.

slight variations in frcqucncy do occur between models.

tectors in one system,

an oscillator beat may occur.

Wl,en using two or ,morc Xill I ill

Synchronizing oscillators

b. "ents together at the collector of transistor (219 (Figure 29, Ipoint II), using iii: O.'i"icro.farad myl.ar capacitor.

At times the system is suc11 that the Null Detector lows may not bc conncctc~! di~-~~~t-

c. ly together. instruments. A IlO-volt, farad isolation capacitor in seri~es with iboth pri~mary and secondary wi~ndin~s o! C!IE i~~:i,i::former.

For several Null Detectors connected together, l,sc a synct,r"ni~zcil bliss :;ysli'T!, :iii

d. shown in Figure 6.

2-11. other considerations beside tile instrument affect accuracy. working with higher voltages are very important with mi~crovolt signals. reads only the signal received at its input; tllcrciorc, it is i~mportant tllat this signal be properly transmitted from the source.

affect accuracy: thermaI noise connections.

ACCURACY CONSIDERATIONS. For sensitive measurcmcnts -

Then,

'Table 4 also offers a quick rcfcrence to correct troubles wllich may occ11r.

use a 1:l transformer havi~ng a fairly higil impedance between tllc Cvil

low power isolation transformer works wit.

prevents an objectionable beat. Connect tllc! cwc in:,t iii-

USC n 0..5-:nicr<v

10 mi~llivolts and bt~1lbi.x -

i:l:Ifcts not Iroticcnblc ,.i'!len

Tl,c, ~lodel vi 7

The fol,i~owing paragraphs indi~cate iactor xiii c:.

, input resistance, thermal emi's,

shi~cldilll: iin<l (. il(.l.: *

1. The thermal noi~sc in any ideal resistance can bc dctarmi~ned Srom tiic Joi~nson !~rlis~'

equation:

EZ",, =

where Erms is the rms noise voltage developed across the voltage source;

T is tile temperature in degrees Kelvin; R is the source resistance in ohms; F is the ampl~ificr bandwidth in cps; k is the Boltzmann constant (1.38 x 10e23 joules / OK).

yor an ideal resistance at room temperature (3OO*K), equation 1 simplilics to

Ii,",

Peak-to-peak meter indi.cations are of "ore interest than tlrc rms vaiuc.

2.

mentally,

temperature, equation 2 becomes

where 13

0477

the peak-to-peak Johnson noi.se is about live times the rms value. At r<10111

EPP

is the peak-to-peak noise voltage developed across tile voltag" source.

PP

4 I< T 11 I; 1:q I

= 1.29 x lo-lo (RF)1'2 xi,

i:xpcri -

= 6.45 x 10-l' (RF)"' I:<,

Very slow response time

MODEL 147 NULL DETECTOR

2-13. INPUT RESISTANCE. obtained using high feedback factors. physical input resistance is partially destroyed. exceed the maximum source resistance listed in Table 2.

but noise, offsets, ranges, the maximum specified source resistance is consistent with Johnson noise considcrations.

2-14.

a.

tween any two junctions of dissimilar metals.

which the Model 147 can measure

b.

Model 147 can have some offset (paragraph 2-5).

touching the circuit, by putting a heat source near the circuit, or by a regular piliter,, of instability, light,

THERMAL EMF'S.

Thermal emf's (thermo-electric potentials) are generated by thermal gradients Ihe-

Thermal emf's can cause the following problems:

Meter instability or zero offset much higher than expected.

1.

Meter is very sensitive to ambient temperature differences.

2.

slow response and instability may result.

corresponding to heating and air conditioning systems or changes in sun-

The Model 147 is a feedback amplifier;

When the source resistance exceeds the amplifier's

amplifier input resistance without feedback - the fecdbacl;

Then the instrument may not operate properly.

Iligher resistances can be used,

These can be large compared to the si!;nals

its input resia:nnc<. is

Normally, do not

On the most sensitive

Note, thougll, the

T%is is seen by

To minimize the drift caused by thermal emf's,

c.

the same thermo-electric powers in the input circuit.

have o thermo-electric power within about f0.25 ,rv/oC of copper.

inbalance of 1oC between these metals would generate a thermal emf of about 0.25 microvolt

At the other extreme, germanium has a thermoelectric power of about 320 ,iv/oC, and silicon

will develop about 420 jrv/% against copper.

Standard physical handbooks contain tables

of thermoelectric powers of materials.

Since the Model 147 input circuit is made of pure copper, the best junction is copper to copper. HOWeVer, copper oxide in the junction will cause thermal emf's on the order of 100 nanovolts per oC or less.

Also, differences in processing of two

pieces of copper can cause thermal emf's

of up to 0.2 microvolt per OC. The Model

1483 Kit contains all necessary equipment to make very low thermal copper crimp joints. See paragraph 2-6.

Besides using similar metals, thermal

d. emf's can be reduced by maintaining constant temperatures, Keep all circuits from open

windows, fans,

similar sources which vary temperature. Connect leads or lugs as close as possible.

Minimize thermal gradients by placing all Separate only with insulation of high heat

junctions physically close on a large heat conductivity. sink.

fore making a connection.

Thoroughly clean all copper leads be-

air conditioning vents and

Crimp together

FIGURI? 7.

use the same metal or metals having

Gold, silver and low-thermal soldcr

This means a temperature

COPPER "AI"ERI

L Bw.II BOLT

Thermal Sink Construction.

1S

OPERATION

MODEL 147 NULL DETECTOR

the ends of each copper wire;

bolt the lugs for each connection point together; mount all stacks of lugs on a thick metal plate having high thermal conductivity. Thermal conductivity between the junctions and the heat sink can be kept at a high level by using mica

washers or high conductivity ceramics for electrical insulation.

Several other techniques will reduce the effects of thermal emf's.

e.

suppression circuit to buckout constant voltages.

If connections must be soldered, use

only cadmium-tin low-thermal solder, such as supplied in the Model 1483 Kit.

metals -

including regular solder -

well-controlled oil bath or a good heat sink is used.

may be used and low thermal emf's obtained if a

Thermal voltages may be calculated

Use the zero

Unlike

from the thermoelectric power of the materials in the junction and the possible temperature difference between the junctions.

z-15.

conductor can produce large signals compared to the instrument's sensitivity.

MAGNETIC SHIELDING.

a. In the

Low

resistance

circuitry

used with the Model 147, magnetic

Lines

cutting a

The amount

of signal developed is proportional to the area enclosed by the circuit and the rate of change of magnetic flux. For example, motion of a 3-inch diameter Loop in the earth's

magnetic field will induce a signal of several tenths of a microvolt.

size of the Loop or moving it more rapidly will increase the signal.

Increasing the

Magnetic fields

from ac power lines will cause even more difficulty.

To reduce the effect of magnetic fields, use magnetic shielding. Where high ac

b.

magnetic fields are present, it may be necessary to magnetically shield the measuring

circuit , the unknown emf circuit or auxiliary equipment in the circuit. Magnetic shielding is available from

several

companies in the form of plates, foil or cable.

Twist input leads to minimize the area enclosed by the circuit loop,

c.

experimental Layout for minimum enclosed area is also of particular

Z-16.

a.

AC SHIELDING.

Due to its narrow bandwidth, the Model 147 is somewhat insensitive to ac voltages

value.

Planning the

superimposed upon a dc signal at the input terminals. However, ac voltages which are large compared with the dc signal may drive the Model 147 ac amplifier into saturation, erroneously producing a dc output at the demodulator.

Usually it is sufficient to connect

the cases of all apparatus in the measurement circuit together and ground at one point.

This provides a "tree" configuration, which minimizes ground

which all shields are connected should be as near as possible

Loops.

to

The common point at

the

circuit

ground of the

Null Detector at its input.

Improper shielding can cause the Model 147 to react in one or more of the following

b.

ways :

Needle jitter or instability,

1. High offset (dc bias). Changing the power cord polarity or the connection between

2.

from 10% to 20% of full scale.

the LO and GND Posts may affect the amount of offset.

Slow response time, sluggish action and/or inconsistent readings between ranges.

3. Amplifier saturation. Observe the wave form with an oscilloscope connected to the

4.

DEMODULATOR TEST Jack (Figure 3).

With the input shorted, it should approximate the

16

0466R

MODEL 147 NULL DETiXTOR

----~

FIGURE 8. Normal Wave Form at Demodulator with Input Shorted. Scale is 0.1 v/cm vertical and 10 msec/cm horizontal.

o?'I:I?A'TION

wave form shown in Figure 8. If excessive pickup occurs, the wave Lorm will reseml,le

that of Figure 9.

The circuit will operate reasonably well as long as the wave form is

not clipped, as shown in Figure 10. At this point a dc offset is introduced.

To minimize pickup, keep the circuit away from ac sources. Shield as carcfullp as

c.

possible. Connect all shields together at the low side of the input or at the LO Terminal,

The voltage induced due to a magnetic flux is proportional to the arca of the loop. 'ThCSk-

fore, minimize loop arcas in the shield connections as

nect

the shield at only one point. Run all wires in the circuit along the same path, so

well as the

input circuitry.

CO,,-

the loop area is only the small difference in position of two adjacent wires.

Strong third harmonic magnetic fields - 180 cps for 60-cps units - may create an

d. 8-cps beat possible nearby sources, such as heavy-duty transformers.

measuring circuit as far as possible from the magnetic field.

at

the Null Detector output and meter. To reduce this effect, turn off all

Remove the Node1 147 and the

If removal does not greatly reduce the beat, magnetic as well as electrostatic shielding around the circuit ~nlny be necessary,

For information concerning your particular shielding problem, contact Pcrl:cc-

tion Mica Corp., 1322 North Elston Street, Chicago, Illinois.

The 8-cps beat will be more apparent at the output terminals, since the meter is

e.

filtered. To minimize the beat,

USC the filter circuit shown in Figure 11.

the Null Detector's l-volt output at Eull scale to 10 millivolts.

duced by a factor of 1O:l.

If the 330 microfarads is objectionably large, increase rhc

resistor sizes by 10 times and use a 33-microfarad capacitor.

The 8-cps beat is re-

Since the recorder outpu;

This divides

0466R

Ii

'OPERATION

is now only 10 millivolts, a non-polar capacitor is not necessary.

The Model 147 line frequency rejec-

f. tion refers to the total ac voltage appearing at the input terminals, Therefore, the Null Detector is affected by the sum of the ripple in the working standard and the unknown source. Because of this, working standards having high ac ripple components

will significantly reduce the amount of ac voltage which may be tolerated in the unknown.

Model

147

MODEL 147 NULL DETECTOR

Shielding is preferable to input fil- FIGURE 11.

g.

ters. Resistive-capacitive filters add corder Output. If~tha 8-cps beat disturbs

noise (equation 1), and the resistance value the measurements, this circuit will reduce must be subtracted from the maximum source the beat 1O:l. resistance in Table 2. Inductive-capacitive

filters rend to create loop instabilities

within the Null Detector. Capacity alone across the input, however, is less Likely to cause Loop instabilities,

2-17.

a. cal connections will have on the potential being measured. IR drops, which in most circuits are insignificant, now become important.

a resistance of approximately 10 milliohms per foot.

6-inch length of this wire will produce five microvolts.

volt would mean using a wire 0.0006 inch long.

b.

be used to eliminate this error. Refer

to Figure 12.

c. the zero suppress may be used to nullify

the voltage.

d. the measuring system fluctuate, they will

develop fluctuating voltages which will appear as noise or drift in the system.

CIRCUIT CONNECTIONS.

When measuring in the microvolt and nanovolt regions,

Four-terminal connections can often

If an unwanted IR drop is constant,

If the currents or resistances in

and it may be used to filter ac components in some cases.

For example, No. 20 AWG copper wire has

A l-milliampere current through a

FIGURE 12.

Connections.

8-cps Filter Circuit for Re-

consider the effect the physi-

To reduce this drop to 0.5 nano-

Current

3

Using Model 147 with 4-Terminal

Leads

Model 147

Leads

ii

t

2-18.

a.

Switch on the back panel (Figure 3).

Use only 250~volt MDL fuses.

b.

The Model 147 can operate satisfactorily from 60 or 50-cps sources, but the best ac re-

jection is achieved when the filter is set for the line frequency.

OPERATING FROM SOURCE OTHER THAN 117 VOLT, 60 CPS.

If the ac power source is 234 volts,

No other adjustment is necessary.

For 50-cps ac pave-s sources,

change the sideband filter capacitors, CL03 and C104.

use a screwdriver to change the Line Voltage

Change the fuse from l/8 ampere to l/16 ampere.

Use Keithley part

MODEL 1.47 NULL DI:TL':CTOR

ClOS-.109M (C103) and C45-.0155M (C104) for 50 cps.

Refer t" Figure 32 for compon<!nt III-

cation.

2-19. RACK MOUNTING. (See Figure 13.)

The Model 147 is shipped for bench use with four

a.

feet

and a tilt-bail.

'i'hC :~i"dcl

4002 Rack Mounting Kit c"nverts the instrument t" rack mounting t" the standard i:I,\ (RL<I?-L\)

19-inch width.

To convert the Model 147, rem"vf the four screws at the bottom ot each sidii "1 t!~<!

b.

instrument case.

Lift off the top cover assembly with

To rem"ve the feet and tilt bail from the bottom cover assembly,

Item

(See Fig. 13) Description

1 cover Assembly

the

handles;

save c11e four SCi-fi”S.

turn the two scr(ii.:s Il<'ilT

Keithlcy Part

No.

17162C

Qunntit!

I

2 Cover Assembly, Bottom (Supplied with

Model 147) 3 4

Angle, Rack

Screw, Slotted, lo-32 UNC-2x1/4 (Supplied

with Model 147) 5 Front Panel (Supplied with Model 147)

176950 1. 1462413

7

--4

---

1

TABLE 5. Parts List for Model 4002 Rack Mounting Kit.

@SCREW

/

i(j)FR PANEL

IGURE 13.

0466R

Exploded View for Rack Mounting,

Using Model 4002 Rack Mounting Kit.

19

Ur'Diu~LUN

MODEL 147 NULL DETECTOR

the back.

The two pawl-type fasteners will release the cover and allow it to drop off.

Remove the feet and the tilt bail and replace the cover (2).

c. Attach the pair of rack angles (3) to the cabinet with the four screws (4) previously

removed. Insert the top cover assembly (1) in place and fasten to the chassis with the

two pawl-type fasteners at the rear.

Store the top cover with handles, feet and tilt-

bail for future use.

20

0466R

MODEL 147 NULL DETECTOR

APPLICATIONS

SECTION 3.

3-l. GENERAL.

meters in null circuits, These are just samples of the circuits available and they do

not exhaust all the possible circuits. The setups which follow demonstrate how the Elodel

147 may be used.

3-2. WORKING SOURCES. tage increment available on 6-dial potentiometers. a stable battery working source with the potentiometer, are generally limited by several inherent problems - instability, short-term noise of several microwIts, pocr line regulation, and several millivolts of ripple, ripple may produce dc voltage due to a slight rectifying action at connection points and switch contacts. Also, working sources having high ac ripple components will significant-

ly reduce the amount of ac voltage which may be tolerated in the unknown. This is because the sc rejection of the Model 147 refers to the total ac voltage appearing at its input terminals, and, therefore, is affected by the sum of the ripple voltages in the working BOUWB and the unknown source.

Follow the operating instructions in Section 2. p~oints brought up in paragraph 2-11 and following,

ThFs section contains dfagrams using the Model 147 with various potentio-

The Model 147 permits resolution compatable with the smallest vol-

APPLICATIONS

When working at this resolutton, use

Line-operated working sources

This hig!I

NOTE

Pay particular attention to the

FIGURE 14.

KElTHLEY MODEL 147

POTENTIOMETER

Circuit Using Guildline 9144 with Keithley Model 147 Null Detector.

.-

GUILDLINE 9144

0466R

21

AH'LICATIONS

MODEL 147 NULL DETECTOR

KEITHLEY MODEL 147

GUILDLINE 436301.

POTENTlOMETER

FIGURE 15.

Circuit Using Guildline 4363DL with Keithley Model 147 Null Detector.

KEITHLEY MODEL 147

“NXHOYH

GUlL DL /NE 9120

EYF

POTENT/OMETER

FIGURE 16. Circuit Using Guildline 9120 with Keithley Model 147 Null Detector.

22

0466

MODEL 147 NULL DI:TIICTOR

Al?PI.ICATLoNS

FIGURE 17. Circuit Using Riddle 605001 with Keithley Model 147 Null Detector.

KEITHLEY MODEL /47

I

?

STD. CELL

em

000

r;;ir, isl

LttN 7556

POTENTlOMETER

,

FIGURE 18. Circuit Using Leeds & Northrup 7556 with Keithlcy Model 147 Null Ljctcctor.

1466

23

APPLICATIONS

KEITHLEY MODEL 147

r

1

ITl I

D.C. GENERATOR ‘8 6 6

999

1 KELVlN RATIO BRIDGE p 0 1

I PPP,

I I

q’ ’

DETECTOR BOOR

ES./. 240

RESISTANCE

STANDARD RS 925

SD P

IO 80

f0

*ID 0

MODEL 147 NULL DETECTOR

24

0466

MODEL 147 NULL DETKTOR

CIRCUIT DESCRIPTION

SECTION 4.

4-1.

a dc amplifier. Feedback is applied to the whole loop.

is amplified, demodulated, dc amplified and applied to the meter. A feedback network samples the signal at the output and compares it to the input. The dc input signal and the feedback signal are compared in the input transformer primary. creases the voltage-difference signal between the two. difference signal; line-frequency sidebands of the 94-cps signal arc filtered out. ac signal is then demodulated by a saturated transistor switch and enters a dc amplifier,

which has a feedback capacitor to filter out the demodulator ripple. The dc amplifier

output is connected to the meter, the output terminals and the feedback network. Ihe feedback resistors determine full-scale range. The zero suppress signal is conneclcd to the feedback point in the input circuit.

GENERAL. The Model 147 consists of a chopper, ac amplifier and demodulator systcim followed 1,::

a.

A mechanical chopper converts the dc input signal to a 94-cps signal. 'The 312 signal

b.

CIRCUIT DESCRIPTION

(See Figure 20.)

'The transformer in-

The ac amplifier amplifies the

Th<!

FIGURE 20.

The power source for the Model 147 is either line voltage or the rechargeable

c. battery. highly regulated supplies. amplifier circuits.

it is necessary and when the line voltage is connected.

4-2.

a.

JlOl, to the center contact of the chopper, GlOl. (See Figure 21.)

0466~

Voltage from either source is applied to a dc-to-dc inverter and then to tnrec

There is also a battery charging circuit to charge the battery when

Refer to Schematic Diagrams 18512F, 17352D and 173531) for circuit designations. INPUT CIRCUIT. The dc input signal is connected through the high terminal of the INPUT Receptacle,

Block Diagram of Model 147 Amplifier Circuits.

The three supplies furnish power to the oscillator and the

NOTE

The feedback signal

25

CIRCUIT DESCRIPTION

MODEL 147 NULL DETECTOR

r

.

*

FIGURE 21. The feedback signal, Vf (the dc amplifier output voltage, Vo, times the feedback ratio,

B )l

is the difference between the two, Vd = Vin - Vf. applied to the Model 147, Vf is zero and the voltage across the primary is entirely Vin. As the output voltage rises,

"in,

determines the amplifier gain.

is applied to the center tap of the input transformer, TlOl. applies a positive and a negative square-wave signal across each half of the primary. The magnitude of the square wave is proportional to the difference between the dc input and the feedback signals.

internal ac pickup.

is applied to the transformer primary.

Or p V, = Vin.

The input compartment is designed to insure high thermal stability and to minimize

b .

1. . circuitry. input receptacle is 99.5% copper; the impurities add to the mechanical strength without creating large thermal emf's.

copper pins and rotor. lugs.

soldering -

Model 147 Input Circuit.

Vf fncreases and Vd decreases to a small value, then Vf =

Only p, which depends upon the RANGE and FUNCTION Switch settings,

TlOl steps up this signal and applies it to the grid of tube Vl.

Thermal stability is obtained in part by using only copper wire in the input

The input transformer primary and the chopper leads are pure copper.

The low voltage portion of the FUNCTION Switch uses pure

All connections to components are made with pure copper crimp

Connections between components are made by bolting the lugs together - not

to reduce thermal emf's.

The dc input signal, Vin, is applied to the chopper.

The signal, Vd,

When the dc input signal is initially

stepped up by the transformer

'The chopper alternately

The

.

2. The input compartment is doubly shielded against magnetic and electrostatic pickup on all sides. further minimizing pickup.

c. The feedback network is formed from the output of the dc amplifier back to the

center tap of the primary of transformer TlOl. feedback ratio used for each range.

4-3. AC AMPLIFIER.

a. The ac amplifier circuit amplifies the 94-cps difference signal which corresponds

76

The wires are physically placed to maintain minimum loop area,

The RANGE Switch, SlO2, selects the

0466R

MODEL 147 NULL DETECTOR

to the dc input signal.

The signal is applied to the grid of tube Vl and further ampli 1 ic'j;

by tube V2. A low-noise silicon transistor, Q3, provides n hi.gb impedance load frx \':i.

The signal is then amplified by transistors Q4 and 00. Potentiometer I<109 , botwe~~l tiie 03 emitter and Q4 base, adjusts the gain to compensate for beta variations. In addi~cioii , each stage has some local degeneration.

Transistor Q5 is for impcdancc matchi~n):. 'I‘ll i! difference signal is amplified by transistors (27 and 98, whicll also form ii full-vavc signal for demodulation.

A series high-Q filter

b.

from

the plate of V2 to circuit ground provides riotit, rcjection at the power-line frequency sidebands. 7'11e values of capacitors Cl03 and i:l(lt+ depend upon the power-line frequency. Due to the high Q of the inductor, the iil,ter forms sharp notches at 34 cps and 154 cps for 60-cps power lines and 44 cps and 144 cps for 50-cps power lines.

'The ac amplifier's 94-cps gain and phase characteristics al-c

affected very little.

The tube type and bias point of Vl are selected for low-noise operation at 94 cps.

c. The high-Q tuned circuit in the plate of Vl has a good signal-to-noise ratio, and it provides a narrow bandwidth around 94 cps.

The tuned circuit's Q is lowered on tile

higher ranges for amplifier stability. 4-4.

DEMODULATOR. Transistors Q9 and QlO in inverted configuration form a trnnsislor

switch demodulator. 'They convert the 94-cps wave from the ac amplifier into a dc vo1ca~:i

with ripple component. Resistors R123 and R124 sum the voltages from each to form rl lullwave rectified signal. Jack J102 allows access to observe the wave form.

'i‘llI 94-cps

oscillator furnishes a square-wave drive for the demodulator.

4-5.

DC AMPLIFIER. The demodulator signal is amplified by two low-drift, high-gain silicon transistors,

a.

Qll and Q12, in differential configuration to compensate for temperature drift. Transis-

tors 413 and Q14 form the second amplifier stage. Total gain is about 500.

follow

current at zero output.

output stage

-

transistors

Q15 and 916 in pnp-npn configuration - draws litclc

Diodes DlOl and D102 limit the output currCnt, protecting

'The emitter-

transistors Q15 and Ql6.

A feedback loop with capacitor Cl15 around the dc amplifier acts as an integrator,

b.

filtering the ripple component of the demodulated wave form, The effective capacity,

which is approximately the value of Cl15 times the dc amplifier gain, and the feedback

factor (or open-loop gain) determine the response speed of the system.

The capacitive

feedback also lessens the noise in the amplifier outside the system bandpass. 4-6. OSCILLATOR. The oscillator circuit, stable to 0.1 cps, has three parts: phase-shift

network for a 94-cps signal, an amplifier to drive the chopper,

and a transistor switch

and phase compensation network for the square-wave demodulator drive.

The phase-shift network consists of capacitors C301 through C303, resistors 11319 thzough R321, and the combined resistance of R303 and R318, which bias transistor Ql7. The input impedance of the emitter follower, tive value of this last resistance.

Transistor Ql8 compensates for signal losses in the

phase-shift network. Potentiometer R319 adjusts the signal frequc?ncy.

the filament of a low-power subminiature tube, Raytheon CK544,

417, has little loading effect on the effec-

Resistor 1~322,

provides variable dcgcn-

eration to maintain a sine wave output to the amplifier.

0365

27

CIRCUIT DESCRIPTION

From the phase-shift network, the signal is amplified and used to drive the chopper.

h .

'Transistor 919 matches the impedance of transistor Q20 to the phase-shift network.

tentiometer

R313 adjusts the signal amplitude.

From transistor 420; the signal is applied

MODliL 147 NUL,L DIXECTOR

PO -

to the primary of tratwformer T301, which drives the class B stage, transistors Q22 and Q23.

After amplification the sine-wave signal is applied to the chopper, GlOl. Transistor Q21 develops the bias voltage for the class B stage, providing ambient temperature compensation for the chopper-drive signal amplitude. The center taps of transformers 'T301 and T302 supply dc current for the class B stage.

c. 'The chopper drive signal is also applied to the primary of transformer T302.

The

transformer drives transistors Q24 and Q25 through a phase-compensating network, resistors R308 to R310, R323 and capacitor C309, which compensates for the chopper phase shift. the transistors alternate between saturation and cut off to form a square-wavt? drive for the demodulator, transistors Q9 and QlO.

4-7. ZERO SUPPRESS.

The zero suppress circuit provides a regulated voltage from the power supplies to

a.

buckout steady background potentials in the input signal. The IO-turn FINE Control,

potentiometer

R168,

is connected between -12 and -1-12 volt outputs.

The resistors I~165

to R167 and R172 in the COARSE Switch, S103, further divide the voltage. The suppress

voltage is divided by an Evenohm 0.25% resistor, R140, copper resistor Rl37A, and copper resistor R141. Using copper resistors for the lowest voltage points shunted by Evenohm resistors provides thermal and resistive stability.

An adjustable current, supplied through resistor R138, provides compensation for

b.

resistive

4-8.

offset. Potentiometer R239 adjusts the current fed to the feedback point.

POWER SUPPLIES (See Figure 22.)

The power supply for

the

Model 147 ,is powered by an unregulated supply :from the line voltage or rechargeable battery. Either source feeds n dc-to-dc inverter and three highly regulated supplies with outputs of +12, -12, and

il.2 volts.

The line voltage, battery and battery charging circuit are controlled through the

a.

POWER SUPPLY Switch, S201. When the switch is in AC,

These power all the other Model 147 circuits.

the battery is charged if nccessarq

and the power supply uses line voltage. When the switch is in OFF, the battery charging

circuit

will operate if necessary; all other circuits are off.

When the witch is in

I~ATTIZRY, the power supply uses the battery; the other two circuits can not operate.

11 . T:he unregulated supply consists of a full-wave rectifier, diodes DZ.12 and D213, and

n droppi.ng resistor, R232.

The AC CONNECTED Lamp,

DS201, is in series with resistor R226,

whj.ch is connected directly across this supply, For battery operation the primary of

rrnnsl'onner T201 is disconnected.

c.

Voltage

Vertex circuit.

voltage to transformer T202.

carrier frequency.

from the unregulated supply or the battery is applied to the dc-to-dc in-

Transistors 928 and Q29 form a switching network to supply an interrupted

The switching frequency is about 2 kc, well away from the

Transformer T202 has a

saturable

ferrite cot". The inverter

circuit

supplies voltages to the three regulated supplies, which are basically the same series

regu.Lator

d . For the 1~12 volt supply, i-rnnsfonncr T202. is div:idcd by resistors R208 and R209 and compared L

28

design.

diodes D206 and D207 full-wave rectify the signal from

The signal is applied to the pass transistor, Q30.

the zencr diode reference, D205.

The output of Q30

0466R

MODEL 147 NULL DETECTOR

CTRCUIT I1I:SCR1~l"~IoN

FIGURE 22.

Block Diagram of Model 147 Power Supplies and Battery Clrarging Circuit.

Transistors Q34 and Q33 amplify any potential difference and apply a signal to the base of transistor Q32. collector voltage of Q33 directly dctcrmincs the current through (132, which comes the -12 volt supply. the base of transistor Q31, junction.

Diode D203 limits the base-to-emitter voltage of the Q30 alld Q3L combinati,ln;

thus also limiting the current which it will pass.

Diodes 0204 and D205 fix the emitter voltage of (~32; tlrcrclfore, the

i:rom

The

current

and therefore the

drop through

resistor I<216 determines the voli~a?ge at

output

voltage througli the base-cmiltcr

Diode I)203 protects

the

pxs transistur

Q30, if the output of the supply is shorted.

For the -12 volt regulated supply,

e.

from transformer T202.

The signal is applied to the pass transistor, Q35.

R217 and R218 divide the 435 output,

ground as a reference. apply a signal. to transistor Q37.

Transistors Q38 and 939 amplify any potcutial diftcrc!ncc and

Transistors 435 and Q36 form a Uarlillgton combi~n;lLi~x,~i ~

and work similarly to that in the ~1+12 volt supply.

supply draws a higher current than the ~1.12 volt supply,

D208 and U209, to protect the pass transistor.

diodes D210 and D211~ Trill-wave rectify the signill

Resistors

thereby comparing it to the ~112 volt supply, usi,n>:

'l'hc differences arc

LIlaC Clue -12 volL

and therefore uses two diodes,

The negative "bootstrap" curreni supply)

is from a filter, resistor R225 and capacitor C210.

The -+I..2 volt supply operates in the same manner as the 112 volt supply with those

f.

di,fferences. The output of the pass transistor, Q40, 1~1.2 volt supply divided down one

tenth.

'The operating voltages for tlic comparator stage,

Q43 and Q44, are obtained from the +12 and -12 volt supplies.

is compared to lllC output of ti1c

ikccpt for the compnra~or

stage, npn transistors arc used.

4-Y.

BATTERY CHARGING CIKCUIT.

The battery charging circuit operates when the I'OWER SUPPLY Switcii, SZOI, ins iii A(:

a.

or OFF position, and only when the battery needs charging.

04661~

29

CIiWJIT DESCRIPTION

The battery voltage is compared to a reference by two cascaded transistors, Q26

b.

and 427.

When it is low, a charging current from transformer T201 is applied to the battery

MODEL 147 NULL DETECTOR

through the BATTERY CHARGING Lamp, DS202, transistor Q27 and diode D216. The reference is zener diode D214; the reference voltage is adjusted by potentiometer R228. The difference between the battery and the reference potentials determines the magnitude of the charge current through Q27. A silicon diode, D216, prevents the battery from being

run down because of leakage currents through 927, a germanium power transistor.

Diode D215 limits the base-to-emitter voltage of the Q26 and Q27 combination, so no more than 400 milliamperes (the rated maximum charge current of the battery) can flow in the circuit.

This circuit protects the bat,tery. It decreases the charging current to a trickle-

c. charge rate as the battery terminal voltage approaches the reference voltage. It also limits the charge current if the battery was used beyond its ampere-hour capacity. Note,

however,

reversal of a cell may occur,

that the battery can be damaged if it is used far beyond its capacity. A polarity

causing heavy circulating currents within the battery.

30

0365

MODi?L 147 NULL DIZECTOR

SECTION 5.

5-l.

cedurcs for the Model 147. possible to maintain the instrument's specifications.

5-2.

high-quality electronic equipment.

Principal maintenance is an occasional chopper rcplaccment.

GENERAL. Section 5 contains the maintcnancc, troubleshooting and calihmtion pro-

It is recommended these procedures be followed as c:loscly 3s

MAINTENANCE SCHEUUJX.

The Model '1.47 requires no periodic maintenance beyond the normal cnrc requirc.d ~1

a.

Components operate well below nmximum ratiirgs.

Suggested Model 147 calibration schcdulc is as follows:

b.

Every four to six months, cl~cck the Model 147 with Llle Keithley Model. 260 N;li,a-

1.

volt source. This will show if the Null Detector is maintaining its specified accurac;?.

Approximately every year, perform an operational check on the amplifiers (par-a-

2.

graph 5-10). This will indicate how well the Null Detector ,is operating.

3. Normally,

are replaced.

the Model 147 does not need recalibrating unless critical components

These part changes are call.ed out by the various circuits in tliis Section

MAINTENANCE

(See paragraph 5-4.)

5-3. PARTS REI'MCEMliNT.

a. The Replaceable Parts List in Section 6 describes the clcciriccil components of :h~ Null Detector. Repl.ace components only as ncccssary, which meet the specifications. R322, which is a subminiature tube filament,

matched transistors (Qll, Q12, Q22, 423) and the two input tubes.

coded 80164 in the Replaccablc Parts List arc purchased only from Keithley Ins~run~cnts or its representative. (If tlic Low-Tlicrmal~ Function Switcll, 5101, i,i?<!dS L^<~!/>l:,cme,,L, ri'-

turn the unit to i(eithtcy :Instrumcnts for this repair).

Component

Battery pack assembly

Mechanical chopper assembly (SW paragraph 5-4.)

Input receptacle assembly Copper feedback resistor assembly R137 Evanohm resistor assembly i:vanoh~n resistor assembly Function switch plate assembly (see paragrnpll 5-3n) Input transformer assembly

The Model 147 uses few special parts except for resistor

the components listed in 'Table 6, several

and USC onl~y rcliabltl replncements

mke S"lf parLs

BA201 GlOl JlOl

11139

Rl40 SLOl

'SlOl.

TABLE 6. and the proper lead length.

instructions given in paragraph 5-3.

04691~

Model 1.47 Pre-assembled Components.

USC only Kcithley parts for replaccmcnts;

Tlicsc parts have lugs crimped on Lhcm

iolloi;

MAINTENANCE

>IOtII:L 1~11~7 NULL I)ETECTOR

I

FIGURE 23,

placing, duplicate location and order of lads on posts. nations.

The physical location of components in the input compartment is critical.

11 . rcpl.acement parts in 1-11~ exact pos:i.tion shown in Figure 23. extraneous ac signals; see paragraph 2-15.

posts greatly affects offset and noise in the Model 147.

cnch lead as it is removed.

6 Kep nuts in the input compartment is 15 inch-pounds.

No . ili~ich have lugs crimped on them. When replacing these parts, metallic abrasive,

~Vol~low the procedures necessary for good low-thermal connections. 5-4. CHOPPER REPLACLWi?NTS.

The chopper is designed ~Cor long lift. I~l"wfvcr) since iC is mechanical, it will

ii

eventually wear and become noisy. At this point,

Removal Procedures.

11 .

1.

move the three thumb screws in the input compartment and the three chopper lead lugs.

Model 147 Input Compartment.

Refer to Figure 7 for general connection construction.

Replace in reverse sequence.

such as Scotch Brite, found in the Model 1483 Kit, or its: equivalent.

Llisconnect the chopper dri.vc coil at connector 5302 (Figure 29).

Note exact physical Location of parts. If re-

Figure 30 gives circuit dcsig-

Circuit loops will introduce

The order of the copper lugs on the insulated

'Tag or record the number on

Maximum torque applied to the

Table 6 lists components

clean the lug with a non-

replacement is necessary.

Carefully re-

I

Place

:1 2

0466R

MODEL 147 KLILL DEl:CC:COR

:.?,\~I !:'I i ::,:'..::I

Carefully slide the degaussing coil, 1.302 (t?igurc 29),

2.

l'rom ti,(i chopper lbd~:;

remove the "1.d chopper.

Replacement Procedures.

c.

Slide the degaussiug coil,

1.

L302 , over the new chopper body irom illc bo!~c,!ll.

Orient so that tllc cut-nrit i.n I-11" coil lits over the ch"ppcr dri~vi! l~cnd.

Mount the chopper and coil in the input compartment.

2.

i)rcss Leads as silLlw:l

in Fj.gure 23.

Degaussing Coil Adjustment Procedures.

d.

With the input shorted, USC the ZERO SUPP1~L:S.S Contrill~s L:" cance 1~ any T/~e~livil~

1.

emf's in the Model 147 input circuit.

USC n differential input LU tile .Cypc 1103 Oscilloscope (~I and - inputs) to obscrvc the wave Lorm bctwecn tllc: collectors oi irai:sisters Q9 and QlO (Points P and Q, Figure 34).

The wave form amplitude varies as tllc degaussing coil is moved along the clltipper

2.

body. Potentiometer R301 (Figure 30) determines tbc effect "f the coil "n the wvc!

form.

Adjust both tbc coil and the potentiometer for mini.mum ;ImpliLudi,.

,:<~Lii~~l-sL

the.rcd and black leads t" the degaussing coil ir necessary.

3. An 8-cps beat at points P and Q may bc present.

USC battery operalion i" ~-c<!ucc

the beat; refer to paragraph 2-3.

5-5. 'TROUBLESHOOTING.

1%~ following procedures give instructions for repairing troubles which mii:ht occ111'

a.

in the Hodcl 147.

mcnt parts.

'Table 7 lists equipment recommended for troubleshooting.

cannot be readily located or repaired,

Use these procedures to troubleshoot and use only spwil:j~w! rcplacc-

cOntact Kcithley Instruments or its 'cl'~~scnl;li:ii,et-

Paragraph 2-19 describes how to remove the Null Detector covc1'.

Paragraphs 5-8,

b.

checking "ut the pow"r supply, order given. Tables 10, refer

to

Section 4 to find

The Schematic Diagrams,

5-9 and 5-10 give step-by-step proccdurcs for trouh1L'sho"iin;: arid

oscillator and amplifier circuits.

11 and 13 are troubleshooting tables for these circuits.

the

more crucial components and to detcrminc their iunclioi!.

1.8512F, 17352D and 17353D, contain the voltages at certai~n

pojnts in the circuit.

Before troubleshooting inside the Model 147,

(paragraph 5-6).

Always check out the power supply and the "sci.lI.at"r

circuits before touching the amplifier circuits.

check the extfrnal circuits

'I?," amplifier circuits

often appear faulty only because of a defect in the power suppty or oscillator circuits.

11 Lllf L~I:oLIl~ II

Follow these in i~!lC

Xl so

0466R

MAINTENANCE

MODEL 147 NULL DETECTOR

Instrument

llewlett-Packard Model 5512A Electronic

Monitor oscillator frequency

USC

Counter, 300-kc counting rate, *O.l% accuracy

Keithley Instruments Model 1488

Short INPUT Receptacle

Low-Thermal Shorting Plug Keithley Instruments Model 260

Signal source for calibrating Model 147

Vanovolt source <cit%ley Instruments Model 2603

Connect Models 147 and 260

Low-Thermal Input Cable (eithley Instruments Model 660 or 660A

Check voltage at output terminals 3-uarded DC Differential Voltmeter, !-O.OZ%, to 1 millivolt

XA Model WV98B Senior Voltohmyst, 11 I$]

Check dc voltages throughout circuit input resistance, i3% accuracy, 0 to 1500 volts dc

Cektronix Type 503 Oscilloscope, dc to 'I,50 I--

Check wave forms for troubleshooting and

-alibrating

I

TABLE 7. Equipment Recommended for Troubleshooting and Calibrating the Model 147.

these instruments or their equivalents.

use

5-6. PRELIMINARY TROUBLESHOOTING PROCEDURES.

Before troubleshooting,

a.

check the outside circuits to the Model 147.

Null Detector from all external effects:

Disconnect all outside circuits from the INPUT and OUTPUT Receptacles, and GND

1.

and LO Terminals.

Connect the Model 1488 Shorting Plug to the INPUT Receptacle.

2.

COARSE Control to OFF,

If battery operation is trouble free, set the POWER SUPPLY Switch to BATTERY.

b.

connect the power cord from the ac power line.

earth ground or to a cornman test equipment ground.

NOTE

Often, after checking out according

to

will function normally. This points to problems in the circuits

outside the Null Detector. Refer

to

Table 4 to check the external

circuit,

C. If ac operation is used,

check the Line Voltage Switch for correct position and the

Fuse for correct rating.

Isolate the

Set the ZERO SUPPRESS

Dis-

Ground the Model 147 case to a convenient

paragraph S-6, the Model 147

34

0466R

COlltrOl

Dcsig. Kcf.

Paragraph

ac amplifier gain adjust

R109

34

5-10

Imeter adjust

battery charging adjust

current compensation adjust

dcgaussing coil compensation oscillator amplitude adjust oscillator frequency adjust

TABLE 8.

Model 147 Internal Controls. The Table lists all internal controls, the

figure picturing the location,

5-7.

CHECK OUT AND CALIBRATION PROCEDURES.

The following procedures give the steps to check out and calibrate the Nod"1 147

a.

R228 I~239 R301

R313 R319

I

36 29

30 37

37

and the paragraph describing the adjustment.

5-8

5-11

5-4 5-9

5-9

circuits. If a circuit fails to check out at any point, refer to the circuit's trrxll)l<-shooting table. Continue as long as the points check out. Use the equipment l~istcd in

Table 7.

Procedures arc given for the power supply,

b.

oscillator and amplifier circuits.

These cover the principal adjustments t" bring the instrument within specifications.

If the Model 147 is not within specifications after performing these checks and

c. calibrations, contact Keithley Instruments or follow the troubleshooting proccdurcs io find the fault.

NOTE

Make sure the power supply and oscillator circuits are operating

correctly before chcckin~ the amplifiers. All circuits dcpcnd

upon properly functioning power supplies.

If taken out of order,

the resulting adjustment may be faulty.

5-8.

outputs check out at any point, refer to Table 10.

POWI?R SUPPLY CIIiSCK OUT AND CALIBRA'L'ION. All circuits depend upon the power supplies.

a.

must

be correct before further checks ar" mad".

Therefore, the 1.12, -12 and ~el.2 v"lL

If the power supplies fail to

After clearing the trouble, continue the

check.

Procedures for Checking Regulated Power Supplies.

b.

0466R

35

MAINTENANCE

MODEL 147 NULL DIITECTOR

1. Connect the Model 1488 Shorting Plug

as follows:

POWER SUPPLY Switch RANGIS Switch FUNCTION Switc'h

ZERO SUPPRESS COARSE Control

Line Voltage Switch

FIGURE 24. Correct Wave Form in dc-to-dc

Inverter. Point E, Figure 35, was

monitored.

Scale is 5 v/cm vertical,

0.2 mseclcm horizontal, Connect the Null Detector t" the ac power line.

position.

to

the INPUT. Set the Model 147 controls

OFF

100

?1LLLIVOLTS

OFF

Set to line voltage

Plug in the power cord. The AC

2.

CONNECTED Lamp should light.

Measure the voltage at the Yellow-

3.

White wire on the POWER SUPPLY Switch

front deck (Point A, Figure 29). It should be -18 volts dc -i2 vdc.

Turn the POWER SUPPLY Switch to AC.

4.

Use the oscilloscope

to

check the wave form at point E (Figure 35) in the dc-to-dc inverter.

Wave form should resemble that

in Figure 24.

5. Measure the signal levels and ripple with respect to low of the three regulated supplies.

c.

1.

Table 9 gives the values. Procedures for Charger Circuit. Disconnect the battery pack; do not

Lot the terminals touch the chassis.

Put the POWER SUPPLY Switch in AC

Set the charger bias voltage to -8.1 volts dc (measured with i3% voltmeter) at

2.

point C,

3.

side of the battery is ground. charging circuit works.

the brighter the l.ight,

Regulated

Power SUPPlY

~I+12 volt B il.6 to 12.8

-12 volt C 11.9 to 13.1 .I-1.2 volt D 1.16 to 1.28

TABLE 9.

Figure 35.

Adjust potentiometer R228 (Figure 36) for this value.

Connect the battery; make sure rhe polarity is correct (red to red).

The BATTERY CHARGING Lamp should light, showing the

'The lamp brightness directly indicates the charge current -

the greater the current.

iQxi.mum Ripple, Test Point, Figure 30

Signal Level,

volts dc

millivolts

peak-to-peak

0.3

2.0 460 * 70

0.2 2oi 3

Signal Level, Maximum Ripple and Resistance for Regulated PoWer Supplies.

IJse the oscilloscope and the Voltohmyst for the measurements.

‘36

The positive

Resistance

to Ground,

ohms

850 ilO

0466R

I

MODEL 147 NULL DliTEC'I'OR

5-9.

OSCILLATOR CIIECK OUT AND CALIBRATION.

MfYLNTENANCE

FIGURE 25.

Correct Wave Form at Point F (Figure 30) in Oscillator Circuit. Ls 2 v/cm vertical, 2 mseclcm horizontal.

If it does.not but resembles Figure 26, Transistors Q22 and Q23 are matched for gain. Keithley Instruments.

SCalt-

MODBL 147 NULL DETECTOR

Set the oscillator frequency to

2.

94 cps 20.1 cps with p"tenti&wter R319

(Figure 37).

Set the oscillator signal amplitude

3.

to 15.4 volts peak-to-peak 1~0.2 v peak-

to-peak,

measured on the oscilloscope.

Adjust with potentiometer R313 (Figure

37). Check the wave form at point F.

4.

It should be essentially sinusoidal, as

in Figure 25.

NOTE

If transistors Q21, Q22 or Q23 are replaced, it may be necessary to change resistor R307. A 27-kilohm

resistor should provide the proper bias for Q22 and Q23. The wave form at point F should resemble Figure 25.

use a 15-kilohm resistor for R307,

Order replacements only from

FIGURE 26.

A

Improper Wave Forms at Point F (Figure 30) in Oscillator Circuit.

B

Wave A

indicates the wrong bias; wave B is distorted. Scale for both is 2 v/cm vertical,

2 msec/cm horizontal.

S-10.

AMPLIFIER CHECK OUT AND CALIBRATION.

a .

Th" cheek out and calibration of the amplifier circuits is divided into tw" parts:

"perntivnal check and gain calibration.

~

The operational check does not have to be followed

38 0466R

MODEL 147 NULL DETECTOR MAINTENANCE

TROUBLE

PROBABLE CAUSE

Unable to adjust fre- Shorted chopper drive quency to 94 cps

Distorted, off-frequency wave form at

circuit for 94 cps at Q19 emitter (Point

Defective Q17, Q18 or (219

point 11 (Fig, 29 or

37) with chopper

disconnected

Low voltage, dis-

torted wave form at

Defective Ql7, Q18, Ql9 or R322 (Fig. 26B)

point F (Fig. 30)

Defective QZO, Q21, Q22, Q23 or R313

(Fig. 26, A or B) faulty components.

Improper bias to Adjust R307 as in note. Q22 ard Q23 (Fig.

260.)

UnstaJll~e frequency

Defective Q17, R319 C301, C302, C303 or Q17 or R319 are most Likely parts. R321, R320, R303, R318

SOLUTION

Disconnect chopper at 5302. Cheek

H, Fig.

29 or 37).

ChCCk for

shorted wiring and chopper coil.

Voltage at point 11 should bc 1 to

2 volts peak-to-peak, sine wvc. If not,

check conqmnents; rcpl,lcc

if faulty.

Check components; replace if fault!

Check the voltage, Q20 to Q23, given on schematic 17353D.

Replace

Check components; replace. <f I,!I!! I~:\

Oscillator Circuit Troubleshooting Table.

by gain calibration.

TABLE 11.

Use this to check the Model 147 operation. If the amplifiers fail

to check out at any point, refer to Table 13.

the check.

NOTE

Check the power supply and oscillator circuits before adjusting the

amplifiers.

the other

two circuits

If

may need recalibration.

Operational Check Procedures.

b.

Connect the Model 1488 Shorting Plug to the INPUT.

1.

as follows:

POWER SUPPLY Switch RANGE Switch 0.3 FUNCTION Switch

ZERO SUPPRESS COARSE Control

ZERO SUPPRESS FINE Control

On the 0.3-microvolt range,

(6:, of full scale).

It me,y be higher if the Shorting Plug is not used.

the meter offset should be less than 0.2 microvolt

After clearing the trouble, continue

are changed, the amplifier circuit

set the front panel controls

BATTERY MICROVOLTS

OFF At one end of rotation

046611

39

MAINTENANCE

Connect the Model 260 to the Model 147 INPUT Receptacle with the Model 2603 Input

3.

Cable.

Adjust the Model 260 for LOO-nanovolt output.

MODEL 147 NULL DETECTOR

NOTE

Follow the operating instructions in the Model 260 Instruction Manual. the input compartment, making good connections and similar details arc very im-

portant in the nanovolt and microvolt regions.

Connect the oscilloscope to the Model 147 OUTPUT. Sot the oscilloscope amplifier

4. to dc coupling, 0.2 volt/cm, the O.l-microvolt range.

SUPPRESS Controls to compensate for residual thermal emf's. Switch to -+ or -; observe the wave form on the oscilloscope. 10% to 90% of final

value)

time base to 0.1 or 0.2 second/cm. Set the Model 147 to

Turn the Model 260 POLARITY Switch to OFF.

Set the ZERO

Turn the Model 260 POLARITY

The response time (from

should be between 0.9 and 1.0 second.

Cautiously adjust po-

tentiometer R109 (Figure 34) for this value.

Potentiometer RL09 is a critical control. affects output ripple, response time.

Adjust this control only if one of these characteristics is

input resistance and maximum source resistance as well as

It adjusts the amplifier gain which

slightly out of specifications.

Gain Calibration ~roced~~?nc.

c.

Connect the Model 260

1.

Connect the Model 66011 Differential Voltmeter to the Model 147 OUTPUT Receptacle.

2.

to

the Model 147 INPUT with the Model 2603 Input Cable.

Closing

Before turning the Model 260

3.

POLARITY

Switch to -1 or -,

adjust the ZERO SUPPRESS Controls for zero output at the output terminals. Use the Model 660A to indicate the zero output. Set the Model 660A to its most sensitive range.

For a given full-scale input signal, measure the output voltage.

4.

It should be 1

volt dc -i-l% for all ranges.

After calibrating the amplifier, adjust the input voltage (or zero suppression) for

5. full-scale outputs as shown on the Model 660A, on any range 1 microvolt and above. Adjust potentiometer RL36 (Figure 34) for

Check the ranges in Table 12.

6.

exactly

full-scale

meter

deflection.

The Table indicates which range resistor would be faulty if any range is not correct. If these ranges check out, all ranges are within specifications.

If a range fails to check, refer to Table 13. Re-zero using the Zero

Suppress Controls before each check.

5-11.

a.

ZERO SHIFT BY SOURCE RESISTANCE.

Potentiometer R239 (Figure 29) adjusts the current fed back to the feedback point.

The current compensates for abnormal shifts in the meter zero as the source resistance

changes. At manufacture, the current is set to allow the Least shift over a range of resistances from near zero to 10 kilohms.

The potentiometer can also be adjusted to permit

no zero shift for a given source resistance if this is desired.

40

0466R

MODEL 147 NULL DIX'I'ECTOR

ml: X'- I: i,:I: ‘\ \i : j,.

5-12.

AMl?LIFIER PHASE CIIECK.

the rear panel.

Turn the ZERO SUPPlU$SS COARSE Control to 3; turn tllc IgINE Culltr<al ii!.;ii~.

Connect the oscill"scopc to the I~I~?.lOl~ULAl'OR 'CliS'I‘ Jack r)!,

from the end point until the oscilloscope indicates that the amp1i.ti.u is not saturn~cr! (the wave form is not clipped at

either

end). rectified sine wave, positive or negative. See Figure 27. phase as in

Figure 28.

Low frequency modulation and s"me bounce off tile envclnpc "I tl~c

The W~VC Form should appear as ;I !ial~f-:.::iv<.

It should not appear "ut oil

signal is normal.

100 Millivolts and all. other ranges

0.03 and 0.3 millivolt

0.1 Millivolt

0.3 Millivolt 1 Millivolt 3 Millivolts 10 Millivolgs 30 Millivol,ts

1.00 Millivolts and 100 Microvolts

TABLE 12.

If any fail,

Range Checkout.

check the listed resistor.

If these ranges are correct,

RL37B, Rl39, RL44 Rl49, R150 11170 R17L R145

RI.46

R147

RL48

R137 ratio

all Model 147 ranges are c"rsect.

FIGURE 27. TOR TEST Jack.

Correct Wave Form at DEMODULA-

Set paragraph 5-12.

is 1. v/cm vertical, 5 msec/cm llorizon-

ta1..

0466R

Scale

E

TROUBLE

High zero offset Short in feedback network. Make sure lugs do not touch each other or

I

PROBABLE CAUSE I

the copper plate in input compartment. Check resistances.

SOLUTION

I

Random zero drift, tens of Noisy chopper Replace chopper; see paragraph 5-4.

nanovolts or more; sometimes

reduced if the cabinet slapped. Response speed is

good.

I

Zero drift greatly affected Maladjusted or dirty FUNCTION by slight movement of FUNCTION Switch within a setting. so the rotor is flush with and makes contact

Abnormal zer" shift as source

resistance changes.

I

Zero drift affected greatly

by temperature changes.

Demodulator does not "clamp" during one-half cycle (Fig.

27).

I

Maladjusted degaussing

Switch. slide rotor away from pins.

Potentiometer R239 is out of ad

iustment.

I

Contaminated INPUT Receptacle,

shorting plug, or connection in input compartment,

Defective Q9, QlO, Q24 or

425.

coil

Adiust (paraeraph 5-4).

Loosen set screws on rotor hub (Figure 30);

Clean rotor

and pins with non-metallic abrasive. with all 3 pins consecutively, two at a time Adjust (paragraph j-11).

I

Clean IhJLIT Receptacle with non-metallic abrasive. surface,

with non-metallic abrasive; be sure to re-

turn leads to posts in original order. Check for sine wave at secondary of T302,

square wave at collector Q24 and Q25 and

base 99 and QlO.

If contamination goes below plated replace receptacle. Clean lugs

Replace faulty components.

Adjust

Greater than 20-mv peak-to

peak ripple at output terminals on ac power. On battery operation, output transformer.

ripple is above 5 mv p-p.

I

TABLE 13 (Sheet 1).

Instrument located near high L80-cps magnetic field, such as poorly shielded heavy-duty

Try turning off possible s"urces one by one. Move instrument from field source.

Amplifier Troubleshooting Table.

TROUBLE

PROBABLE CAUSE

SOLUTION

esponse speed very slow, 'ossibly zero offset also .igh.

pecifications with R109.

Cannot adjust to

Low ac amplifier gain, due to bad active element.

Improper amplifier phasing.

Lox gai;? in dc amplifier.

Leaky or shorted C115.

set to 0. l-gv range, ZERO SUPPRESS COARSE

to 3, FINE to an easily readable signal. With oscilloscope, check for square wave at Vl grid, and sine wave of each succeeding stage. Check dc voltages, Vi through Q8, given on schematic 18512F. Replace faulty components.

See paragraph 5-11. If use lissajous patterns to check phase from grid Vl through each stage to base 47.

Shifts of up to about 30" are acceptable.

Check capacitors and active elements. Unsolder and lift one end of R123 and R124.

See points M and S, Figure 34. Apply 10 to

100 mv to base of Qll to zero nieter, Change

input by 1 millivolt; output should shift

0.3 to 3.0 volts. If not, or if more than

100 mv is required to zero, check transis-

tors,

Ql2 are matched for offset. Replace only vith parts purchased from Keithley.

Check; replace if faulty.

beginning with Qll 2nd Q12. Qll and

at

input and output

waveform

is incorrect

.OO-millivolt and all other x;lges out of calibration, :ll sane direction.

)nly 0.03-microvolt or millirolt ranges O"t of calibra:ion.

ill microvolt ranges out of :alibration. :anges are good.

)ne range out of calibration.

The millivolt

T>.BLI: 13 (alcct 2).

R144, R139, or R137 out of tolerance.

R149 or RL50 out of tolerance.

Rl37 ratio B to A, out of tolerance.

Corresponding resistor in

Table 12 out of tolcrancr.

,Wpliiier Troublcshootin~~, 'Table.

Check resistors; replace if faulty.

Check resistor; replace if faulty.

MAINTENANCE

MODEL 147 NULL DETECTOR

FIGURE 29.

some test points are shown above.

R241, located on PC 76, are reached between the two printed circuit board modules.

Top View of Model 147 Chassis.

Refer to Parts List for circuit designations.

Locations of components, printed circuits and

44

R237 to

0466R

MODEL 14

MAINTLTANCE

MODEL 147 NULL DIXECTOR

FIGURE 31.

Transistor Locations on Printed Circuit 76.

46

FIGURE 32.

Capacitor and Diode Locations on Printed Circuit 76.

0466R

.:; ;

MAINTENANCE

MODEL 147 NULL DETECTOR

FIGURE 35. Resistor and Test Point Locations on Printed Circuit 74, Bottom Face.

Connect to point E at either place, not

to both points simultaneously.

48

FIGURE 36.

Component Locations on Printed Circuit 74, Top Face.

0466R

MODEL 147 NULL DETECTOR

MAINTKNANCi:

FIGURE 37.

Resistor and Test Point Locations on Printed Circuit 75.

An alternate location for point H is shown in Figure 29.

0466R

FIGURE 38.

Capacitor and Transistor Locations on Printed Circuit 75.

MAINTENANCE

MODEL 147 NULL DETECTOR

i?IGURE 39.

Resistor Locations on RANGE

Switch (~102). on opposite side.

Figure 40 shows resistors

3 .

FIGURE 40,

Resistor Locations on RANGE Switch (5102). tors on opposite side.

Figure 39 shows resis-

50

0477

SECTION 6.

REPLACEABLE PARTS

MODEL 147 REPLACEABLE PARTS LIST

(Refer to Schematic Diagrams 18512F,

MODEL 147 NULL DETECTOR

173523) and 17353D for circuit designations)

CAPACITORS

Circuit

Desig. Value

Cl 01 Cl02 Cl03 (60 Hz) Cl03 (50 Hz) Cl~O4 (60 Hz) Cl04 (50 Hz) Cl05

.01.35 uF .Ol j,F .184 IIF .109 pF .0135 UF .0155 P-IF

Not Used

Cl.06 .22 vF a07 .012 ~.IF Cl08

4.7 ~.IF

Rating 100 "

16 v

1.00 v 100 v 100 v Poly 100 v

50 "

100 v Poly

1.0 v ETB 05397

Cl09 100 pF 15 v Cl10

Cl11 Cl12

c 11~ 3 Cl14 Cl15

Cl.16 Cl.17 Cl18 Cl19

Cl20

.Ol uF 1000 v

25 uF 16 v 100 pF 15 v EAl

10 PF 10 PF

20 v 20 "

25 uF 10 v

Not Used Not Used

200 P-IF

.047 LIP

Y

3v ETB 20 v 500 v Poly

Mfg. Mfg.

Type Poly 84171

CerD

MY MY

Code Part No.

PE-143J

71590

UK16-104 12673 32M 12673 32M 84171 PE-133J

Poly

MY

84171 PE-153.J

84411 601PE 84171 PE-123.J

K4R7JlOS C-71-4.7M

EAl 29309 JC-6-100-15-8P CerD 72982 811Z5V103P

EAl 56289 TL1157-1

29309 JC-6-lOO-15-8P

ETT 05397 ETT 05397

KlOJZOK

ETT 05079 (non-polar)

14655 NLW200-3

MPF 97419 M2W-R-.047M

71590 CPR-XXXJ

Keithley Part No.

C-45-0.0135M

Fig. Ref.

21 C-238-.OlM 32 C-105-.184M C-105-.109M C-45-.013%

32

32 C-45-.0155M 32

C-41-.22M

32 C-45-.OlZM 32

32 C-210-100M C-22-.OlM

C-104-25M C-210-1OOM

32

32 c-80-1OM 32 c-80-1OM 32 C-106-25M 32

C-48-200M C-143-.047M

30

32 C-138-X

C201 c202

C203 C204 C205

C206 C207

C208 C209

c210

Not Used Not Used Not Used

100 uF 100 uF

.Ol !a!F

100 I-IF

100 uF

.Ol uF

100 ,,F

c21.1 100 uF c212 500 vF C213 500 uF C21.4

c301 C302

c303 c304 C305

.Ol pF 1000 v CerD 72982

.22 PF .22 PF

.l uF 100 pF 10 vF

52

15 v EAl 15 v EAl

1000 "

CerD 72982 811Z5V103P 25 v EAl 15 " EAl 56289

29309 JC-6-lOO-15-8P 29309 JC-6-lOO-15-8P

56289

89D226 C-94-1OOM

JC-6-lOO-15-8P 1000 v CerD 72982 811Z5V103P 25 v EAl 56289

89D226 c-94-1oOM

C-210-1OOM 32 C-210-1OOM 32

c-22-.olM 32

32

C-210-1OOM 32

C-22-.OlM 32

32

25 v EAl 29309 JC14-500-25-8P C-94-1OOM 32 25 v

EAl 29309

JC14-500-25-8P C-94-500M 36

25 v EAl 29309 JC14-500-25-8P C-94-500M 36

811Z5V103P C-22-.OlM 36

50 v 50 v

50 "

MY MY MY

15 v EAl 29309 JC-6-lOO-15-8P c-210-100~i

15 v EAl 56289

84411 84411

601PE C-41-.22M 38 601PE C-41-.22M 38

84411 6OlPE c-41-.lM

89D159 C-93-1OM

38 38 38

0477

MODEL 147 NULL DETECTOR

CAPACITORS (Cont'd)

Circuit Desig.

C306 100 l.lF 15 v EAl 29309 JC-h-lOO-15-8P c307 100 ,,F 15 " lL4l 29309 JC-6-100-15-W

C308 2 uF 50 " MPCb 14752 625BlA205 c309 .22 UF 50 " MY 84411 6OlPE c310 470 pF 1000 " CerD 71590 DD471,

c311 470 pF 1000 v CerD 71590 DD471~

Circui Circuit

Desig. DlOl

D102 D103 D104

D201

D202

D203 D204 Sil.icon D205 Zeller

Value

TYPO Silicon

Silicon zener Zf?lEr

Not Used

Silicon lN645

Rating Type

NUlUbC3f

lN645 lN645 lN709 lN709

lN645 01295 Special 80164

Mfg.

Code Part No.

DIODl?S

Mfg.

Mfg. Code

01295 01~295 12954

1.2954

01295

Kcithley

Part No. C-2l~o-l~ooN 38

C-210-IOOM C-215-2)1 C-41-.22M 38 C-64-4701' C-64-4701'

Keithley Part No.

RF-14 32 RF-14 DZ-21~ 32 nz-21

RF-~14 RF-L4 32

DZ-,L3 32

Fig.

Ref.

38 130

--

Fig.

Ref.

32 32

D206 Silicon D207 Silicon

D208 Zener, 2.6V

n209

D210 Silicon

D211 Silicon D212*7\ Silicon D212*** Silicon D213 Silicon D214 ZeniT D215 Silicon 0216 Silicon

circuit Mfg.

Desig.

DA201

DS201

--- Pilot Light Assembly, Red (Mfg. No. 8141~0-231)

Not Used

Description Battery Pack Assembly, h-volt 4-amp-hr nickel-

cadmium

Bulb, AC CONNECTED, bayonet base (Mfg. No. 49) 08804 PI.-23

lN645 01.295 lN645 01295

lN702A 01295 lN645 01295 lN645 01295

lN645 01295 lN645 01295 lN645 01295 lN713 12954 lN645 01295 lN645 01295

MISCELLANEOUS PARTS

Code

80164 Model 1489 29

72619 PL-5R 2

RF-l.4 ~3 2 RF-14 32 DZ-33 32

RF-1~4 32 RF-14 32

RF-14 32 RF-14 36 RF-14 36 DZ- 1.4 36 RF-14 36 RF-14 36

Keithley Fig.

Part No. Ref.

2

K* Schematic Diagram 18512F ""*Schematic Diagram 17352D

0477

53

MISCELLANEOUS PARTS (Coni'd)

MODEL 14.7 NULL DI5~IICI:OI:

Circuit Mfg. Keilhley

x202

1“01(117v)

F201(234v)

_-_ 11202

Cl01 Chopper Assembly JlOl

__-

J1.02

---

51~03

-__

J201

J202**

(n

03

Bulb, BATTERY CIIARGLNG, bayonet base (Mfg.

No. 49)

Pilot Light Assembly, Amber (Mfg. No. 8141~0-233) Iruse, slow below, l/8 amp (Mfg. Type MDL)

Fuse)

slow blow, I/lb amp (Mfg. Type MDL) Fuse Holder (Mfg. No. 342012) Fuse, 1 amp, 8 AC (Mfg. No. 361001.) Fuse Holder

Receptacle Assembly, INPUT Plug,

Phone Jack,

Specials,

Di>MODLJLATOR TEST (Mfg. No. 257)

Mate of JLOl

Phone Plug, Mate of 5102 (Mfg. No. 225) Receptacle, Microphone, OUTPUT (Mfg. No. 80-PC2ii)

l'lug, Microphone, Mate of 51.03 (Mfg. No. 80-MC2M) Terminal Block (Mfg. No. 3008)

Connector (Mfg. No. PSC4SS-15-11)

08804

7 2 6 ~1. 9

71400

7 1~400

75915

80164

7~1002 CS-65 83330

02660 02660 cs-33

83330

09922

PL-23

'PL-5A FlJ- 20

m-21

l%I- 3 I'L' 1

~1~9031A

CS-146

CS-32

x-47 CS-238

Fig.

2

30 30

29

3

29

J 30 1"‘

530 2""

Connector (Mfg. No. PSC4SS-15-11)

Receptacle

. Locking Ring (Mfg. No. 12G-lLb30)

Receptacle (Mfg. No. 126-1429) Body (Mfg. No. 126-1425)

Dindi.ng Post, T,O (Mfg. No. lIF21RC) Binding Post, GND (Mfg. No. DF21.GC)

Shorting Link (Mfg. No. 938-L)

Choke,

Choke, 120/80 hy

.--

(1‘) 1~urnished accessory

Schemati~c

Diagram 1~8512F

200 hy

09922

02660 02660 02660

58474 5847LI BP-I~IG

24.655

801~64 cw- 1 80164 CII- 5

CS-?,?R

CS-Ihi

CS-1~63

CS-161.

BP- 1~ 1R liP-6

29

3 3

29 29

54

MODEL 147 NULL DETECTOR

REPLACFABLE PARTS

MISCELLANEOUS PARTS (Cont'd)

Circuit Desig. Description

L301 L302

Ml01

---

Not Used Degausing Coil

Meter

Cord Set,

6 feet (Mfg. No. 4638-13) 93656

Cable Clamp (Mfg. No. SR-5P-1) Rotary Switch Assembly less components, FUNCTION

Knob Assembly, Function Switch

s102

---

s103

Rotary Switch less components, RANGE

Switch Assembly with components, Range

Knob Assembly, Range Switch Rotary Switch less components, ZERO SUPRESS

COARSE

---

5201

---

Switch Assembly with components, Coarse

Knob Assembly, Coarse Switch Rotary Switch less components, POWER SUPPLY

Knob Assembly,

Power Supply Switch

Mfg.

Keithley

Code Part No.

80164 80 164

M-8 29 ME-14

Fig.

Rfi

‘9

co-5 3

28520

80164

cc-4

W-161

80164 16323A 80164 SW-157 2

80164 176320 80164 16323A

80164 80164 80164

80164

W-58 17626B 14838A

SW-158

80164 18393A

2

5202

Slide Switch, 117-234 v Knob Assembly, Fine Control

TlOl Transformer Assembly T201 Transformer T202 Transformer

T301 Transformer

T302 Transformer

Circuit Desig.

RlOl R102 R103 R104 R105

Rl06 R107 R108 R109 RllO

Value Rating

6.8

kn lO%,

ll4W

10 kn lO%, 1/4w

4.7

Mn

lO%, 1/2w

250 kn l%, l/2 w

22

kn

lO%, l/2 w

250 kn l%, l/2 w 100 kn lO%, l/2 w 22 k$l lO%, l/2 w 100 I~(2 20%, .2 w

4.7 kn lO%, l/2 w

80164 80164 80164

80164 80164 80164 80164

RESISTORS

Type

camp

Mfg.

code

01121 CB-683-10%

Mfg.

Part No.

camp 01121 CB-103-10% COlIlP 01121 EB-475-IO%

DCb 79727 CFE-15

Camp 01121 EB

DCb 79727 CFE-15

Comp 01121 EB Comp 01121 ED CbVar 80294 30685 Camp 01121 EB

SW- 15 1 3 151lOA 2

18435B 29 TR-63 29 TR-65 29 TR-64 30 TR-68 30

Keitbley Part No.

R76-68K R76-10K

Fig. Ref.

32 32

Rl-4.7M 32

RlZ-250K 34 Rl-22K 33

R12-250K 33 Rl-100K 33 Rl-22K 33 RP40-100K 34 Rl-4.7K 34

WC 1 f tile

0477

low-thermal Function Switch needs replacement,

return unit for this repair.

5 5

RlVLACUBLE PARTS

MODU. 147 NIJLL DETECTOR

RESISTORS (Cont'd)

Circuit Mfg. Desig.

Rl 1~ 1. R112

Rl1~ 3 lUL4

R115

Rll6

R117

1<118

RI.19 R120

Xl21 R122

R123 RI24 R125

R126 1~127

Kl28

R129 RI30

Value Rating

22 k<l

27 ki)

10 k!l 10 kg

470 il

4.7 I(?

4.7 kil

4.7 k!:

4.7 k<i

8.2 kn 150 0

8. 2 k!) 10 k<l :1.0 I<0

50

k!,

50 kj?

250 :1 120 kl 120 k<1

12 ks?

Type Code Part No. Part No. Comp

Camp

Comp Comp C01llp

Comp

camp Comp COIIIP C0mp

Camp Comp DCb DCb DCb

01121

011~21

0112:t

01121

01121.

01121

0 1 1 2 1~ EB Rl-4.7K

01121. ER Rl-4.7K

01121 01121

79727 79727 79727

1x% 79727

DCb

79727

DCb 79727 DCb 79727 C0lllp

01.~1,21

Mfg.

EB

Keitldey

RI-22K

I?B Rl-27K ED Rl-1OK

En

Rl- 1OK

EB Rl-470

EB Rl-4.7!<

EB ED

Rl-4.7K Rl-8.2K

EB Rl-150

EB Rl-8.2K ax-15 CFE-15

R12-10K R12-10K

CFII- 1.5 Rl2-50K

CFE-15 R12-50K

WE-15 R12-250 CFE-15

Rl2-120K

C%l?-1.5 RI.Z-1.2011

EB Rl-12K

Fig. Ref.

33 34 34 34 33

33 33 33 33 33

34 33 34 34 34

33

33 34 34 33

R131 12 Iii‘ R132 25 I<<, R133 470 I: R134 100 12 R135 8 6 kc

R136 2 kc R137A & 13 1. kc? & 1 j, R138 20x, I.12 w

LO 8 c:

Special

Rl39 1~11 a l/4'%, l/3 13 R1.40 1. . 11 I<(,

R~1.41 RL42

10 I<<>

1.02M R1~43 9: R144 R145

900 P 99

Iii

RI.46 32.3 ii:) RI47

9 ki: R148 2.33 I<:? R1~49 9OG 1'

R1.50 1.00 (r

l/4%, l/3 w 5 '%

1. % , 11 2 w 1,x, l/ 2 w

l/4%, l/3 w

1./4'%., l/3 w l/4%, l/3 w

l/4Yv, l/3 w

1./4%, l/3 'id

1/4~L, l/3 \%I

1. I4 % , I.13 w

C0lUp

01121

DCb 79727 Camp C01Ilp

01,121

01121

DCb 79727 WTAI a r 80294

ww

80164

cb 80'164

WkkllC wwcnc

ww

MtI!

DCb

80164 80164

80164

07716

79727 wwWenc Ol686 wwelnc 01686

wwellc 01686 wwenc 01686 wwer1c 01686 wwenc 01686 wwenc 01686

EB Rl-12K

CFE-15 RlZ-251~

I?B Rl-470 EB Rl-100 cFl1-:1.5 Rl2-8.6K

3067s RP35-2K

17627A

18442A 17635A 17636A

RlE-19-10K CEC CFE-15

7010 7010

R94-1.02M

X12-A

R105-900

R105-99K

7010 RIO5-32.3K 7010 RlOS-9K 7010 Rl05-2.33K 70 1.0

Rl05-900

7010 Rl05-100

33 34 33 33

34

30

30 30

39

40 40

40 40 40

39

MODEL 147 NULL DETECTOR

REPLACEABLE PARTS

RESISTORS (Cont'd)

Circuit Mfg.

Desig. Value Rating Type code la51

K152 R153 R154

R155 R156

R157 R158 R159 R160

R161 R162

R163

R164 R165

R166 R167

R168 R169 R170

R171

R172

R173 R174 R175

3.3 Mn *1 MR x470 ICC2 *lOO kR

*27 IcCi

Not Used

330 k62 150 kQ

68 kSI

22 kn 10 ka

4.7 kn 1 kll

470 n

3.3 MI1

1 MS1 100 kQ

10 kn

*

1 ML1 332 kfi

10 kc1 15 kbl

x

*

lO%, 1/2w

lO%, l/ZW

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

lO%, lf2W lO%, 1/2w lO%, 1/2w lO%, lf2W

lO%, ll2W lO%, 1/2w lO%, 1/2w lO%, 1/2w l%, ll2W

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

3%, 1..5w lO%, 1/2w l/Z%, lf2W

l/4%, l/3W l%, ll2W l%, 1/8W lO%,

1l4W

lo%, 1/4w

camp camp camp camp camp

camp C0lllp Camp Comp

camp Camp camp camp DCb

DCb

wwvar Comp

MtF

wwenc

DCb

MtF

COTlIp

camp

01121 EB

01121 ED

01121 IiB

011.21. I?B 01121

01121 KB 01121 liB 01121 EB 01121 ED

01121 l?B 01121 l?B

01121 ED

01121 EB 79727 CF1'-15

79727 CFE-15 79127 CFE-15

73138 7216 01121 EB 07716 CEC

01686 7010

79727 CFE-15 07716 CEA-TO-15K

011.21. cn-* 01121 CB-*

Mfg. Kei~thley

Part No.

Part No. Ref.

Rl-3.3M 40 RI.-1M Kl~-470K K1~-.LooK

BB-273-10%

Rl-27K

Rl~-330K Rl-150K RI-68K KI-22K

Rl-1OK Rl-4.7K

R:l,- IRK

1~1-470

RlZ-3.3M Rl2-1M

R12-100K RP41~-1OK

RI-" R61-1El

RlO5-332K 39 K12-10K K88-l5K 32

R-76-9< R-76-h

Fig.

39 39 39 39

40 40

40

40 39

39 39 39

.A * xx

**

29

34 39

* *

32 32

R201

R202 R203 R204 R205 R206

R207 R208

R209

R210 R211

R212 R213

R214 R215 R216 R217 R218

Not Used Not Used Not Used Not Used Not used Not Used

1 kR

6.98 kQ

6.98 kCi

4.7 kR

2.7 kn

6.8 kQ

22 R

2.7 k,G

15 kR

22 kR

10 kn

lO%, lI2W

l%, ll2W

l%, 1/2w lO%, 1/2w

lO%, 1/2w

lO%, 1/2w lO%,

ll2W

lO%, l/ZW

lO%, 1/2w

lO%,

112w

l%, 1/2w l%,

IIZW

camp DCb DCb Comp Comp

camp

camp camp camp

camp DCb DCb

01121 EB 79727 CFE-15-6.98K 79727 CFE-15-6.98K 01121 EB 01121 ED 01121 EB

01121 EB Ol.121 ED 01121 EB 01121 EB 79727 WE-15 79727 CFl?-15

* Nominal value, factory set. ** These resistors are located in 5103, Figure 29.

0477

RI-1K

RlZ-6.98K R12-6.98K Rl-4.7K Rl-2.7K Rl-6.8K

RI-22 RI-2.7K Ill-15K RI-22K R12-10K

R12-10K

33

34 33 33 33 34

33 34 34

34 34 34

57

REPLAWABLE PARTS MODEL 147 NULL DETECTOR

s>ESISTORS (Cont'd)

Circuit

Mfg.

Keithley Fig.

Dcsig. Value Rating Type Code Part No. Part No. Ref. R219

R220 R221

R222

R223

R224

R225

R226 R227

R228

R229 R230

R231 R232

R233 R234 11235

R236

R237

R238 R239 R240 R241

4.7 kn 10 kn

10 kc1

2.7 ki>

2.7 R

4.7 kn 1 kil

*220 0

330 a 1 kn

1.8 kn 680 0

10 a

18 R

100 r,

1.5 kg la

75 kn 1 ki, 1 ko

10 kn 100 ka 100 ksl

l%, 112 w lO%, l/2 w

l%,

l/2 w

lO%,

l/2 x.7

lO%, l/2 w

lO%,

l/2 w

lO%, l/2 w

57 3w 5%: 3 w

lO%,

l/2 w

l%,

l/2 w

lO%,

l/2 w

D

5/,, 3 l"J

5%, 3 w lO%, l/2 w

1.07>, l/2 w

5%, 3 w

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

lO%, l/2 w

lO%,

l/2 w

lO%, l/2 w

DCb 79727 CFE-15 Rl2-4.7K

Comp 01121 ED Rl-1OK DCb 79727 CFE-15 R12-10K

Comp CLXllp Comp

01121 EB Rl-2.711 01121

EB

Rl-2.7

01.121 EB RI.-4.7K

Comp 01121 F.B Rl-1K

ww 44655 ww 44655 wwvar

80294 30675 RP39-1K DCb 79727 COTlIp

ww

01121 EB Rl-680

44655 ww 44655

4400 4400

WE-15 Rl2-1.8~

4400

4400 Comp 01121 EB Comp

ww 44655

DCb

01121

I?B Rl-1.5K

4400

79727 CFII-15 R12-75K

R92-220 R92-330

R92-10 R92-18 Rl-100 36

R92-1

Comp 01121 ED Rl-1K camp 01121 EB Rl-1K wwvar Comp

80294

01121

3067s

EB

camp 01121 EB

RP35-10K RI-100K Rl-100K

33 33

34 34 33 34

33 35

36

35 35

36 36

29 29 29 29 29 29

R301 R302 R303 R304 R305

R306 R307 R308 R309 R310

R311 R312

R313

R314

R315

1~316

R317

11318

8. 2 ks>

"15 kQ

4.7 kcl

4.7 kn

4.7 k?

Not Used

10 0 5 kn

6.8 ki2

4.7 kn

2. 5 ki? 10 kc1 12 kn

lO%, 5 w lO%, lU2 w lO%, l/2 w l%,

l/2 w

lO%, l/2 w

lO%, lO%,

lO%, 112 w

lO%, lO%, lO%, lO%,

l%,

1/z w

l%,

l/2 w

lO%,

" Nominal value, factory set.

58

l/2 w l/2 1.

l/2 w l/2 w l/2 w l/2 w

l/2 w

wwvar 71450 AW

RP34-2 Comp 01121 EB Rl-0 camp 01121 EB Rl-12K DCb 79727 CFE-15 Comp 01121

EB

Rl2-5K

RI-4.7K Comp 01121 EB Rl-8. 2K

Comp 01121 EB

Rl- 15K Comp 01121 ED Rl-4.7K camp 01121 EB Rl-4.7K Comp 01121 EB Rl-4.7K

Comp

01121

EB

Rl-10 37

wwvar 80294 30675 RP39-5K

Comp 01121 Comp 01121

EB EB Rl-4.7K

RI-6.8K 37

DCb 79727 CFE-15 R12-2.5K DCb 79727 CFE-15 R?2-10K

30

-_ 37

37 37

37 37 37 37 37

37 37 37

37

Comp 01121 EB Rl-12K 37

0468R

MODEL 147 NULL DETECTOR

REPLACEABLE PARTS

RESISTORS (Cont'd)

Circuit Desig. Value Rating

R319 R320

R321 R322 R323

R324 R325

Circuit

Desig.

2 kn

2.2 kQ

4kJl

Special (lamp)

4.7 ks, 10 ti 10 kn

lO%,

l/2 w

l%,

l/2 w

l%,

l/2 w

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

l/2 w

Mfr.

Desia. Code Part No.

':Q~FET, i+chan. (DUAL) SIL

-Q~~FET, N-c~~~.(DUAL) SIL Q3NPN, Case TO-106 2N5134 Q&NPN, Case TO-106

2N5134

95 2N1381

FNOTE: Qlb and Q2b are not used.

2Nl381

:;

2N1381 2Nl381

$7 QlO

2N1381 2Nl381

Mfg.

TYPO

wwvar

Code 80294

DCb 79727 DCb 79727

Special 80164 Comp 01121 camp 01121 Comp 01121

TRANSISTORS

Mfg.

E411 E411 07263 07263

01295 01295 TG-8

01295 'TG- 8 01295 TG-8 01295 01295 'E-8

Mfg.

Part NO.

Keithley Part No.

3067s RP39-2K CFE-15 R12-2.2K

CFE-15

R12-4K

PL-32

EB EB EB

Rl-4.7K Rl-1OK Rl-1OK

Keithley

TG-118 'TG-118 TG-65 'K-65

TG-8

'TG- 8 31

Fig. 1lfT.

37 37

37 37 37

37 37

Fis. Ref.

31 31 31

31

QllNPN, Case TO-106 2N5134 Q12NPN, Case TO-106 2N5134 413 2N1381 914 2Nl381

Q15 Q16

2Nl605A

2N651 Q17NPN, case TO-106 2N5134 Ql8NPN, Case TO-106 2N5134

Q19 Q20

Q2l Q22

2N1605

2N1381

2N1381 01295 TG-8 38

2N1381

423 2N1381 ~24

2N1381 01295 TG-8

07263 07263 01295 n1295 'TG- 8 02735

04713

TG-65 TG-65

31 31

TG-8 31

31

TG-16

31

TG-9 31 07263 TG-65 38 07263

~~-65

93332 TG-22 01295 TG- 6

01295 'TG-8 01295 'CC-8

38 38 38

425 2N1381 01295 'TG-8 38 Q26

2N1183 02735 TG-11 36 427 2N1535 04713 TG-7 36 428 2N651 429 2N651 430 2N1381 01295

04713 TG-9 36 04713 TC-9 36

'TG- 8 31

0477

59

REPLACEABLE PARTS

MODEL 147 NULL DETECTOR

TRANSISTORS (Cont'd)

Circuit Des-&.

431 932 Q33 Q34

Q35 PNP, Case TO-5 436

437

Q38

Q39 940 Not Used

Q41 Not Used 442 Not Used 443 Not Used 444 Not Used

Circuit

Desig. Number

Number

2N1381 01295 2Nl381 01295 TG-8 2N1381 2N1381 40319

2N1381 01295 TG-8 2Nl381 01295 TG-8 2~1381 01295 TG-8 2Nl381 01295 TG-8

Mfg.

Code

01295 TG-8 01295 TG- 8 02735 TG-50

VACUUM TUBES

Mfg.

Code Part No. Ref.

Keithley Part No.

TG-8

Keithley

Fig. Ref.

31 31 31 31 31

31 31 31 31

Fig.

v1 Not Used

V2 Not Used

MODEL 1481 REPLACEABLE PARTS LIST (F)

Description

Plug Assembly Cable Assembly, 48 inches Copper Alligator Clips (2) (Mfg. No. 6005)

MODEL 1482 REPLACEABLE PARTS LIST

Description

Plug Assembly Cable Assembly, 48 inches

Mfg.

Code

80164 Model 1486 80164 76545 AC-9

Mfg.

Code 80164 Model 1486

80164

Keithley

Part No.

14731B

Keithley Part No.

14731B

(F) Furnished accessory

60

MODEL 147 NULL DETECTOR

REPLACEABLE PARTS

MODELS 1483, 1484 REPLACEABLE PARTS LIST

Description

Crimp Tool for Copper lugs

iI8 Nylon Screws

88 Nylon Hex Nuts Copper Bolt-on Lugs

Copper Spade Lugs Copper Hook Lugs Copper Splice Tubes

Low-Thermal Cadmium-Tir Solder Copper Alligator Clips (Mfg. No

6005.1

Shieldkd Cable Insulated 1120 Copper Wire Non-metalic Abrasive

,112l Allen-Bradley Corp.

Milwaukee, Wis.

11295 Texas Instruments, Inc.

Semi Conductor-Components Division

Dallas, Tex.

11686 RCL Electronics, Inc.

Riverside, N. J.

'2660 Amphenol-Borg Electronics Corp.

Broadview, Chicago, Illinois 13050 Potter co.

2735 Radio Corp. of America

Connnercial Receiving Tube and Semiconductor Division Somerville, N. J.

4713 Motorola, Inc.

Semiconductor Products Division Livingston, N. J. Phoenix, Arizona

5079 Tansitor Electronics, Inc.

Bennington, Vt.

5397 Union Carbide Corp.

Linde Division Kemet Dept. Cleveland, Ohio

Mfg.

Quantity

1 50 50

100 100 100

100

Code 80164

80164 80164 80164 80164 80164 80164

10 feet 80164

10 76545

10 feet 80164

100 feet

80164

3 pads 80164

08804 Lamp Metals and Components

12673 Wesco Division

12954 Dickson Electronics Corp.

14655 Cornell-Dubilier Electric Corp.

15909 Dawn Division Thomas A. Edison

24655 General Radio Co.

28520 Heyman Mfg. Co.

44655 Ohmite Mfg. Co.

Keithley Used on

Part No. TL-1

-

17340A

17339A 17336~ 17338A

-

AC-9

SC-5 MS-1

17774A

Kit Model

1483 1483, 1484 1483, 146~1 1483, 1484 1483, 1~484 1483, 1484 1483, 1484 1483, 1484

1483, 1484 1483, 1484 1483, 1484

1483, 1484

Department G. E. Co.

Cleveland, Ohio

of Atlee Corp.

Greenfield, Mass.

Scottsdale, Ariz.

Wesson, Miss.

Newark, N. J.

Industries McGraw Edison Co.,

West Concord, Mass.

Kenilworth, N. J.

Skokie, Ill.

7716 International Resistance Co.

Burlington, Iowa

‘nwL!L 1,

(Sheet 1). tio*e List o* suggeste*

^. _. --

Code for Manufacturers, Cataloging Handbook

0468R

56289 Sprague Electric Co.

North Adams, Mass.

MallutaCt”rCrS.

,-

(&xsed on tifderal Supply

H4-1.)

61

REPLACEABLE PARTS

MODEL 147 NULL DETECTOR

58474 Superior Electric Co., The

Bristol, Corm.

71002 Birnbach Radio Co., Inc.

New York, N. Y.

71400 Bussmann Mfg. Div. of

McGraw-Edison Co.

St. Louis, MO.

71450 CTS Corp.

Elkhart, Ind.

72619 Dialight Corp.

Brooklyn, N. Y.

72982 Erie Technological Products, Inc.

Erie, Pa.

73138 Helipot Division of

Beckman Instruments, Inc. Fullerton, Calif.

73445 Ampcrex Electronic Co. Division of

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

75042 International Resistance Co.

Philadelphia, Pa.

75915 Littelfuse, Inc.

Des Plaines, Ill.

79727 Continental-Wirt Electronics Corp.

Philadelphia, Pa.

80164 Keithley Instruments, IX.

Cleveland, Ohio

80294 Bourns Laboratories, Inc.

Riverside, Calif.

83125 General Instrument Corp.

Capacitor Division Darlington, S. C.

83330 Smith, Herman II., Inc.

Brooklyn, N. Y.

84171 Arco Electronics, Inc.

Great Neck, N. Y.

84411 Good-All Electric Mfg. Co.

Ogallala, Nebr.

91.662 ~lco Corp. Willow Grove, Pa.

93332

Sylvania

Electric

Products, Inc.

Semiconductor Products Division

Woburn, Mass.

93656 Electric Cord Co.

Caldwcll, N. J.

76545 Mueller Electric Co.

Cleveland, Ohio

TABLE 15 (Sheet 2).

Code List of Suggested Manufacturers.

Code for Manufacturers, Cataloging Handbook H4-1.)

62

(Based on Federal Supply

0

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BATTERY Ch’ARG/NG

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(4.3 K

-

r’

?232 vv-

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v

R233

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C2/3

500

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7202 + 7

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BATTERY

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Keithley 147 Service manual

Specifications and Main Features

Frequently Asked Questions

User Manual