HP 1123A User's manual

HP 1123A User's manual
SC TOPERATING AND SERVICE
MANUAL
VOLTAGE PROBE
1123A
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OPERATING AND SERVICE MANUAL
MODEL 1123A
VOLTAGE PROBE
SERIALS PREFIXED: 842
See Section VII for Instruments With Other Serial Prefixes
Copyright HEWLETT-PACKARD COMPANY/COLORADO SPRINGS DIVISION 1968
1900 GARDEN OF THE GODS ROAD, COLORADO SPRINGS, COLORADO, U.S. A.
PRINTED: DEC 1968
02632-1
Table of Contents
Section Title
I GENERAL INFORMATION : © = «= * ~*~
1-1. Introduction * * * = * = «= = = =
1-5. Warranty © * ** © ccc
1-7. Accessories Supplied : = © © °°
1-9. Instrument Identification: * * *
1-11. Scope of Manual + «+ = = = = °°
II INSTALLATION ** * = =» = = «= =»
2- 1 General + + 4° + + + 2 + 1 4 a
2-3. Initial Inspection: = * = = * * * =
2-4. Mechanical Check * * * > *
2-6 Electrical Check * = «= * = < "
pe 8 Claims * © «© °° = = = «= = = = =
2-10. Repackaging for Shipment + * *
2-13. Installation * * + rre
Ш OPERATION « « + « ¢ « « « + + + oo
3-1. General - - - - + + + + + + + + 26
3-3. Connectors and Accessories
3-5 Output Connector - + + + - -
3-7 Blocking Capacitor Tips - - -
3-9. Divider Tips ++ 2 + e e e e. e
3-13. Accessories * "ree
3-16. Operating Procedures = - «+ * -
IV PRINCIPLES OF OPERATION » + > - -
ii
H= > HS > HS HS Бо не ны +
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4-30.
BOTAR H"
TABLE OF CONTENTS
e EA
Introduction
Simplified Circuit Theory
Attenuator Probe
Impedance Converter * * ©
Constant Voltage Source
Constant Current Source
Miller Effect
Differential Amplifier
. Functional Description
* #& = ® & # +
= " -
* * - +
. Detailed Theory of Operation * * *
= #0 = # x = 7
Source Follower
Constant Current Source
Emitter Follower «= * * = =» =
Differential Amplifier
Intermediate Amplifier * *
Intermediate Amplifier Gain © *
Constant Voltage Source
Temperature Compensation
Output Amplifier
Feedback to Minimize DC
Temperature Drift
DC Gain and Offset Adjustment
APPENDIX I- » » -
Model 10214A
Model 10215A
Model 10217A
Model 10228A
. - " +
ж +» es =»
Model 1123A
Page Section Title Page
- + 1-1 V PERFORMANCE CHECK AND
. e 1-1 ADJUSTMENTS e + e о те чт и + + + "O 5-1
1-1 5-1. Introduction © * + + rs 5-1
"1-1 5-3. Test Equipment * * + * «e... 5-1
«> 1-1 5-5. Simplified Performance Check 5-1
«> 1-1 5-7. Performance Check + 111141 5-1
5-11. Preliminary Set-up * + - + * °° 0-1
* * 2-1 5-13. Input Balance Check «<=. 5-1
"2-1 5-14. DC Offset Check « «= =» «+ 5-1
+ * 2-1 5-15. Gain Check * * * «ree 5-1
* * 2-1 5-16. Sine Wave Compression
ve 2-1 Check a e о e + в я в а = = во 5-2
: * 2-1 5-17. Pulse Compression Check + + 5-2
* * 2-1 5-18. Input Capacitance Check - * - * - 5-3
‚+ 2-1 5-19, Pulse Response Check * * + - » 5-3
5-20. Bandwidth Check +++ «e 5-3
. . 3-1 5-21. Noise Check "reee 5-4
. 3-1 5-22. Adjustments © + + * "e 5-4
- 3-1 5-26. Preliminary Set-up * = - - - + - 5-4
« - 3-1 5-28. Input Balance Adjust * * * * <>" 5-4
. 3-1 5-29. DC Offset Adjust * * * ‘+ = += - 5-4
« - 3-1 5-30. Gain Adjustment * * = ©» © * * * 5-4
e - 3-1 5-31. Pulse Response Adjustment 5-5
« * 2-1
"> 4-1 VI REPLACEABLE PARTS © «+ = =r = «= = 6-1
4-1 6-1. Introduction * * * “NT 6-1
cr 4-1 6-4. Ordering Information * * * * * * * 6-1
. . 4-1
. PUE VII MANUAL CHANGES AND OPTIONS * + + - 7-1
4-9 7-1. Manual Changes : + + «~*~ «~~ = = °° 7-1
4-9 7-3. Older Instruments * * * * * * * 7-1
4-9 7-5 Newer Instruments - * * =~ = = °° 7-1
4-3 7-7. Options: «+ = = «= = + = + cee 7.1
4-3 7-9. Special Instruments * * * * * * * * * 7-1
. € 4-3
* 4-3 VIII SCHEMATICS AND TROUBLESHOOTING : 8-1
- 4-4 8-1. Introduction * * * = = °°» = 8-1
- 4-4 8-3. Schematic Diagrams * * * * * * 8-1
- - 4-4 8-6. Component Identification = * = © ~ 8-1
* 4-4 8-8. Reference Designation * = © = © - 8-1
- 4-4 8-13. Troubleshooting + * * = = = ~*~ 8-1
- 4-4 8-17. Waveforms * * * * "Et 8-2
- 4-4 8-19. DC Voltages * **** ** * " "" 8-2
8-21. Repair and Replacement “'" “ ' © 8-2
© 4-4 8-23. Servicing Printed Circuit
4-5 Boards se # »s + + + + e a + a 8-2
se a eae ae a ee ee ae eee IA-1
ae e Re a a e a e e a e a e 6 IA-1
4 re e e e e e e e e > e "e a e. IA-3
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02632-1
Model 1123A List of Illustrations
LIST OF ILLUSTRATIONS
Figure Title Page Figure Title Page
1-1. Model 1123A Voltage Probe - - + + + + - 1-1 4-6 Differential Amplifier + + + + ++ +++ = 4-3
4-7 Functional Block Diagram - + + + + ++» 4-5
3-1. Model 1123A Voltage Probe and
Accessories > + + + + + + "+888 80 3-0 5-1 Gain Check Test Set-up -* + + + + + + = = 5-1
3-2 Installation and Zero Adjustment: - - + - 3-2 5-2 DC Blocking Assembly Schematic - - - - 5-2
3-3. Remote Operation - - + + + + - « « « « 3-3 5-3 Compression Test Set-up - - + + + + +» 5-2
3-4. High Impedance Loads - - « + + - + + += 3-4 5-4 Pulse Compression Test Set-up - - + - - 5-2
3-5 100:1 Divider Compensation * +)" + + - 3-5 5-5 Input Capacitance Test Set-up - + + + + - 5-3
3-6 Model 1123A used as Buffer Amplifier 5-6 Pulse Response Test Set-up - - боб + = - 5-3
for Sync or Trigger Signals - - - + - - 3-6 5-7 Bandwidth Test Set-up - - + «e... 5-4
3-7. Using DC Offset + ere. 3-7 5-8 Noise Test Set-up - + + + + + + + + + +0 5-4
5-9 Adjustment Location - - - - - ++ + +5-5/5-6
4-1 Attenuator Probe (100:1) - « «==. 4-1 8-1 Unit System Reference Designation 8-1
4-2 Impedance Converter * * = «==... 4-1 8-2 Component Identification, Assy Al 8-3
4-3, Constant Voltage Source + + * + + + = + = 4-2 8-3 Model 1123A Waveforms * * * * * * * " * 8-4
4-4 Constant Current Source + + + * + + + +" 4-2 8-4 Component Identification, Assy A2 8-5
4-5 Miller Effect « + © + ° + + 48008800 4-2 8-5 Model 1123A Schematic Diagram 8-5
LIST OF TABLES
Table Title Page
1-1. Specifications + + + + + + + + 0 + 45 60 4120 1-0
2-1. Shipping Carton Test Strength - « + + «+ + + + <= 2-1
5-1. Required Test Equipment * + « + + + + + + += = 5-0
9-2. Pulse Response Adjustments “reee 5-5
6-1. Reference Designators and Abbreviations- - - - 6-1
6-2. Replaceable Parts - - + + + + + + + + 6 + reo 6-2
7-1. Manual Changes + < + + + + 1548648600 0 7-1
8-1 Schematic Symbols and Conventions - - - - - - 8-0
8-2. Waveforms and DC Voltage Measurement
Conditions «4 + #1 1 e = + ое ов ое 4 4 a = wm + a 5 8-4
02632-1 iii
Section I
Table 1-1
Model 1123A
Table 1-1. Specifications
BANDWIDTH
DC to greater than 220 MHz (3 dB down).
PULSE RESPONSE
RISETIME
Less than 1.6 ns (10% to 90%), over full dynamic
range.
OVERSHOOT, RINGING, PERTURBATIONS
4% pk-pk with Model 1802A (dc to 100 MHz); 6% pk-
pk with 1 GHz system (probe must be properly
terminated in 50 ohms).
GAIN
Adjustable to X1 into 50-ohm load.
DYNAMIC RANGE
OUTPUT: +0.5 V peak.
INPUT: +0.5 V peak around a reference voltage
which can be offset with variable control from 0
to £0. 5 Vdc.
NOISE
Increases noise level by less than 300 u V pk-pk
when used with Model 1802A (dc to 100 MHz).
DRIFT
PROBE TIP ASSEMBLY: Less than 100 u V/" C.
AMPLIFIER ASSEMBLY: Less than 1 mV/ C.
INPUT IMPEDANCE
100k ohms shunted by approximately 3.5 pF.
OUTPUT IMPEDANCE
50 ohms.
MAXIMUM INPUT
+50 V (dc + peak ac).
GENERAL
WEIGHT
Net, 2 1/4 pounds (1,0 kg); shipping 4 1/4 pounds
(1,9 kg).
POWER
Supplied by Model 1802A plug-in. HP Model 1122A
Power Supply may be used to power up to four
Model 1123A Active Probes.
LENGTH
Over-all length is approximately 4 1/2 feet.
ACCESSORIES FURNISHED
MODEL 10214A 10:1 DIVIDER
Increases input impedance to 1 megohm shunted by
approximately 3 p¥. Increases input dynamic
range to +5 V and maximum input voltage to +350 V
(de + peak ac). Divider accuracy, +5%.
MODEL 10215A 100:1 DIVIDER
Increases input impedance to 1 megohm shunted by
approximately 3 pF. Increases input dynamic
range to+50 V and maximum input voltage to +500 V
(de + peak ac). Divider accuracy, +5%.
MODEL 10217A BLOCKING CAPACITOR
Provides 0.001 uf, ac-coupling with lower cut-off
of 1.6 kHz, or 160 Hz when using divider. Adds
less than 3 pF shunt capacitance, maximum input
voltage +50 V (dc + peak ac), or +200 V (de + peak
ac) when using divider.
MODEL 10228A BLOCKING CAPACITOR
Provides 0. 18 uF, ac-coupling with lower cut- off of
12 Hz, or 1.2 Hzwhen using divider. Adds less
than 25 pF shunt capacitance; maximum input volt-
age +50 V (de + peak ac), or +200 V (de + peak ac)
when using divider.
MODEL 10229A HOOK TIP
May be used for circuit probing directly or with di-
viders and blocking capacitors.
1-0
02632-
1
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ue
Model 1123A
Section I
Paragraphs 1-1 to 1-12
SECTION |
GENERAL INFORMATION
1-1. INTRODUCTION.
1-2. The HP Model 1123A Voltage Probe is shown in
Figure 1-1. The probe provides low input capacitance,
high input impedance, high current gain, and wide
bandpass. Itis designed to operate with oscilloscopes
or other measuring devices having 50-ohm inputs;
however, when used with a 50-ohm feed-through ter-
mination, it can be used with an instrument having a
high input impedance.
1-3. During operation, the Model 1123A allows the
operator to probe circuits operating at relatively high
frequencies without significant loading effects. High
input impedance is maintained by a field effect tran-
sistor (FET) mounted close to the probe tip.
1-4. Power for the probe is provided by a connector
on the front panel of the HP Model 1802A Dual Chan-
nel Vertical Amplifier plug-in or the HP Model 676A
Phase/Amplitude Tracking Detector. When operated
with other instruments, the Model 1122A Power Sup-
ply must be used to obtain power. Refer to Table 1-1
for complete specifications onthe Model 1123A Probe.
1-5. WARRANTY.
1-6. This instrument is certified and warranted as
stated on the inside front cover of this manual. Should
afailure occur within the time stated on the warranty,
contact your nearest HP Sales/Service Office immedi-
ately.
1-7. ACCESSORIES SUPPLIED.
1-8. The standard Model 1123A Voltage Probe is sup-
plied with the following tips: Model 10217A, High
Frequency Blocking Capacitor, Model 10228A, Low
Frequency Blocking Capacitor; Model 10214A, 10:1
Divider; Model 10215A, 100:1 Divider; and the Model
10229A, Hook Tip.
1-9. INSTRUMENT IDENTIFICATION.
1-10. Hewlett-Packarduses a two-section, eight-digit
serial number to identify instruments. The first 3
digits (preceeding the dash) are the serial prefix which
identifies a series of instruments; the last five digits
identify a particular instrument within a series. The
serial number appears on a plate on the rear panel.
All correspondence with Hewlett-Packard in regard
toan instrument should reference the complete eight-
digit serial number.
1-11. SCOPE OF MANUAL.
1-12. This manual provides operating and service
information for the HP Model 1123A Voltage Probe.
Information in this manual applies directly to the in-
strument (as manufactured) with serial numbers pre-
fixed by the three digits indicated on title page. If
the serial prefix of the instrument is different from
that on the title page, a "Manual Changes" sheet is
supplied. Technical corrections (if any) to this manual,
due to known errors in print, are called "Errata"
and are shown on the change sheet. For information
on manual coverage of any HP instrument, contact
the nearest HP Sales/Service Office (addresses are
listed at the rear of this manual.
SEHIAL NO ne ‘a
: 3 apt
К’ 1123A VOLTAGE
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Figure 1-1. Model 1123A Voltage Probe
02632-1
1-1
|
Model 1123A
Section II
Paragraphs 2-1 to 2-14
SECTION Hi
INSTALLATION
2-1. GENERAL.
2-2. This section contains preliminary inspection,
and installation procedures for the HP Model 1123A
Voltage Probe. In addition, unpackingandclaims pro-
cedures are discussed in the event damage to the in-
strument occurs during transit.
2-3. INITIAL INSPECTION.
2-4. MECHANICAL CHECK.
2-5. Upon receipt of this instrument, a complete
visual inspection of the shipping carton should be per-
formed. If there is evidence of rough handling or
damage to the carton, do not unpack the instrument
until the carriers agent is present. Inspect the Model
1123A for damage such as bent or broken parts. If
damage is found refer to Paragraph 2-8 for recom-
mended claims procedure. If no physical damage is
apparent, perform the electrical checks in Section V.
Retain all packaging material for possible future use.
2-6. ELECTRICAL CHECK.
2-7. This check will determine if the instrument is
stilloperating within the specifications listed in Table
1-1. The performance and accuracy are certified as
stated inthe warranty on the inside frontcover of this
manual. If the instrument does not operate as spec-
ified, refer to Paragraph 2-8for recommended claim
procedure.
2-8. CLAIMS.
2-9. If physical damage is found or the Model 1123A
does not operate as specified, notify the carrier and
the nearest HP Sales/Service Office immediately. The
Sales/Service Office will arrange for repair or re-
placement without waiting for a claim to be settled
with the carrier.
2-10. REPACKAGING FOR SHIPMENT.
2-11. If the instrument is to be shipped to a Sales/
Service Office for repairs, attach a tag showing own-
02632-1
er's name andaddress, instrument model number and
complete eight digit serial number, and a description
of service required.
2-12. The original shipping carton may beused ex-
ceptfor any accordion pleated pads. If original carton
and packaging material are not available, the follow-
ing materials should be used:
a. A double-walled carton (refer to Table 2-1 for
test strengths required).
Table 2-1. Shipping Carton Test Strengths
Gross Weight (Ibs.) Carton Test Strength (1bs.)
Up to 10 200
10 to 30 275
30 to 120 350
120 to 140 500
140 to 160 600
b. Heavy paper or sheets of cardboard to protect
all instrument surfaces (use a non-abrasive material
such as polyurethane or a cushioned paper around all
projecting parts).
с. Atleast 4 inches of tightly packed, industry ap-
proved shock absorbing material, such as an extra
firm polyurethane foam.
d. Heavy duty shipping tape to secure outside of
the carton.
2-13. INSTALLATION.
2-14. The Model 1123A Voltage Probe should be con-
nected as shown in Section III. There are two con-
nectors to attach; a BNC at the input of the Vertical
Amplifier plug-in anda power connector for operating
voltages. Before use, do the performance check in
Section V to insure that the instrument is operating
according to the specifications given in Table 1-1.
2-1
Section III Model 1123A
Figure 3-1
HI3A VOLTAGE PROBE
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1. Power Connector. Three pin connector accepts 7. Hook Tip. Allows operator to connect probe to
+15 volts, -12.6 volts, and power supply com- component leads or wires while leaving his hands
mon. free for making adjustments, etc.
2. Output Connector. BNC Connector furnishes 8. Model 10217A Blocking Capacitor Tip. For use
tout si 1f 50-oh . а when examining a high frequency signal which
output signal from a 50-ohm source impedance. has a large dc offset.
3. Amplifier. Provides current gain to drive 50- 9. Model 10214A Divider Tip (10:1). Used to in-
ohm loads; e.g., the Model 1802A Dual Channel crease dynamic range of probe system by pro-
Vertical Amplifier. ducing a 10:1 attenuation to the signal.
. . . 10. Model 10215A Divider Tip (100:1). Performs
4. Zero Adjustment. = Adjusts bias on probe cir- same function as 9 (above) except attenuates
cuitry to set dc offset at amplifier output. 100: 1
5. Voltage Probe. Performs hightolow impedance 11, Model 10228A Blocking Capacitor Tip. For use
conversion and supplies sufficient power gain to when examining low frequency signals which have
drive the Amplifier. Designed to operate with a large dc offset.
inputs of £.5 volts at the tip. 12. Model 1122A Power Supply (optional). Furnishes
6. Ground Clip-lead. Used to connect signal com- +15 volts and -12.6 volts to power four Model
mon to amplifier common. 1123A Voltage Probes.
Figure 3-1. Model 1123A Voltage Probe and Accessories.
3-0 02632-1
Model 1123A
Section III
Paragraphs 3-1 to 3-17
SECTION III
OPERATION
3-1. GENERAL.
3-2. This section furnishes the information necessary
tooperate the Model 1123A Voltage Probe. Eachcon-
nector, adjustment, andaccessory is explained briefly
in Figure 3-1. Several operating set-ups are given
to show equipment versatility and to familiarize the
operator with typical measurement operations.
3-3. CONNECTORS AND ACCESSORIES.
3-4. Although the functional descriptions in Figure
3-1 are brief, they provide a quick reference for the
operator. Some of the functional areas are explained
herein more detail to ensure a thorough understand-
ing of their operation.
3-5. OUTPUT CONNECTOR.
3-6. Output signals from the Probe Amplifier are
transferred to the BNC output connector from an
emitter-follower stage whose output impedance is main-
tained at 50 ohms. Due to the high frequency capa-
bility of this instrument, it is important to keep this
output matched with a 50-ohm load; e. g., the Model
1802A Dual Channel Vertical Amplifier.
3-7. BLOCKING CAPACITOR TIPS.
3-8. The Model 1123A Voltage Probe is de coupled;
therefore, when measuring small ac signals riding on
large offset levels, it is necessary to use a de blocking
capacitor. BothModels, 10217A (for high frequencies)
and 10228A (for low frequencies), can be used with
the Model 1123A Voltage Probe.
Do not apply steps or ac voltages larger
than 50 volts peak as they will damage the
input FET in the probe.
3-9. DIVIDER TIPS.
3-10. A 900k ohm resistor inseries with the input pro-
duces a 10:1 attenuation in the Model 10214A Divider
02632-1
Tip, since the input resistance of the probe is 100k
ohms. Thistipcontainsa parallel capacitor for com-
pensation.
3-11. The Model 10215A Divider Tip produces 100:1
attenuation, and contains a manual compensation ad-
justment. (For theory of operation refer to Simpli-
fied Circuit Theory in Section IV.)
3-12. When divider tips are used in conjunction with
the probe, maximum input voltage is increased with
each divider. With the Model 10214A the maximum
input voltage is +350V and with the Model 10215A it
is +500V.
3-13. ACCESSORIES.
3-14. Allprobe adapter tips are designed to fit snuggly
over the end of the Voltage Probe. Combinations can
be used to produce a desired result; e. g., both a di-
vider tip and de blocking tip can be used together.
When used together, however, the blocking capacitor
must be used in front of the divider tip. The hook
tip can also be used with any of these combinations.
3-15. The Model 1122A Power Supply produces suffi-
cient power to operate four HP Model 1123A Voltage
Probes. Byusing this supply, it is possible to operate
up to four active probes at remote locations. Connect
a 50-ohm coaxial cable from the oscilloscope input to
the remote Voltage Probe and turn onthe power supply.
3-16. OPERATING PROCEDURES.
3-17, To familiarize the operator with the versatility
of the Model 1123A Voltage Probe, Figures 3-2 through
3-7 have been added. All figures contain an instru-
ment picture and required written steps to obtain pro-
per operating conditions. Each control has a callout
which corresponds to the step number of the proce-
dure. It is assumed that the operator is familiar with
the Model 180-Series Oscilloscope and knows how to
obtain proper vertical and horizontal sweep settings.
For some of the following operations it is necessary
to use AUTO SWEEP MODE and INT synchronization.
3-1
- Section II
Model 1123A
Figure 3-2
<—IBOA
IBOZA
f——23A
I23A-B-8
1. Connect the Model 1123A Voltage Probe in IN- 5. Set DISPLAY to A.
PUT A of Model 1802A Dual Channel Vertical
Amplifier. 6. Position A trace on center horizontal graticule
2. Attach HP Model 1123A power connector to ap- line.
propriate power jack. 7. Set Polarity switch to +.
Set Polarity switch to OFF,
4. Set VOLTS/DIV selector to . 01 (Vernier in CAL 8. Adjust ZERO ADJ potentiometer until trace is
position). on center horizontal graticule line.
Figure 3-2. Installation and Zero Adjustment
3-2 02632-1
Model 1123A Section III
Figure 3-3
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123A
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1123A-B-9
1. Connecta 50-ohm coaxial cable between INPUT A
of a 180-Series Vertical Plug-in and the output
connector of the Model 1123A Voltage Probe.
Note
When used in this manner, the 50-ohm
coaxial cable must be terminated with
50 ohms at the load.
2. Connect power connector tothe Model 1122A Power
Supply.
I: 3. Select the necessary vertical sensitivity andhori-
| zontal sweep to make desired measurements,
Note
For highfrequency measurements, loss
in the 50-ohm cable must be considered.
0
Figure 3-3. Remote Operation
02632-1 3-3
|
Section III Model 1123A
Figure 3-4
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Note
When the Model 1123A Voltage Probe is
used with vertical plug-ins having high
INPUT impedance, itis necessary touse
a 50-ohm feedthrough terminator (such
as an HP Model 101004).
1. Using a 50-ohm feedthrough terminator, connect
the Voltage Probe output connector to INPUT A of
any vertical plug-in whose input impedance is rela-
tively high; e.g., the Model 1801A Vertical
Plug-in.
2. Connect power connector to appropriate supply.
3. Make oscilloscope settings in same manner as for
any standard operation.
3-4
Figure 3-4. High Impedance Loads
02632-1
Model 1123A
Section III
Figure 3-5
shown in Figure 3-2.
Voltage Probe.
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I23A—B- II
Note 6. Make necessary oscilloscope settings to obtain
several cycles of square wave Calibrator sig-
Dynamic range of the HP Model 1123A nal. (Display should be five divisions high. )
is +.5 volts, however, it can be ex-
tended by using divider tips.
1. Perform installation and Zero adjustment as halfinthe direction necessary to produce a per -
2. Slip the 100:1 attenuator tip on the end of the 9. Tighten locking nut making sure that compensa-
3. Connectthe groundclip-lead to the Probe shank, Note
andattach to groundterminal at Calibrator output. When corners contain peaks, the probe
4. Set VOLTS/DIV selector to . 02. tip is over-compensated; however, if
9. Probe the 10 volt Calibrator output. under-compensated.
7. Loosengrooved locking nut on 100:1 adapter tip.
8. Holdbackendof 100:1 attenuator, and turn front
fect square wave.
tion remains correct.
the corners are rounded off, the tip is
02632-1
L— ———Ñ[ÑÑ
Figure 3-5. 100:1 Divider Compensation
3-5
Model 1123A
Section II
Figure 3-7
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1123A-B~13
Note Position horizontal trace on center graticule line.
Signals which are +1 volt in ampli- о. Set INPUT switch to +UP,
tude or small signals with .5 volts . , ве
to 1 volt dc offset may be observed 6. with Model 1 ЗА sel Adjust, position trace
without exceeding the +.5 volt dy- - enter screen.
namic range of the Model 1123A. 7. Signal should be 5 divisions in amplitude with
its baseline 2,5 divisions below center screen.
1. Toobserveasignal from 0 to 1 volt inamplitude, Note
make setup as shown in Figure 3-2.
. Output DC Level may be set from -.5
Set INPUT switch to OFF. to +. 5 volts to shift the dynamic range
Set VOLTS/DIV to . 2V. at the input accordingly.
Figure 3-7. Using DC Offset
02632-1 3-7
Model 1123A
Section IV
Paragraphs 4-1 to 4-13
SECTION IV
PRINCIPLES OF OPERATION
4-1. INTRODUCTION.
4-2. This sectioncontains theory of operation for the
Model 1123A Voltage Probe. The text is divided into
three sub-sections, (1) Simplified Circuit Theory,
(2) Functional Description, and (3) Detailed Theory of
Operation. Eachtypical circuit function is discussed
once, either inthe simplified theory, or as it appears
in the main signal path of the detailed theory. The
Functional Descriptionis discussed at block level for
a quick overall understanding of instrument operation.
4-3. SIMPLIFIED CIRCUIT THEORY.
4-4. Severalcircuits inthe Model 1123A are common
circuits and are discussed in their simplified forms.
By so doing, the detailed text is reserved for explain-
ing signal flow, special circuits and modifications to
basic circuits. Emitter followers, inverting amplifi-
ers, and other simple networks are not discussed.
4-5. ATTENUATOR PROBE.
4-6. Attenuator probes (or probe tip adapters) are
used to extend the dynamic range of associated in-
struments. This isaccomplished by a voltage divider
in the probe (or tip). Figure 4-1 is an example of
a typical 100:1 divider which includes compensating
capacitors.
Cl
Ka COMPENSATION
A ADJUSTMENT
TIP A N EL
INPUT “ a 7 7
00K
R2 | ez Reb с
OK 7R I50PF ок $ y
| |
oe — =
H23A-A-1
provide compensation. To keep the impedance ratio
equal to 100:1 at high frequencies, C1 and C2 should
be adjusted to the same ratio as R1/R2.
4.8. IMPEDANCE CONVERTER.
4-9. Although there are several methods of accomp-
lishing impedance conversion, the circuit shown in
Figure 4-2 has been chosen due to- its frequent
usage in HP instruments. To reduce loading of cir-
cuits being tested, high impedance inputs are used.
The field effect transistor (FET) provides this high
input impedance (similar to a vacuum tube).
+V
HIGH Z
INPUT
SOURCE
LOW Z
OUTPUT
R2 -v
gm |
A ®
E out | Bot
R2 + —
gm
—V 2зд-д-2 |
Figure 4-1. Attenuator Probe (100:1)
4-7. Toprovide 100: 1 attenuation, the ratio of R1 to
R2 in parallel with the load (Ry) must be 100: 1.
Since R1 is 900K and equivalent to R2, and Rp, is
approximately 9K, the dc ratio is correct. For high
frequencies, however, the load impedance at the di-
vider output varies due to the load capacitance, Cg,
which is the input capacitance of the probe. To min-
imize the effects of Cr (which might be 2 to 3 pico-
farads), a large capacitor (C2) is added across the
output. This large capacitance performs twofunctions,
(1) it minimizes the effects of load capacitance, and
(2) with C1 it comprises a capacitive divider which
provides a 100: 1attenuationat high frequencies. Var-
iable capacitor C1 is added in parallel with R1 to
02632-1
Figure 4-2. Impedance Converter
4-10. Source follower Q1 coupled with emitter fol-
lower Q2 produces a high to low impedance conver-
sion. Due to the high input impedance of Q1, the
input resistance is established by R1. Output im-
pedance is determined by Ql and Q2. Emitter fol-
lower Q2, connected to the source output, furnishes
additional current amplification, thus reducing the
output impedance even more. The output impedance
(from emitter of Q2 to ground) can be calculated
using the equation shown in Figure 4-2.
4-11. CONSTANT VOLTAGE SOURCE.
4-12. As its name implies, the constant voltage
source supplies a constant voltage to the load. This
circuit is often used to prevent erroneous results
caused by fluctuating supply voltages.
4-13. Figure 4-3 shown one method of obtaining a
constant voltage source. Voltage divider R1/R2 es-
tablishes the desired voltage level at the base of Q1.
4-1
—;————Ú———————][——————————Ú——)é————[Ú[o
Section IV
Paragraphs 4-14 to 4-21
Since the voltage drop across the emitter-base junc-
tion of Q1 remains relatively constant, the voltage at
the emitter is approximately 0. 6 volts more positive
than the base voltage. This circuit is an emitter fol-
lower, and as such, has a low impedance output. Es-
sentially, this circuit approximates a voltage source
whose source impedance is near zero. To calculate
the output impedance, use the equation given in Figure
4-3.
-V
Tb+Rb
£ out =ret B+ |
CONSTANT VOLTAGE
TT
|
VARIABLE
27 LOAD
/$ RESISTANCE
J |
A.
== 1123A-A-3
Figure 4-3. Constant Voltage Source
4-14. CONSTANT CURRENT SOURCE.
4-15. Tomaintaina known current through a varying
load, a constant current source must be available.
The source bias current in a FET must be held con-
stant to minimize parameter variations. The circuit
shown in Figure 4-4 will provide this constant cur-
rent.
+IOV
--7
|
VARIABLE
24 LOAD
a
KA
RESISTANCE
<
NH23A-A-4
Model 1123A
emitter-base junction results in a constant voltage
at the emitter of Q1. As shown in Figure 4-4, the
values used will produce a voltage drop of +4. 4 volts
across resistor R3. Simple calculations show that
there is a constant current in the collector circuit
of approximately 88 milliamps. This current remains
constant regardless of changes in the load resistance,
as long as Q1 does not become saturated.
4-17. MILLER EFFECT,
4-18. The Miller Effect in an amplifier results from
the transistor interelement capacitance between base
and collector. Figure 4-5 is a simple common
emitter amplifier with Miller Capacitance (C1) shown
in dotted lines. Miller capacitance is detrimental in
wide-band high-frequency circuits having high voltage
gain, since its effects are amplified by the gain of the
stage. Amplification of the effects of C1 is due to the
out of phase (and amplified) signal at the collector
of Ql. This amplified signal causes more current to
be drawn from the base of Q1 through C1, thereby
making C1 look like a large capacitance. Negative
feedback is produced by C1; consequently, at high
frequencies the capacitive reactance decreases caus-
ing amplifier gain to decrease. At low frequencies,
the Miller Effect is insignificant due to the size of
C1, which is usually a few picofarads.
4-19. The effects of C1 can be reduced by two means,
(1) by making the source resistance low, and (2) by
having a low amplifier gain.
Figure 4-4. Constant Current Source
4-16. Voltage divider R1/R2 establishes a voltage
at the base of Q1 which provides forward bias to the
transistor. The inherent 0.6 volt drop across the
4-2
+V
| — OUTPUT
oo el
SOURCE |
— ANN — —
RI
|
|
| Ql
„об |
N23A-A-5
Figure 4-5, Miller Effect
4-20. DIFFERENTIAL AMPLIFIER.
4-21. Differential amplifiers come in a wide variety.
The one shown in Figure 4-6 will be used for ex-
planation because of its similarity to the ones used
inthis instrument. Its ability to reject common mode
signals (e.g. noise or 60-Hz signals common to each
02632-1
Model 1123A
input) while producing a differential output make it an
excellent choice for many applications. As its name
suggests, only the difference between the two inputs
is amplified. This makes the differential amplifier
suitable for many comparator or control functions.
When used in power supply regulator circuits, a fixed
reference at one input (B) can be compared to another
voltage source at the other input (A). The difference
between the two inputs is amplified and the output (C),
or complement (D) can then be used as a correction
signal to bring one input into balance with the other.
+V
|
RI R3
DIFFERENTIAL
OO
INPUT 0 (=F INET
di.
—V
1123A-A-6
Figure 4-6. Differential Amplifier
4-22. With zero volts (no signal) applied to the inputs,
the current through R2 divides equally through Q1 and
Q2. Considering either transistor as a separate
amplifier, it can be seen that when the base of Q2,
for example, is at zero volts the current flowing
through the forward biased emitter base junction
clamps the top of R2 at approximately -0. 6 volts. As
long as the base of Q2 remains at zero volts, a con-
stant current (Ig) will flow through R2. If the voltage
applied to input À goes slightly positive, the current
(11) through Q1 increases, causing the voltage drop
across R1 to increase. Since R2 is a constant cur-
rent source, when Id increases Iy must decrease,
thereby decreasing the voltage drop across R3. When
the input voltage at input A goes ina negative direc-
tion, the opposite will happen, i.e. I; decreases and
I9 increases causing the voltage across R1 and R3 to
change in opposite directions. These voltage changes
are 180° out-of-phase; therefore, the output signal
generated between points C and D is differential.
4-23. Normally, input A accepts the signal voltage
and input B is the reference (or ground) signal. Oc-
casionally, long leads are required to connect one
instrument to another. Consequently, noise or 60 Hz
pickup is often induced on the signal leads. The
differential amplifier only amplifies the difference
02632-1
Section IV
Paragraphs 4-22 to 4-33
between the two inputs; therefore, the undesirable
common mode signal is rejected.
4-24. FUNCTIONAL DESCRIPTION.
4-25. Figure4-7 is a functional block diagram which
shows the major stages of the Model 1123A Voltage
Probe. The high impedance and low capacitive input
provides minimum loading to circuits being examined.
The Impedance Converter functions basically as de-
scribedabove and provides the high to low impedance
conversion. The incoming signal is then applied to
a Differential Amplifier which provides impedance
matching to drive the 100-ohm coaxial cable. To
keep signal losses to a minimum, a Constant Current
Source and Constant Voltage Source are used to supply
power to part of the probe and amplifier circuitry.
4-26. The incoming signal from the probe assembly
is applied to an Intermediate Amplifier whose input
impedance is matched to the cable. An Output Amp-
lifier provides current gain and impedance matching
to drive a 50-ohm load.
4-27. To maintain low dc drift inthe probe assembly,
several amplifier stages are used in a closed loop
feedback configuration. The output of A2Q4 is summed
with an amplified and inverted input at the Error
Amplifier. Any resulting offset is amplified and fed
back to the probe. This feedback signal controls the
dc level of the Differential Amplifier in the probe and
causes the output to increase or decrease until the
offset at the Error Amplifier is zero. When the error
is zero, the dc output voltage at connector P1 is
correct.
4-28. DETAILED THEORY OF OPERATION.
4-29. The overall function of the Probe having been
discussed inthe preceeding paragraphs, the following
paragraphs now provide a stage-by-stage detailed
description of the entire Probe circuit. Refer to the
schematic diagram, Figure 8-1, in conjunction with
the following text.
4-30. SOURCE FOLLOWER.
4-31. To insure minimum loading to the circuit being
tested, source follower A1Q1 is used immediately
following the probe tip due to its input impedance
characteristics. Resistor A1R2 across the input per -
forms two functions: (1) it establishes a fixed 100k
ohm input resistance for the probe, and (2) fixes the
gate bias on A1Q1 when no signal is present at the
input. Resistor A1R1 furnishes overload protection
up to 50 volts by limiting the gate current of A1Q1.
High frequency response is maintained by A1C1. Re-
sistor A1R3 is used as a damping resistor to mini-
mize the effects of lead inductance.
4-32. CONSTANT CURRENT SOURCE.
4-33. Source Follower, A1Q1, is biased by the Con-
stant Current Source A2Q9. Resistor values in the
base and emitter circuits of A2Q9 establisha constant
current of D milliamps to bias the source follower
4-3
| | |
Model 1123A
low drift usinga FET source follower unless a matched
pair is used or the drain bias current supply is vari-
able. A feedback amplifier is used to establish the
de output level and low frequency gain. By using this
type of feedback amplifier, de drift in the probe tip
assembly is almost completely eliminated.
4-51. Tounderstand how the feedback system operates,
assume an input of 0.5 volts at the probe tip. From
previously established gain, assume a 1 volt output
at the emitter of A2Q4. The 0.5 volt input produces
a 10 microamp current flow through A1R2 to the base
of A2Q11. Differential Feedback Amplifier A2Q10/
Q11 provides a gain of -0.5 which results in 0.25
volts at the emitter of A2Q10. The gain of this amp-
lifier is set by the ratio of the feedback resistor
(A2R28) to the input resistor (A1R2). Input Balance
Adjust (A2R32) is adjusted during calibrationto insure
zero volts at the base of A2Q11 and at the probe tip
with no signal applied.
4-52. With -0. 25 volts at the bottom of A2R39 and
1 volt at the top of A2R44, the input to the Error
Amplifier (the base of A2Q8) should see a null (Zero
volts) at the summing point. If no error is present
at the base of A2Q8B, the feedback signal does not
change. The Differential Input Amplifier A1Q3/Q4
is not affected, and the output remains constant.
4-53. If the output at the emitter of A2Q4 were slightly
more positive than 1 volt, the summing point would
go slightly positive, increasing the forward bias on
A2Q8B. The resulting small decrease in collector
voltage on A2Q8B is coupled to the base of A2Q6.
After amplification and inversion by A2Q5/Q6, the
02632-1
feedback signal is connected to the base of A1Q4. Be-
cause this signal has increased in a positive direction,
it causes increased conduction in A1Q4. Due to the
differential connection of A1Q3/Q4, current in A1Q3
decreases. Due to the decrease in A1Q3 collector
current, the collector voltage increases. Transistor
A2Q1 inverts this signal causing it to go less positive.
Consequently, the output at A2Q4 goes negative,
bringing the signal back into balance at the summing
point.
4-54. Tt should be understood that this feedback amp-
lifier circuitry forms a closed loop around the probe
amplifier, and that operation is instantaneous. When
properly adjusted, the instrument will track from in-
put to output providing a 1:1 dc output to any 50 ohm
load. The dc temperature drift characteristics are
determined by the feedback amplifier. The only com-
ponent affecting temperature drift in the probe tip
assembly is AIR2. In the amplifier assembly drift
determined by A2Q8A/B and A2Q11A/B which are
matched pairs. Therefore there is almost no dc
drift due to temperature changes.
4-55. DC GAIN AND OFFSET ADJUSTMENT.
4-56. Potentiometer A2R38 and A2R41 apply a dc
input signal to the feedback system which can be ad-
justedfor the desired de output level. If it is desired
tolook ataninput signal 0 volts to +1 volts, the probe
output canbe adjusted to -0. 5 volts, thus when the in-
put signal goes to +1 volt, the output goes to +0. 5 volts.
In this manner, a +1 volt signal can be observed without
exceeding the +0.5 volt dynamic range of the probe.
DC gain of the feedback system is adjusted by A2R43.
Section IV
Paragraphs 4-34 to 4-50
into the desired operating range. Diode A2CR2 tem-
perature compensates the current source A2Q9, keep-
ing the output current to A1Q1 constant.
4-34. EMITTER FOLLOWER.
4-35. Source Follower A1Q1 followed by emitter fol-
lower A1Q2 constitutes an impedance converter. It
accepts signals through its high impedance input, and
furnishes the signal to differential amplifier stage
A1Q3/Q4 from its low impedance output. As explained
previously, the low output impedance of emitter
follower A1Q2 produces maximum bandwidth by mini-
mizing the effects of Miller capacitance in the follow-
ing stage, A1Q3. Capacitor A1C4 bootstraps the source
resistor of A1Q1 thus maintaining constant current
biasing of A1Q1l and eliminating high frequency dis-
tortion. High frequency stabilization is maintained
by A1R4 and A1C2.
4-36. DIFFERENTIAL AMPLIFIER.
4-37. Differential Amplifier A1Q3/Q4 performs two
important functions: (1) it provides current amplifi-
cation which is required to drive the four-foot, 100-
ohm coaxial cable (W1) which connects the probe tip
and amplifier assembly and (2) it provides the means
for introducing a dc voltage to counteract variations in
gate to source voltage of Q1 and therefore, establish
the probe dc level at the probe output. The amplifier
is designed for a gain of one to minimize the Miller
Effect. Inductor A1L1 compensates for collector
capacitance of A2Q3 and better terminates the sending
end of the 100-ohm coaxial cable. It also provides
some high frequency compensation.
4-38. Feedback from the output amplifier, A2Q4 is
applied to the base of A1Q4. This feedback signalis
generated as a result of an offset (or error) between
input and output levels, detected at the base of A2Q8B
(the summing point for input and output currents).
When an error is detected, it causes an increase or
decrease inthe voltage difference between the base of
A1Q3 and A1Q4. This error signal is fed through
A2Qland A2Q4 causing the output level to change until
the resulting error signal at A2Q8B drops to zero.
Thus the feedback network maintains the desired de
level from input to output.
4-39. INTERMEDIATE AMPLIFIER.
4-40. Transistor A2Q1l receives the signal through
cable Wi. Resistor A2R1 terminates the cable with
100 ohms to provide impedance matching at its output
end. Inductor A2L1 compensates for loading caused
by the input capacitance of A2Q1. Common emitter
stage A2Q1 provides a voltage gain of approximately
2.2 and contains both emitter and collector peaking
networks for maintaining a flat frequency response.
Emitter peaking is accomplished by frequency com-
pensating adjustments C3, C4, C5, R5, R7, В8, R10
and R48. Collector peaking furnishes additional com-
pensation with L3 peaking medium frequencies and
L2 peaking high frequencies.
4-4
Model 1123A
4-41. INTERMEDIATE AMPLIFIER GAIN.
4-42. To determine Intermediate Amplifier gain, the
total emitter resistance inthe circuit of A2Q1 is equal
to the sum of resistors R5, R6 and the internal re-
sistance of Q1 (totaling approximately 90 ohms for
all three). Collector load resistance is equal to the
equivalent of A2R11 in parallel with A2R15 (approxi-
mately 200 ohms). Therefore, the low frequency gain
of A2Q1 is about 2.2. Potentiometer A2R5 provides
low frequency gain adjustment. Capacitor A2C9 is a
temperature compensated capacitor (with a large
negative temperature coefficient) which isusedto com-
pensate for the inherent negative temperature coef-
ficient of transistor high frequency response in all
stages.
4-43. CONSTANT VOLTAGE SOURCE.
4-44. A constant voltage source, comprised of A2Q2
and A2Q3, furnishes a stable voltage level to the
emitter network of A2Q1. Zener regulator VRI,
temperature compensated by CR1, produces a fixed
voltage drop; therefore, the resulting level at the
base of A2Q2 remains constant. The majority of
current through the diode network supplies probe
circuitry. Due to the differential amplifier A1Q3/Q4
used in the probe, the current through CR1 and VR1
is relatively constant. Transistor A2Q3 provides
feedback around A2Q2 thus lowering the output im-
pedance of Q2 making it a more effective voltage
source.
4-45. TEMPERATURE COMPENSATION.
4-46. Transistor A2Q1 is temperature compensated
by A2Q2. Careful examination shows the base/emit-
ter junction of A2Q2 plus L1 and R1 are in parallel
with the base/emitter junction of A2Q1 plus R5 and
R6. During normal operation, the sum of the voltage
drops across each of these strings is equal. Since
the change in voltage across these base/emitter junc-
tions is equal, they cancel each other and thus do not
affect the output level of A2Q1.
4-47. OUTPUT AMPLIFIER.
4-48. Output Amplifier A2Q4 is an emitter follower
which provides a low output impedance of 50-ohms
for proper impedance matching. This instrument ex-
hibits a 50-ohm source impedance and is designed to
drive a 50-ohm load. The source impedance, looking
into connector P1, consists of A2R45 added to the
small internal emitter resistance of A2Q4. At high
frequencies the internal resistance increases, caus-
ing the output impedance to increase; however, due
to capacitor A2C13 whose reactance decreases at
high frequencies, and R46/C 14, the output impedance
remains relatively constant at 50 ohms.
4-49. FEEDBACK TO MINIMIZE DC TEMPERATURE
DRIFT.
4-50. Since the temperature coefficient of the gate to
source voltage of a FET is dependent on the bias
current applied to the drain, it is impossible to get
02632-1
Section IV
Paragraphs 4-51 to 4-56
AZ | AMPLIFIER ASSEMBLY |
CONSTANT
VOLTAGE
Al CUE DRABE Acera TT TT SOURCE
АН acne PROBE ASSEMBLY | | 02,03 %
| | — > COMPENSATION
Ç | “04 ADJUSTMENTS
| / ‘р,
4' 110 o
в = / LOW
PROBE я | O FREQ
TIP CONV Wi FRE We
AMP OUTPUT Pe
INPUT | | Q1,Q2 AMPL TERME NU
$R2 Q3,04 AN - y eu
| + | PES ev
1 Ji nn er 2
= + CONSTANT
| | CURRENT
| SOURCE
LU o Jj | 09
INPUT
BALANCE DC OFFSET
ADJ dro $R38 ADJ
: < > VA
a <
| 2 |
| y |
DIFF Ih
FEEDBACK
| 910,91! W3 po
! +15V +15V
i 12.6 V — 12.6 Y
| COMMON
| R28 + =
= — — — — — — — - (123A-B-I
Figure 4-7. Functional Block Diagram
4-5
Section V
Model 1123A
Table 5-1
Table 5-1. Required Test Equipment
Recommended Instrument Required Characteristics
Type Model
DC Voltmeter HP 412A 100 mV +1%
Oscilloscope
HP 180A w/1801A or
1802A and 1820A
. 005 V/Div 2 psec /Div
1424 А
Square Wave HP 211A 500 Hz - 10 kHz 160 mV
Generator
Power Supply HP 1122A -12.6 V 120 m7, +15 V 150 mA
Power Supply HP 6206A 10.5 V 20 mA
Oscillator HP 200CD 2 kHz - 200 kHz 40 mV pk-pk
Oscilloscope HP 140A w/ 1410A and 100 mV/cm 2 usec/cm
Pulse Generator HP 213B 100 psec risetime 500 mV
RX Meter HP 250B Measure 3-4 pF at 100 MHz
VHF Signal Generator HP 608D 230 MHz 1 V pk-pk
Accessories Required:
(2) 50-ohm Tee connectors HP Model 10221A
(2) BNC Tee connectors HP Part No. 1250-0281
(4) BNC to GR Adapter HP Part No. 1250-0050
(2) BNC to N Adapter HP Part No. 1250-0780
(1) 10 dB Pad GR 874 G10
5-0 02632-1
—— ee
Model 1123A
Section V
Paragraphs 5-1 to 5-15
SECTION V
PERFORMANCE CHECK AND ADJUSTMENTS
5-1. INTRODUCTION.
5-2. This section contains procedures for perform-
ance check and adjustments. The purpose of this in-
formation is to deter mine whether or not the instrument
is operating within the specifications as listed in Table
1-1, and if not, how to calibrate the instrument. Physi-
cal location of all internal adjustments is shown in
Figure 5-9. Troubleshooting information, component
andassembly locations, and schematic diagrams are
located in Section VIII.
5-3. TEST EQUIPMENT.
0-4. Testequipment neededto check and maintain the
instrumentis listedin Table 5-1. Similar or equiva-
lent test equipment may be usedif necessary. Due to
the unique design of this instrument, some of the test
equipment required is not commercially available.
Steps are given in the performance check andadjust-
ment procedure to build the test fixture necessary to
accomplish the procedure. When making adjustments,
a non-metallic screwdriver or alignment tool should
be used.
5-5. SIMPLIFIED PERFORMANCE CHECK.
5-6. A simplified performance check consisting of
selected checks within the over-all procedure is
recommended as a quick check to ensure that the in-
strument is operating properly. To accomplish the
quick check, steps 5-13 thru 5-15 and 5-19 should be
performed. If a thorough performance check is re-
quired, all steps in the procedure must be performed.
5-7. PERFORMANCE CHECK.
5-8. The purpose of this performance check is to de-
termine whether or not the instrument is operating
within its listed specifications. This check may be
used as part of an incoming quality control inspection,
aperiodic operational check, or to check the calibra-
tion after repair and/or adjustments are made.
5-9. Enter the readings of the initial performance
check on the Performance Check Record on Page
5-7/5-8. The form may then be removed and filed in a
safe place so that readings taken at a later date can
be compared to the original readings.
5-10. Itisrecommended that the performance checks
be done in the sequence given because succeeding
steps dependupon control settings and results of pre-
vious steps. If necessary, steps may be done individu-
ally by referring to control settings and results prior
to the desired step.
5-11. PRELIMINARY SET-UP.
5-12. Connect the HP Model 1123A to an appropriate
power source.
02632-1
a. Apply power and allow 5-minute warm-up.
5-13. INPUT BALANCE CHECK.
a. Connect the Voltmeter to the probe tip pin.
b. Connect the Voltmeter ground lead to probe
ground.
с. Observe a reading of 0 volts £1 mV.
5-14. DC OFFSET CHECK.
a. Connect a 50-ohm load and Tee connector to
the output BNC.
b. Connectthe Voltmeter to the center conductor
of the Tee connector.
c. Connect Voltmeter ground lead to probe ground.
d. Observe a reading of 0 volts +5 mV.
5-15. GAIN CHECK.
a. Connectthe equipment as shown in Figure 5-1.
b. Set the controls as follows:
VERTICAL AMPLIFIER
VOLTS/DIV - - - + + + «+ « « « « + .02 V
DISPLAY ee ee ee ee ee ae ae ALT
COUPLING ser w+ se ss ee se esa DC
TIME BASE
SWEEP TIME - + + - + + + + +" .2 msec
TRIGGER PP TT AUTO
р
1820A
> 10"
CABLE — CABLE
BNC
TEE
BNC TON
1123A-A-14
Figure 5-1. Gain Check Test Set-up
5-1
Section V
Paragraphs 5-16 and 5-17
SQUARE WAVE GENERATOR
FREQUENCY * *** "1" 11 1°" 500 Hz
AMPLITUDE ©‘: * - Set for 8 div display
с. Repeat step b above with SWEEP TIME set to
20 psec with 5 kHz input, and 5 usec with 10 kHz
input.
d. In each of the above conditions, the output of
the probe shall be within +1% (+0. 4 minor divisions)
of the input square wave.
5-16. SINE WAVE COMPRESSION CHECK.
Note
The DC Blocking Assembly used in this
check allows the input signal to be super -
imposedona +0. 5 volt de level. The DC
Blocking Assembly must be assembled for
this test (see Figure 5-2), however care
must be taken to minimize perturbations
caused by the high frequency signal path.
LOW FREQUENCY
220UF
IN HE OUT
Ll 220uF| [I
= |=
< 1000
>
2 1000 e !
? N
sn
IN > << + т. 10.5V
I | = |
A
5 N
HIGH FREQUENCY
I123A- A-2!
Model 1123A
ISOA
TiO o
ZA o| je
a. o o
[BOTA am
n ? o
IO CABLE ь р
I820A
> DC BLOCKING
ASSEMBLY
— 10 CABLE 1123A
_SPECIAL
500 LOAD
500 LOAD “ene TEE
GR TO BNC CU SON TEE
1123A-A-20
Figure 5-3. Compression Test Set-up
g. Change Oscillator frequency to 200 kHz and
Sweep Time to 2 usec/div.
h. Repeat steps d thru Г.
i. Ineachof the above cases, the signal compres-
sion should be less than 8% (signal amplitude should
be greater than 7. 4 divisions).
5-17. PULSE COMPRESSION CHECK.
a. Connect the equipment as shown in Figure 5-4.
b. Set controls as follows:
SAMPLING VERTICAL AMPLIFIER
VOLTS/CM + + + + ++ 8445555 10 mV
VERNIER - - adjust for 10 em display
Figure 5-2. DC Blocking Assembly Schematic
a. Connectthe equipment as shown in Figure 5-3.
b. Set instrument controls as follows:
VERTICAL AMPLIFIER
VOLTS/DIV “+ ere . 005
COUPLING акне ов ов ев, АС
VERNIER : + «os fully cw
TIME BASE
SWEEP TIME - - + + o 2 msec
MODE #8 +8 4 a aa 4 a e ea AUTO
SINE WAVE GENERATOR
FREQUENCY * * + + «= = + + «+ «+ 2 kHz
AMPLITUDE - - adjust for 8 div display
c. Adjust Power Supply output for +10.5 volts.
d. SetswitchonDC Blocking Assembly to the OFF
position.
e. Display should be a sine wave, 8 divisions in
amplitude with no visible distortion.
f. Set switch to plus position and then to minus
position. Observe the signal amplitude in each case.
5-2
1424 А
6206A Y
( 62 A
OC BLOCKING
ASSEMBLY,
!
o o +a
—
-
—— BNC TO GR
10 DB PAD
GR TO BNC
POWER CABLE
—— EXTENSION
123A
>
lO CABLE
/ GR TO BNC
TOR
SON TEE 500 TEE
3'BNC TO BNC ‚500 LOAD
/
\
(5 GR TO BNC
2138 “N TO BNC
N23A-A-19
Figure 5-4. Pulse Compression Test Set-up
02632-1
Model 1123A Section V
Paragraphs 5-18 to 5-20
SAMPLING TIME BASE SAMPLING VERTICAL AMPLIFIER
SWEEP TIME + © « eo 10 ns VOLTS/DIV : - +=. a 50 mV
LEVEL/MODE - + + + + + <= FREE RUN VERNIER + (к. Set for 10 cm display
SCANNING = «eee. NORMAL
SYNC PULSE + + .. ON PULSE GENERATOR
TRIGGER -. + + . . 2. 242244442040 +
PULSE GENERATOR OUTPUT: + « + . . + 2 + 424 4 44440 +
PULSE + + + + «+ + oc vv ov oe + SENSITIVITY + + + + ++ Obtain Trigger
TRIGGER - - + + + + + 442 42 42 0 +
. c. Observearisetime of less than 1. 6 nsec. Over-
SENSITIVITY for triggered output shoot and ringing shall be less than +3% (3 mm). Per-
c. Adjust Power Supply output for +10.5 volts. turbations shall be less than 6% (6 mm) pk-pk.
d. Setthe switch on the DC Blocking Assembly to
the OFF position. SYNC PULSE
e. Amplitude of the pulse should be 10 cm. Over- / Jao PULSE
shoot and ringing should be less than 6% (6 mm). / OUTPUT
f. Set the polarity switch on the DC Blocking As- N
sembly to plus and then minus. The pulse must be e 9
repositioned on screen each time. CAS —\ Î
213B
g In each of the conditions in step f, the pulse TRIGGER
should be greater than 9.2 cm inamplitude. Overshoot INPUT
and ringing should be less than 6% of signal amplitude. 500 TEE
508 LOAD
5-18. INPUT CAPACITANCE CHECK. 11234 —e
a. Connect the equipment as shown in Figure 5-5. \
quip su | GR TO N 502
b. Set Frequency of RX Meter to 100 MHz. N TO BNC TEE
c. Adjust DETECTOR TUNING and null RX Meter. S08 —
\
d. Apply power to the probe and insert the probe \\ TO
tip into the adapter. BNC
GR TON
e. Capacitance should be from 3 to 4 pF.
11234-A-16
[122A Figure 5-6. Pulse Response Test Set-up
oo
| o 5-20. BANDWIDTH CHECK.
——. POWER CORD a. Connectthe equipmentas shown in Figure 5-7.
500 —- EXTENSION
LOAD PROBE b. Set controls as follows:
SAMPLING TIME BASE
H23A —= o TIME/DIV . - « + + + 11244220 2 nsec
mo 9 TRIGGER - + + + + + + + + + + + + = +INT
SCANNING ++ + + = « + « «+ NORMAL
2508 RX METER SAMPLING VERTICAL AMPLIFIER
VOLTS/DIV : + + re к кок) 100 mV
1123A-A-15 VERNIER - « - + + + + + + + + +0 fully cw
TRIGGER e a ae A E A > A
Figure 5-5. Input Capacitance Set-up OSCILLA TOR
5-19. PULSE RESPONSE CHECK. FREQUENCY + + + + « + « + = + 220 MHz
a. Connectthe equipment as shown in Figure 5-6. c. Insert the Probe of Model 1410A into the con-
b. Set controls as follows: nector labeled B.
SAMPLING TIME BASE d. Adjust Oscillator output for 10 cm display.
a e. Move the Probe of Model 1410A to the connec-
TIME /DIV 10 ns tor labeled A and insert the Model 1123A Probe into
MAGNIFIER =~ - «o-oo о X10 the connector labeled B
SYNC MODE “+: - «= = = «+» = + AUTO -
SYNC PULSE бб ттт ON f. Observe a signal of greater than 0. 71 V pk-pk
SCANNING © бб! NORMAL (7.1 em) in amplitude.
02632-1 5-3
|
Section V
Paragraphs 5-21 to 5-30
.—CH B PROBE
ода E
оо 007 1410A
o 140A O —
| сани Mn 0
POWER CORD — 08D PAD
EXTENSION _— 50 TEE
a
1080 PAD
? BNC TO GR
sosp_ [OOO
3' CABLE
PROBE
et
1123A-A-18
Figure 5-7. Bandwidth Test set-up
5-21. NOISE CHECK.
a. Connect the equipment as shown in Figure 5-8.
b. Set controls as follows:
VERTICAL AMPLIFIER
SYNC SOURCE + « «= « «= + « «+ + +o . A
VOLT/DIV (Both Channels) - - - - © .01
INPUTS + + + + + + + + 4 e e a e. OFF
DISPLAY ee a Aa a a e a en B
TIME BASE
TIME /DIV #84 8 4 e e e E E e» 1 LL sec
TRIGGER : + + + + + + + + 4 + + 45 AUTO
c. Switch INPUT of both channels to +UP.
d. Noise should not increase by more than 300
ju volts (0. 3 divisions).
Note
It may be necessary to shield the probe
tip to prevent noise pick-up.
о o
of Jo ——ieca
o o
1801A— | оо —— [820A
—
50 N 8" CABLE
'SIIZ3A
PROBE
— — 7
1123A-A-23
Figure 5-8. Noise Test Set-up
5-22. ADJUSTMENTS.
9-23. The purpose of the adjustment procedure is to
establish proper calibration so the instrument will per-
form as indicated in the specifications given in Table
1-1. Physicallocation of all adjustments is shown in
5-4
Model 1123A
Figure 5-9. Recommended test equipment is listed
in Table 5-1.
5-24. It is recommended that the adjustment proce-
dure be done in the sequence given because succeed-
ing steps depend upon control settings and results of
previous steps.
5-25. When internal adjustments are made, a special
cover (HP Part No. 01123-04102) should be used to
maintain proper cover to circuit capacitance and oper-
ating temperature. If the cover is not used, allow the
circuit to reach operating temperature, then remove
the cover and make the required adjustment. Replace
the cover and wait for circuit to reach operating tem-
perature again before checking the results of the ad-
justment.
5-26. PRELIMINARY SET-UP.
5-27. Connect the HP Model 1123A to anappropriate
power source and allow a five minute warm-up.
5-28. INPUT. BALANCE ADJUST.
a. Connect the Voltmeter to the probe tip pin.
b. Connect the Voltmeter ground lead to probe
ground.
c. SetInput Balance AdjustA2R32 for O volts +1 mV.
5-29. DC OFFSET ADJUST.
a. Connect a Tee connector and 50-ohm load to
output BNC.
b. Connecta Voltmeter to the center conductor of
the Tee connector.
c. Connect the Voltmeter ground lead to probe
ground.
d. Adjust A2R38 fully cw, then fully ccw making
sure adjustment range is greater than +0.5 volts to
-0.5 volts.
e. Set A2R38 for a reading of O volts +5 mV.
5-30. GAIN ADJUSTMENT.
a. Connect equipment as shown in Figure 5-1.
b. Set controls as follows:
SQUARE WAVE GENERA TOR
FREQUENCY * «+ + + +8 +880 = 100 Hz
AMPLITUDE Set for 8 div display
VERTICAL AMPLIFIER
VOLTS/DIV - «= + + + + + «oo ooo . 02
DISPLAY Poe es ee esse sw ae ALT
COUPLING 28 = = + 3 8 1 4 e > DC
TIME BASE
TIME/DIV: * + + et 2 msec
TRIGGER + + + +7 + « «+ +. AUTO
c. Adjust A2R43 so that the square wave output of
probe is the same amplitude as input to the probe.
d. Reset TIME/DIV switch to . 5 msec and adjust
A2R5 to make leading edges of the square waves identi-
cal.
e. Change Square Wave Generator FREQUENCY
to 1 kHz and Time Base Plug-in TIME /DIV to 50 1 бес.
02632-1
Ш , _ ae =
Model 1123A Section V
Paragraph 5-31
f. Adjust A2R8 for same flatness and shape of both c. Make appropriate adjustments as listed in
square waves. Table 5-2 to obtain optimum risetime and pulse re-
g. Change Square Wave Generator frequency to sponse.
20 kHz and Time Base Plug-in TIME/DIV to 5 usec. Note
h. Adjust A2R10 for same flatness and shape of
both square waves. Because of adjustment interaction, it
i. In each condition above, amplitudes of both may be necessary to repeat the proce-
square waves should differ by less than 1% (+. 4 minor
divisions).
5-31. PULSE RESPONSE ADJUSTMENT. Table 5-2. Pulse Response Adjustments
a. Connectthe equipment as shown in Figure 5-6. Adjustment Adjusts
b. Set controls as follows:
SAMPLING TIME BASE C3 thru C5, R7 and R48 Corner
TIME/DIV : * rr о 10 nsec C3 and R7 Level of top
MAGNIFIER ee se eae ee a ae a a Xi
MODE: = © © = © «= © ccm AUTO C4 First peak
SYNC PULSE ere ae we eee aa es ON
SCANNING © бол! NORMAL C5 and R48 Level of top
SAMPLING VERTICAL AMPLIFIER
VOLTS/DIV + + + + + « « «+ « 50 mV
VERNIER + + + + > = Set for 10 em display d. Risetime should be less than 1. 6 nsec.
PULSE GENERA TOR e. Overshoot and ringing should be less than 3%
TRIGGER- -: ... 112211411200 ; (1.5 minor divisions).
OUTPUT : + + + © + vv eee eee + f. Perturbations should be less than 6% pk-pk
SENSITIVITY - - To obtain triggered output (3 minor divisions).
HIGH FREQ HIGH FREQ
RESPONSE NO. | PHASE NO. |
ca
MID-FREQ HIGH FREQ
RESPONSE NO.I RESPONSE NO. 2 INPUT BALANCE
RIO C3 R32
DC OFFSET
R38
Wi
We —— LD EN
CS R5
DC GAIN HIGH FREQ LOW FREQ GAIN
RESPONSE NO.3
R8
MID-FREQ HIGH FREO
RESPONSE NO. 2 PHASE NO. 2 N23A-A-22A
Figure 5-9. Adjustment Location
02632-1 5-5/5-6
|
Model 1123A
PERFORMANCE CHECK RECORD
Performance Check Record
Paragraph Check Min Reading Max
5-13 Input Balance
step c None 0 V +1 mV
5-14 DC Offset
step d None 0 V +5 mV
5-15 Gain
step d 7.9 div 8. 1 div
5-16 Sine Wave
Compression
step i 7.4 div None
5-17 Pulse Compression
step e None 6%
step g 9.2 cm 10.0 cm
5-18 Input Capacitance
step e 3 pr 4 pF
9-19 Pulse Response
step c "Risetime" None 1. 6 nsec
" "Overshoot" None 3%
" "Perturbations" None 6%
9-20 Bandwidth
step Î 7.1 cm None
5-21 Noise
step d None 1.5 minor div
02632-1 5-7/5-8
Model 1123A
Section VI
Paragraphs 6-1 to 6-7
SECTION VI
REPLACEABLE PARTS
6-1. INTRODUCTION.
6-2. This section contains information for ordering
replaceable parts for the instrument. Table 6-2 lists
the parts in alpha-numerical order of their reference
designations and provides the following information
for each item:
a. HP Part Number.
b. Total quantity (TQ) used in instrument; given
only first time a part number is listed.
c. Description of part; see Table 6-1 for list of
reference designators and abbreviations.
6-3. Parts not identified by a reference designation
are listed in Table 6-2 under miscellaneous.
6-4. ORDERING INFORMATION.
6-5. To order replacement parts from Hewlett-
Packard Company, address the order or inquiry to
the nearest HP Sales/Service Office (list at rear of
manual) and supply the following information:
a. HP Part Number of item(s).
b. Modelnumber and eight-digit serial number of
instrument.
c. Quantity of parts required.
6-6. To order a part not listed in the table, provide
the following information:
a. Model number and eight-digit serial number of
instrument.
b. Descriptionof part including function and loca-
tion.
6-7. Component descriptions given in Table 6-2 are
as complete as possible to assist in obtaining replace-
ment parts from manufacturers other than HP. How-
ever, many parts are manufactured only by HP, or
are produced by other manufacturers toHP proprietary
specifications, and are therefore available only from
HP. Actual manufacturer and manufacturers part
number for non-HP parts will be supplied upon request.
Contact the nearest HP Sales/Service Office.
Table 6-1. Reference Designators And Abbreviations
REFERENCE DESIGNATORS
A = assembly F = fuse M = meter TB = terminal board
B = motor FL = filter MP = mechanical part TP = test point
Cc = capacitor H = hardware P = plug V = vacuum tube, neon bulb,
CP = coupling IC = integrated circuit Q = transistor photocell, ete,
CR = diode J = jack R = resistor VR = voltage regulator (diode)
DL = delay line K = relay RT = thermistor W = cable
Ds = device signaling {lamp} L = inductor 5 = switch X = socket
E = misc. electronic part LS - speaker T = transformer Y = crystal
ABBREVIATIONS
amp = amperes gl = glass mtg = mounting rf = radio frequency
ampl = amplifier grd = grounded) my = mylar
s-b = slow-blow
h = henries n = nano (1079) Se = selenium
bp = bandpass Hg - mercury n/c = normally closed sect = section(s)
hr = hour(s) ne = neon semicon = semiconductor
car = carbon HP = Hewlett-Packard n/o = normally open Si = silicon
Cow = counterclockwise npo = negative positive zero sil = silver
cer = ceramic if. - intermediate freq. (zero temperature si = slide
сое? = coefficient impr = impregnated coefficient) spl = special
com = common incd : incandescent nsr = not separately
comp = composition incl = include(s) replaceable Ta = tantalum
conn = connector ins = insulation(ed) td = time delay
ert = cathode-ray tube int = internal obd = order by description tel = toggle
cw = clockwise ‚ ох = oxide Ti = titanium
k = kilo (10°) tol = tolerance
depc = depasited carbon pc = printed circuit trim = trimmer
lin = linear taper pr = picofarads =
elect = electrolytic log = logarithmic taper 10-12 farads
encap = encapsulated Ipf - low pass filter piv = peak inverse voltage Lu = micro (10-6)
ext = external p/o = part of
m = milli (1075) porc = porcelain var = variable
| = farads meg = mega (10°) pos = position(s)
fet = field effect metflm = metal film pot = potentiometer w = Watts
transistor met ox = metal oxide pk-pk = peak-to-peak w/ = with
fxd = fixed mir = manufacturer w/o = without
minat = miniature wvdc = de working volts
Ge = germanium mom = momentary rect = rectifier WW = wirewound
02632-1 6-1
Section VI
Model 1123A
Table 6-2
Table 6-2. Replaceable Parts
Rel Description
art No.
Desig HP Part Ko TQ (See Table 6-1.)
A1 01123-66504 1 | A: Probe
Note
The Probe Board Assembly is not a field repairable item.
If trouble is evident, the entire probe assembly (A1) should
be returned to HP for repair or replacement.
A2 01123-66502 1 | A: Probe Amplifier
C1 0180-0230 3 | C: fxd ta 1 uf 50V
C2 0160-0127 1 | C: fxdcer 1 uf 25V 20%
C3 0121-0060 2 | C: var cer 2-8 pF
C4 0121-0060 C: var cer 2-8 pF
C5 0121-0114 1 | C: var cer 7-25 pF
C6 0160-0161 1 | С: fxd mylar .01 uf 200V 10%
C7 0160-0154 1 | C: fxd mylar . 0022 uf 200V 10%
C8 0150-0121 9 | C: fxd cer .1 uf 50V 3%
C9 0160-3285 1 | C: fxd cer 1.5 pF 500V 1%
C10 0150-0121 C: fxd cer . 1 uf 50V 30%
C11 0180-0116 1} C: fxdta 6.8 uf 35V 10%
C12 0150-0093 2 | C: fxdcer .Oluf 100V +80 -20%
C13 0160-2246 1 | C: fxd cer 3.6 pF 500V 1%
C14 0160-2249 1 | С: fxd cer 4.7 pF 500V 1%
C15 0180-0230 C: fxd ta 1 uf 50V 20%
C16 0180-0230 C: fxd ta 1 uf 50v 20%
C17 0150-0093 C: fxd cer . 01 uf 100V +80 -20%
CRI 1901-0049 1} CR: si
CR2 1901-0040 4 | CR: si
thru
CR5
Li 9100-2598 1 | L: fxd.075 uh
L2 9140-0146 1 | L: fxd 10 uh 10%
L3 9100-2276 1 | L: fxd 100 uh 10%
L4 9100-2258 3 | L: fxd 1.2 uh 10%
L5 9100-2258 L: fxd 1.2 uh 10%
L6 9100-2258 L: fxd 1.2 uh 10%
Q1 1853-0061 1] Q: si PNP
Q2 1853-0036 11 Q si PNP
Q3 1854-0071 3 | Q: si NPN
Qu 1854-0372 1 | Q: si NPN $22277
Q5 1853-0020 3 | Q si PNP
Q6 1853-0020 Q: si PNP
Q7 1853-0020 Q: si PNP
Q8 1854-0374 2 | Q: si NPN Dual
Q9 1854-0071 Q: si NPN
Q10 1854-0071 Q: si NPN
Q11 1854-0374 Q: si NPN Dual
R1 0757-0401 1 | R: fxd metflm 100 ohms 1% 1/8w
R2 0757-0924 2 | R: fxd metox 1k ohm 2% 1/4w
R3 0757-0924 R: fxd metox 1k ohm 2% 1/4w
R4 0757-0900 1 | R: fxd metox 100 ohms 2% 1/4w
R5 2100-2060 1 | R: var cer metflm 50 ohms 30% 1/2w
6-2 02632-1
Model 1123A Section VI
Table 6-2
Table 6-2. Replaceable Parts (Cont'd)
Ref No. Description
Desig HP Part No TQ (See Table 6-1.)
A2 (Cont'd.)
R6 0757-0397 1] R: fxd metflm 68.1 ohms 1% 1/8w
R7 2100-1788 3| R: var cer metflm 500 ohms 30% 1/2w
R8 2100-2030 2| R: var cer metfim 20k ohms 30% 1/2w
R9 0757-0911 1] R: fxd metox 300 ohms 2% 1/4w
R10 2100-2030 R: var cer metflm 20k ohms 30% 1/2w
R11 0757-0282 1| R: fxd metflm 221 ohms 1% 1/8w
R12 0757-0936 1| R: fxd metox 3. 3k ohms 2% 1/4w
R13 0757-0968 1| R: fxd metox 68k ohms 2% 1/4w
R14 0757-0405 1| R: fxd metflm 162 ohms 1% 1/8w
R15 0757-0928 1] R: fxd metflm 1.5k ohm 1% 1/4w
R16 0757-0296 1| R: fxd metox 200 ohms 2% 1/2w
R17 0757-0075 1| R: fxd metox 470 ohms 2% 1/2w
R18 Deleted
R19 0757-0957 1| R: fxd metox 24k ohms 2% 1/4w
R20 0757-0912 1| R: fxd metox 330 ohms 2% 1/4w
R21 0757-0929 1| R: fxd metox 1, 6k ohm 2% 1/4w
R22 0757-0958 21 R: fxd metox 27k ohms 2% 1/4w
R23 0757-0972 2| R: fxd metox 100k ohms 2% 1/4w
R24 0757-0955 1| R: fxd metox 20k ohms 2% 1/4w
R25 0757-0972 R: fxd metox 100k ohms 2% 1/4w
R26 0757-0967 2| R: fxd metox 62k ohms 2% 1/4w
R27 0757-0975 1| R: fxd metox 130k ohms 2% 1/4w
R28 0757-0458 21 R: fxd metflm 51. 1k ohms 1% 1/8w
R29 0757-0459 21 R: fxd metflm 56, 2k ohms 1% 1/8w
R30 0757-0967 R: fxd metox 62k ohms 2% 1/4w
R31 0757-0958 R: fxd metox 27k ohms 2% 1/4w
R32 2100-1788 R: var cer metflm 500 ohms 30% 1/2w
R33 0757-0920 21 В: fxd metox 680 ohms 2% 1/4w
R34 0757-0920 R: fxd metox 680 ohms 2% 1/4w
R35 0698-6994 1 В: fxd metox 30 ohms 2%-1/4w
R36 0698-7077 1] R: fxd metox 15 ohms 2% 1/4w
R37 0757-0941 1] R: fxd metox 5. 1k ohms 2% 1/4w
R38 2100-2610 1| R: var cer metflm 5k ohms 10% 1/2w
R39 0757-0458 R: fxd metflm 51. 1k ohms 1% 1/8w
R40 0757-0943 И R: fxd metox 6. 2k ohms 2% 1/4w
R41 0757-0976 1| R: fxd metox 150k ohms 2% 1/4w
R42 0757-0459 R: fxd metflm 56. 2k ohms 1% 1/8w
R43 2100-2031 1] R: var cer metflm 50k ohms 30% 1/2w
R44 0757-0470 1] R: fxd metflm 162k ohms 1% 1/8w
R45 0757-0393 1] R: fxd metflm 47, 5k ohms 1% 1/8w
R46 0757-0398 1] R: fxd metfim 75 ohms 1% 1/8w
ВАТ 0757-0408 1] R: fxd metflm 243 ohms 1% 1/8w
R48 2100-1788 R: var cer metflm 500 ohms 30% 1/2w
VR1 1902-0799 1| VR: 7.5V zener 5% lw
VR2 1902-3203 1/ VR: 14.7V zener 5% 400 mw
Wi 01123-61301 W: 2 inch ground lead
W2 01123-61302 W: 2 1/2 inch ground lead
w3 01123-61601 W: 4 1/2 foot coax
W4 01123-61603 W: 9 inch 3 conductor
02632-1
Section VI
Model 1123A
Table 6-2
Table 6-2. Replaceable Parts (Cont'd)
Rel 40 Description
t No.
Desig HP Раз TQ (See Table 6-1.)
MISCELLANEOUS
1205-0010 1 Heat sink
01123-04101 1 Cover
1251-2229 5 Socket
01123-26101 5 Pin
01123-63201 1 Connector Assy - output
1251-2088 1 Plug-Power
6-4 02632-1
Model 1123A
Section VII
Paragraphs 7-1 to 7-10
SECTION VII
MANUAL CHANGES AND OPTIONS
7-1. MANUAL CHANGES.
7-2. This manual applies directly to standard Model
1123A Voltage Probe having a serial number prefixed
by 842- (refer to Paragraph 1-9). The following para-
graphs provide instructions for modifying this manual
to cover older (lower serial prefix) or newer ( higher
serial prefix) instruments. Refer to the separate
"Manual Changes" sheet supplied with this manual for
Errata.
7-3. OLDER INSTRUMENTS.
7-4. Table 7-1 contains information on changes re-
quired to adapt this manual to an older instrument
(lower serial prefix). Check Table 7-1 for your in-
strument serial prefix, and make the changes indicat-
ed. Notethatthese changes adapt the manual to cover
a particular instrument as manufactured; and there-
fore will not apply to an instrument subsequently mod-
ified in the field.
7-5. NEWER INSTRUMENTS.
7-6. As changes are made to the Model 1123A Volt-
age Probe, newer instruments may have serial prefixes
higher than 842-. The manual for these instruments
Table 7-1. Manual Changes
Instrument Serial Prefix
Number
Incorporate Change(s)
Numbered
827 - 1
02632-1
will be supplied with a "Manual Changes" sheet which
contains the required updating information. If the
change sheetis missing, contact the nearest HP Sales/
Service Office.
7-7. OPTIONS.
7-8. Options for an HP instrument are standard mod-
ifications to the standard instrument, andare installed
at the factory. At the presnet time, no options are
offered for the Model 1123A Voltage Probe.
7-9. SPECIAL INSTRUMENTS.
7-10. Modified versions (per customer specifications)
of any HP instrument are available on special order.
The manual for these special instruments (having
electrical modifications), includes a separate insert
sheet, which describes the modifications and any
changes requiredin addition to any "Manual Changes"
sheet (refer to Paragraph 7-6). Contact the nearest
HP Sales/Service Office if either of these sheets are
missing from the manual for a special instrument,
being sure torefer to the instrument by its full speci-
fication number and name.
CHANGE 1
Table 6-2, Page 6-2,
Al: Change to HP Part No. 01123-66501.
Page 8-5, Figure 8-5,
A1R14: Delete.
Al1C9: Delete.
7-1
Section VIII Model 1123A
Table 8-1
Table 8-1. Schematic Symbols and Conventions
Refer to MIL-STD-15-1A for schematic symbols not listed in this table.
о
= Etched circuit board
ed circui ar = Field effect transistor
(N-channel)
wn
It
Front panel marking
Breakdown diode
Rear panel marking
Front panel control = Tunnel diode
y
.. DOOÓ
7 = Screwdriver adjustment = Step recovery diode
Р/О = Part of = Circuits or components drawn
with dashed lines (phantom) show
— . .
CW = Clockwise end of vari- function only and are not intended
|
i
dy
“тт ©
to be complete. The circuit or
component is shown in detail on
another schematic.
able resistor
(
Li
fs =
1
NeCo = No connection
Unless otherwise indicated:
resistance in ohms
\/ = Waveform test point capacitance in picofarads
(with number) inductance in microhenries
V = Common electrical point Wire colors are given by
(with letter) not necessarily numbers in parentheses
ground _ using the resistor color code
[ (925) is wht-red-grn |].
a 0 - Black 5 - Green
= — = Single pin connector 1 - Brown 6 - Blue
2 - Red 7 - Violet
3 - Orange 8 - Gray
= Pin of a plug-in board 4 - Yellow 9 - White
(with letter or number)
Switch wafers are identified
as follows:
If
Primary signal flow
IF IR 3 3R IF. R
= Secondary signal flow
* = Optimum value selected
at factory, average
value shown; part may
have been omitted.
2F 2R
8-0 02632-1
Model 1123A
Section VIII
Paragraphs 8-1 to 8-14
SECTION VIII
SCHEMATICS AND TROUBLESHOOTING
8-1. INTRODUCTION.
8-2. This section contains Model 1123A diagrams,
component location pictorials, troubleshooting infor-
mation and repair and replacement procedures.
8-3. SCHEMATIC DIAGRAMS.
8-4. Schematic diagrams appear on right hand pages
that unfold outside the right edge of the manual. These
"throw clear" pages allow viewing the schematics
while referring to another section. Text can be fol-
lowed by unfolding the appropriate "throw clear’ page.
8-5. Schematics are drawn primarily to show the
electronic function of an instrument. A given sche-
matic may include all or part of several assemblies.
Schematics also include dc voltages and waveform
measurement test points. Waveforms applicable to
each schematic are shown opposite that schematic.
DC voltage and waveform measurement conditions are
shown in Table 8-2. Information about symbols and
conventions used in these schematics is provided by
Table 8-1.
8-6. COMPONENT IDENTIFICATION.
8-7. Chassis mountedparts, not on an assembly, are
shown on a fold out page. Assembly mounted compo-
nents are shown on page opposite the schematic. When
anassembly appears on more than one schematic, all
components are identified opposite the schematic on
which the assembly first appears.
8-8. REFERENCE DESIGNATION.
8-9. The unit system of reference designation, used
in this manual, is in accordance with the provisions
of the American Standard Electrical and Electronics
Reference Designations. Minor variations, due to de-
signand manufacturing, may be noted. A brief expla-
nationis presented here for those unfamiliar with the
designation system.
8-10. Each component is identified by a letter-number
combination. For example R1, R2;---C1, C2; etc.
This letter-number combination is the basic designa-
tion for eachcomponent. Components which are sepa-
rately replaceable and are part of an assembly have,
inadditiontothe basic designator, a prefix designation
which identifies the assembly on which the component
is located. Components not mounted on an assembly
have only the basic reference designation.
8-11. Figure 8-1 isusedas anexample. The basic ref-
erence designationappears three times, however each
R1 is identified by a designation formed by combining
component, assembly and sub-assembly designators.
Consider the R1 on sub-assembly A1. The complete
designation of that resistor is A2A1R1. Now, R1 con-
nected between assembly Al and the complete instru-
ment has only the designation R1 because it is not
mounted on an assembly. This system applies to all
classes of components; C, CR, Q, etc.
8-12. Assembliesare numberedfrom 1, consecutively.
If an assembly number is assigned and later deleted,
this number is not reused.
8-13. TROUBLESHOOTING.
8-14. The first and most important requirement for
successful troubleshooting is a thorough understanding
of how the instrument is designed to operate. Section
III (Operation) and Section IV (Theory of Operation)
of this manual are intended to provide the operator
with the necessary understanding to troubleshoot this
instrument. Many times suspected malfunctions are
COMPLETE INSTRUMENT
AI(ASSEMBLY)
A2 (ASSEMBLY)
AI(SUB-ASSEMBLY)
1123A-B-2
Figure 8-1. Unit System Reference Designation.
02632-1
8-1
Section VIII
Paragraphs 8-15 to 8-24
caused by improper control settings or system hook-
up. Therefore, it is recommended that the operator
become as familiar as possible with the operation of
the Model 1123A before troubleshooting.
8-15. Tolocateatrouble, start with a thorough visual
inspection of front panel control settings and hook-up.
Look for burned or loose components, mis-wiring or
any condition which suggests a trouble. Square pin
wiring is shown on each component pictorial. Refer
tothese callouts, after a board has been replaced, to
assure proper connections. Correct any faults lo-
cated in instrument performance before continuing to
troubleshoot.
Note
Test point jacks shown on schematics are
used in various checks and adjustments
and do not correspond to waveform test
points.
8-16. The first electrical check should be to insure
that proper voltages are coming on to the printed cir-
cuit boards. Check the Low Voltage Power Supply
(LVPS) to insure all voltages are correct. Use the
overall block diagram (Section IV), the schematic dia-
grams, andthe waveform photos adjacent toeach sche-
matic. This procedure will isolate the trouble to a
particular circuit. When trouble appears probable in
a circuit, check the dc voltages given on the schematics.
8-17. WAVEFORMS.
8-18. Typical waveform measurement points (refer to
Table 8-1) are located at strategic points along the
main signal path. The numbers inside the symbol re-
fer to a corresponding waveform photo. Conditions
for making the waveform measurements are given in
Table 8-2.
8-19. DC VOLTAGES.
8-20. DC voltage levels are shown on schematic dia-
grams for all active components (transistors, mainly).
Conditions for making dc voltage measurements are
given in Table 8-2. In locating points on printed cir-
cuit boards, note a small dot on the board identifies
the emitter lead of transistors, the source lead of a
field effect transistor (FET), the cathode lead of diodes,
and the positive side of electrolytic capacitors. On
dual transistors only, the tab denotes the collector
leads.
8-21. REPAIR AND REPLACEMENT.
8-22. The following paragraphs provide procedures
for replacing components and special considerations
for removing components from printed circuit boards.
Section VI provides a detailed parts list to permit or-
dering of replacement parts. If satisfactory repair
or replacement cannot be accomplished, notify the
8-2
Model 1123A
nearest HP Sales/Service Office (addresses at rear of
this manual) immediately. If shipment for repair is
recommended, see Section II of this manual for repack-
ing and shipping information.
8-23. SERVICING PRINTED CIRCUIT BOARDS.
8-24. Printed circuit boards in this instrument have
components mounted on one side, conductive surfaces
on both sides, and plated through component mounting
holes. Hewlett-Packard Service Note M-20E contains
useful information on servicing and repair of printed
circuit boards. Some important considerations are
as follows:
a. Use a 37 to 47.5 watt chisel tip soldering iron
with a tip diameter of 1/16 to1/8 inch, and a small
diameter rosin core solder.
b. Components may be removed by placing the
soldering iron to component leads on either side of the
board. If heat is applied to the component side of the
board, greater care is required so as not to damage
components. Extreme care is requiredtoavoid damage
to semiconductor devices. Damage may be minimized
by gripping component lead between soldering iron
and the component using a pair of long nose pliers.
с. If a component is obviously damaged or faulty,
clip the leads close to the component, then unsolder
the leads from the board.
d. Large components, such as potentiometers,
may be removed by rotating the iron from one leadto
another while gently applying pressure to lift the com-
ponent from the board.
e. Excessive heat or force will destroy the lami-
nate bond between the metal plated surface and the
board. If this should occur, the lifted conductor may
be cemented down with a small amount of quick drying
acetate base cement having good insulating properties.
If this repair cannot be accomplished, a section of
good conducting wire may be soldered along the dam-
aged area.
f. Beforereplacinga component, heat the remain-
ing solder in the component hole and clean it out with
a toothpick or similar object. Sharp pointed metallic
toolsare not recommended because they may damage
the plated through surface of the hole.
g. Tin and shape leads of replacement component
to fit existing holes.
h. Install components in the same position as the
original component (refer to Paragraph 8-20).
j. Whenremoving or replacing square pin connec-
tings, be sure to pull straight up for removal and re-
placement. These connections can loosen and cause
poor contact.
02632-1
Model 1123A Section VIII
Figure 8-2
C7 Сб RIO Q4 CS R9 Q3 Q2 C3 Ql R3
Li ce R8 ca CI
П2ЗА- А — |
Nu = ER? \ | . —— \ т - - | - ! |
EA La ! "1 = r 4 в j ей т о В ZA
5 ia — - a : | 3 Tr, e A Nee
yl ir Se)” IT NAN el du > a
Figure 8-2. Component Identification, Assy Al
02632-1
8-3
Section VIII
Figure 8-3 and Table 8-2
Model 1123A
Table 8-2. Waveform and DC Voltage Measurement Conditions
WAVEFORMS
The test point waveform, as given in figures preced-
ing the schematic diagram, were taken under the
following conditions:
MODEL 180A /AR (TEST OSCILLOSCOPE)
DISPLAY INT
MAGNIFIER X1
HORIZONTAL PLUG-IN
TRIGGERING INT
SLOPE +
SWEEP MODE AUTO
VERTICAL PLUG-IN
Polarity +UP
DISPLAY A
INPUT AC
Model 140-Series Sampling System:
For waveforms and , use test set-up
and connections given in Paragraph 5-19.
Any exceptions to these conditions are noted adja-
cent to the applicable waveform photo.
DC VOLTAGES
The DC Voltage readings, as given on the schematic
diagram, were taken with the Model 1123A discon-
nected from Oscilloscope with power applied.
All voltages are measured with reference to chassis
ground.
Voltage readings are considered normal if >. ithin
+10% of voltage given on schematic.
\/ DOS V/DIV XY
=2 MSEC
№ «02 V/DIV
«2 MSEC
\/ «005 V/DIV Y
«2 MSEC
y SK HZ INPUT
«02 V/DIV №7 SOMV/CM
„ZMSEC 2138 PULSE IONSEC/CM
«02 V/DIV № SOMV/CM
20 USEC 2138 PULSE 10 NSEC/CM
E
«005 V/DIV \/ +02 V/DIV
«2 MSEC 2MSEC | h2xa-6-3
Figure 8-3. Waveforms at Test Points
8-4 02632-1
Model 1123A
aa La
02632-1
REF | GRID | REF | GRID | REF | GRID | REF | GRID | REF | GRID | REF | GRID | REF | GRID | REF | GRID
DESIG | LOC |DESIG | LOC |DESIG | LOC |DESIG | LOC |DESIG | LOC |DESIG | LOC |DESIG | LOC |DESIG | LOC
eL Te=a с12 Гс-4 LI I'D-2 Q6 | B-4 re le RIT 1B-2 R29 |E-3 R40 |E-3
C2 D-2 C13 B-3 L2 C-4 QT в-4 R7 D-2 R19 E-4 R30 D-3 R41 E-3
ES D-3 C14 B-3 L3 C-3 Qs B-3 RE C-3 R20 E-4 R31 E-2 R42 E-3
C4 C-3 C15 B-4 LA B-4 Q D-4 RO D-4 R21 E-4 R32 E-2 R43 B-3
CS C-3 C16 B-2 L5 B-2 Q10 D-3 RIO C-3 R22 B-4 R33 E-2 R44 C-3
c& с-3 ci7 C-2 L6 B-3 Qui D-3 R11 B-3 R23 B-4 R34 E-2 R45 B-2
ce Es CRI D-4 Ql C-2 Rl C-2 R12 D-4 R24 B-3 R35 E-2 R46 B-3
cg C-4 CR2 E-4 Q2 D-2 R2 E-2 R13 C-4 R25 B-4 R36 E-2 R47 C-3
Co B-3 CR3 D-4 93 E2 RI D-2 R14 C-4 R26 B-3 R37 E-4 R48 D-3
C10 D-4 CR4 E-4 Q C-2 R4 D-2 R15 C-3 R27 D-4 R38 E-3 VR1 D-4
Cll D-4 CRS E-2 Q5 D-4 RS D-3 R16 B-3 R28 D-3 R39 D-3 VR2 E-3
IN23A—A—17
Figure 8-4. Component Identification, Assy A2
PRO
TIP
TIP
NOTE ls # DENOTES FACTORY SELECTED ITEM,
MAY BE OMITTED.
NOTE 2. * MAY VARY FROM -0.6V TO +l.4Vs
Reference designations within assembles
are abbreviated Add assembly designation
as prefiz to form complete designation
eg A1 où assembly AZ is AZR1|
COPYRIGHT 1968 BY HEWLETT-PACKARD CO.
1123 А - PROBE —827
REFERENCE DESIGNATIONS
Al AZ
ci-9 CI-I7
Li CRI-5
Ql-4 LI-6
RI-14 QI-Il
RI-48
vRI, 2
CHASSIS
Pl, 2
wi-3
DELETED: RIB
section VIII
Figures 8-4 and 8-5
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SRIO
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Hi FREQ % 20K$ MID FREQ #% M0 FREQ
\/ RESP NO, 2 RESP NO«2 RESP NOs! cI? GND )
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A oi | AMPLIFIER 3.6
a al / O.7V 1% N/
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RII cg 2 RIS AAA pt
221 le SPF ду $ 1500 R45 Pl
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# SEE NOTE 2 9 162K
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R39
SlelK
< +15Y +50MV +1e2V
AAA ААА «= +15 У |
net 00 zoo |
>
DIFFERENTIAL 303 I
ми ак Big
L DC OFFSET e ná
Rá2
Q10,Ql IAB QIIB nos + a ADJ $ 56.2K
R32 è
E > 5.00 ness
Hull A = = |2 „6 \
CRS E -25 MV R34 -l2v R37
| iz 680 5100 |
— -.6
Figure 8-5. Model 1123A Schematic Diagram
8-5/8-6
Model 1123A
Appendix I
APPENDIX |
ACCESSORIES
MODEL 10214A 10:1 DIVIDER
1. DESCRIPTION.
2. The HP Model 10214A 10:1 Divider is a signal
probing accessory for the HP Model 1425A/1410A
oscilloscope sampling system. The Model 10214A is
illustrated in Figure 1. The divider offers essentially
a constant impedance to the probe regardless of the
impedance to which the divider is connected. Since
the divider maintains a constant output impedance, it
can be used in point-to-point circuit probing without
experiencing a base-line shift or requiring response
adjustments on the oscilloscope. Specifications for
the Model 10214A are listed in Table 1.
3. CONNECTIONS.
4. The Model 10214A is connectedto the probe of the
sampling system by sliding the probe into the bady
portion of the divider.
5. USE WITH OTHER ACCESSORIES.
6. If the circuit to be probed contains dc potentials,
the HP Model 10217A Blocking Capacitor must be used
in conjunction with the Model 10214A.
Table 1. Specifications
ATTENUATION: 10:1 +5% over bandpass of the
sampling system.
INPUT IMPEDANCE: 1megohm shunted by 2. 5pF.
EFFECT ON RISETIME OF SYSTEM: Negligible.
MAXIMUM INPUT VOLTAGE: 350V de, 20V pk-
to-pk ac.
7. CIRCUITS.
8. The schematic of the Model 10214A is shown in
Figure 2. The major components of the divider are
resistor R1 and a metal sleeve which is spring load-
ed to hold R1 in place. The capacitance of C1 is the
capacitance between R1 and the metal sleeve; C2 is
the capacitance between the metal sleeve and the di-
vider body. The capacitance of C1 determines the
the high-frequency division ratio of the divider. At
low frequencies, the division ratio is accomplished
between R1 and the 100k-ohm resistance of the sam-
pling system probe. Resistor R2 and inductor Ll
critically damp resonance at the divider input and
output. Capacitor C3 represents the stray capacitance
present within the assembly.
02632-1
Figure 1. Model 10214A 10:1 Divider
9. MAINTENANCE.
10. The only maintenance recommended for the Model
10214A is to run a performance check if a malfunction
is suspected, and to adjust the capacity of CI.
11. PERFORMANCE CHECK.
12. Perform the following checkout procedure as an
acceptance check or if a malfunction in the divider is
suspected. Test equipment required for the perform-
ance check is listed in Table 2.
a. Set Pulse Generator controls as follows:
REP RATE - + + + + + + + + neo 100-1M
VERNIER °° * = = - Set to 500 kHz output
PULSE DELAY and VERNIER - - as required
PULSE WIDTH - + + + « + « « « + « + ‚5-5
VERNIER Set for exactly 1 usec output
PULSE POLARITY - - + + = + + + « «+ + + +
PULSE AMPLITUDE . . - + + + + + = ++ «+ 1
VERNIER - + + + + - Set for 1 volt output
‚10214A 10:1 DIVIDER |
| С! |
| le 5PF
: |
Bl A
| SO MAA a SAMPLING
y to < PROBE
| BE 900K T13PF OKT 2PF
a 7 = IO214A-A-1
Figure 2. Model 10214A Divider
Schematic Diagram
Appendix I
Table 2,
Model 1123A
Test Equipment
RECOMMENDED INSTRUMENT
REQUIRED CHARACTERISTICS
TYPE MODEL
Pulse HP 222A 1 MHz repetition rate, 0.5 usec pulse width
Generator
Sampling HP 1425A 1 GHz Bandwidth
Oscilloscope 1410A
50-ohm Tee HP10221A 1 GHz Bandwidth
50-ohm Load GR 874-W50 1 GHz Bandwidth
b. Set Oscilloscope controls as follows:
Function Selector» + + + + + + += CHANNEL À
SENSITIVITY + + + «+ « + « + « . . 100 mv/em
VERNIER + + + + + «+ +... CALIBRATED
SMOOTHING »* + + - - - NORMAL (optimized)
SCANNING + + + + + « «+ « + INTERNAL
DENSITY » 8 a a e e e e a ae e a as CW
TIME SCALE MAGNIFIER = + * * + + "= X2
DELAY ве зе, as required
TIME SCALE + + + + « « + « « . .. 1 :.sec/cm
VERNIER AO NAAA . +. a s CAL
MODE STABILITY -adjust for stable triggering
TRIGGERING: + + + + + + «+ . +... NORMAL
TRIGGER SLOPE + + « + + + += as required
с. Connect 50-ohm Load to 50-ohm Tee.
d. Connect loaded 50-ohm Tee to Pulse Generator
OUTPUT.
e. Connect Oscilloscope CHANNEL A probe to 50-
ohm Tee. A 10-cm pulse should appear on the CRT.
f. Insert Model 10214A 10:1 Divider between probe
and 50-ohm Tee, and change oscilloscope SENSITIVITY
to 10 mv/em. A10(=0.5)cm pulse should be obtained.
IA-2
13. ADJUSTMENT PROCEDURE.
14. The following procedure adjusts the probe for
optimum capacity. If the 10:1 division ratio is incor-
rect, replace the divider. Adjust the probe capacity
as follows:
a. Use the divider to monitor a 75-kHz square
wave on the sampling oscilloscope.
b. Adjusttheoscilloscopetoobtaina 10-centimeter
display and optimize oscilloscope response.
¢. The overshoot on the display should be 3%.
d. If the overshoot is not 3%, disconnect the di-
vider and adjust the slotted plate in the female con-
nector.
e. Repeat steps b through d until the overshoot is
3%. Keep the response optimized during the adjust-
ment procedure.
15. REPLACEABLE PARTS.
16. There is only one replaceable part in the Model
10214A, the probe pin, HP Part No. 5020-0457. Con-
tact the nearest HP Sales/Service Office for replace-
ments.
02632-1
Model 1123A
Appendix I
MODEL 10215A 100:1 DIVIDER
1. DESCRIPTION.
2. The HP Model 10215A 100:1 Divider is a signal
probing accessory (see Figure 1) which is designed
for use with the Model 1123A Voltage Probe only.
The divider increases the dynamic range of the Model
1123A to +50 volts. Specifications for the HP Model
10215A are listed in Table 1.
Table 1. Specifications
ATTENUATION: 100:1 +5 over bandpass of the HP
Model 1123A.
INPUT IMPEDANCE: 1 megohm shunted by 3 pF.
EFFECT ON RISETIME OF 1123A: Negligible.
MAXIMUM INPUT VOLTAGE: 500 Vdc overload,
50 V peak signal with HP Model 1123A.
3. CONNECTIONS.
4. The Model 10215A is connected to the probe by
sliding the probe into the body portion of the divider.
5. USE WITH OTHER ACCESSORIES.
6. If the circuit tobe probed contains dc potentials,
an HP Model 10217A or 10228A Blocking Capacitor
may be used in conjunction with the Model 10215A.
Whenused together, however, the Blocking Capacitor
should be used in front of the Divider Tip.
7. CIRCUITS.
8. A schematic of the Model 10215A is shown in
Figure 2. The major components of the divider are
resistor R1, whichisused to damp lead inductance at
the divider input. Resistor R1 and R2, with the 100k
ohm parallel input resistance inthe probe, accomplish
the divisionratioat low frequencies. At high frequen-
cies the division is determined by C1 and C2.
9. MAINTENANCE.
10. The only maintenance recommended for the
Model 10215A is to perform the performance check
procedure if a malfunction is suspected, and compen-
sation adjustment of the divider tip.
02632-1
Figure 1. Model 10215A
11. PERFORMANCE CHECK.
12. Theperformance check procedure may beused
as anincoming quality assurance inspection, or as an
aid to troubleshooting. Test equipment required to
check and maintain the Model 10215A is listed in
Table 2.
a. Set controls as follows:
Square Wave Generator
FREQUENCY *:* =» * * * * * " " 10 KHz
SYMMETRY =~ = = = = + © ~~ CENTERED
AMPLITUDE Rae a A AE AA EA . 05
MODEL IO215A
¡ 100.1 DIVIDER
|
Ci
025-3
A
50
naw—— —< —
3 PROBE
i | N
| |
R2
900K | L ce
R3 2 130
10K $
| = |
| |
ро |
1Q215A- A-1
Figure 2. Schematic Diagram
Appendix I
Monitor Oscilloscope Vertical Amplifier
DISPLAY: + == ==... CHANNEL B
VOLTS/DIV vee a ss ee ss ae aa ‚ 005
COUPLING - - + + + + + + + + + + + e DC
Monitor Oscilloscope Time Base
TIME /DIV “+ 4 + + + + + + >» + = 9 20 u sec
MODE - + + + + + + + + + > + + + + © AUTO
Table 2. Required Test Equipment
Model 1123A
b. Make test set-up as shown in Figure 3.
с. Adjust VERNIER for 8 division vertical display.
Я. Insert Model 10215A between probe and 50-ohm
tee.
e. Switch AMPLITUDE control on Square Wave
Generator to 5.
f. Deflection should be within 0. 4 divisions (+5%)
of full 8 divisions.
13. ADJUSTMENT PROCEDURE.
14. Thefollowing procedure contains steps to adjust
the divider compensation.
a. Use test set-up as shown in Figure 3.
b. Holdfrontportionof divider and loosen locking
sleeve by turning ccw.
c. Holdlocking sleeve and front portion while ad-
justing rear portion for optimum pulse response.
d. Tightenlocking sleeve making sure pulse does
not change.
15. REPLACEABLE PARTS.
16. Replaceable parts for the Model 10215A are
listed in Table 3. When ordering parts, be sure to
include model number and HP Part Number. Sales/
Service Office addresses are listed at the rear of this
Operating Note.
Table 3. Replaceable Parts
Description HP Part No.
Required
Instrument Type Characteristics
Square Wave | HP 211B 10 kHz
Generator
Monitor HP 180 À w/ 50 MHz
Oscilloscope { 1801A, 1820A
2118
© ©
O ==
и
50077
OUTPUT
1122 A
rd
о ое
O oo
10215A-A-2
Figure 3. Test Set-up
IA-4
10215-60701
10215-61501
10215-67701
10215-67702
5020-0457
Nut, locking
Resistor & Spring Assembly
Body Assembly, Rear
Body Assembly, Front
Probe Pin
02632-1
Model 1123A
Appendix I
MODEL 10217A BLOCKING CAPACITOR
1. DESCRIPTION.
2. The HP Model 10217A Blocking Capacitor is a
probing accessory for the HP Model 1425A/1410A
oscilloscope sampling system. The Model 10217A is
illustrated in Figure 1. The blocking capacitor is
used to isolate the sampling probe from dc potentials
present in the test circuit. Specifications for the
Model 10217A are listed in Table 1.
3. CONNECTIONS.
4. The Model 10217A is connected to the sampling
probe by sliding the probe into the body portion of the
blocking capacitor.
5. USE WITH OTHER ACCESSORIES.
6. The Model 10217A is used with the sampling probe
as described above. It may also be used with the
Model 10214A 10:1 Divider and the Model 10216A
Isolator.
Table 1. Specifications
CAPACITANCE: 0.001 LF.
MAXIMUM INPUT VOLTAGE: +50 Vdc, 50V pk-
to-pk ac. (+200V whenusedwith 10:1 Divider.)
SAG: 1% on 1 usec pulse. (0.1%on 1 usec when
Model 10214A 10:1 Divider is used.)
SHUNT CAPACITANCE: Less than 3.0 pF.
7. CIRCUITS.
8. The schematic of the Model 10217A is shown in
Figure 2. The blocking capacitor is a 0.001-pF low-
inductance capacitor which is used to keep dc poten-
tials in the circuit under test from reaching the vertical
amplifier. Itis capable of blocking +100 volts dc from
10217A BLOCKING |
| CAPACITOR
| IR AO SAMPLING
I Ci DON | PROBE
|
IOOOPF
| 4:02 00K 2PF
1 3PF |
cds
_ — 1
10217A—A-1
Figure 2. Model 10217A Blocking Capacitor Schematic
02632-1
Figure 1. Model 10217A Blocking Capacitor
ground. Inductor L1providedtodamp any resonances
that may be developed in the circuit, and capacitor C2
represents the stray input capacitance present within
the assembly.
9. MAINTENANCE.
10. The only maintenance recommended for the Model
10217A is to run a performance checkif a malfunction
is suspected.
11. PERFORMANCE CHECK.
12. Perform the following procedure as an acceptance
check or if a malfunction in the blocking capacitor is
suspected. Test equipment required for the perform-
ance check is listed in Table 2.
a. Set pulse generator controls as follows:
REP RATE a. e a ое ее о ® + +» ео 100k-1M
VERNIER * « «o Set for 500 kHz output
PULSE DELAY and VERNIER * as required
PULSE WIDTH . eo + © т | т ея вече . 5-5
VERNIER - - » Set for exactly 1 usec output
PULSE POLARITY . e & » e + + = = a a eo » +
PULSE AMPLITUDE + + «= = co co» o>» 1
VERNIER «+ » > + » _- - Set for 1 volt output
b. Set oscilloscope controls as follows:
Function Selector - = + = = * * * CHANNEL A
SENSITIVITY + recreo 100 mV/cm
VERNIER - + + + * + * > * * CALIBRATED
SMOOTHING + - - + = , NORMAL (optimized)
SCANNING . = + + ® + + + ® т ФФ *# INTERNAL
DE NSITY в vs + ® +» + + + 5 + о & + + + + =» cv
TIME SCALE MAGNIFIER © * * * * * * * X10
DELAY + « « + + + + ++ +» 0 as required
TIME SCALE + +» + + + «= = «+ = 1 usec/cm
VERNIER e =» a ао в т + ео в . вое ss = CAL
Model 1123A
Appendix I
Table 2. Test Equipment
RECOMMENDED INSTRUMENT
REQUIRED CHARACTERISTICS
TYPE MODEL
Pulse
Generator HP 213B Risetime less than 100 ps
Sampling
Oscilloscope HP 1425A/1410A 1 GHz Bandwidth
50-ohm Tee HP 10221A 1 GHz Bandwidth
50-ohm Load GR 874-W50 1 GHz Bandwidth
MODE STABILITY . adjustfor stable triggering
TRIGGERING . . . . . «+. « «+. . NORMAL
TRIGGERING SLOPE . . . . . . .. required
c. Connect 50-ohm load to 50-ohm tee.
d. Connect loaded 50-ohm tee to pulse generator
OUTPUT.
e. Connect Model 10217A to oscilloscope CHAN-
NEL A probe, and insert into 50-ohm tee.
f. Adjust VERTICAL POSITION, pulse generator
DELAY, and oscilloscope DELAY to observe a 10-cm
pulse.
g. Change the system sensitivity to 10 mV/cm,
and adjust VERTICAL POSITION to observe top of
pulse on CRT. Sag shall be less than 1 cm.
13. REPLACEABLE PARTS.
14. There is only one replaceable part in the Model
10217A; probe pin, HP Part No. 5020-0457. Contact
the nearest HP Sales/Service Office for replacements.
If it is determined that the blocking capacitor is faulty,
it must be replaced in its entirety.
02632-1
Model 1123A
Appendix I
MODEL 10228A BLOCKING CAPACITOR
1. DESCRIPTION.
2. The HP Model 10228A Blocking Capacitor is a
signal probing accessory (see Figure 1). The Model
10228A is used to isolate an instrument from dc po-
tentials present in the test circuit. Specifications
for the Model 10228A are listed in Table 1.
Table 1. Specifications
CAPACITANCE: 0. 18uF
MAXIMUM INPUT VOLTAGE:
when used with divider tip).
RISETIME : (Driven from 259 source) < 4.5 nsec.
SHUNT CAPACITANCE: Less than 25 pF.
+50V dc (+200V
3. CONNECTIONS.
4. The Model 10228A is connected to the probe by
sliding the probe into the body portion of the blocking
capacitor.
5. USE WITH OTHER ACCESSORIES.
6. The Model 10228A may be used in conjunction
with the probe as described above or it may be used
with the Model 10214A 10:1 Divider, the Model 10215A
100:1 Divider, and the Model 10229A Hook Tip.
7. CIRCUITS.
8. A schematic diagram of the Model 10228A is
shown in Figure 2. The blocking capacitor (C1) is a
0.18uF low-incuctance capacitor which is used to
keep de voltages in the circuit under test from reach-
ing the Vertical Amplifier. It is capable of blocking
+50 volts dc from ground. Inductor L1 is provided to
dampen the lead inductance. Capacitor C2 represents
the stray circuit capacitance within the blocking Ca-
pacitor Assembly.
9. MAINTENANCE.
10. The only maintenance recommended is to run
a performance checkifoperation is improper. There
are no adjustments or replaceable parts (except for
the probe pin) for the Model 102284.
11. PERFORMANCE CHECK.
12. The following procedure may be used as an in-
coming quality assurance check, or if the Blocking
Capacitor is not functioning properly. Test equipment
required for the procedure is listed in Table 2.
a. Set Pulse Generator controls as follows:
TRIGGER - + + + = + + = «+ tv tev uv POS
OUTPUT - + + + + + + + 2 + a sv so « + POS
SENSITIVITY + + + + "+ For triggered output
02632-1
Figure 1. Model 10228A
b. Set Sampling Oscilloscope controls as follows:
CHANNEL SELECTOR - + . . . CHANNEL À
MILLIVOLTS/CM - ++ + + +10 4006 10
SMOOTHING «+ + + e +. + + + + + + + NORMAL
POLARITY + + - . . + + + + + + + + + + = +UP
VERNIER + + + + + + +0 = For 10 cm display
TIME/CM +++ + + «+ vo vv oo 10 nsec
MAGNIFIER + + + + к ee. oe er oc o. X1
SCANNING + + + + + + + + + + + + = NORMAL
SYNC PULSE . - + . . +. +. + + + ao ao ON
TRIGGER - + + + + + + + + + « + FREE RUN
c. Make connections as shown in Figure 3.
d. Adjust Channel À POSITION control to observe
a 10 cm display.
e. Overshoot should be less than 5%.
f. Switch MAGNIFIER to X10.
в. Risetime from baseline to flat portion of pulse
top should be less than 4.5 nsec.
13. REPLACEABLE PARTS.
14. There is only one replaceable part for the Model
10228A, which is the probe pin, HP Part No. 5020-0457.
For replacements, contact the nearest HP Sales /Service
Office, listed at the rear of this Operating Note.
Table 2. Test Equipment
INSTRUMENT CHARACTERISTICS
TYPE MODEL
Pulse Gen- HP 213B 100 psec risetime
erator
Sampling HP 140A 1GHz Bandwidth
Oscilloscope w/1410A,
1424A
Test HP 180A 50 MHz Bandwidth
Oscilloscope w/1801A,
1821A
IA-7
Model 1123A
Appendix I
MODEL 10228A |
BLOCKING CAPACITOR |
RI Cl LI
5| Oel8UF BEAD
< — jm < © +— PROBE
|
1.02 |
TT 25 IOOK T
|
102284A-A-]
Figure 2. Schematic Diagram
«-1424A
TRIGGER
oN 410A ,-213B
° | PULSE OUT
| O oO 9
a С N TO BNC
A ll
140 N | 3" BNC
3 BNC CABLE
CABLE
BNC TO N
CHANNEL A N TO GR
PROBE 10 DB ATTEN
<
50 TEE
INSERT 50 0 LOAD
10228A
HERE
I0228BA-A-2
Figure 3. Test Set-up
02632-1
IA-8
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