HP 185B Service manual

I.

:

HP

..

.

This vintage Hewlett Packard document was

preserved and distributed by

Archive

www.

'

Please visit us on the web

..

On-line curator: Tony Gerbic

hparchive.com

!

203210-

222-

@

1

1.

2

1

thru 3 01000

MANUAL

250-

317-00901 thru

CHANGES

MODEL 185B

OSCILLOSCOPE

Manual Serial Prefixed: 144-

Manual Printed: OCT 1962

1

thru 6

1

thru 8

432446-

525-

1

thru thru 12

1 1

thru 14

11

230245-

1

thru 4 348-

1

thru 5 430-

1

thru 9

1

thru 10

534-

1

thru 13, 15

28 December 1965

Supplement A for

185B-901

Serial Prefix Make or Number Manual Changes

203210222230-

1

2

1. 1

thru 3

1

thru 4

Manual Changes Model 185B

Serial Prefix Make

or

Number Manual

,250-

317317-00901 thrul 01000

348-

I

Cbsnges

1

thru 6

lthru7

1

thru

8

1

thru9

Page

2/9

432446525534-

1

thru

11

1

thru 12

1

thru 14

1

thru 13, 15

245-

ERRATA Add the following:

(cont'd)

CHANGE

CHANGE 2

1

Reference Desienation

C123

C160

L115 C425

C426

C427

C614

C615

C616

L608

1

thru 5

A302: HV Transformer Assembly: includes C309, C310, T301, V303, and V304;

Stock No. 185A-llA; Mfr. 28480; Mfr. Part No. 185A-llA; TQ C309, C310: Same description and @ Stock No. L603: Same description and T301: HV Transformer;

130B-llB-1; TQ 1;

V303, V304: Tube electron: 5642; @Stock No. 1920-0001; Mfr. 28480; Mfr.

1920-0001; TQ 2; RS 2.

Section VI and schematic diagrams,

Add the following:

Value

0.05 pf

pi

0.005

360 ph

0.05

pf

8200 pf

0.05 pf

pf

0.05

pf

0.1

pf

100 ph

(Note: For instruments

under CHANGE 2 except Q209.) Section VI and schematic diagrams,

C616: Delete. QlOl, Ql02, Q103, Q209: Change to

Mfr. 01295; Mfr. Part No. 2N388A.

R611: Change to

28480; Mfr.

The Internal Graticule Cathode-Ray

Model 185B Oscilloscope. The CRT formerly supplied, without internal graticule,

is

still available

Figure

5-26,

Change wiring

430-

@

RS

1.

C: fxd, and junction of R128 and +lOOV.

C: fxd, and ground.

Coil: fxd, RF, 360 ph. (On+6.3VlinebetweenR107 andC110.

C:

pin 10 [+12. 6V] , and ground.)

C: fxd, cer, 8200 pf, 500VDCW. (Between

C-IOOVJ

C: fxd,

J1,

C: fxd, cer, 0.05

between C: fxd,

between +12.6VF and ground. C: fxd, cer, 0.1

between +12.6V [BRN wire] Coil: fxd, RF, 100 ph.

this change] and C607 on -12.6V line.)

cer,

0.05

cer,

0.005

)

fxd, cer, 0.05

,

and ground

cer,

0.05 pf, +80% -20%, 1OOVDCW. (Between

pin 5 [-12.6V] , and ground.)

-

12.6V and ground.

cer,

0.05 pf, +80% -20%, 1OOVDCW.

serial

prefixed 222- and above, make

@

Stock No. 2100-0351;

Part

No. 2100-0351.

as

Option 05. This change obsoletes Option 03.

as

shown

in

1

thru 10

as

C312; change TQ column to 3.

@

Stock No.

Stock No. 130B-llB-1; Mfr. 28480; Mfr.

pf,

20%, 400VDCW. (Between ground

pf,

+80% -20%, 1OOVDCW. (Between

pf,

+80% -20%, 1OOVDCW. (On A602

pf,

+80% -20%, 50VDCW.

Tube

Figure

1.

as

L601, L602.

Description

)

500VDCW. (Between T103, pin 8,

J1,

pin 9

)

(On

A602

)

(On

S601A

,

and ground.)

(On

A602 between C614 [added by

all

component changes listed

@

Stock No. 1851-0024; Transistor 2N388A;

R:

var,

WW,

is

now supplied

4K ohms,

as

a

IO%,

standard part of the

1;

Part

J1,

RS

0.

No.

Part

@

1150-0052

0150-0014

9140-0038 0150-0096

0150-0082

0150-0096

0150-0121

9 140-0029

4W; Mfr.

($3

No.

Stock No

28 December 1965

Manual Changes Model 185B Page 3/9

Serial Prefix Make or Number Manual Changes

203210222230245-

CHANGE 2

(con t

'

d)

1

1.

2

1.thr1.1 1

1

r

thru 4

hru

I

-

3

5

7

I

1

I

Serial Prefix or Number

250317-

317-00901 thru

O1OOO

348-

430-

L601

35UH

n

R613

IO

-

T

Make

Manual Changes

-

4

+

12.6VF

Serial or Number Manual Changes

432446-

0603

Prefix

525-

534-

(k

Make

1

thru

11

1

thru

12

1

thru 14

1

thru 13.15

CHANGE 3

I

+12.6VF

I

Section

VI

and schematic diagrams,

Q209: Change to

Mfr. Part No. 2N2218.

Q603: Change to

Mfr. PartNo. 2N384.

R436: Change to

Mfr.

Part

R604: R607: Change to

R610: Change to Add the following:

Change to factory selected value.

Mfr. 01121; Mfr.

Mfr.

28480; Mfr. Part No. 0767-0011.

C134: C: fxd, elect, 20

Mfr. Part No. 40D-181-A2. and R155. reference designation corrections.

110

Figure

@

Stock No. 1854-0013; Transistor: silicon, 2N2218; Mfr. 04713;

@

Stock No. 1850-0041; Transistor: germanium, 2N384;

@

Stock No. 0819-0023; R: fxd,

No. 0819-0023.

$3

Stock No. 0683-3015; R: fxd, comp, 300 ohms, 5% 1/4W;

Part

@

Stock No. 0767-0011; R: fxd, metal film, 20K ohms, 5%, 3W;

)

Note: See Errata section of this manual change sheet concerning

i.

WW,

5 ohms, 5%, 55W; Mfr. 28480;

No. CB 3015.

pf,

25VDCW; @ Stock No. 0180-0076; Mfr. 56289;

(Connects between ground and junction of R154

Mfr.

02735;

28 December 1965

Manual Changes Model 185B

Page

4/9

Prefix

Serial or Number Manual Changes

203210222230245-

CHANGE

(cont'd)

3

Make Serial

1

1.

2

1

thru 3

1

thru 4

1

thru 5

C617: C: fxd,

Mfr. Part No. SM-62-N1500. and R610.

5604: Connector: BNC; @ Stock No. 1250-0083;

UG-l094/U.

L116: Coil: fxd, RF, 1OO'ph;

3100-15-101.

R268: R: fxd, comp, 82K ohms,

Mfr. Part No. EB 8231.

or Number Manltal-€hm@s

Prefix

2 50317-

317-00901 thrul 01000

I

1

thru 6

1

thru

1

thru

1

thru 9

Make

7

8

432446-

525-

534-

1

E-kL-i

cer,

62

pf,

lo%,

SOOVDCW; @ Stock No. 0150-0087; Mfr. 91418;

(Connects between ground and junction of R607

)

Mfr.

(Insert in line between J601 and A602 [circuit board 185E65Pl

(Insert in line between SlOlA and junction of R154 and R155.)

@

Stock No. 9140-0029; Mfr. 99848; Mfr.

lo%,

1/2W; @ Stock No. 0687-8231; Mfr. 01121;

(Connect

a8

shown in Figure 2.)

91737; Mfr. Part No.

thru

11

thru 12

thn

14

th.ru

13,15

Part

No.

.

)

CHANGE 4

28 December 1965

Section

Figure

L

Figure 2.

VI

Add C244: C: fxd, CR107, CR108, CR112, CR113, CR114: Change to Add CR223: Diode: germanium;

QlKChange to @ Stock No. 1854-0003; Transistor: silicon; Mfr. 28480; Q201: Change to Q603: Change to

Disconnect R272 end which attaches to junction

and schematic diagrams,

cer,

0.1

pf,

40%

Mfr. 56289; Mfr. Part No. 33C41. silicon; Mfr. 28480; Mfr. Part No. 1901-0040.

1910-0016. (Connects between R267 and S203A; anode side connects to S203A.

Note:

Do

not add CR223

Mfr. Part No. 1854-0003.

@

Mfr. Part No. 1850-0062. Mfr.

Part

5-17,

to junction of R501 and S204.

Stock

@

Stock

No. 1850-0029.

if

instrument

No.

1850-0062; Transistor: germanium; Mfr. 28480;

No.

1850-0029; Transistor: germanium; Mfr. 28480;

-20% 50VDCW; @ Stock (Connects in

@

Stock

No.

1910-0016; Mfr. 28480; Mfr.

serial

prefix

of

Q210 and R255B and reconnect

parallel

($3

Stock No. 1901-0040; Diode:

is

No.

0150-0084;

with

CR221.

250- or above.

)

Part

No.

)

Manual Changes Model 185B

Page 5/9

I

Serial Prefix Make

or

Number Manual Changes

250-

317-00901 thru

348430-

CHANGE 5 Figure 5-29 and Section

A

Q401, Q402,

9405,

Q416: Change to

PNP, selecte3 YTfr. 28480;

VI,

Yfr.

1

thru 6

1

thru 9

1

thru

10

’@

Stock No. 5080-0427; Transistor: germanium,

?art

FTo.

5080-0427.

432-

1

thru

11

thru 14

CHANGE 6 Figure 5-29 and Section VI,

to

‘$3

CR407, CR410, CR413: Change

Mfr.

10%;

R444: Change to

28480; Mfr. Part No. 1902-0034.

@

Stock No. 0758-0015;

Stock No. 1902-0034; Diode: breakdown, 5.76V,

R:

fxd, metal film, 220 ohms, 5%

1/2W;

Mfr. 28480; Mfr. Part No. 0758-0015.

R458: Change to

‘$3

Stock No. 0758-0014; R: fxd, metal film, 180 ohms, 5%, 1/2W;

Mfr. 28480; Mfr. Part No. 0758-0014.

R463: Change to

$3

Stock No. 0816-0022; R: fxd,

ww,

1500 ohms, 576 1OW;

Mfr. 28480; Mfr. Part No. 0816-0022.

Section

VI

and schematic diagrams,

Add the following:

L114: Core: ferrite bead;

56-590-65/4A.

(Connects in

of C151 and R179.

R196: R: fxd, comp, 10 ohms, 1096, 1/4W;

Mfr. Part No. CB 1001. (Connects in and ground.

)

R447, R459: R: fxd, metal film, 680 ohms, 57% 1/2W;

Mfr. 28480; Mfr. Part No. 0758-0031.

‘$3

Stock No. 9170-0029; Mfr. 02114; Mfr.

series

)

with C152 between capacitor and junction

@

Stock No. 0684-1001; Mfr. 01121;

series

with C141 between capacitor

($3

Stock No. 0758-0031;

Part

No.

(Connect R447 between -12.6V output and junction of Q415 and CR410; connect R459 between ground and junction of Q412 and CR407.

)

Table 6-2,

Delete @ Stock No. 185A-12G. Add the following:

Probe: Clip Adapter; Probe: Clip;

@

9

Stock No. 5040-0403; Mfr. 28480; Mfr.

Stock No. 5040-0404; Mfr. 28480; Mfr.

Part

No. 5040-0404.

Part

No. 5040-0403.

CHANGE

7

Figure 5-17 and Section VI,

28 December 1965

pf,

40%

Add C237: C: fxd, cer, 0.1

Mfr. 56289; Mfr. Part No. 33C41. +12.6VF and CR209.

CR201: Change to @ Stock

)

No.

-20%, 50VDCW; @ Stock No. 0150-0084; (Connects between ground and junction

1901-0050; Diode: silicon; Mfr. 28480; Mfr.

of

Part

No.

1901-0050.

CR210, CR212, CR216: Change to

($3

Stock No. 1901-0040; Diode: silicon; Mfr. 28480;

Mfr. Part No. 1901-0040.

CR219: Change to

@I

Stock No. 1901-0025; Diode: silicon; Mfr. 28480; Mfr. Part

NO.

1901-0025.

CR220: Change to @ Stock No. 1902-0068; Diode: breakdown, 80.6V, 5%; Mfr. 28480;

Mfr.

Part

CR221: Change to

Mfr.

Q207: Change

Mfr. 348-

No. 1902-0068.

@

Part

No. 1902-0074.

to

($3

Part

or

above.

Stock No. 1850-0091; Transistor: germanium, 2N2048; Mfr. 56289;

No. 2N2048. Note:

Stock No. 1902-0074; Diode: breakdown, 7.15V, 5%; Mfr. 28480;

Do

not change Q207

if

instrument

serial

Prefix

is

203210222-

1

2

1,

1.thru

Manual Changes Model 185B

250- lthru6 317-

317-00901

3

01000

1

thru

1

thru thru

7

8

Page

6/9

432-

1

thru

1

thru 12

1

thru 14

11

23024 5-

CHANGE 8

CHANGE 9

CHANGE 10

1

thru 4

lthru5

Figure 5-29 and

Q418, Q419:

Mfr.

Section VI, Change to

Part

No. 1850-0040.

$9

Stock No. 1850-0040; Transistor: 2N383; Mfr. 28480;

Tables 6-1 and 6-2,

C402: Change to

CR136: Change

$9

Stock No. 0180-0164.

to

@

Stock No. 1901-0050.

Figure 5-17,

A

Q207: Change type to 2N2635.

Figure 5-26 (as modified by CHANGE 2),

pf);

Add: electrolytic capacitor C618 (3000

R613/L607 junction and ground (observe polarity). C618

connects between +12.6VF

is

clamps to left-side gusset below CALIBRATOR switch. Wire from board A602

is

BRN/ORN.

mounted

at

right of

by

+

lead to

cable

Tables 6-1 and 6-2,

Add C618:

Mfr. 56289; Mfr.

Q207: Change to @ Stock No. 1850-0158; Transistor: GE, PNP, 2N2635; Mfr 04713.

A

(Replacement for discontinued item.

($3

Stock No. 0180-0271; C: fxd, elect, 3000

Part

No. 34D308H015JT4.

)

(EIA

type 2N2048 may

pf,

-10% +loo% 15VDCW;

if

used

available.

Figure 5-13,

C160 (added in CHANGE 1): Change value to 2.2

pf.

Add: C161 (200 pf); capacitor connects between ground and junction of R147/CR137.

Figure 5-26,

to

2.2

C615 (added in CHANGE 1): Change value

fl.

Tables 6-1 and 6-2,

C160, C615: Change to

Mfr. 56289;

Mfr.

Add C161: C: fxd,

($3

Stock No. 0160-0128; C: fxd,

Part No. 5C15.

cer,

200 pf, 5%, 500VDCW; Mfr. 56289; Mfr.

cer,

2.2

1.4

20%, 25VDCW;

Part

No. 40C.

)

CHANGE

11

CHANGE 12

28 December 1965

Figure 5-13,

C130: Change value to 56 pf. C159: Change value to 3300 Q102: Change transistor type

pf.

to

special 2N1310,

R142: Change value to 47K.

Tables

6-1 and 6-2,

C130: Change to

Mfr. 28480; Mfr.

C159: Change to

@

Stock No. 0140-0081;

Part

No. 0140-0081.

@

Stock No. 0150-0079; C: fxd, 3300

Mfr. 15450; Mfr. Part No. 811-000-Y5F0332K.

Q102: Change to

Mfr.

Part

R142: Change to

Mfr. 01121;

@

Stock No. 1851-0036; Transistor: special 2N1310; Mfr. 28480;

No. 1851-0036.

@

Stock No. 0686-4735; R: fxd, comp, 47K ohms, 5%, 1/2W;

Mfr.

Part

No. EB 4735.

Figure 5-29 and Section VI,

F405: Change to

@

Stock No. 2110-0067; Fuse: cartridge, 0.3 amp; Mfr. 28480;

Mfr. Part No. 2110-0067.

($3

C:

fxd, mica, 56

Stock No. 1851-0036.

pf,

18,

500VDCW;

pf,

IO%,

500vDCW;

Manual Changes Model 185B Page 7/9

Circuit

1

1,

2

1

thru 3

1

thru 4

1

thru 5

Cut out Figure A204: Change stock number to 185B65R. CR207, CR208: Delete. Q205, Q206: Delete 2N743 designation. R275: Change value to 11K ohms.

Figure 5-29,

A401: Change stock number to 185B-65s.

R469: Change value to 909 ohms.

V401:

Tables 6-1 and 6-2,

Make changes

203210222230245-

CHANGE 13 Figure 5-17,

Action

Reference

Serial or Number

430-

3

and tape in place on Figure 5-17.

Change tube type to 8228. Delete pin numbers and replace with dot

to

indicate anode.

as

follows:

Prefix

2

50-

317317-00901 thru 01000

348-

@

Stock No.

Make

Manual Changes

I

1

thru 6

I

1

thru

7

1

thru 8

1

thru 9

1

thru

10

Description

1

a

Serial

or

I

432-

I

446-

Prefix

Number Manual Changes

I

Mfr.

Make

1

thru

1

thru 12

1

thru 14

1

th~

11

13.15

Mfr

Part

.

No.

Change Change Change Add Delete

Delete

Change Change

Delete Change Change Delete Delete

Delete Delete Delete Delete Delete

Change Change Change Change Change

A201 A204 A401 c220 CR207

CR208

Q205 Q206

R201 R210 R213 R214 R215

R216 R217 R218 R219

R220

R230 R275

R277

R278 R279

185B- 19G 18

5B- 6 5R

18 5

B- 6 5s

0140-01 52

1910- 001 6

1910- 0016

1854- 0082

0767- 0009 0811-1509

2

100- 0497 0727-0060 0727-0090

0727-0047 0687- 5601 0686-3305 0686- 1005 0686-1005

0757-0843 0811- 1507 0757-0442 0698-3476 0757-0283

Assy: Switch, TIME SCALE MAGNIFIER Assy: Etched circuit, TIME BASE Assy: Etched circuit, C: fxd, mica,lOOO pf, 5%, 300 vdcw

LV

POWER SUPPLY

---

Transistor: Silicon, NPN

---

R

fxd,

ww,

R; var,

27Kohms,

ww,

500 ohms, 10% 5w

176,

7w

---

R: fxd, mefflm, 15.OK ohms,

R: fxd, R: fxd, mefflm, 10. OK ohms, R: fxd, mefflm, 6000 ohms, R: fxd, mefflm,

ww,

11K ohms, 3%, 5w

2000

ohms,

l%,

1%

176,

1%,

1/2w

1/8w 1/8w 1/8w

DM16F102;

28 December 1965

1

thru

1

thru 4

Manual Changes Model 185B Page 8/9

Serial

Prefix

or Number Manual Changes

3

317-00901 thru 01000

348430-

Make

1

thru8

1

thru

1

thru 10

Serial Prefix Make or Number Manual Changes

1

thru

11

1

thru 12

1

thru 14

1

thru

9

13,15

1

CHANGE 13

(Cont'd)

~~

Action

Change Change

Change Change Add

Add Add Add Add Add

Add

Add Add Add Add

Add Change Change Change Change Change Change

Circuit

Reference

R280 R281 R282 R283 R288

R289 R290

R291 R292 R293

R294 R295 R296 R297 R298

R299 R414 R415 R429 R431 R469

V401

@

Stock No.

0757-0280 0757-1100 0757-0407 0757-0407 0757-0280

0757- 0273 0757- 0438 0757- 0442 0'757-0453 0757-0416

0757-0410 0757-0401 0757- 03 94 0757-0388 0683-2005

081

1

-

13

35 0812-0051 0811- 1508 0811-1337 0811-1337

07

57- 08 19

1940-0012

Description

R: fxd, metflm, 1000 ohms, R: fxd, metflm, 600 ohms, R: fxd, metflm, R: fxd, metflm, R: fxd, metflm, 1000 ohms,

R: fxd, meffln,, R: fxd, mefflm, 5.11K ohms, R: fxd, metflm, R: fxd, mefflm, R: fxd, metflm, 511 ohms,

R:fxd, metflm, 301 ohms, R: fxd, mefflm, 100 ohms, R: fxd, mefflm, 51.1 ohms, R: fxd, metflm, 30.1 ohms, R: fxd, comp, ZOohms, 5%, 1/4w

R: fxd, R: fxd, R: fxd, R: fxd,

R: fxd,

R: fxd, mefflm, 909 ohms, Tube: Electron, VR, sub-minat, type 8228

ww, ww, ww, ww, ww,

200

ohms,

200

ohms,

3.01K ohms,

10. OK ohms,

30.1K ohms,

11K ohms, 3%, 3w 15K ohms, 3%, 3w

17Kohms,

20K ohms, 5%, 3w ZOKohrns, 5%, 3w

1%, 1%, 1%,

I%,

l%,

1%,

17%

1%,

3%, 4w

17%

1/8w 1/8w 1/8w

1%,

I%,

1/8w 1/8w

1/8w

1/2W

1/8w

1/8w 1/8w 1/8w 1/8w

1/8w 1/8w

Mfr.

Part No.

CB

2005

8228/ZZlOOO

.

CHANGE 14

CHANGE 15

28 December 1965

I

i

~

Tables 6-1 and 6-2,

Q201,

Q202:

Tables 6-1 and 6-2,

Q201, Q202: Change to hp Stock No. 1853-0003; Transistor: Silicon, PNP; Mfr 28480.

Change to hp Stock No. 1853-0009; Transistor: Silicon, PNP; Mfr 28480.

Serial Prefix Make or Number Manual Changes

222-

1

thru

3

25031

-1

01

7-

000

thri.

1

1 1

thru thru thru

6

7

8

Serial Prefix Make or Number Manual Changes

1

thru

11

1

thru

12

1

thru

14

230245-

CHANGE

(Cont’d)

13

I

1 1

thru thru

4 5

348- 1

430- 1

CUT 4LONG DOTTED LINE

1-

- - - - - - - - -

CUT 4LONG DOTTED LINE

thru thru

- -

9 10

I

534-

1

thru

13 , 15

1

28

December

1965

Figure

3

I

I I

-1

I

OPERATING AND

SERVICE

MANUAL

MODEL

SERIALS

PREFIXED:.

1856

144-

OSCILLOSCOPE

Copirieht 1501

?AOE

WEWlE??-?ACKAID COHPANY

MI11

ROAD.

PA10 AllO. CALIFORNIA,

1961

U.S.A.

Table of Contents

Model

185B

TAB18

Section Page I GENERAL INFORMATION

1.1

.

Introduction

1.3

.

Options

1.6

.

Instrument Identification

1.8

.

Description

1.14

.

Cathode-Ray Tube Warranty

II

PREPARATION FOR USE

.

Incoming Inspection

2.1

2.2

.

2.4

.

2.6

.

2.8

.

2.10

.

2.12

.

Installation

.

2.13

.

2.16

2.18

.

2.20

.

Associated Equipment Available

2.22

.

Reshipment

III

OPERATINGINSTRUCTIONS

Introduction

3.1

.

Front Panel Controlsand Connectors

3.4

.

Rear PanelConnectors

3.6

.

The Principle of the Sampling

3.8

.

Triggering the Model

3.13

.

3.14

.

General

3.17

3.27

3.30

3.31

3.35

3.37

IV

PRINCIPLESOFOPERATION

4-

4.4

4.5

4.7

4.9

4.13

4.17

4.19

4.21

4.23

4.26

4.31

4.32

4.34

4.36

Triggering Methods

.

Effects of FM and Jitter

.

Pulse

.

Observation of Intermittent Pulses

.

Examining Pulse Irregularities

.

Operating Instructions

1

.

Introduction

.

BlockDiagram Description

.

General

.

Input Circuits

.

Ramp-GateGenerator

.

Time-Base Circuits

.

Calibrator

.

Vertical Amplifier

.

Horizontal Amplifier

.

Time.BaseDetermination

.

TunnelDiode Operation

.

Triggering Circuits

.

General

.

Trigger Input

.

Ramp-Gate Generator Circuits

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

MechanicalInspection Power Requirements 230-Volt Operation Three-Conductor Power Cable Operational Check

Cooling Cabinet Mount

Rack Mount

Oscilloscope

Electronic Switch

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

Analysis

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

........

...........

.....

...........

....

........

.....

......

.......

...........

.........

..........

...........

..........

...........

.........

...........

.........

......

185B

....

......

....

.....

......

arid

.......

......

.....

......

.......

.

. .

.

OF

1-1

1-1 1-1

1-3 2-1

2-1 2-1 2-1 2-1 2-1 2-1 2-1

2-1 2-1

2-1 2-2 2-2

3-1 3-1 3-1 3-3

3 -4 3-4 3-4 3-5 3-6 3-6 3-6 3-6 3-6

4-1 4-1 4-1

4-1 4-1

4-1 4-1 4-2

4 -2 4-2 4-2 4-2 4-3 4-3 4-3 4-4

CONTENTS

Section Page

IV PRINCIPLES OF OPERATION (Cont'd)

4.46

.

Ramp-Gate Extender

Voltage Generator Circuits

4.54

.

Time-Base Circuits

4.56

.

Comparator

.

4.66

4.71

4.77

4.81

4.87

4.95

4.96

4.101

4-103.High-Voltage

4.106

V

MAINTENANCE

5.1

5.3

5.5

5.6

5.8

5.10 5- 12

5.15

5.17 5 . 30

5.31

5.34

5.37

5.41

5.43

5.45

5.47

5.51

5.53

5.57

5.59

5.67

5.68

5.69

5.70

5.72

5.73

5.75

VI

REPLACEABLE PARTS

6.1

6.4

Time Scale/Time Scale

Relationship

.

Delay Circuits

.

Comparator Blocking Oscillator

.

Horizontal-Scancircuits

.

Calibrator

.

Vertical Amplifier

.

General Operation

.

Transients

.

Low-Voltage Power Supplies

.

Introduction

.

Test InstrumentsRequired

.

Periodic

.

Cleaning

.

General Maintenance

.

Cabinet Removal

.

Troubleshooting

.

System Troubleshooting

.

SectionalTroubleshooting

.

Repair

Access

.

and Fan Motor

.

Replacement of Semiconductors

.

Servicing Etched Circuit Boards

.

CRT Replacement Adjustment Following Repair

. .

Adjustments

Low-Voltage

.

High-Voltage

.

Vertical Amplifier

.

Sync Circuit

.

Time Base

.

Performance Check

.

Time Calibrator

.

Sync Pulse

.

Amplitude Calibrator

.

Time Scale

.

Minimum Delay

.

Trigger Sensitivity

.

Introduction

.

Ordering Information

..........

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

..........

Plower

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

...........

Maintenance

the

Air

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

to Power Transistors

..........

Power

..........

...........

..........

...........

and

Ramp-

.......

.........

Magnifier

.........

.....

........

.......

Supply

....

...

....

.......

Filter

.....

......

........

.........

....

........

......

...

'Supplies

Supply

...

.......

........

......

........

.......

.........

.......

.

4-6 4-7 4-7

4-8 4-9 4-9 4-10 4-12 4-12 4-12

4-13 4-13

4-13

5-1 5-1 5-1

5-1

5-4

5-5

5-5 5-6 5-6 5-6 5-7

5-7

5.16

5-10

6-1 6-1 6-1

~

ii

01255-1

Model

185B

LIST

Of

ILLUSTRATIONS

List

of

List of Tables

Illustrations

Number Title Page

1.1

.

1.2

2.1

2.2

3.1

3.2

3.3

3.4

3.5

3.6

3.7

3.8

3.9

3.10

3.11

3.12

3.13

3.14

4.1

4.2

4.3

4.4

4.5

4.6

4.7

4.8

4.9

4.10

4.11

4.12

Model

.

Cathode-Ray Tube Warranty

.

Associated

.

Dimensions for

.

Operating Controls and Connectors

.

Rear Panel Controls

.

Viewing Signals Above

.

Viewing Signals Below

.

Viewing Signals Below

.

Viewing Signals Below

.

Free Running Trace

.

Unmagnified Trace

.

Magnified Trace

.

Viewing Delayed Signal

.

Using Delayed Trigger

.

Delayed Sync Pulse

.

External Scan

.

Recording the Signal

.

Overall BlockDiagram

.

Time-Base Determination

.

Tunnel-Diode Operation

.

Triggering-Circuit Block Diagram

.

Tunnel-Diode Count-Down Circuit Ramp Generator

. .

Time-Base BlockDiagram

.

Ramp Voltage vs Time

.

Effects of Delay

.

Staircase Generator

.

Vertical Amplifier Block Diagram

.

High-Voltage Power Supply

185B

Oscilloscope

Dual-Trace Vertical Plug-In

($9

Equipment Available

Rear

with

Support

.........

10

kc

10

kc by Using

Delayed Trigger

SYWC

PULSE OUT

Circuit under Test

Block Diagram

...........

10

kc by Using

..........

10

kc when the

..........

.........

..........

...........

........

..........

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

.........

.....

....

........

.....

........

......

.......

Model

187B

Unit

.

1-0

......

...

.....

...

......

...

1-3

2-0 2-3

3-0 3-2 3-5

3-5 3-5

3-5 3-7 3-8 3-9 3-10 3-11 3-12 3-13 3-13

4-0

4-2 4-3

4-4

4-5 4-6 4-8 4-a 4-10 4-11

4-13 4-13

Number Title Page

5.1

.

Driving the Trigger Circuit

.

Trigger Circuit Waveforms

5.2

Disassembly for Power Transistor

.

5.3

Replacement

.

MinimumDelay Measurement

5.4

5.5

.

Calibrator Instrument Setup

.

Top View, Model

5.6

5.7

.

Left Side

5.8

.

Right Side View, Model

5.9

.

Bottom View, Model

.

5.10 5 .ll

5.13

5.14

5.15

5.16

5.17

5.18

5.19

5.20

5.21

5.22 . A602

5.23

5.24 5-25

5.26

5.27

5.28

5.29 5 .30

5.31

5.32 . A302

5.33

A103

.

Waveforms

5.12

.

Parts Location, Switch Assemblies

.

Trigger Circuit, Schematic Diagram

.

A204

.

Waveforms

.

Parts Location, Switch Assemblies

.

Time-Base Circuit, Schematic Diagram

.

A1

.

Waveforms

.

Assembly Location

.

Main Vertical Amplifier,

Schematic Diagram

.

Waveforms

.

Assembly Location

.

Parts Location, Calibrator and Sync Pulse

Switch,

.

Calibrator and Sync Pulse Generator,

Schematic Diagram

.

A401

.

Assembly Location

.

Low-Voltage Power Supply,

Schematic Diagram

.

A301

.

Assembly Location

.

High-Voltage Power Supply,

Schematic Diagram

View,

Component Location

and

A2

Component Location

S601,

and

A402

Component Location High-Voltage Rectifier Assembly

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

185B

Model

185B

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

..........

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

..........

with Amp1 . Conn

.........

Component Location

..........

.........

..........

......

.....

......

........

185B

......

185B

......

.......

...

.

.......

...

.....

........

.......

.

5603 . 5-23

.

.......

.

........

5-3 5-3

5-5 5-8 5-8 5-11 5-12 5-12 5-13 5-16 5 . 16 5-17 5-17 5-18 5-18 5-18 5-19 5-20 5-20 5-21

5-21 5-22 5-22 5-23

5-23 5-24 5-24

5-25 5-26 5-26 5-26

5-27

LIST

Number Title Page

1.1

.

Specifications

2.1

.

Associated Equipment Available

.

3.1

5.1

5.2

5.3

5.4

01255-1

Methods of Triggering

.

Recommended Test Equipment

.

System Troubleshooting

.

Resistance to Ground

.

Adjustments Following Tube, Transistor,

and

Diode Replacement

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

....

........

.....

........

.........

.......

1-1 2-2 3-4 5-0 5-2 5-4

5-6

Of

TABLES

Number Title Page

5.5

.

Time Scale Adjustments

5.6

.

Condensed Test and Adjustment

Procedure

5.7

.

Amplitude Calibrator Accuracy

.

Time Scale Calibration Check

5.8

6.1

.

Reference DesignationIndex

.

Replaceable Parts

6.2

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

.......

....

.....

..........

5-8 5-9

5-10 5-10

6-2 6-24

iii

Section

Figure

I

1-1

Model

185B

Y

Figure 1-1. Model 185B Oscilloscope with Model 187B Dual-Trace Vertical Plug-In Unit

1-0

~

01255-1

Model

185B

Paragraphs

Section I

1-1

to

1-10

SECTION

GENERAL INFORMATION

1-1.

INTRODUCTION.

1-2.

This manual gives operation and maintenance

information for the An operational check operation performance check specifications during incoming inspection paragraph

1-3.

1-4.

P2

phosphor with external graticule.

options, however, are available:

a.

b. Option c. Option

d:

e.

1-5.

option

differences in crt persistence, color, and oscilloscope photography techniques, instruments with or without option are, however,

(see section VI).

in this manual apply to all options unless otherwise indicated.

is

given in paragraph

5-67.

OPTIONS.

The

Model

Option

Option Option

1.

P1

Internal graticule in cathode ray

3.

7.

P7 phosphor

11.

P11

31.

P31 phosphor

Option

31

1

is

available only with option

3

are operationally interchangeable. There

some differences in component parts

@

Model

to

185B

assure basic instrument

2-10.

that

may be used for verifying

185B

is

normally supplied with

phosphor

is

not available with option

All

references to the Model

Oscilloscope.

A

complete

is

given in

The following

tube

3,

3.

Other than

and

185B

I

1-6.

INSTRUMENT IDENTIFICATION.

1-7.

Hewlett-Packard Company uses a two-section

eight-digit serial number (e.g.

first

three digits of the serial number onyour instru-

ment are not

with

this manual which define differences between

your instrument and

sheets are missing, your Hewlett-Packard engineering representative can supply you with the necessary information.

144-,

change sheets have been supplied

this

a

1-8.

DCSCRl?TlON.

1-9.

GENERAL. The

provides

ena

will

below

spaced. signal

operate reliably.

above obtain jitter-free presentation.

1-10.

high speed characteristics nique. Using this system the entire signal under examination taken on different occurrences of the input at slightly later points along the waveform.

a

with repetition rates to

visual display of very high-speed phenom-

present a steady display of pulse repetition rates

100

kc even when the signals are randomly

For frequencies above

is

divided down

100

kc, more uniform spacing

PRESENTATION. The Model

is

scanned, with each succeeding sample

@

Model

so

that the input circuitry will

As

the input frequency increases

by

000-00000).

manual. If

1000

mc. The instrument

100

185B

kc,

is

these

Oscilloscope

the

185B

using the sampling tech-

Each time such a

If the

change

incoming

required

obtains

to

it8

I

HORIZONTAL

Sweep Speeds:

10 ranges, within between ranges and increases fastestunmaanified sweep speedto sweep the exception of time represented by

of

the unmagnified sweep.

Magnification:

7

calibrated ranges

and

X100.

speed to sweep speed

Intensity and sample density are not affected by

magnification.

Delay Control:

Three-turn when using magnified sweep. Permits any tion of unmagnified trace

10

nsec/cm

Vernier gives continuous adjustment

&5%.

4

is

maintained at all magnifier settings with

Increases maximum calibrated sweep

0.1

nsec/cm; with vernier, maximum

is

further extended to

variable delay control

to

10

psec/cm, accuracy

nsec/cm. Accuracy of the basic

X1,

X2,

X5,

X10, X20, X50,

0.04

is

to

be

viewed on screen.

01255-1

Table

first

nsec/cm.

available

1/4

por-

1-1.

Specifications

cm

Minimum Delay (input trigger

Less than faster. On slower sweep

lay increases to

5

psec on the lO-psec/cm range.

Sample

Continuously adjustable from approximately 70 samples per trace

Scanning Functions:

Internal

for normal viewing.

Record

approximately

Manual

knob.

External

approximately input impedance greater than

120

Density:

-

X

-

X

-

X

-

nsec at

a

maximum of approximately

to

axis

driven

axis driven by internal slow ramp;

60

seconds for one trace.

axis driven by manual scan control

X

axis

driven

12

volts for 10-cm deflection,

to

start

100

nsec/cm sweep and

speeds,

1000

by

minimum de-

samples per trace.

internal staircase

external voltage;

25,000

Specifications cont'd

of trace):

ohms.

1-1

Section

Table

I

1-1

(cont‘d)

1-1.

Table

“RIGGER FUNCTIONS Normal-External Trigger

to

Amplitude: 450 mv

volts rms or 100 volts peak will not damage input circuit.

Width: 5 nsec at minimum amplitude.

Rate:

50 cps to 1 mc speed setting. Maximum 100 mc on the 200 nsec/cm

Jitter:

Input Impedance: 50 ohms nominal

Sensitive-External Trigger

Amplitude: *15

Width:

Rate: Same as normal

Jitter:

Input Impedance: 50

High Frequency

Input Frequency: 50 to Sensitivity: 200 mvpeak-to-peak. Operates from

Jitter: 4% of cycle from 50 to 400 mc;

Signal at Input Connector: Less than 15 mvpeak-

Input Impedance: 50 ohms nominal, ac coupled.

SYNC PROBE The 185B-21A (use with any trigger function) in-

creases input impedance to more than 7500 ac coupled; reduces sensitivity by approximately 4:l at 10 mc and higher and by approximately 20:l

at

low frequencies.

SYNC PULSE OUTPUT Amplitude: Positive; at least 1.5 v into 50 ohms Rise Time: Less than 2 nsec Width: Approximately 5 psec Recurrence: One pulse per sample

CALIBRATOR Voltage:

20 mv, 100 mv,

Time:

Approximately 5 psec burst of 50 mc sinewave.

Frequency accuracy

Less than 0.03 nsec or 0.02% of the time represented ever

is

approximately 5:l in the “smoothed” response position.

Reflection from step of

by

greater (fast rise Signals). Reduced

to

rms or 10 volts peak circuit.

5 nsec at minimum amplitude

Same as normal

of 200 nsec/cm smaller signals at some increase in jitter. Up

to 5 volts rms or 15 volts peak will not damage input circuit.

from 400 to 1000 mc to-peak, approximately 10 mc Reflection from step of

less than 8%.

i2 volts peak. Up

on

the lO-Fsec/cm sweep

rate

increases

and

faster

the

unmagnified speed, which-

1/2

nsec

is

*200 mv peak. Up to 5 volts

will

not damage input

ohms

nominal, dc coupled

1000

mc forsweepspeeds

and

faster

1/2

nsec rise time

200

mv, and 1000 mv;

dc

less

8%

rangee.

coupled. than

of Cycle

*2%.

Specifications (cont’d)

X-Y

RECORDER OUTPUT

X-

and

to

5

to

8%.

is

ohms,

&

minals in all positions of the scanning control. In the

MANUAL and RECORD positions the voltage

can

be

ventional

Horizontal Output: Approximately

of sweep v/cm).

Vertical Output: Approximately

graticule, impedance approximately 1,000 ohms.

GENERAL Cathode Ray

5AQ mono accelerator with P2 phosphor normally supplied. 2900-volt accelerating potential,

External Graticule (standard):

Edge lighted with controlled illumination, 10 cm

by

axes have 2-millimeter subdivisions.

Power: 115 or 230 volts

approximately

Dimensions:

Cabinet Mount: 14-5/8 inches high, 19 inches

wide, 22-1/8 inches deep

Rack Mount: 12-1/4 inches high, 19 inches

wide, 21 inches deep behind panel

Weight:

Cabinet Mount: Net 65 lb Accessories Furnished: 185B-21A Sync Probe Accessories Available:

185A-39A Plug-In Extender

185A-21C Resistive Divider Probe, 5:l division,

185A-21D Resistive Divider Probe,

185A-21E Resistive Divider Probe, 50:l divi-

185A-21F Resistive Divider Probe,

AC-16W 3-ft RG-55 cable for 185A-21C,D,E,F

Associated Instruments:

187B Dual Trace Vertical Amplifier

187B accessories available:

187A-76A BNC Adapter 187A-76B Type 187B-76C 10: 187A-76D Blocking Capacitor 187B-76E 50-ohm T Connector Model Model 908A 50-ohm Coaxial Termination 187B-76F Adapters 187B-76G Probe Socket

Model 213A Pulse Generator,

Model 185B

Y-axis

used to make pen recordings with a con-

signals are available at rear

X-Y

recorder.

to

+13 volts at end of sweep (1.2

Source

impedance approx. 20,000 ohms.

-1

volt at bottom (0.2 v/cm), Source

0

volt

+1

volt at top of

at

ter-

start

Tube:

P1,

P7, and

10 cm, marked in centimeter squares. Major

300

250 ohms

sion, 500 ohms

sion, 2500 ohms sion, 5000 ohms

llOOA

nsec

rise

time k350 mv amplitude

P11

watts

N

Adapter

1

Divider

Delay Line

phosphors available.

*IO%,

50 to

less

60

1O:l

divi-

1OO:l

divi-

than 0.5

cp8,

A.

1-2

01255-1

Model

185B

Paragraphs

Section I

1-11

to

1-15

sample

is

taken, the

“spot"

on the

crtis

moved hori-

zontally along the waveform. Thus, a complete pic-

ture of

a

repetitive high speed signal

is

synthesized by a buildup of image-retaining “dots” on the oscilloscope face

1-11.

The Model ranging from nanoseconds per centimeter depending on the of the TIME SCALE switch. Any part time scale can by adjusting the TIME SCALE MAGNIFIER

as

a graph

185B

10

microseconds per centimeter

be

expanded without loss

is

provides

plotted point by point,

10

basic

time

scales

setting

of

this

of

calibration,

switch.

to

10

basic

Built-in time and amplitude calibrators provide a convenient means vertical calibration. Intensity of pendent of duty cycle, and vertical deflection may adjusted up

185B

to

provides output signals for

of

checking

10

centimeters. In addition, the Model

both

horizontal and

the

trace

X-Y

recorders and

is

inde-

be

provides means for controlling the display either manually or externally.

1-12.

VERTICAL AMPLIFIER. The vertical system

of the Model

such as the Model

185B

includes aplug-in vertical amplifier

187B.

It

is

this amplifier which determines vertical characteristics such as bandpass, sensitivity, etc. The vertical plug-in unit

of

the

basic

1-13.

F’igure

185B-21A

Model

Sync Probe shown in

185B

Oscilloscope.

1-1

illustrates the Model

the

figure with the oscilloscope. The Model Vertical Amplifier plug-in unit

Table

1-1

1-14.

CATWODLRAY

1-15.

The cathode-ray tube supplied with the Model

185B

is

lists

guaranteed against electrical failure for one year from the date Company. The cathode-ray trated in figure in the appendix of

is

shown installed, although the

not part of the basic oscilloscope.

the specifications for the Model

TUBE

WARRANTY.

of

sale

by

the

tube

warranty

1-2.

A

sheet

for your use

this

manual.

is

not part

187B

185B.

is

Dual Trace

The

supplied

185B.

Hewlett-Packard

is

illus-

is

included

IEWLETT-PACKARD

01255-1

CO.

PAOC

MILL

ROAD.

PAL0

Figure

ALTO. CALIF.

1-2.

U.S.A.

Cathode-Ray

Tube

Warranty

1-3

se~tian

Figure

n

2-1

Model

185B

MODEL DUAL TRACE

I

CAL AMPL I F I ER

VERT

1878

MODEL 196A/B

OSCILLOSCOPE

CAMERA

MODEL IlOOA

DELAY LINE

MODEL DELAY

2-0

I

00A-76

LINE LOAD

A

Figure

2-1.

CONNECTING

Aellociated

@

Equipment

Available

MODEL l85A-76A SYNC TAKE-OFF

UP

-Y-93

01255-1

Model 185B

Section

Paragraphs 2-1

to

II

2-19

SECTION

PREPARATION

2-1.

INCOMING INSPLCTION.

2-2. MECHANICAL INSPECTION. 2-3. Upon receipt of your Model 185B, check the

contents against the packing strument for any obvious damage received in transit.

If

damage

(Refer ditional information.) all re-usable packing material until an operational

check

2-4. POWER REQUIREMENTS.

2-5. The Model 185B requires

115 or 230 volts which can deliver approximately

2-6. 230-VOLT OPERATION.

2-7. operated switch ment. The existing fuse should

2-ampere slow-blow fuse.

Be erly for the line voltage power supplies may switch

2-8. THREE-CONDUCTOR POWER CABLE, 2-9. To protect operating personnel, the National

Electrical Manufacturers' Association (NEMA) ommends grounded. This instrument conductor power cable which, when plugged into an appropriate receptacle, grounds the instrument. The offset pin on the power cable three-prong connector

is

the ground pin. To preserve the protection feature when operating the instrument from outlet, use connect the green pigtail to ground.

2-10. OPERATIONAL CHECK. 2-11. The following procedure

for checking basic operation controls mentioned in the following procedure shown in figure 3-1. A complete check-out procedure

to

verify specifications

a.

Install the vertical plug-in unit.

gain

to

b.

Turn INTENSITY

c.

Set

100 NSEC/CM,

is

evident, file claim with the carrier.

to

the

warranty sheet in

To

has

been successfully completed.

*lo%,

If

.230-volt operation

is

provided on the rear of the instru-

CAUTION

sure

to

set

the 115-230 volt switch prop-

is

set

to the wrong position.

that

the instrument panel and cabinet

a

three-prong to two-prong adapter and

approximately 50 mv/cm.

full

SCANNING to INTERNAL, TIME SCALE to

DENSITY full clockwise, MODE

list

and inspect the in-

this

facilitate reshipment, keep

single phase,

is

desired, a screwdriver-

be

is

equipped with a three-

of

is

given in paragraph 5-67.

counterclockwise.

manual for ad-

a

power

300

be

to

be

damaged

is

given

the Model 185B. All

source

50

to

watts.

replaced with

used. The

a

60 cps,

if

this

two-contact

as

a

means

Set

vertical

of

rec-

be

are

to

II

FOR

FREE RUN, TIME SCALE MAGNIFIER and CALIBRATOR AND SYNC PULSE OUTPUT switches full counterclockwise.

d. Center HORIZONTAL POSITION and VERTICAL

POSITION controls.

e.

minutes

vertical plug-in input

f.

pears.

and readjust HORIZONTAL POSITION and VERTICAL POSITION controls as necessary.

g.

h

mately five cycles of

2-12.

a

2-13. COOLING.

2-14. The Model 185B uses tem within the cabinet. The air intake and filter cated on ment, choose of clearance around rear and sides of cabinet..

2-15. the

be

coated with a

No.

filter

cooling. Refer to paragraph

procedures.

2-16. CABINET MOUNT. 2-17. The Model 185B cabinet mount

instrument. ated with plane.

ment to a better viewing angle. Be sure to maintain clearance required for proper cooling mentioned in

paragraph 2-14.

2-18. RACK MOUNT. 2-19. The standard rack model

rear-support pins and bushings. The bushings installed on rear flanges. The pins are for use in mounting the instrument tended to mate with bushings when instrument stalled. Do not mount the instrument with only frontpanel screws, particularly

to

any

support pins securing front panel to rack are not supplied. Install instrument

USE

Turn the Model 185B on and allow about

for

the instrument

to

Rotate INTENSITY clockwise until a

If

the crt remains

Adjust FOCUS for a

resultant presentation should

The

a

INSTALLATION.

to

maintain tolerable operating temperatures

rear

of instrument. When mounting instru-

a

site

that provides

AIR

air

FILTER. Before operating the Model 185B,

filter,

3

from Research Products Co. In addition, the

should

A

vibration or shock.

located at rear of instrument, should

filter

be

cleaned periodically to insure proper

The instrument

its

front panel in a verticalor near-vertical

bail

is

provided for raising front of instru-

are

shown in figure 2-2. Screws for

as

follows:

to

the 50-mc connector.

50-mc sine wave.

adhesive such

stabilize. Connect the

blank,

press BEAM FINDER

thin,

well-defined

a

forced-air cooling

at

least three inches

as

5-6

for proper cleaning

be

is

intended

is

at

installation and are in-

if

installation

Location dimensions for

to

supplied with

trace

approxi-

Filter

a

portable

be

is

two

ap-

trace.

sys-

are

lo-

Coat

oper-

two are

is

in-

subject

01255-1

2-

1

Section Paragraphs

II

2-20

to

Model 185B

2-23

(9-1

196A/B

Oscilloscope Camera

187B

Dual

Trace Amplifier

1

lOOA

Delay

Line

Sync Take-Off

11OOA-76A

Delay Line

Resistive Dividers

185A-21C 185A-21D 185A-21E 185A-21F

AC-16W

Cable

Load

Use

A

High quality camera for use in permanently recording oscilloscope presentations

~~ ~~

A dual-channel vertical amplifier

(plug-in) for Model 185B (shown installed in figure

Overcomes inherent oscilloscope delay,

allowing

rate

Inserted

line

sumdied

~~

Termination for

(normally suppliedwith Model system)

~

These dividers provide a means for

obtaining

capacitance input

Delay

(All

cable terminated in 50 ohms)

Connecting

Dividers

rise

pulses

to

between

permit sync

with

a

high-impedance, low-

Line

or other 50-Ohm systems.

dividers must

cable

1-1)

times of slow repetition

be

viewed

signal

Model

llOOA

for 185A-21C/F

line

take-off

llOOA

Delay Line

to

Model llOOA

be

used with

and delay

(normally

system)

llOOA

Features

Image

to

object ratio:

(1:

1

available)

Model 196B allows oscilloscope

photograph on either internal

external

I

Sensitivity 4 mv/cm Badwidth:

1000 mc

Input

2 pf nominal

Rise Time: 0.25

Delay:

Insertion

6

db for both

Termination Resistance: 50

graticule oscilloscopes

DC

to

Impedance:

120

ne

Loss:

channels

l:O.

9

to

200 mv/cm

800mc ueable

lOOK shunted

M

ohma

or

1

to

by

c

3

Division

Input Res.

250 5:

a

500

2500 50:

5000

Ratio

10:

100:

Max

Inpl

VRMS

1

1 1

10 15

35

50

J

186A

Switching Time Tester

I

a.

Fabricate a bracket for rear support pins and

fasten pins

b.

c.

port

2-20.

2-21.

is

available from Hewlett-Packard Company crease the usefulness of your Model 185B. Additional equipment in unit. Refer to the manual for operating information regarding your particular plug-in or contact your nearest

this

information.

2-2

in

place.

Install

Lift instrument into place, engaging rear-sup-

pins, and secure front panel firmly to rack.

bracket at

ASSOCIATED EQUIPMENT

Figure

2-1 and

is

available for use with the vertical plug-

@

representative and he

rear

table

Measures switching time of transistors,

diodes and tunnel diodes. Teste pulse

response of active and passive net-

works. Triggers Model 185B in

vance of pulse output. Accessory universal adapter available.

of rack.

AVAILABLE.

2-1 show equipment

will

supply you with

to

that

in-

to

Pulse output: 0.1 Pulse Rise Time: Pulse Repetition

ad-

2-22.

2-23. dent, repack the instrument using the following procedure

shipping container, taking in their original positions. (If was discarded, more may Hewle

able,

RESHIPMENT.

If,

after

as

a

a.

If

possible, repack the Model 185B in

tt-

Packard Engine e r ing Representative.)

b.

If

the original packaging material

proceed as follows: (1) Wrap instrument in heavy paper or plastic. (2)

Use around panel

continuously variable

Collector Supply:

Base

Supply:

I

incoming inspection, damage

guide.

care

be

plenty of packing

all

sides of instrument and protect

with

cardboard strips.

material

20 volts peak

LRss

than 1 nsec

Rate:

5 kc

to

50 kc,

0

to

*SO volts

0

to

+lo

volts

is

its

(at

is

least

original

all

material

not avail-

01255-1

to

replace

the

packing

obtained from your

evi-

pads

4

in.)

I

Model

185B

(3)

Place

cardboard

or metal

(4)

Mark the Instrument”,

instrument thus protected

or wooden

bands

to

packing

seal

box

box,

container.

with

‘‘

Fragile”,

and use heavy tape

etc.

Note

If

instrument Packard Company for service or repair, attach type of service or repair

correspondence, model number

serial number.

a

is

to

be

shipped

tag

identifying owner and indicating

refer

and

to instrument by

complete eight-digit

to

desired.

in a heavy

“Delicate

Hewlett-

In

any

REAR

OF

INSTRUMENT

Figure

Paragraph

Dimensions for Rear Support

2-2.

Section

2-23

II

Cmt’d

01255-1

2-3

Section

Figure

111

3-1

Model 185B

1.

Power switch. Energizes instrument.

2. INTENSITY. Adjusts brilliance of spot on the cathode-ray

3.

SCALE. Adjusts with graticule on option 3 instruments.)

4.

FOCUS. Adjusts focus of spot on the cathoderay

tube.

5. BEAM FINDER. Helps locate a presentation

that

is

6.

SCANNING. Adjusts mode of horizontal deflection.

7. SCAN (MANUAL) or DENSITY (INTERNAL).

Used

to

density.

8. TIME SCALE. Adjusts basic time scale of presentation.

9.

VERNIER. Provides continuously variable time scale between TIME SCALE ranges.

10.

TIME SCALE MAGNIFIER. Expands time

scale

11.

DELAY. Enables operator magnified presentation.

12. HORIZONTAL POSITION. Adjusts horizontal

positioning of presentation.

tube.

scale

brilliance. (Aligns trace

deflected

manually scan display or

off

selected

the

crt.

by

TIME SCALE control.

to

adjust scan

the

basic

view any part of

13.

INPUT. Connection for trigger input. Sensitivity: SENSITIVE i200 mv; NORMAL i200 mv to 2 volts.

14.

STABILITY. Adjusts trigger stability.

15. MODE. Adjusts trigger sensitivity. May

set

to

FREE RUN.

16. TRIGGER SLOPE. Selects desired trigger slope polarity.

17.TRIGGERING. Set frequency and amplitude

18. HIGH FREQUENCY STABILITY. ger stability on HIGH FREQ. position of TRIGGERING.

19.Model 187B

plug-in unit. Not part of

20.SYNC. PULSE OUTPUT. Provides

sync pulse out for triggering to use as a

21.50 MC. Provides a pulsed 50-mc output.

22. AMPLITUDE DC (OPEN CLRCUIT). Provides output of four calibrated dc voltages.

23,CALIBRATOR AND SYNC PULSE. Selects

calibrated to appropriate connectors.

Dual

test

dc

this

switch according

of

trigger signal.

Adjusts

Channel Vertical Amplifier

basic

oscilloscope.

a

test

circuits, or

pulse.

voltages or sync pulse outputs

be

to

trig-

delayed

~~

Figure

3-0 01255-1

3-1.

Operating Controls and Connectors

Model 185B

Paragraphs 3-1

Section

to

111

3-5

SECTION

0

P

ERATI

3-1.

INTRODUCTION.

3-2.

This

tion of all controls in the Model 185B Oscilloscope.

If

more theoretical information

Section 3-3. The vertical amplifier system for the Model

185B includes

for operating the plug-in unit are contained in the in-

struction manual for

3-4.

3-5. Figure 3-1 shows

trols and gives a short description of theiruse. Num-

bers

ure

3-1

dicate operational procedure. More detailed information related to

a. BEAM FINDER. Pressing the BEAM FINDER reduces gain of horizontal and vertical amplifiers to a point where a “lost” presentation may adjusted HORIZONTAL POSITION and VERTICAL POSITION controls.

b. SCALE. The SCALE control adjusts intensity of graticule on those instruments provided withanexternal graticule. On internal graticule instruments, SCALE aligns trace with graticule.

c. INPUT. This connector chronizing circuits. These circuits insure an exact time relationship between input signal and moment of sampling. To operate properly, the sampling oscilloscope nal that supply step

i).

d. TRIGGERING. The TRIGGERING switch may

be

set to SENSITIVE, NORMAL or HIGH FREQ.

pending on amplitude and frequency of trigger signal.

SENSITIVE position 200 millivolts with a frequency below 100 mc. Do not exceed 10 volts peak input on SENSITIVE position. NORMAL position nals (200 mv to position should be used for trigger signals of

plitudes above 100 mc. The input circuits on HIGH

FREQ. position 1000 mc circuits.

Do

peak to INPUT when TRIGGERING SITIVE. Doing

section contains information on the func-

is

desired, refer

IV,

Principles of Operation.

a

plug-in unit. Detailed instructions

that

particular unit.

FRONT PANEL CONTROLS AND

CONNECTORS.

all

front panel operatingcon-

in figure 3-1 are given

to the photograph and do not necessarily in-

these

to

center of cathode-ray tube using the

either

must

be

is

time-related to the input signal, or must

a

sync pulse to trigger circuit under

is

2

volts) below 100 mc. HIGH FREQ.

will

so

they may

not connect any voltage exceeding 10 volts

divide down signals

be

CAUTION

so

may damage inputcircuits.

to

relate the

controls

is

accurately triggered by a sig-

used for trigger signals below

used for higher amplitude sig-

used

to

is

listed

be

the input

operate synchronizing

is

on SEN-

N G I

text

in fig-

below:

found and

to

the syn-

test

all

as

high as

to

(see

de-

am-

111

NSTRU

adjusts frequency of count-down oscillator, enabling

it

either positive-going or negative-going slope signal.

of input circuits same point on input signal.

full

sync circuits will at a 100-kc rate. quency above near 100 of the input signal.

triggering stability for repetition

by

PUT connector provides

is

With sync pulse from SYNC PULSE OUTPUT connected in Model 185B delaying input signal for the purpose of examining

fast

wave output, synchronized with pulse from SYNC PULSE OUTPUT. Frequency of sine wave cycles. This signal reference on the cathode ray tube, or for checking time

nector provides dc voltages selected by CALIBRATOR AND SYNC PULSE switch for calibration of vertical amplifier in oscilloscope. Voltages selected are accurate to within i3$~ of selected value.

when in sync pulse output and pulsed 50-mc output to appropriate jacks. On other positions of this switch, voltage CUIT) connector

mines time time calibration of fications when VERNIER control clockwise.

fine adjustment between any TIME SCALE switch, resulting in continuous variation of time scale from

CTI

0

NS

e.

HIGH FREQUENCY STABILITY. This control

to

lock

in

at a submultiple of input trigger frequency.

f.

TRIGGER SLOPE. The TRIGGER SLOPE switch

may

be

used

to

synchronize Model 185B circuits

of

g. MODE. The MODE control adjusts sensitivity

clockwise

kc

h. STABILITY. The STABILITY control adjusts

varying hold-off time in triggering circuits.

i.

SYNC

PULSE OUTPUT. The SYNC PULSE OUT-

delayed 130 nanoseconds from trigger initiation.

to

circuit under

rise

time.

MC. This connector provides

j.

50

scales

k. AMPLITUDE (DC OPEN CIRCUIT). This con-

m. CALIBRATOR AND SYNC PULSE. This switch,

full

is

supplied to AMPLITUDE (DC OPEN CIR-

n. TIME SCALE. The TIME SCALE switch deter-

p. VERNIER. The VERNIER control provides

so

they

will

trigger reliably

If

MODE control

to

FREE RUN position, Model 1858

free

run,

i.e.

sample automatically

If

they

are

triggered withafre-

100

kc,

they

will

but

will

synchronize with a submultiple

test,

is

overcome. The effect

is

valuable for setting up a time

on oscilloscope.

counterclockwise position, connects both

as

explained in step

scale

in nsec or p sec per centimeter. The

this

switch

operate

a

fast

inherent delay (0.1 psec)

is

two

IO

psec/cm to 3 nsec/cm

at

a

frequency

rates

above 100

rise

time pulse

is

similar

a

pulsed sine

is

50 mega-

k.

correct within speci-

is

full Counter-

steps selected

on

trigger

at

the

is

set

kc

that

to

a

dc

by

a

01255-1

3-1

Section

Figure

III

3-2

Model

185B

1.

Regulated dc output connector instruments.

2.

Channel A vertical output voltage deflection present on 187B). Sensitivity 0.2 volt/cm, Graticule Center:

3.

Channel B vertical

as

item

0

2.

volt.

For

output.

this

use

for

use with future

for

connector (with Model

with

X-Y

Same

characteristics

vertical

recorder.

-

4. OUTPUT TIME BASE SCAN. Horizontaldrive voltage

with

Sweep

5. INPUT EXT SCAN. Connect drive

volts/cm, Input Range:

6.

115-230 Volt Switch.

used.

volt operation, 2-ampere slow-blow fuse 230-volt operation (see section

is

available at

X-Y

recorder. Sensitivity:

Start:

0

volt.

signal

to

this

connector. Sensitivity:

0

Use

4-ampere slow-blow fuse

Set

this

connector.

external

to

12

volts.

to

line voltagebeing

VI).

1.2

volb/cm,

horizontal

for

POWER

CORD

For

use

1.2

115-

for

3-

Figure

2

3-2.

Rear-Panel Controls

01255-1

Model

185B

Paragraphs

Section

3-6

to

111

3-7

.

q.

TIME SCALE MAGNIFIER. The TIME SCALE MAGNIFIER switch selected by TIME SCALE switch by TIME SCALE MAGNIFIER switch.

r.

DELAY. The DELAY control selects any part of unmagnified presentation for magnification; with delay control you effectively slide cathode-ray tube along expanded presentation

divides

the value

by

number selected

to

view portion you

that

has

been

i.e.,

want

8.

SCANNING. The SCANNING switch determines

type

of horizontal deflection

point

it

should

beam across the face of the cathode-ray tube

relation The beam may of the tube and yet the time ample,

185B

deflection; they

to

50

provides a choice

(1)

INTERNAL. The time

setting of TIME SCALE and TIME SCALE

MAGNIFIER switches. On INTERNAL, the beam of the tube DENSITY control and sampling frequency.

(2)

MANUAL. On MANUAL position, scanning

accomplished DENSITY (INTERNAL) control. Manual operation may sweep the only visible portion of trace illuminated by setting of MANUAL SCAN control. The time scale in seconds per centimeter

is

determined again

MAGNIF'IER and TIME SCALE switches. Man-

ual scan

it

is

e.g., when RECORD. On RECORD position, operation

exactly the same as on MANUAL except in very slowly across time scale determined by setting SCALE MAGNIFIER and TIME SCALE switches.

RESET OR EXTERNAL. The RESET OR EXTERNAL position

vides a means for resetting scan when oper-

ating on RECORD position,

a

means of scanning with an external signal.

An input connector, INPUT EXTERNAL SCAN,

is

horizontal input,

t.

SCAN (MANUAL) - DENSITY (INTERNAL), The function of this control depends on setting of SCANNING switch. NAL, the SCAN (MANUAL)

control adjusts number of samples per centimeter and hence the density of sample dots viewer. Reducing scan density ing up the physical speed of horizontal sweep,

be

emphasized

its

time scale in seconds per centimeter.

take

10

nanoseconds per centimeter. The

are

as

is

automatically swept across the face

at

an actual speed determined

by

be

thought of as a condition where

is

always present on oscilloscope, but

is

useful in

necessary

fast

spikes are present on waveform.

this

case the beam

provided on rear of instrument for external

With

SCANNING switch

that

will

be

used.

At

that

apparent speed of

has

seconds to go across the face

scale

could

be,

for ex-

Model

of

four

follows:

adjusting SCAN -(MANUAL)

to

carefully trace presentation,

has

modes of horizontal

scale

is

determined

is

that

by

setting of TIME SCALE

x-Y

recorder work when

is

automatically swept

the

face of the tube

of

two

functions:

or

-

DENSITY (INTERNAL)

has

the effect of speed-

1)

2)

it

provides

set

to

INTER-

as

seen by the

TIME

it

this

no

by

is

part

is

that at

pro-

i.e.,

-

a

the actual speed oscilloscope face. However, turning

no effect on time scale in seconds per centimeter on

cathode-ray tube. On the MANUAL position of the SCANNING switch, the SCAN (MANUAL) (INTERNAL) control moves dot along presentation explained in step EXTERNAL positions of SCANNING, the SCAN

UAL) - DENSITY (INTERNAL) control

3-6.

REAR PANEL CONNECTORS.

3-7.

Figure

and gives a short description of their uses.

figure

the figure to the photograph and do not necessarily indicate operational procedure. The following paragraphs give more detailed information about

connectors:

nector

sory instruments. The following voltages

able with reference to ground (pin

Channel terminals for use in driving an the Model nector

0

(0.2

20,000

Channel terminals. Output characteristics of CHAN B are identical

scan voltage available at this connector to drive horizontal of X-Y recorder. The output from OUTPUT TIME BASE SCAN and Source impedance

means of controlling scan with an external signal. The scan voltages required supplied by OUTPUT TIME BASE SCAN connectors, i.e., about HORIZONTAL POSITION centered). Input resistance varies with setting minimum

connects Model voltage setting selected.

fuse

3-1,

a.

5401,

is

intended

1)

Pin b,

2)

Pin c,

3)

Pin d,

4)

e,

b.

OUTPUT CHAN

A

is

approximately

volt in center, and

volt/cm). Source impedance

ohms.

c.

OUTPUT CHAN

B

to

d. OUTPUT TIME BASE SCAN. The horizontal

+12

volts

e.

INPUT EXT SCAN. This connector provides

0

volt

+13

is

f.

115-230

(see

section VI).

to

produce one complete picture on

this

control

-

has

DENSITY

as

s(2).

On RECORD and RESET

3-2

shows

all

connectors on

the numbers in figure

is

3-2

inoperative.

rear

relate

OR

(MAN-

panel

As

in

text

in

these

regulated dc output connector. This con-

to

supply

dc

power tofuture acces-

are

avail-

a):

+12.6

volts

-12.6

volts

+250

volts

-100

volts

A.

The vertical output from

of the plug-in unit

187B

installed. The output from this con-

+1

-1

B.

of the plug-in unit

those of CHAN

that

has been selected

is

approximately 0 volt at sweep

at

sweep termination

is

approximately

is

available at these

X-Y

recorder with

volt at top of graticule,

volt at bottom of graticule

is

approximately

The vertical output from

is

available

A.

by

at

these

SCANNING

is

axis

start

(1.2

volts/cm).

20,000

ohms.

a

are

the same

to

position scan at left edge of crt, and

volts to position scan at right edge (with

of

time scale VERNIER

32.3K.

volt switch. This switch automatically

185B

power transformer for line

Be

sure

to use correct line

as

but

those

the

01255-1

3-3

Section Paragraphs

III

3-8

to

3-15

Table

3-1.

Methods

of

Triggering

Model 185B

r

3

r

Waveform

Types

Trigger Freq

Over 10

Below

Below 10

10

kc

Possible

Trigger Ckt

Measurement?

to

under

no

Ext

Trig

Gen

4vailable

no

---

Delay

iequired

‘

(no,

test

delay

120 ns)

Line

no

Yes

no

yes

if

ckt

>

1

Xefer

Figure

3-

3

3-4

3-5

3-6

to

3-8.

THE

PRINCIPLE

OSCILLOSCOPE.

3-9.

The action of the sampling oscilloscope issim-

llar

to a strobe light that nization with a turning device, resulting in an apparent slow motion--or the effect of taking moving pictures of a rapidly spinning wheel where shutter speed rotation of the wheel, causing the wheel to appear be turning very slowly, or even turning backwards.

3-10. The sampling of the oscilloscope same way. The sampler plug-in in this case would represent the camera shutter and lens. The sampling circuit input voltage occurs over and over again, sample taken on a succeeding repetition of input sig-

nal

reference point on input signal. 3-11. THE VIEWING ‘WINDOW”. There

maximum and minimum time during which sampling oscilloscope may complete each observation. In the Model 185B, maximum time imum time approximately

is

and at a slightly later time with respect to same

is

nearly

is

accomplished in almost exactly the

opened for very short periods of time and

at

that

time

OF

THE

SAMPLING

is

slightly out of synchro-

the

same as the time for one

signal

is

carefully measured. This

is

0.3

with the sampling

with

each succeeding

is

acertain

100 pseconds and min-

nanoseconds. This time

camera

to

is

referred

120 nanoseconds for the “window” to open after trig-

ger

is

100

pseconds will require special triggering tech-

niques when 3-12. In

cuits must be delayed, or used to permit viewing leading edge of this signal. The following paragraphs will describe different methods available for solving some synchronization problems you may encounter in sampling oscilloscope technique.

3-13.

3-14. GENERAL. 3-15.

be

synchronized with a signal signal received by vertical amplifiers. Furthermore, the system must because sampled signal never actually enters oscilloscope circuits, and therefore ternally for synchronization (in the case 187B, signal figures 3-3

and

measurement situations, and give recommended

instrument arrangement.

to

as

theviewing“window”. Since

received, signals with a period greater than

it

is

necessary to view rise time.

this

case, either

TRIGGERING THE MODEL

As

in any oscilloscope, the

be

is

sampled at probes). Table 3-1 and

to

3-6

list

the

signal

to

an

advanced trigger must

185B.

Model

that

is

time-related to

externally synchronized.

is

not available in-

common types of waveforms

it

sampling

type

185B must

This

of

Model

takes

cir-

be

of

is

3-4

01255-1

Model 185B

Section

III

Paragraphs 3-16 to 3-21

3-16. TRIGGER REPETITION RATE. Model 185B accepts triggers

with

repetition

rates

between 50 cps

and 1000 mc. However, an internal hold-off circuit

limits

maximum sampling rate to about 100 kc. STABILITY provides limited control over hold-off circuit to permit adjustment for maximum stability when

the trigger rate exceeds 100 kc. For frequencies above 100 mc,

a

countdown circuit (adjusted with HIGH

FREQ. STABILITY) reduces frequency of trigger sig-

nal to approximately 10 mc

cuits

will

be

triggered reliably.

so

that synchronizing cir-

3-17. TRIGGERING METHODS.

is

3-18. When limited time-scale speed

lem, and

of synchronizing Model 185B

in a train, and the screen. For

signal frequency must

than one pulse

jitter

is

not excessive, the simplest method

is

to

trigger on one pulse

to

view several succeeding pulses on

this

to

be

will

occur in the 100 Fsec viewing

possible, however, the

at

least

10

notaprob-

kc

so

that

more

“window” of oscilloscope. The following paragraphs

describe a few conditions that dictate

the

method

of

synchronization, and therefore the instrument setup

that

shculd

MODEL

be used.

1856

MODEL

A

IIOOA DELAY LINE

I1

L

1858

SYNC

185A-76A

DELAYED TRIGGER

TAKE-OFF

CIRCUIT

UNDER

TEST

J

LD-S-

574

Figure 3-4. Viewing Signals Below 10 kc by Using

Delayed Trigger to Drive Circuit under Test

to

fall

within 100 Fsec window.

In

order

to

see

the

leading edge, then, you must trigger oscilloscope

just ahead of an input pulse to allow the leading edge

to

fall within time window.

CIRCUIT

QQQ

185

B12IA SYNC PROBE

UNDER

TEST

L

LO-S-576

Figure 3-3. Viewing Signals Above 10 kc

3-19. SIGNAL REPETITION RATES ABOVE 10

Synchronizing on signals above 10

kc

presents few

problems since one or more pulses of a train may

KC.

be

viewed in oscilloscope “window”. The recommended instrument setup for viewing signals above 10 kc shown in figure 3-3, while operating procedures described in figures 3-7 to 3-9. Remember signals above 100 mc, TRIGGERING must

HIGH

FREQ., and STABILITY adjusted withbothHIGH

be

that

set

is

are

for

to

FREQUENCY STABILITY and STABILITY controls.

Note

If

it

is

necessary to examine very fast time (e.g., 10 ns) signals between 10 approximately 100 kc,

it

will not

be

rise

kc

and

possible

using the above method, to magnify presen-

tation sufficiently to examine rise time. It

will

be

necessary in this

case

to resort to

one of the trigger methods given for signals

below 10 kc.

kc

LD

by

-8-173

LD-S-515

Using

SYNC PULSES

Figure

3-

on signals under

will

1100A-76A SYNC TAKE-OFF

DELAY LINE

3-5. Viewing Signals Below

SYNC PULSE OUT

to

Drive Circuit under Test

10

21. Several methods are available for synchronizing

10

kc. Generally the method used

depend on characteristics of circuit under

MODEL

11OOA DELAY LINE

LOAD

1858

test

3-20. SIGNAL REPETITION RATES BELOW

When signal repetition rate

is

below 10 kc,

10

signal

KC.

does not occur frequently enough to allow a full cycle 01255-1

Figure 3-6. Viewing Signals Below 10 kc

when the Circuit under Test Cannot

be

Driven by Synchronizing Pulses

3-5

Section Paragraphs 3-22

III

to

3-38

Model 185B

and the associated equipment available. Table and figures 3-4 to 3-6 give three additional basic instrument setups. Each of them below:

3-22. METHOD ONE (figure 3-4). It trigger Model 185B from a separate source and then delay this same signal to trigger the circuit under measurement

120 ns

An important consideration in this method

is

often possible to tolerate some deterioration of the driving pulses by the delay line or delay circuit, since these pulses serve only to trigger the measured circuit. with sufficiently fast rise time triggering, there

presented to oscilloscope.

3-23. METHOD TWO (figure 3-5). You may use the signal from SYNC PULSE OUTPUT connector to trigger circuit under test. This signal

that

is

scope sweep. See figure 3-12 for basic operating

procedures, If you cannot drive

frequency (100 kc), you can use a repetition rate generator such as

to trigger Model 185B at any rate between 50 cps and

100 kc to produce sync pulses. The sync pulse from

Model 185B when connected to a 50-ohm load.

3-24. METHOD THREE. There are times when the circuit under 10 kc and cannot be driven by any type of sync pulses. This

is

erator must be used for instrument setups and figure 3-10 for operating instructions.

is

(if

inherent delay of measured circuit

or

more, external delay will not

As

long as drive pulses arrive at the circuit

is

no loss of information on signals

suitably delayed from triggering of oscillo-

@

Model

211A

is

normally a +1.5 volt (minimum) pulse

test

operates at repetition rates under

typically the case when a mercury pulse gen-

used. In

this

to

trigger oscilloscope.

case, the signal to be viewed

is

described briefly

is

possible

be

to

provide reliable

is

a

fast

test

circuit at trigger

Square Wave Generator

See figure 3-6

3-1

to

is

required).

is

that

rise

pulse

it

signal fm and jitter become more severe as trigger repetition rate increases. maximum fm trigger signal without affecting the display can expressed as:

where

The formula indicates mc trigger, 0.05% fm for a 100-mc trigger.

3-29. For trigger repetition

there

are

situation should be reliable with up to mc region and correspondingly frequencies.

3-30.

3-31. OBSERVATION

3-32. Due Model 185B screen represents true instantaneous nal amplitude, useful information may from signals

3-33. For instance, occasionally missing, normally on the crt except that appear long the base line. The density of dots in pulse relative to that in the approximate percent

If

self

base

50% of the time, pulse and base line

same.

PULSE ANALYSIS.

the pulse

will

line will be continuous. If the pulse

or

jitter

Maximum fm

f

=

trigger repetition rate in mc

two

count-down circuits in series, and the

is

more complex. However, triggering

to

the

fact

that

are not 100% periodic.

if

of

is

missing most of the time, the pulse

be

represented

As

a

general guide, the

which can

a

maximum of 5% fm for

OF

INTERMITTENT PULSES.

that

one pulse in a pulse trainis

that

pulse will

be

present in the

=

5/f

a

rate8

above 100 mc,

0.05%

fm in the 100-200

less

fm at higher

each sample plotted on

be

a

be

series of dots

sig-

obtained

displayed

will

the

base

line

will

indicate the

time

that

the pulse

by

a

series of dots, while

is

will

missing.

is

appear the

the

present

be

1-

it-

3-25. The signal, decreased in amplitude by any attenuation in the resistive sync probe, 185A-76A sync take-off where Half

the

signal

is

used directly to trigger Model 185B, while the other in unit. When using method three, remember that the resultant vertical calibration of SENSITIVITY setting times probe attenuation times

2.

3-26. The Model approximately nals.

If

a

coil of 3/4 inch

mately 105 feet long to provide about 120-ns delay.

3-27.

3-28. When trigger repetition rate each trigger actuates jitter in trigger signal have no effect upon display (provided there

being viewed).

100 kc and 100 mc, the internal hold-off circuit of

Model 185B comes into play, and

3-6

EFFECTS OF

half

llOOA

1

gc, which

still

wider bandwidth

is

no

For

is

delayed and

delay line

is

sufficient for most sig-

is

or

larger Styroflex cable approxi-

FM

AND JITTER.

a

sampling cycle, and fm and

jitter

between trigger andsignal

trigger repetition rates between

is

fed

to

Model

it

is

divided in

fed

to

vertical plug-

will

be the product

has

a

passband of

desired, you can use

is

below 100kc,

effects

half.

of trigger-

3-34. Conventional oscilloscopes indicate missing pulses by allowing brightness of wave compared line indicates relative frequency of occurrences. You can see that presentation in the form of relative num-

ber

of dots

mation of relative brightness of wave and

3-35. EXAMINING PULSE IRREGULARITIES. 3-36. Figures 3-7

you may expand and examine any portion of a pulse. The horizontal

100

by

vertical ITY control on Model 187B, to a point where a signal

that

fill

the entire 10 x 10 cm graticule,

3-37.

3-38. Figures 3-7 through 3-14 give step-by-step operating instructions. Each step the control

keyed by the same number,

is

setting the TIME SCALE MAGNIFIER. The

axis

initially occupied l/6000th of the screen may

OPERATING INSTRUCTIONS.

or

base

line to

actually easier

to

3-9 describe a method

axis

may be expanded

may be expanded, using the SENSITIV-

connector to which the step refers

strike

through. The

to

brightness of

to

interpretthan an

by

is

numbered and

base

by

which

a

factor of

01255-1

base

esti-

line.

is

Model

185B

Section

Figme

111

3-7

P

I'

(Power Switch on)

1.

Set SCANNING

2.

Set MODE full clockwise.

3.

Set INTENSITY as desired.

4.

Adjust position controls to place trace on crt.

01255-1

to

INTERNAL.

Figme

5.

6.

7.

3-7.

Free Running Trace

If

no trace

and readjust position controls

Adjust FOCUS for a well-defined trace.

Trace should appear approximately as illustrated.

is

visible, press BEAM FINDER

as

necessary.

3-7