HP 10811a, 10811b schematic

Model 10811A/B

Errata

Title & Document Type: 10811A/B Quartz Crystal Oscillator Operating &

Service Manual
Manual Part Number: 10811-90002
Serial Prefixes: 2028
Revision Date: August 1980

HP References in this Manual

This manual may contain references to HP or Hewlett-Packard. Please note that Hewlett-Packard's former test and measurement, semiconductor products and chemical analysis businesses are now part of Agilent Technologies.

Changes to this Manual

No changes have been made to this manual, with the exception of correcting the odd
spelling and grammatical errors. In some places original photographs may be replaced
or augmented with modern digital photographs. (it’s weird looking at an old BW HP
manual and seeing a color photograph… still gets me)
All pages are scan at 600 DPI and in some cases (schematics) scaled down to fit
8½x11 page. If you wish to print on 11x17 or larger just print the page and scale to fit.

About this Manual

This manual is reproduced from scans of an original document, which is then converted
using my own custom designed OCR software, and then edited in Microsoft

®

Word 2003.

This means that what you see here is not a scan of a scan/copy with text overlays.
OCR errors may exist and as such the user of this document should take care and use
common sense when referencing this documentation.

Copyright Notice

This documentation is © Copyright 1980 Hewlett Packard and © Copyright 2006, Jack Hudler, [e-mail].

Permission to use and redistribute this documentation for non-commercial and internal
corporate purposes is hereby granted, free of charge.
Any redistribution of this documentation or its derivates must include this copyright
notice.

You may not sell this documentation or its derivations without written consent.
You may modify this documentation as necessary, but you may not sell derivative works
based on it.
You may include this documentation with the equipment/hardware on which it is used
for the purposes of selling the equipment/hardware. If you advertise that a copy of this
documentation is included in the sale, you must state that is for “Free”.

Meaning if you want to gratuitously toss in a copy of the manual on an eBay sale, it’s ok
with me as long as you state it’s for free. No you can’t sell a digital archive of manuals
and say it includes a free copy of this documentation. You must give it away with
equipment.
I think you get the spirit of the copyright; it takes a lot of hours to scan and replicate a
manual. I just want this used in the spirit in which is it given.
Agilent if you have questions or wish to include this in your archive, please email me.

Model 10811A/B

Page Intentionally Left Blank

Model 10811A/B

Model 10811A/B

10811A/B

QUARTZ CRYSTAL OSCILLATOR

OPERATING AND SERVICE MANUAL

SERIAL PREFIX: 2028

This manual applies to Hewlett-Packard Model 10811 A/B Oscillators with serial prefix number 2028.

Also covers oscillators with HP Part Numbers 10811­60101 and 10811-60105.

OTHER SERIAL PREFIXES

For serial prefixes above 2028, a "Manual Change" sheet is included with this manual.

First Edition - August 1980

©Copyright 1980

by

HEWLETT-PACKARD COMPANY

5301 Stevens Creek Blvd.

Santa Clara, CA 95050

All Rights Reserved

MANUAL PART NUMBER 10811-90002 Microfiche Part Number 10811-90003

Model 10811A/B

TABLE OF CONTENTS

I. GENERAL INFORMATION ..................................................................................2

1-1. INTRODUCTION....................................................................................................2

1-4. SPECIFICATIONS ................................................................................................. 2

1-6. SAFETY CONSIDERATIONS................................................................................2

1-8. INSTRUMENTS COVERED BY THIS MANUAL...................................................2

1-13. DESCRIPTION.......................................................................................................4

1-19. HP Part Number 10811-60101 and 10811-60105 ..........................................4

1-22. RECOMMENDED TEST EQUIPMENT .................................................................4

II. INSTALLATION..................................................................................................6

2-1. INTRODUCTION....................................................................................................6

2-3. INITIAL INSPECTION............................................................................................6

2-5. PREPARATION FOR USE .................................................................................... 6

2-6. Power Requirements.......................................................................................6

2-10. Single Source Regulated Power Supply .........................................................7

2-12. ELECTRONIC FREQUENCY CONTROL (EFC)...................................................7

2-16. 10 MHz FREQUENCY OUTPUT SIGNAL ......................................................7

2-18. OVEN MONITOR OUTPUT...................................................................................8

2-20. MATING CONNECTORS AND MOUNTING ......................................................... 8

2-23. INSTALLATION INSTRUCTIONS...................................................................9

2-25. INSTALLATION INSTRUCTIONS (HP INSTRUMENT) ...................................... 10

2-28. OPERATING ENVIRONMENT ............................................................................10

2-34. STORAGE AND SHIPMENT ............................................................................... 11

2-35. Environment ..................................................................................................11

2-37. PACKAGING........................................................................................................ 11

2-38. Original Packaging ........................................................................................11

2-40. Other Packaging............................................................................................11

III. OPERATION ....................................................................................................12

3-1. INTRODUCTION..................................................................................................12

3-3. BASIC POWER-UP DESCRIPTION.................................................................... 12

3-7. FREQUENCY ADJUSTMENT .............................................................................12

3-9. FREQUENCY ADJUSTMENT PROCEDURE ..................................................... 12

3-10. ACCURACY VS ADJUSTMENT INTERVAL.......................................................13

IV. OPERATIONAL VERIFICATION ........................................................................16

4-1. INTRODUCTION..................................................................................................16

4-3. OPERATIONAL VERIFICATION ......................................................................... 16

4-5. EQUIPMENT REQUIRED....................................................................................16

4-7. TEST RECORD ...................................................................................................16

4-13. OPTIONAL CONTROLLERS AND COUNTERS................................................. 21

4-14. Optional Controllers....................................................................................... 21

4-16. Optional Counters..........................................................................................22

V. ADJUSTMENTS ...............................................................................................25

5-1. INTRODUCTION..................................................................................................25

5-3. EQUIPMENT REQUIRED....................................................................................25

5-5. FACTORY SELECTED COMPONENTS.............................................................25

5-7. ADJUSTMENT LOCATION .................................................................................25

5-9. SAFETY CONSIDERATIONS..............................................................................25

5-11. OSCILLATOR FREQUENCY ADJUSTMENT .....................................................25

5-13. Offset Calculation: .........................................................................................26

5-14. OUTPUT AMPLITUDE ADJUSTMENT ...............................................................27

Model 10811A/B

VI. REPLACEABLE PARTS.................................................................................... 29

6-1. INTRODUCTION..................................................................................................29

6-3. ORDERING INFORMATION ...............................................................................29

6-5. HP PART NUMBER ORGANIZATION ................................................................29

6-7. Component Parts and Materials ..........................................................................30

6-10. GENERAL USAGE PARTS .................................................................................31

6-12. Specific Instrument Parts ..................................................................................... 31

6-14. Factory Selected Parts......................................................................................... 31

6-20. REPLACEABLE PARTS LIST LAYOUT..............................................................31

VII. MANUAL CHANGES........................................................................................ 37

7-1. INTRODUCTION..................................................................................................37

7-3. MANUAL CHANGES ...........................................................................................37

7-5. NEWER INSTRUMENTS.....................................................................................37

VIII. SERVICE.................................................................................................... 39

8-1. INTRODUCTION..................................................................................................39

8-3. SCHEMATIC DIAGRAM SYMBOLS AND REFERENCE DESIGNATORS ........ 39

8-5. REFERENCE DESIGNATORS............................................................................39

8-6. Theory of Operation.......................................................................................39

8-8. OVERALL BLOCK DIAGRAM THEORY .............................................................39

8-13. MAIN OSCILLATOR THEORY OF OPERATION................................................42

8-18. ELECTRONIC FREQUENCY CONTROL (EFC).................................................43

8-20. AUTOMATIC GAIN CONTROL (AGC) ................................................................ 44

8-23. RF OUTPUT IMPEDANCE MATCHING AND OUTPUT BUFFER......................45

8-25. VOLT AGE REFERENCES (5.7V AND 6.4V) .....................................................45

8-27. OVEN HEATER AND CONTROLLER THEORY................................................. 46

8-35. PRECISION VOLTAGE REFERENCE................................................................47

8-37. OVEN CONTROLLER TURN-ON CURRENT LIMITING .................................... 47

8-39. HEATER TRANSISTOR BALANCE ....................................................................48

8-41. REPAIR AND TROUBLESHOOTING.................................................................. 49

8-42. Inspection ......................................................................................................49

8-44. REPAIR................................................................................................................49

8-45. Printed Circuit Component Replacement......................................................49

8-47. Replacing Integrated Circuits ........................................................................49

8-50. TROUBLESHOOTING.........................................................................................50

8-57. DISASSEMBLY FOR TROUBLESHOOTING AND REPAIR...............................51

8-61. SPECIAL TEST CONNECTOR FOR 10811A ..................................................... 52

8-65. SPECIAL CABLE FOR THE 10811 B.................................................................. 53

8-67. SPECIAL PARTS REPLACEMENT CONSIDERATIONS ................................... 53

8-69. OVEN CONTROLLER TROUBLESHOOTING....................................................55

8-70. General..........................................................................................................55

8-74. Normal Operation ..........................................................................................56

8-76. TROUBLESHOOTING.........................................................................................56

8-80. Troubleshooting Cautions..............................................................................56

8-82. Flex Damage .................................................................................................56

8-84. OSCILLATOR TROUBLESHOOTING.................................................................58

8-86. NORMAL OPERATION .......................................................................................58

8-88. OSCILLATOR TROUBLESHOOTING TECHNIQUES ........................................ 58

8-92. TROUBLESHOOTING INFORMATION...............................................................59

Model 10811A/B

LIST OF TABLES

Table 1-1. Specifications Table .............................................................................................................. 3

Table 1-2. Recommended Test Equipment ...........................................................................................5

Table 2-1. Input Voltages/Voltage Coefficients ...................................................................................... 6

Table 3-1. Accuracy vs Adjustment......................................................................................................14

Table 4-1. Operational Verification Descriptions..................................................................................17

Table 4-2. Operation Verification Procedure........................................................................................18

Table 4-3. 5316A Program Codes........................................................................................................22

Table 4-4. Operational Verification Record ..........................................................................................24

Table 6-1. Replaceable Parts ...............................................................................................................32

Table 6-1. Replaceable Parts (Continued)...........................................................................................34

Table 6-2. Manufacturers Code List ..................................................................................................... 35

Table 8-1. Temperature Set Resistor List.............................................................................................54

Table 8-2. Oven Controller Troubleshooting Tree................................................................................57

Table 8-3. Oven Circuit Voltages·.........................................................................................................61

Table 8-4. Oscillator Section Normal Voltages (see Notes 1, 2, 3)...................................................... 61

LIST OF FIGURES

Figure 1-1. 10811A and 108118 Oscillators...........................................................................................1

Figure 2-1. Single Source Regulated Power Supply..............................................................................7

Figure 2-3. 10811A Supply and Output Connections............................................................................ 8

Figure 2-4. 10811B Supply and Output Connections............................................................................9

Figure 2-5. Mechanical Mounting Dimensions.....................................................................................10

Figure 3-1. Oscillator Adjustment Set-Up............................................................................................. 13

Figure 4-1. BASIC Program..................................................................................................................21

Figure 4-2. HPL Program......................................................................................................................21

Figure 5-1. Oscillator Adjustment Setup ..............................................................................................26

Figure 5-2. 10811A Amplitude Adjustment Set-up............................................................................... 27

Figure 5-3. 108118 Amplitude Adj Set-up ............................................................................................ 28

Figure 8-1. Schematic Diagram Notes................................................................................................. 40

Figure 8-2. 10811A/B Overall Block Diagram.......................................................................................41

Figure 8-3A. Basic Colpitts- Type Oscillator.........................................................................................42

Figure 8-3B. Main Oscillator Schematic Design...................................................................................42

Figure 8-4. Mode Suppression............................................................................................................. 43

Figure 8-5. Frequency Tuning Circuit...................................................................................................43

Figure 8-6. EFC ....................................................................................................................................44

Figure 8-7. Automatic Gain Control (AGC)...........................................................................................44

Figure 8-8. Output Amplifiers ...............................................................................................................45

Figure 8-9. Voltage References............................................................................................................46

Figure 8-10. Oven Control Circuits....................................................................................................... 47

Figure 8-11. Turn-on Current Limit Circuit............................................................................................48

Figure 8-12. Heater Transistor Balance Circuit. ................................................................................... 48

Figure 8-13. 10811A/B Special Test Connector................................................................................... 52

Figure 8-14. Oven Controller Block Diagram....................................................................................... 55

Figure 8-15. Oven Controller Schematic Diagram............................................................................... 64

Model 10811A/B

PREFACE

This manual is designed to present the information required by the user to effectively operate and maintain the 10811A/B Quartz Crystal Oscillator.

In limiting the depth of coverage of this manual, a certain amount of previous knowledge on the part of the
reader must be assumed. A variety of additional related documentation is available. These materials
address the specific areas of interest, and should be used whenever necessary to supplement this
manual. Users unfamiliar with precision time keeping and frequency standards, for example, may wish to
refer to the 10811A/B Documentation Map for further information.

The following references can provide additional information about the theory and use of precision frequency sources and quartz oscillators.

1. Application Note 52-1 Hewlett-Packard Fundamentals of Time and Frequency Standards.

2. Application Note 52-2 Hewlett-Packard Time Keeping and Frequency Calibration.

3. Application Note 200-2 Hewlett-Packard Fundamentals of Quartz Oscillators.

U.S. National Bureau of Standards, Monograph 140, Time and Frequency Theory and

4.

Fundamentals available from:

Superintendent of Documents
U. S. Government Printing Office
Washington

5. In 1990 the NIST replaced the Monograph 140 document with this interim collection of

documents

The 10811A/B Quartz Crystal Oscillator has two manuals available. The Operating Instruction

Manual is supplied with the oscillator and is intended for the user that desires only operating
information. The Operating and Service Manual is a complete document containing both
operating and servicing information. The Operating and Service Manual (This manual) is not
supplied with the oscillator, but is available by ordering HP Part No. 10811-90002 (of course

they won’t sell you one). The Operating Instructions Manual is a duplication of Sections I, II,

and III of the Operating and Service Manual. Any references in the Operating Instructions
Manual to Sections IV, V, VI, VII, and VIII should be considered references to the Operating
and Service Manual.

, D.C. 20402

NIST/TN1-339 or visit time NIST Time and Frequency Publication Database.

10811A/B Documentation Map

Model 10811A/B

Figure 1-1. 10811A and 108118 Oscillators

1

Model 10811A/B

SECTION I

GENERAL INFORMATION

1-1. INTRODUCTION

1-2. This manual provides information pertaining to the installation, operation, testing, adjustment, and

maintenance of the HP Model 10811A/B Quartz Crystal Oscillator.
and 10811B.

1-3. This manual is divided into eight sections, each covering a particular topic. The topics by section

number are shown below. Sections I, II, III appear in the Operating Instructions Manual. Sections
I through VIII appear in the Operating and Service Manual.

Section Topic
I General Information
II Installation
III Operation
IV Performance Tests
V Adjustments
VI Replaceable Parts
VII Manual Changes
VIII Service

Figure 1-1 shows the 10811A

1-4. SPECIFICATIONS

1-5. Specifications are listed in Table 1-1. These specifications are the performance standards or

limits against which the oscillator may be tested.

1-6. SAFETY CONSIDERATIONS

1-7. The Model 10811A/B Component Oscillator is a Safety Class III product and must be powered

from a source which is electrically isolated from the mains (line circuits). Safety information
pertinent to the operation and servicing of this instrument is included in the appropriate sections
of this manual.

1-8. INSTRUMENTS COVERED BY THIS MANUAL

1-9. Attached to the instrument is a serial number plate. The serial number is in the form 0000A00000.

It is in two parts; the first four digits and the letter are the serial prefix and the last five are the
suffix. The prefix is the same for all identical instruments; it changes only when a change is made
to the instrument. The suffix, however, is assigned sequentially and is different for each
instrument. The contents of this manual apply to instruments with the serial number prefix(es)
listed under Serial Prefix on the title page.

1-10. An instrument manufactured after the printing of this manual may have a serial number prefix that

is not listed on the title page. This unlisted serial number prefix indicates the instrument is
different than those described in this manual. The manual for this new instrument is accompanied
by a yellow Manual Changes supplement. This supplement contains "change information" that
explains how to adapt the manual to the newer instrument.

1-11. In addition to change information, the supplement may contain information for correcting errors in

the manual. To keep this manual as current and accurate as possible, Hewlett Packard
recommends that you periodically request the latest Manual Changes supplement. The
supplement for this manual is identified with the manual print date and part number, both of which
appear on the manual title page. Complimentary copies of the supplement are available from
Hewlett-Packard.

2

Table 1-1. Specifications Table

Model 10811A/B

Frequency Stability

of Terms)

Long Term (Aging Rate): <5 X 10
after 24-hour warm-up. See Note 1.

-7

<1 X 10
Short Term: Refer to tables and figures
above.

/year for continuous operation.

: (See Definition

-10

/day

Environmental Sensitivity:

Temperature: <4.5 X 10-9 over a -55°C to

71°C range. <2.5 X 10­71 °c range.

Operating:-55°C to +71 °C.
Storage: -55°C to X85°C.

Load: <5 X 10
ohm load. <5 X 10
1KΩ load.

-10

Power Supplies:

Oscillator Supply: <2 X 10

change. <100μv ripple and noise required.
Oven Supply: <1 X 10­<30 mv ripple and noise required.
Gravitational Field: <4 X 10
shift (turn-over).
Magnetic Field: <-90 dBc sidebands due
to 0.1 millitesla (1 Gauss) rms at 100 Hz.
Humidity (typical): 1 X 10
40°C.
Shock (survival): 30g, 11ms, ½ sinewave.
Altitude (typical): 2 X 10-9 for 0 to 50,000 ft.

Warmup

10 min. after turn-on within 5 X 10-9 of final
value, at 25°C and 20 Vdc. See Notes 1 &

2.

9

over a O°C to

for a ±10% change in 50

-10

for a ±25% change in

-10

for 1%

10

for 10% change.

-9

for 2g static

-9

for 95% RH at

Adjustment

Coarse Frequency Range: >±1 X 10-6 (±

10 Hz) with 18 turn control.
Elec. Frequency Control (EFC): ≥1 X 10
(1 Hz) total, control range -5 Vdc to +5 Vdc.

Output

Frequency: 10 MHz
Voltage: 0.55 ± 0.05 V rms into 50 ohm.

1V rms ±20%, into 1K ohm.
Harmonic Distortion: Down more than 25
dB from output.
Spurious Phase Modulation: Down more
than 100 dB from output (discrete
sidebands 10 Hz to 25 kHz).

Power Requirements

Oscillator Circuit: 11.0 to 13.5 Vdc. 30

mA typical. 40 mA max.
Oven Circuit: 20 to 30 V dc; turn on load
is 42 ohm minimum. Steady-state power
drops to a typical value of 2.0W at 25°C in
still air with 20 Vdc applied.

Connectors

10811A: Mates with CINCH 250-15-30-210
(HP 1251-0160) or equivalent (not
supplied).
10811B: Solder terminals and 5MB Snap­on connectors. Mates with Cablewave
Systems, Inc. #700156 or equivalent (not
supplied).

Accessories Available:

Service Manual: HP 10811-90002: (not

supplied). This Manual.

Size:
72 mm X 52 mm X 62 mm, (see Figure

1). (2-13/16" X 2-1/32" X 2-7/16", 14 cu.

-7

in.).

Weight: 0.31 kg (11 oz.)
Definition of Terms

Long-Term Frequency Stability is de-

fined as the absolute value (magnitude)
of the fractional frequency change with
time. An observation time sufficiently
long to reduce the effects of random
noise to an insignificant value is implied.
Frequency changes due to
environmental effects must be
considered separately.

Time Domain Stability

deviation) is defined as the two-sample
deviation of fractional frequency
fluctuations due to random noise in the
oscillator. The measurement bandwidth
is 100 kHz.
Frequency Domain Stability is defined
as the single sideband phase noise-to­signal ratio per Hertz of bandwidth (a
power spectral density). This ratio is
analogous to a spectrum analyzer
display of the carrier versus either
phase modulation sideband.
See "NBS-Monograph 140" for
measurement details.

σ

(τ) (Allan

γ

Notes:

1. For oscillator off-time less than 24 hours.

2. Final value is defined as frequency 24 hours after turn-on.

*Specifications describe the instrument's warranted performance. Supplemental characteristics are
intended to provide information useful in applying the instrument by giving TYPICAL or NOMINAL, but
non warranted performance parameters. Definition of terms is provided at the end of the specification
section.

3

Model 10811A/B

1-12. For information concerning a serial prefix that is not listed on the title page or in the Manual

Changes supplement, contact your nearest Hewlett-Packard office.

1-13. DESCRIPTION

1-14. The HP Model 10811A/B Quartz Crystal Oscillator is an extremely stable, compact, low power

source of 10 MHz. The 10811 A/B has a very fast warm-up time, exhibits excellent temperature
characteristics and has low phase noise and power consumption.

-6

1-15. The 10811A/B has the ability to be adjusted over a range of 20 Hz (2 X 10

sensitive enough to allow adjustment to better than 0.1 Hz (1 X 10
controlled electronically over a 1 Hz (1 X 10

-7

) range with an externally applied voltage to the EFC.

-8

). The frequency can also be

1-16 The 10811A/B is field repairable, thus allowing the oscillator to be quickly placed back into

service.

1-17. The 10811A/B requires two external power supplies. The power supply requirements are listed in

Section II.

1-18. The 10811A and 10811B are identical, except for the connections. The 10811A uses a standard

15 pin printed circuit connector. The 10811B uses filtered-feedthrough terminals for power and
oven monitor, and 5MB subminiature rf snap-on connections for the 10 MHz output and EFC.

1-19. HP Part Number 10811-60101 and 10811-60105

1-20. The 10811-60101 is a 10811A in which phase noise, magnetic field and 2g turn-over are not

specified. The 10811-60101 is physically identical to the 10811A.

-9

1-21. The 10811-60105 is a 10811-60101 with specifications of <1.5 X 10

short-term stability for a 1-second averaging time. The 10811-60105 is physically identical to the
10811A.

for aging and <1 X 10

), yet the control is

-11

for

1-22. RECOMMENDED TEST EQUIPMENT

1-23. The test equipment required to maintain the Model 10811A/B is listed in Table 1-2. Other

equipment may be substituted if it meets or exceeds the critical specifications listed in the table.

4

Model 10811A/B

1

0

/day

(Op

Table 1-2. Recommended Test Equipment

INSTRUMENT REQUIRED CHARACTERISTICS MODEL NO.

1. Frequency Analyzer* Phase noise measurement at 10 MHz 5390 5390A* cannot measure 10811 specs above 10 Hz

2. Frequency Counter** 10 MHz range, HP-IB programmable, 2 ns 5345A** resolution

3. Computing Controller** HP-IB compatible 9835A or 9825A **

4. Frequency Reference Short term stability ≤5x10
Long term stability <5x10

-12

/second 5065A, 5061A

-

tion 004),

or 105A/B***

5. Sampling Voltmeter ±3% accuracy at 10 MHz 3406A

6. General Purpose Bandwidth ≥ 10 MHz 1740A Oscilloscope

7. Frequency Doubler Operates at 10 MHz 10515A

8. Mixer Amplifier** 10 MHz Mixer/50 dB gain K79-59992A**

9. Spectrum Analyzer 10 MHz/70 dB range 8552B/8553B

10. Power Supply 480 mA @ 20V (2 required) 6215A

11. DC Voltmeter Any HP type digital or analog

12. Torque Screwdriver 2-30 inch-lb. (0.2 to 3.4 newton meters) 8730-0012

13. Feedthru Termination 50 ohms 11046B

14. BNC to Miniature Use for 10811B Only 05060-6116 Coax Adapter

15. Test Connector For testing 1 0811A See para. 8-61 *Not needed if items 2, 3, 4 are available. **Not needed if HP 5390A Frequency Stability Analyzer is available. ***If a 105A/B is used, its performance must be verified.

5

Model 10811A/B

SECTION II

INSTALLATION

2-1. INTRODUCTION

2-2. This section contains installation instructions for the 10811 A/B Quartz Crystal Oscillator. Also

included is information about initial inspection and damage claims, preparation for using the
oscillator, and packaging, storage and shipment.

2-3. INITIAL INSPECTION

2-4. Inspect the shipping container for damage. If the shipping container or cushioning material is

damaged, it should be kept until the contents of the shipment have been checked for
completeness and the oscillator has been checked mechanically and electrically. The contents of
the shipment should be as shown in
are given in Section IV. If the contents are incomplete or if there is mechanical damage or defect,
or if the oscillator does not pass the Performance Tests, notify the nearest Hewlett-Packard office.
If the shipping container is damaged, or the cushioning material shows signs of stress, notify the
carrier as well as the Hewlett-Packard office. Keep the shipping materials for the carrier's
inspection. The HP office will arrange for repair or replacement at HP option without waiting for
the claim settlement.

Figure 1-1; procedures for checking electrical performance

2-5. PREPARATION FOR USE

2-6. Power Requirements

2-7. The 10811A/B requires two power sources. One supplies power to the oscillator circuitry and the

other supplies power to the oven heaters.
effect of a change in these voltages on the output frequency.

Table 2-1. Input Voltages/Voltage Coefficients

Input Circuit

Oscillator/

Amplifier

Oven Controller

2-8. Both the 10811A and 10811 B have separate ground return paths for each section (oscillator and

oven circuits). Both grounds may be tied together or operated at any reasonable difference in
potential. Note the oscillator supply ground and 10 MHz output have a common ground return.
The outer housing for both oscillators is tied to this ground point. The 10811 B filtered
feedthrough grounds are also tied to the outer housing.

2-9. In order to maintain the high spectral purity of the 10811A/B output signal, the supply voltages

must be relatively clean. The supply ripple and noise on the 12-volt line (oscillator supply) must
be kept below 100 µV rms and the 20-volt line (oven supply) ripple and noise must be kept below
30 mV rms with both measured in the 10 Hz to 25 kHz range. A 1% change of the 12-volt supply
(oscillator) will cause ≤2
(oven) will cause a ≤1

Required

Voltage

11.0-13.5V dc

Noise <100 µV

20-30V dc 10% <1 X 10

Power drops to steady state value (≈2W)

within 10 min. at 25°C with 20V dc applied.

X 10

-10

X 10

Required Current/Power

30 mA typical, 40 mA max.

Turn on load is 43 ohms minimum

-10

change in output frequency. A 10% change in the 20-volt line

change in output frequency.

Table 2-1 lists the required supply voltages and the

Voltage Coefficients

Voltage

Change

1% <2 X 10

Frequency

Change

-10

-10

6

Model 10811A/B

2-10. Single Source Regulated Power Supply

2-11. A single source of +20 to +30V dc with 10% regulation may be used to power both the oven and

oscillator amplifier circuits if a simple IC regulator is used. A suggested circuit is shown in Figure
2-1. The resistor and capacitor connected to terminals 3 and 4 of the IC minimize ripple and noise
in the regulated output.

Figure 2-1. Single Source Regulated Power Supply

2-12. ELECTRONIC FREQUENCY CONTROL (EFC)

2-13. The EFC allows the oscillator to be tuned over a 1 Hz range (1 x 10-7) by applying -5 to +5 volts

to the EFC input. As the EFC voltage goes positive the output frequency will go lower. Conversely,
as the EFC voltage goes negative, the output frequency will go higher.

2-14. Since noise on the EFC line affects the oscillator's stability (noise appears as FM on the output),

care must be taken to ensure that a relatively noise free EFC voltage source is used. The noise
level must be kept below 100 µV to maintain good stability performance.

2-15. The EFC input should be connected to oscillator circuit ground if not used. A shorting plug (1250-

0911) is supplied with 10811B for this purpose. The EFC input on the 10811A should be
grounded at the printed circuit connector by wiring pins 5 and 6 together.

2-16. 10 MHz FREQUENCY OUTPUT SIGNAL

2-17. The 10 MHz output is ac coupled from a source impedance of approximately 50 ohms. The signal

level is .55 ±.05 into a 50 ohms load or 1-volt ±20% into a 1 K ohm load.

7

Model 10811A/B

2-18. OVEN MONITOR OUTPUT

2-19. The OVEN MONITOR OUTPUT is an indicator of oven warm-up. At initial turn-on (warmup) the

oven monitor will go to approximately 1.5 volts BELOW the oven power supply voltage. After the
oven cuts back, the output will drop to approximately 3.5 volts (at 25°C). The output impedance of
this circuit is 10,000 ohms.

Figure 2-2 shows an oven monitor LED indicator circuit.

Figure 2-2. Oven Monitor LED Circuit

2-20. MATING CONNECTORS AND MOUNTING

2-21. The 10811A Oscillator requires a 15-pin printed circuit connector. The recommended connector is

the CINCH 250-15-30-210 (HP 1251-0160). The 10811A can be secured with two 6-32 screws,
1/4-inch long.
the mechanical mounting dimension for the 10811A and 10811B.

Figure 2-3 shows the power supply connection for the 10811A. Figure 2-5 shows

8

Figure 2-3. 10811A Supply and Output Connections

Model 10811A/B

2-22. The 10811 B Oscillator uses solder terminals with filtered feedthrough capacitors for power and

oven monitor outputs and 5MB subminiature rf snap-on connectors for the 10 MHz output and
EFC. The 10811 B also has one internally threaded mounting stud on the bottom cover and two
located on the top. The three studs are threaded for 4-40 screws, 1/4-inch deep. These mounting
studs may be used with vibration isolators such as the LORD #J2924-2-1 (HP Part No. 1520-

0094). However, for ease of testing and interfacing, a 6-pin Amphenol connector is attached. If
you wish to use this connector, the following parts are required to build its mate.

Description Quantity HP Part No. Amphenol Part No. Receptacle 1 1251-4297 221-1508

Pin-Female 5 1251-4734 220-883-03

Guide-Pin 2 1251-0597 221-590

If you do not wish to use the Amphenol connector, it may be easily removed. The 5MB connectors mate
to Cablewave Systems, Inc. #700156 or equivalent HP Part No. 1250-0885 (not supplied).
shows the connections for the 10811 B Oscillator.

Figure 2-4

Figure 2-4. 10811B Supply and Output Connections

2-23. INSTALLATION INSTRUCTIONS

2-24. Figure 2-5 shows the mechanical mounting dimensions of the 10811A/B Oscillators for use in

custom installation. Since all quartz oscillators are sensitive to shock, vibration, radiation fields,
and ambient temperature changes, to obtain the best performance from your 10811A/B, these
factors should be taken into consideration. To optimize performance therefore:

1. The 10811A/B should be mounted in an area that has a minimum amount of vibration or shock
accelerations. In addition, the 10811 A/B should be mounted so that the vibrational forces act
along the "minimum G sensitivity" axis shown in

2. The 10811A/B should be mounted as far as possible from transformers or fan motors that radiate electromagnetic fields.

3. The 10811A/B should be mounted away from the main system airflow in order to isolate it as much as possible from ambient temperature changes.

Figure 2-5.

9

Model 10811A/B

Figure 2-5. Mechanical Mounting Dimensions

2-25. INSTALLATION INSTRUCTIONS (HP INSTRUMENT)

2-26. The 10811 A may be installed in most Hewlett-Packard instruments that already have a 10544A

or 10544B oscillator or has provisions for it. The 10811A may be exchanged directly without any
circuit change or modification.

2-27. If the instrument does not have a 10544A oscillator installed, but is available as an option, then

the service manual for that instrument should be consulted to see if an oscillator support board
(power supplies) is required. Once the support board is installed, the 10811A can be installed in
place of the 10544A. Consult your nearest sales and service office for more details.

2-28. OPERATING ENVIRONMENT

2-29. TEMPERATURE. The 10811A/B may be operated in temperatures from -55°C to +71°C.

2-30. MAGNETIC FIELDS. Sidebands due to 0.1 milliTelsa (1 Gauss) rms at 100 Hz will be down more

than 90 dB from carrier.

-9

X 10

2-32. ALTITUDE. The frequency change will be typically 2

2-33. SHOCK. The 10811A/B can withstand a shock up to 30 Gs for 11 ms, 1/2 sine wave.

for altitudes up to 15.2 km (50,000 ft.).

10

Model 10811A/B

2-34. STORAGE AND SHIPMENT

2-35. Environment

2-36. The 10811A/B may be stored or shipped in environments with the following limits: Temperature ····························· -55°C to +85°C Altitude ······································ 15.2 Km (50,000 feet)

2-37. PACKAGING

2-38. Original Packaging

2-39. Containers and materials identical to those used in factory packaging are available through

Hewlett-Packard offices. If the instrument is being returned to Hewlett-Packard for servicing,
attach a tag indicating the type of service required; return address, model number, and full serial
number. Also, mark the container Fragile to ensure careful handling. In any correspondence, refer
to the instrument by model number and full serial number.

2-40. Other Packaging

2-41. The following general instructions should be used for repacking with commercially available

materials.

1. Wrap instrument in heavy paper or plastic. (If shipping to Hewlett
center, attach tag indicating type of service required; return address, model number, and full
serial number.)

2. Use strong shipping container. A double-wall carton made of 350-pound test material is adequate.

3. Use a layer of shock-absorbing material 70 to 100 mm (3 to 4 inch) thick around all sides of the instrument to provide firm cushioning and prevent movement inside container. Protect control panel with cardboard.

4. Seal shipping container securely.

5. Mark shipping container FRAGILE to insure careful handling.

6. In any correspondence, refer to instrument by model number and full serial number.

-Packard office or service

11

Model 10811A/B

SECTION III

OPERATION

3-1. INTRODUCTION

3-2. This section contains operating information including operating characteristics and operating procedure.

3-3. BASIC POWER-UP DESCRIPTION

3-4. The following paragraph is a basic description of the actions occurring when power is applied to

the oscillator. This description assumes the oscillator is at room temperature (25°C).

3-5. When power is applied to the oscillator, 10 MHz will appear at the output. The oven controller

circuit will go into its full warm-up mode. In this mode the maximum heating power is applied to
the oven mass. The oven mass is a metal casting surrounding the oscillator circuits and crystal.
The OVEN MONITOR output will be approximately 1.5 volts below the oven power supply voltage.
In about 10 minutes, the oven will have heated to the proper temperature. The oven controller will
begin to regulate at this temperature, and the OVEN MONITOR will drop to approximately 3.5
volts. It is normal for the oven current to drop momentarily to a low value when the oven
temperature first reaches maximum. This lasts less than second and is a typical circuit action.

3-6. After the first 10 minutes have passed, the oscillator may be initially adjusted using the following

procedure. The oscillator should be readjusted after 24 hours for maximum accuracy. Periodic
adjustment schedule can be determined by the procedure described in

paragraph 3-10.

3-7. FREQUENCY ADJUSTMENT

3-8. The frequency adjustment is the only periodic adjustment required. This may be initially adjusted

after 10 minutes of warm-up and then readjusted after 24 hours.

3-9. FREQUENCY ADJUSTMENT PROCEDURE

a. Connect reference frequency standard (multiple or submultiple of 10 MHz) to the EXTERNAL

SYNC INPUT of the oscilloscope.
b. Connect oscillator output (10811A/B) to Channel A. Set the sweep speed to .1 μs/div.
c. Set the oscilloscope to EXTERNAL TRIGGER and adjust the oscilloscope so that its sweep is

synchronized to the reference frequency. The pattern will appear to move.
d. Using an insulated tuning tool, adjust oscillator frequency adjustment (FREQ ADJUST on the

10811AIB) for minimum sideways movement of the oscilloscope pattern.
e. By timing the sideways movement (divisions per second on the oscilloscope), the approximate

offset can be determined based on the oscilloscope sweep speed shown in

Figure 3-1

12

Model 10811A/B

f. For example, if the trace moves 1 division in 10 seconds and the sweep speed is 0.01 μs/div., the

oscillator's frequency is 1 x 10
from the calibration,

Table 3-1. The calculation can also be made by the following formula:

-9

different from that of the reference frequency, as can be seen

where Δf/f = offset of the oscillator with respect to the reference standard Δt = the movement of the

oscilloscope pattern (1 div. X .01 μs/div.) = .01, μs t = time required for Δt to occur.

Figure 3-1. Oscillator Adjustment Set-Up

3-10. ACCURACY VS ADJUSTMENT INTERVAL

3-11. Table 3-1 shows the required adjustment interval to maintain a required accuracy. If the aging

rate is known to be 3 x 10
(The specification for aging is <5 X10
can be expected to gradually decrease, and typically will reach 1 X 10

Example:

Known aging rate···········································3 X 10
Maximum allowable error ·····························5 X 10

-10

/day, then a more precise adjustment interval can be determined.

-10

/day, but aging is typically less than this.) The aging rate

-10

/day

-9

-10

/day within 1-year.

13

3-12. Find the line on

allowable error (accuracy) on the horizontal axis. Follow the maximum allowable error vertically

until it crosses the oscillator's known aging rate. Move horizontally to the left and read the

minimum calibration interval in days.

Model 10811A/B

Table 3-1 corresponding to the oscillator's aging rate. Then find the maximum

maximum allowable error
known aging rate (per day)

Example:

3-13. From

3-14. The minimum calibration interval may also be determined from the following formula:

-9

5 x 10

3 x 10

(maximum allowable error)

-10

/day (known aging rate) = 16.67 days (~17 days) 3 X 10

Table 3-1, the oscillator should be adjusted approximately every 17 days.

= calibration interval in days

-10

/day (known aging rate)

14

Table 3-1. Accuracy vs Adjustment

Model 10811A/B

Page Intentionally Left Blank

15

Model 10811A/B

SECTION IV

OPERATIONAL VERIFICATION

4-1. INTRODUCTION

4-2. The tables in this section test the instrument's performance using the specifications of Table 1-1

as the performance standards. All tests can be performed without access to the interior of the

instrument.

4-3. OPERATIONAL VERIFICATION

4-4. The Operational Verification, Table 4-2, can be performed to give a high degree of confidence

that the 10811A/B is operating properly without performing the complete performance tests. The

operational verification should be useful for incoming QA, routine maintenance, and after

instrument repair.

4-5. EQUIPMENT REQUIRED

4-6. Equipment required for the operational verification is listed in the recommended test equipment in

Section I,

given in the table may be substituted for the recommended model(s).

Table 1-2, and in Table 4-1. Any equipment that satisfies the critical specifications

4-7. TEST RECORD

4-8. Results of the Operational Verification, Table 4-2, may be tabulated on the Operational

Verification Record,

4-9. If the 10811A/B Oscillator is to be tested outside its normal installation, a special test connector

may be used for applying power to the oscillator. The connector also has a BNC connector for the

10 MHz output signal. A photo, parts list, and construction information is located in Section VIII.

The connector should be used under the following circumstances:

a. If the 10 MHz output is not easily accessible.
b. If there is a buffer amplifier between the 10811A/B output and the oscillator output jack

on the rear panel of the instrument.
c. Troubleshooting.
d. If testing of the oscillator in its normal installation causes erroneous measurements (e.g.,

fan noise, vibrations, noisy circuits, etc.). If in doubt, use the special test connector.

4-10.

Table 4-1 lists the five sections of the operational verification and their descriptions.

Table 4-4.

16

Model 10811A/B

Table 4-1. Operational Verification Descriptions

1. Amplitude (0.55 volts (±0.05 volts/50Ω, 1 volt ± 0.2 volt/1kΩ).
a. Equipment required:

BNC-to-BNC Cable
500 and 1 KΩ loads
3406A AC Voltmeter

2. Harmonic Distortion (-25 dB below 10 MHz output signal).
a. Equipment required:

141T Display Section
8553B Spectrum Analyzer - RF Section
8552B Spectrum Analyzer - IF Section
BNC-to-BNC Cable

3. Spurious Signals - Signals unrelated to the 10 MHz output signal (-100 dB below the 10 MHz
output signal).

NOTE
Due to the complexity of measuring signal 100 dB
below a reference, this procedure will verify that no
spurious signals exist greater than 65 dB below the
normal 10 MHz output signal.

4.
a. Equipment required:

141T Display Section
8553B Spectrum Analyzer - RF Section 8552B
Spectrum Analyzer - IF Section
BNC-to-BNC Cable

5. Short Term Stability (5 X 10

-12

for 1-second averaging; 1 X 10

-11

for 10811-60105).

a. Equipment required:

5065A Rubidium Vapor Frequency Standard
5061A Option 004, or 105A/B, See Table 1-2
HP Model 5390A may be used in place of the following:

10830A Mixer
5345A Electronic Frequency Counter with Option 011
9825A Calculator with 98210A and 98213A or 98214A or 98216A

98034A HP-IB Interface
10515A Doubler
6-Plug AC Power Strip 3
BNC-to-BNC Cables

6. Long Term Stability -<5 X 10

-10

over 24 hours; 1.5 X 10-9/24 hours for 10811-60105.

a. Equipment required:

HP 1740A 100 MHz Oscilloscope,
105A/B Quartz Crystal Oscillator,
5065A Rubidium Frequency Standard, or 5061A Cesium Beam Frequency Standard.
See Table 1-2.

4-11. In the following tests, the power supply voltages to the oscillator are not shown. They are

assumed to be:

Oscillator Circuits ........................................ +12V dc

Oven Circuits ............................................... +20V dc

4-12. Any supply voltages within the specified limits listed in

Table 1-1 may be used and will not affect

the operational verification. The voltages are only reference points and are used throughout this
manual.

17

Model 10811A/B

Table 4-2. Operation Verification Procedure

1. Amplitude Test

Procedure:

a. Set the 3406A Voltmeter to the l-volt range.
b. Insert the 3406A Voltmeter probe into the 1 volt jack on the front panel.
c. With the CAL button out, set the 3406A to zero by adjusting the ZERO control on the front

panel.

d. Press the CAL button and adjust the 3406A to read 1V by adjusting the CALIBRATE control

on the front panel.

e. Remove the probe from the 1-volt jack and conned to the 10811A/B output through a 50 ohm

termination.
f. Verify amplitude of 0.55 volts ±0.05 volts. Mark the test card.
g. Remove the 50Ω termination and replace with a 1 kΩ termination.
h. Verify amplitude of 1 volt ±0.2 volt.

2. Harmonic Distortion
a. Set 141T Spectrum Analyzer controls to:

TUNING STABILIZER·········································· OFF
BANDWIDTH ······················································30 kHz
SCAN WIDTH per Division ·································5 MHz/div.
INPUT ATTENUATION ·······································50 dB
VIDEO FILTER ····················································OFF
SCAN TIME ························································· 10 ms/div.
SCAN MODE ······················································INT
SCAN TRIGGER ·················································AUTO
LOG REF LEVEL ················································+10
LOG/LINEAR Switch············································10 dB LOG

b. Connect the output of the 10811A/B to the spectrum analyzer input.
c. Apply power to the oscillator and spectrum analyzer. Allow 10 minutes for oscillator to

stabilize.

d. Adjust Spectrum Analyzer FREQUENCY control so that 10 MHz signal is at left-edge of

display (center frequency, approximately 35 MHz).

e. Adjust LOG REF LEVEL vernier control (right hand knob) so that 10 MHz signal is at top of

display gratitude. Verify that all harmonics of the 10 MHz signal are more than 25 dB down.
Leave spectrum analyzer connected for next test.

3. Spurious Output Signals
a. Use the test setup as described in Test 2.

b. Set the Spectrum Analyzer controls to:

TUNING STABILIZER·········································· OFF
BANDWIDTH ·······················································1 kHz
SCAN WIDTH ······················································.05 MHz
INPUT ATTN························································ 50 dB
LOG REFERENCE ··············································+10 dBm
SCAN TIME··························································0.1 s/div.
VIDEO FILTER ····················································100 Hz
SCAN MODE ······················································INT
SCAN TRIGGER ·················································AUTO
FREQUENCY······················································· 10 MHz (0-11 MHz RANGE)

c. Adjust FREQUENCY so 10 MHz signal is at center of display. Adjust LOG REF LEVEL so

signal is at top of graticule.

d. Set TUNING STABILIZER switch "on" (up) and reset Spectrum Analyzer controls as follows:

BANDWIDTH ·······················································.03 kHz (30 Hz)
SCAN WIDTH ······················································5 kHz
SCAN TIME··························································10 s/div.

18

Model 10811A/B

Table 4-2. Operational Verification Procedure (Continued)

e. Set INTENSITY and PERSISTENCE controls for an easily readable display at the 10 s scan

time.

f. Verify that there are no repeating signals above a level 65 dB below the 10 MHz signal (i.e., no

signals between -64 dB and 0 dB). Allow the analyzer to sweep through several times to verify
that no signals repeat on successive sweeps. Signals greater than -65 dB indicate possible
spurious signals on 10811A/B output. Be sure there is no other equipment nearby that could be
radiating signals into the measurement. Be sure power supplies meet noise specifications as
described in

Table 1-1.

4. Short-Term Stability

NOTE

If the model 5390A frequency stability analyzer is available it should be used in place of the text described below. Follow instructions in the 5390A operating manual to make measurement.

a. Connect the equipment as follows:

NOTE

Arrange the instruments as shown. Keep all signal leads away from
power cords and HP-IB cable. DO NOT FORGET THE 10515A
DOUBLER ON THE 5065A OUTPUT. Connect all ac power to the same
strip so that all ground paths are as short as possible. DO NOT STACK
THE INSTRUMENTS. Use coax for all signal leads.

b. Set the 5345A address to 18:

A5 A4 A3 A2

1 (16) 0 (8) 0 (4) 1 (2) = 18
c. Allow 1-hour warmup to stabilize the test equipment and the 10811A/B.
d. Set the 5345A front panel controls as follows:

FUNCTION ·········································································· FREQ A
GATE TIME ········································································· 1 s
SAMPLE RATE ··································································· max (ccw)
GATE CONTROL INPUT (REAR PANEL) ·························· INTERNAL
A LEVEL ·············································································· PRESET
B LEVEL ·············································································· PRESET
A IMPEDANCE ··································································· 50 ohm
B IMPEDANCE ··································································· 50 ohm
A ATTENUATOR ································································ X1
B A TTENUATOR ······························································· X1

19

Model 10811A/B

Table 4-2. Operational Verification Procedure (Continued)

A COUPLING······································································· DC
B COUPLING······································································· DC
A SLOPE··············································································+
B SLOPE ·············································································+
CHECK/COM/SEP ······························································SEP

e. Adjust the 10811A/B to read ≈9.5 Hz (reading must be less than 10 Hz).

NOTE

The display on the 5345A should be changing only in
the .001 Hz or .0001 Hz digits. This represents
frequency deviations of parts in 10

11

and 1012,

respectively.

f. Type the program from Figure 4-1 into the 9835A calculator. (See paragraph 4-13 for use

of other controllers and counters.)

g. Press "RUN". When the program asks for the number of samples, enter "100" and press

CONTINUE.

h. Allow 2 to 3 minutes for the program to finish. Verify a short-term stability of less than 5 X

-12

.

10

NOTE
Measurement of short-term stability is somewhat difficult and exacting.
If the 10811A/B fails this test, be sure no signal sources other than the
test reference are operating near the measurement system, as these
can cause interference with the measurement. Other sources of error
are vi brat ion, nearby electrical equipment, poor shielding, or motors
that can radiate signals into the 10811A/B. The failure to connect the
HC input (to ground) can cause poor frequency stability as can a noisy
voltage being used for the EFC control. If another oscillator is available
(known to be good), verify the accuracy of the measurement system.
This could save considerable troubleshooting time.
Two other possibilities external to the oscillator are the oven and
oscillator power supplies. These must be stable in order for the circuits
to function properly. See

Table 1-1, Specifications, and paragraph 2-6

for power supply noise requirements.

5. Long-Term Stability

NOTE

The 10811A/B will typically take 24 to 48 hours to reach its specified
aging rate after storage or shipment. In some cases, if extreme
environmental conditions were encountered during storage, the
10811A/B could take up to 1-week to achieve its specified aging rate.

a. Connect reference frequency standard (multiple or submultiple of 10 MHz) to the EXTERNAL

SYNC INPUT of the oscilloscope.
b. Connect the output of the 10811A/B to CHANNEL A INPUT. Adjust sweep speed to 0.1 μs/div.
c. Set oscilloscope to EXTERNAL TRIGGER and adjust it so that its sweep is synchronized with

the reference frequency. The oscilloscope pattern will probably be moving.
d. Carefully adjust oscillator frequency control so that pattern on oscilloscope stops. Use a higher

sweep speed on oscilloscope for better resolution.
e. When the oscillator is adjusted as close as possible to frequency, measure the frequency as

described in

paragraph 5-13.

f. Allow the oscillator to remain undisturbed for 48 hours, then again measure the frequency. The

difference between the frequency measured in step e and that measured in this step is the aging

rate per 48 hours and should be less than 1 X 10

hours so that the frequency offset measured will be well in excess of the system resolution. In

many cases the daily aging rate of <5 X 10

-10

-9

. The measurement is allowed to run for 48

per day can be verified in 24 hours.

20

Model 10811A/B

Figure 4-1. BASIC Program

4-13. OPTIONAL CONTROLLERS AND COUNTERS

4-14. Optional Controllers

4-15. Figure 4-2 lists the program for the 9825A Calculator.

Figure 4-2. HPL Program

21

Model 10811A/B

4-16. Optional Counters

4-17. Table 4-3 shows the program codes set required when using the 5316A counter. Replace line 4

(HPL) or line 40 (BASIC) with the appropriate codes. Be sure the optional counter address is set
to "18".

5316A
(gate time must be set manually to 1 s on the front panel)

Table 4-3. 5316A Program Codes

22

Model 10811A/B

Page Intentionally Left Blank

23

Model 10811A/B

Table 4-4. Operational Verification Record

24

Model 10811A/B

SECTION V

ADJUSTMENTS

5-1. INTRODUCTION

5-2. This section describes the adjustments required to maintain the 10811A/B operating
characteristics within specifications. Adjustments should be made when required, such as after a
performance test failure or when components are replaced that may affect an adjustment.

5-3. EQUIPMENT REQUIRED

5-4. The test equipment required for the adjustment procedure is listed in Table 1-2, Recommended
Test Equipment. Substitute instruments may be used if they meet the critical specifications.

5-5. FACTORY SELECTED COMPONENTS

5-6. Some of the values in the parts lists are selected during manufacturing to meet circuit
requirements. These parts are marked with an asterisk (*) in the parts list and schematic diagrams, with
average value shown.

5-7. ADJUSTMENT LOCATION

5-8. Adjustment locations are identified in this section and in the component locators in Section VIII,
Schematic Diagrams.

5-9. SAFETY CONSIDERATIONS

5-10. This section contains warnings and cautions that must be followed for your protection and to
avoid damage to the equipment.

WARNING

MAINTENANCE DESCRIBED HEREIN IS PERFORMED WITH POWER
SUPPLIED TO THE INSTRUMENT, AND PROTECTIVE COVERS
REMOVED. SUCH MAINTENANCE SHOULD BE PERFORMED ONLY
BY SERVICE-TRAINED PERSONNEL WHO ARE AWARE OF THE
HAZARDS INVOLVED (FOR EXAMPLE, FIRE AND ELECTRICAL
SHOCK). WHERE MAINTENANCE CAN BE PERFORMED WITHOUT
POWER APPLIED, THE POWER SHOULD BE REMOVED.
BEFORE ANY REPAIR IS COMPLETED, ENSURE THAT ALL SAFETY
FEATURES ARE INTACT AND FUNCTIONING, AND THAT ALL
NECESSARY PARTS ARE CONNECTED TO THEIR PROTECTIVE
GROUNDING MEANS.

5-11. OSCILLATOR FREQUENCY ADJUSTMENT

5-12. The following frequency adjustment procedure is the same for both the 10811A and 10811B.

Allow the oscillator to warm up for 24 hours before making this adjustment. See

a. Connect reference frequency standard (multiple or submultiple of 10 MHz) to the EXTERNAL

SYNC INPUT of the oscilloscope. Adjust oscilloscope so that sweep is synchronized with
reference frequency.

Figure 5-1.

25

Model 10811A/B

Figure 5-1. Oscillator Adjustment Setup

b. Connect oscillator output to Channel A of the oscilloscope. Adjust sweep speed so pattern

movement can be seen.

c. Adjust oscillator frequency adjustment (FREQ AD) on 10811A/B Crystal Oscillator unit) for

minimum sideways movement of the 10 MHz displayed signal. Increase oscilloscope sweep
speed for greater resolution.

5-13. Offset Calculation:

a. By timing the sideways movement (divisions per second on the oscilloscope), the approximate offset

can be determined based on the oscilloscope sweep speed as shown below.

b. For example, if the trace moves 5 divisions in 10 seconds and the sweep speed is 0.01 μs/div., the

oscillators signal is within 5 X 10-9 of the reference frequency. The calculation can also be made as
follows:

Where:

Δf/f is the normalized frequency difference between the 10811A/B and the reference signal
Δt is the change observed in the oscilloscope

t is the time required for Δt to occur.

26

Model 10811A/B

5-14. OUTPUT AMPLITUDE ADJUSTMENT

5-15. The output amplitude is adjusted by the setting of the variable resistor R6 which is in the
feedback of the AGC circuitry. It is not accessible from the outside of the oscillator.

5-16. The following procedure should be used to adjust the output amplitude only if the output level falls
outside the specified level, or repairs have been made to the main oscillator or AGC circuitry.

1. Remove oscillator from instrument.

WARNING

THE OSCILLATOR'S INTERNAL OVEN MASS TEMPERATURE MAY
BE AS HIGH AS 85°C (185°F). TO AVOID SERIOUS BURNS DO NOT
REMOVE OSCILLATOR CIRCUITS AND/OR OVEN MASS ASSEMBLY
FROM THE OUTER HOUSING UNTIL THE OSCILLATOR HAS
SUFFICIENTLY COOLED (APPROXIMATELY 1 HOUR WITH BOTTOM
COVER AND FOAM INSULATOR REMOVED). THE OUTER HOUSING
TEMPERATURE IS NOT A RELIABLE INDICATION OF THE INTERNAL
TEMPERATURE.

2. Remove bottom cover and allow oscillator to cool (if previously operated). To remove cover:

a. For the 10811A, remove the three screws securing the bottom cover. Remove the two screws

securing the P.c. edge connector to the outer can. Remove the top foam insulator to expose
the oscillator circuits.

CAUTION

DO NOT pull the oscillator out of the outer
housing by pulling on the P.C. edge
connector or flex circuit!!

b. For the 10811B remove the four

screws securing the bottom
cover. Disconnect the bottom
cover flex circuit from the seven
pin connector.

3. Once the oscillator is cool enough to
handle, remove the oscillator assembly by
pushing on the tuning capacitor (top of
oscillator) with a long, small diameter tool
until the oscillator assembly can be
removed freely.

NOTE

Under no circumstances should the oven
circuit be operated with the oven mass
removed from the outer housing. To do so
will cause damage to components inside the
oven mass.

4. Obtain HP Model 6215A Power Supply or
equivalent. Preset power supply to 12V dc.
Turn off power supply before proceeding
to next step.

Figure 5-2. 10811A Amplitude Adjustment Set-up

27

5. For the 10811A, connect Model 6215A Power
Supply to pins 2 Hand 3 (+) of a 15 pin printed
circuit connector.

a. Insert the 10811A P.c. edge connector

into the 15 pin P.c. connector. (See
Section VIII for a special 10811 A test
connector.)

b. Connect pin 1 of the 15 pin pc connector

through a 50Ω termination (use pin 2 as
ground) to a 3406A Sampling Voltmeter.

Figure 5-2. Do not apply power to

See
the oven circuits.

c. For the 10811B, reconnect the flex

circuit attached to the bottom cover and
connect the 6215A as shown in

Figure
5-3. DO NOT APPLY POWER TO THE

OVEN CIRCUITS. A Micon to BNC
adaptor is available for the 10 MHz
output (HP Part Number 05060-6116).

d. For both 10811A and B, turn on the

6215A power supply and adjust R6 AGC
control for .55V rms ±50 mV as read on
the 3406A Sampling Voltmeter. R6 is
accessible through the small hole in the
side of the oven mass.

6. Turn off the 6215A power supply and reas­semble the oscillator.

Model 10811A/B

Figure 5-3. 108118 Amplitude Adj Set-up

28

Model 10811A/B

SECTION VI

REPLACEABLE PARTS

6-1. INTRODUCTION

6-2. This section contains information for ordering replacement parts. Table 6-1 lists parts in

alphanumerical order of their reference designators and indicates the description and HP Part
Number of each part, together with any applicable notes. The table includes the following
information.

a. Description of part (see abbreviations below).
b. Typical manufacturer of the part in a five-digit code; see list of manufacturers in
c. Manufacturer's part number.
d. Total quantity used in the instrument (Qty column).

6-3. ORDERING INFORMATION

6-4. To obtain replacement parts, address order of inquiry to your local Hewlett-Packard Sales and

Service Office (see lists at rear of this manual for addresses). Identify parts by their Hewlett
Packard part numbers.

Table 6-2.

a. Instrument model number.
b. Instrument serial number.
c. Description of the part.
d. Function and location of the part.
e. Check digit.
f. Quantity required.

6-5. HP PART NUMBER ORGANIZATION

6-6. The following is a general description of the HP part number system.

29

Model 10811A/B

g

A

6-7. Component Parts and Materials

6-8. Generally, the prefix of HP part numbers identifies the type of device. Eight-digit part numbers are
used, where the four-digit prefix identifies the type of component, part, or material and the four-digit suffix
indicates the specific type. Following is a list of some of the more commonly used prefixes for component
parts. The list includes HP manufactured parts and purchased parts.

Prefix Component Part Material
0121- Capacitors, Variable (mechanical)
0122- Capacitors, Voltage Variable (semiconductor)

0140- Capacitors, Fixed
0150­0160- Capacitors, Fixed
0180- Capacitors, Fixed Electrolytic
0330- Insulatin
0340- Insulators, Formed
0370- Knobs, Control
0380- Crystals
0470­0490- Relays
0510- Fasteners

0674- through 0778- Resistors, Fixed (non wire wound)
0811- through 0831- Resistors (wire wound)

1200- Sockets for components
1205- Heat Sinks
1250- Connectors (RF and related parts)
1251- Connectors (non RF and related parts)
1410- Bearings and Bushings
1420- Batteries
1820- Monolithic Digital Integrated Circuits
1826- Monolithic Linear Integrated Circuits
1850- Transistors, Germanium PNP
1851- Transistors, Germanium NPN
1853- Transistors, Silicon PNP
1854- Transistors, Silicon NPN

1855- Field-Effect- Transistors
1900- through 1912- Diodes
1920- through 1952- Vacuum Tubes

1990- Semiconductor Photosensitive and Light-emitting Diodes
3100- through 3106- Switches

8120- Cables

9100- Transformers, Coils, Chokes, Inductors, and Filters

6-9. For example, 1854-0037, 1854-0221 and 1851-0192 are all NPN transistors. The first two are
silicon and the last is germanium.

Capacitors, Fixed,

Materials

dhesives

30

Model 10811A/B

6-10. GENERAL USAGE PARTS

6-11. The following list gives the prefixes for HP manufactured parts used in several instruments, e.g.,

side frames, feet, top and bottom covers, etc. These are eight-digit part numbers with the four­digit prefix identifying the type of parts as shown below:

Type of Part P/N Suffix
Sheet Metal 5000- to 5019­Machined 5020- to 5039­Molded 5040- to 5059­Assembly 5060- to 5079
Component 5080- to 5099

6-12. Specific Instrument Parts

6-13. These are HP manufactured parts for use in individual instruments or series of instruments. For

these parts, the prefix indicates the instrument and the suffix indicates the type of part. For
example, 05328-60001 is an assembly used in the 5328A. Following is a list of suffixes commonly
used.

Type of Part
Sheet Metal -00000 to -00499
Machined -20000 to -20499
Molded -40000 to -40499
Assembly -60000 to -60499
Component -80000 to -80299
Documentation -90000 to -90249

P/N Suffix

6-14. Factory Selected Parts

6-15. Some of the values in the parts list are selected during manufacture to meet circuit requirements.

These parts are marked with an asterisk (*) in the parts list and schematic diagrams, with average
values shown.

6-16. The 10811A/B Oscillator contains only one factory selected part which is R20 OVEN

TEMPERATURE SET resistor. This resistor is supplied with the crystal, should the crystal require
replacement.

Table 8-1 lists the various resistors and their corresponding part numbers.

6-20. REPLACEABLE PARTS LIST LAYOUT

6-21. The 10811A and 10811 B Oscillators are identical internally, except that the 10811 B has had the

15-pin pc edge connector removed and a 7-pin connector (11) placed on the board for the 10811
B bottom cover flex circuit (see
Thus the parts lists for the circuit boards are identical. The parts lists are set up in the following
manner:

1. 10811A and 10811B Circuit Board Components and Miscellaneous Parts.

2. 10811A and 10811B Transistor Mounting Hardware.

3. 10811A and 10811B Oven Mass Assembly and covers.

4. 10811A Mechanical Parts (Housing).

5. 10811B Mechanical Parts (Housing).

Figure 8-15). The only other difference is the outer housings.

31

Table 6-1. Replaceable Parts

Model 10811A/B

Reference

Designation

10811-60001 3 1 CIRCUIT BOARD COMPONENTS 10811A/B 28480 10811-60001
C1 0121-0511 6 1 TUNING CAPACITOR 28480 0121-0511
C2 0160-0576 5 11 CAPACITOR-FXD .1uF ±20% 50VDC CER 28480 0160-0576
C3 0160-5109 0 1 CAPACITOR-FXD 15pF ±5% 50VDC CER 0±30 28480 0160-5109
C4 0160-0576 5 CAPACITOR-FXD .1uF ±20% 50VDC CER 28480 0160-0576
C5 0160-0576 5 CAPACITOR-FXD .1uF ±20% 50VDC CER 28480 0160-0576
C6 0160-4935 8 CAPACITOR-FXD 510pF ±1% 100VDC CER 72982 8121-100-COGO-511F
C7 0160-0576 5 CAPACITOR-FXD .1uF ±20% 50VDC CER 28480 0160-0576
C8 0160-5110 3 1 CAPACITOR-FXD 62pF ±1% 50VDC CER 0±30 28480 0160-5110
C9 0160-0576 5 CAPACITOR-FXD .1uF ±20% 50VDC CER 28480 0160-0576
C10 0160-3874 2 2 CAPACITO R-FXD 10pF ±.5PF 200VDC CER 28480 0160-3874
C11 0160-0576 S CAPACITOR-FXD .1uF ±20% 50VDC CER 28480 0160.0576
Cl2 0160-4512 7 2 CAPACITOR-FXD 120pF ±5% 200VDC CER 51642 200-200-NP0-121J
C13 0160-3479 7 3 CAPACITO R-FXD .01uF ±20% 100VDC CER 28480 0160-3879
C14 0160-0576 5 CAPACITOR-FXD .1uF ±20% 50VDC CER 28480 0160-0576
C15 0180-2617 1 1 CAPACITOR-FXD 6.8uF +.10% 35VDC TA 25085 D6R8G81B35K
C16 0160-0576 5 CAPACITOR-FXD .1uF ±20% 50VDC CER 28480 0160-0576
C17 0160-3874 2 CAPACITOR-FXD 10pF ±.5pF 200VDC CER 28480 0160-3874
C18 0160-4947 2 1 28480 0160-4947
C19 0160-3879 7 CAPACITOR-FXD .01uF ±20% 100VDC CER 28480 0160- 387 9
C20 0160-3879 7 CAPACITOR-FXD .01uF +.20% 100VDC CER 28480 0160-3879
C21 0160-0576 5 CAPACITOR-FXD .1uF +.20% 50VDC CER 28480 0160-0576
C22 0160-0576 5 CAPACITOR-FXD .1uF +.201 50VDC CER 28480 0160-0576
C23 0160-4512 7 CAPACITOR-FXD 120pF +.5% 200VDC CER 51642 200-2 00- NP0-121J
C24 0160-0576 5 CAPACITOR-FXD .1uF +.20% 50VDC CER 28480 0160-0576
CR1 0122-0244 4 1 DIODE-VVC 100PF 5% C4/C25-MIN=2 BVR-30V 28480 0122-0244
CR2 1901-0869 2 1 DIODE-CUR RGLTR 1N5297 DO=7 04713 1N5297

CR3 1902-0984 4 1
CR4 1901-0535 9 3 DIODE-SCHOTTKY 28480 1901.0535

CR5 1901-053S 9 DIODE-SCHOTTKY 28480 190100535
CR6 1901-0535 9 DIODE-SCHOTTKY 28480 1901-0535
E1 9170-0029 1 FERRITE BEAD (FOR Q1) 28480 9170-0029
F1 2110-0617 6 1 FUSE-THERMAL (10811-80008) 28480 2110-0617
L1 9100-2280 5 S INDUCTORRF-CH-MLD 220uH 10% .10SDX.26LG 28480 9100.2280
L2 9140-0352 2 1 INDUCTORRF-CH-MLD 330nH 1% .10SDX.26LG 28480 9140.0332
L3 9140-0353 3 1 INDUCTORRF-CH-MLD 430hN 1% .10SDX.26LG 28480 9140.0353
L4 9100-2276 9 1 INDUCTORRF-CH-MLD 100uH 10% .10SDX.26LG 28480 910002276
LS 9100-2280 5 INDUCTORRF-CH-MLD 220uH 10% .10SDX.26LG 28460 9100-2250
L6 9100-2280 5 INDUCTORRF-CH-MLD 220uH 10% .10SDX.26LG 28480 910002280
L7 9100-2280 5 INDUCTORRF-CH-MLD 220uH 10% .10SDX.26LG 28480 9100.2280
L8 9100-2280 5 INDUCTORRF-CH-MLD 220uH 10% .10SDX.26LG 28480 9100.2280
Q1 1854-0853 3 3 TRANSISTOR, SPL 2N5179 28460 1854-0853
Q2 1954-0853 3 TRANSISTOR, SPL 2N5179 28480 1854-0853
Q3 1854-0853 3 TRANSISTOR, SPL 2N5179 28480 1854-0853
Q4 1854-0831 7 2 TRANSISTOR NPN 2N6429A T0-92 PD=625mW 01713 2N6429A
Q5 1854-0831 7 TRANSISTOR NPN 2N6429A T0-92 PD=625mW 04713 2N6429A
Q6 1854-0023 9 1 TRANSISTOR NPN S1 TO-18 PD=360mW 28480 1854-0023
Q7 10811-80001 0 2 TRANSISTOR NPN SI DARL TO-22049 PD=70W 04713 10811-80001
Q8 10811-80001 0 TRANSISTOR NPN SI DARL TO-220AB PD=7OW 04713 10811-80001
Q9 18S4-0833 9 1 TRANSISTOR NPN PD.600Mw FT6600m142 28480 1554-0833
R1 0698-7284 5 5 RESISTOR 100K 1% .05W F TC.0+•100 24546 C3-1/8-T0-1003-G
R2 0698-7284 5 RESISTOR 100K 1% .50W F IC60+.100 24546 C3-1/8-T0-1001-G
R3 0699-0073 8 2 RESISTOR 10M 1% .125W F IC60+6,100 28480 0699.0073
R4 0699-0073 8 RESISTOR 10M 1% .125W F TCs0+.100 28480 0699.0073
R5 0698-7263 0 1 RESISTOR 13.3K 1% .05W F TCs0+•100 24546 C3-1/8-T0-1332-G
R6 2100-2489 9 1 RESISTOR-TRMR 5K 10% C SIDE-ADJ 1-TRN 30983 ETS0X502
R7 0698-7272 1 1 RESISTOR 31.6K 1% .05W F TC=0±100 24546 C3-1/8-T0-3162-G
R8 0698-7232 3 RESISTOR 681 1% .05W F TC=0±100 24546 C3-1/8-T0-681R-G
R9 0698-7256 1 2 RESISTOR 6.61K 1% .05W F TC=0±100 24546 C3-1/8-T0-6811-G
R10 0698-7256 1 RESISTOR 6.61K 1% .05W F TC=0±100 24546 C3-1/8-T0-6811-G
R11 0698-7244 7 1 RESISTOR 2.15K 1% ,05W F TC=0±100 24546 C3-1/8-T0-2151-G
R12 0698-7261 8 1 RESISTOR 11K 1% .05w F TC=0±100 24546 C3-1/8-T0-110244
R13 0698-7224 3 RESISTOR 316 1% 1% .05W F TC=0±100 24546 C3-1/8-T0-316R-G
R14 0698-7280 1 1 RESISTOR 68.1K 1% .05W F TC=0±100 24546 C3-1/8-T0-6812-G
R15 0698-7284 5 RESISTOR 100K 1% .05W F TC=0±100 24546 C3-1/8-T0-1003-G
R16 0698-7235 6 RESISTOR 909 1% .05W F TC=0±100 24546 C3-1/8-T0-909R.G
R17 0698-7260 7 2 RESISTOR 10K 1% .05W F TC=0±100 24546 C3-1/8-T0-1002-G
R18 0698-3903 7 5 RESISTOR 8.6K .1% .05W F TC=0±10 28480 0698.3903
R19 0696-3903 7 RESISTOR 11.6K .1% .05W F TC=0±10 28480 069803903
R20* 0698-0096 3 1 RESISTOR 968 1% .125W F TC=0±100 03888 PME55-1/8-T0-9680-F
R20* 0698-3495 2 1 RESISTOR 866 1% .125W F TC=0±100 24546 C4-1/8-T0-866R-F
R20* 0698-3512 4 1 RESISTOR 1.18K 1% .125W F TC=0±100 24546 C4-1/8-T0-1181-F

HP Part

Number C D

Qty

DIODE-ZNR 6,4V 2% DO=7 PD = .4W
TC=+.002%

Description

Mfr

Code

28480 1902.0984

Mfr Part Number

32

Model 10811A/B

Table 6-1. Replaceable Parts (Continued)

Reference

Designation
R20* 0698-3700 2 1 RESISTOR 715 1% .125W F TC=0±100 24546 C4-1/8-T0-715R-F

R20* 0698-4014 3 1 RESISTOR 787 1% .125W F TC=0±100 24546 C4-1/8-T0-787R-F
R20* 0696-4196 2 1 RESISTOR 1.07K 1% .125W F TC=0±100 24546 C4-1/8-T0-1071-F
R20* 0696-4460 3 1 RESISTOR 649 1% .125W F TC=0±100 24546 C4-1/8-T0-649R-F
R20* 0696-4465 6 1 RESISTOR 931 1% .125W F TC=0±100 24546 C4-1/8-T0-931R-F
R20* 0698-4469 2 1 RESISTOR 1.15K 1% .125W F TC=0±100 24546 C4-1/8-T0-1151-F
R20* 0698-5652 9 1 RESISTOR 500 1% .125W F TC=0±100 24546 C4-1/8-T0-500R-F
R20* 0698-6970 4 1 RESISTOR 1.04K .5% .125W F TC=0±50 28480 0698-6970
R20* 0698-6973 7 1 RESISTOR 1.25K .25% .125W F TC=0±25 28480 0698-6973
R20* 0696-6981 7 1 RESISTOR 1.29K .5% .125W F TC=0±50 28480 0698-6981
R20* 0698-7201 6 1 RESISTOR 34.6 1% .05W F TC=0±100 24546 C3-1/8-T00-34R8-G
R20* 0698-7207 2 1 RESISTOR 61.9 1% .05W F TC=0±100 24546 C3-1/8-T00-61R9-G
R20* 0698-7212 9 1 RESISTOR 100 1% .05W F TC=0±100 24546 C3-1/8-T0-100R-G
R20* 0698-7214 1 1 RESISTOR 121 1% .05W F TC=0±100 24546 C3-1/8-T0-121R-G
R20* 0698-7217 4 1 RESISTOR 162 1% .05W F TC=0±100 24546 C3-1/8-T0-162R.G
R20* 0698-7219 6 1 RESISTOR 196 1% .05W F TC=0±100 24546 C3-1/8-T0-196R-G
R20* 0698-7220 9 2 RESISTOR 215 1% .05W F TC=0±100 24546 C3-1/8-T0-215R-G
R20* 0698-7222 1 1 RESISTOR 261 1% .05W F TC=0±100 24546 C3-1/8-T0-261R-G
R20* 0698-7223 2 1 RESISTOR 287 1% .05W F TC=0±100 24546 C3-1/8-T0-287R-G
R20* 0698-7224 3 2 RESISTOR 316 1% .05W F TC=0±100 24546 C3-1/8-T0-316R-G
R20* 0698-7225 4 1 RESISTOR 348 1% .05W F TC=0±100 24546 C3-1/8-T0-348R-G
R20* 0696-7226 5 1 RESISTOR 383 1% .05W F TC=0±100 24546 C3-1/8-T0-383R-G
R20* 0698-7227 6 1 RESISTOR 422 1% .05W F TC=0±100 24546 C3-1/8-T0-422R-G
R20* 0696-7228 7 1 RESISTOR 464 1% .05W F TC=0±100 24546 C3-1/8-T0-464R-G
R20* 0698-7229 8 2 RESISTOR 511 1% .05W F TC=0±100 24546 C3-1/8-T0-511R-G
R20* 0698-7230 1 1 RESISTOR 562 1% .05W F TC=0±100 24546 C3-1/8-T0-562R-G
R20* 0698-7231 2 1 RESISTOR 619 1% .05W F TC=0±100 24546 C3-1/8-T0-619R-G
R20* 0698-7232 3 4 RESISTOR 681 1% .05W F TC=0±100 24546 C3-1/8-T0-681R-G
R20* 0698-7233 4 1 RESISTOR 750 1% .05W F TC=0±100 24546 C3-1/8-T0-750R-G
R20* 0698-7254 5 1 RESISTOR 825 1% .05W F TC=0±100 24546 C3-1/8-T0-825R-G
R20* 0698-7235 6 2 RESISTOR 909 1% .05W F TC=0±100 24546 C3-1/8-T0-909R-G
R20* 0698-7236 7 1 RESISTOR 1K 1% .05W F TC=0±100 24546 C3-1/8-T0-1001-G
R20* 0698-7237 8 1 RESISTOR 1.1k 1% .05W F TC=0±100 24546 C3-1/8-T0-1101-G
R20* 0696-7238 9 1 RESISTOR 1.21K 1% .05W F TC=0±100 24546 C3-1/8-T0-1211-G
R20* 0698-7239 0 1 RESISTOR 1.33K 1% .05W F TC=0±100 24546 C3-1/8-T0-1331-G
R20* 0757-1100 8 1 RESISTOR 600 1% .125W F TC=0±100 24546 C4-1/8-T0-601-F
R21 0698-3903 7 RESISTOR 8.6K .1% .05W F TC=0±10 28480 0696-3903
R22 0698-8827 4 2 RESISTOR 1M 1% .125W F TC=0±100 28480 0696-6627
R23 0698-6827 4 RESISTOR 1M 1% .125W F TC=0±100 28480 0696-6627
R24 0699-0071 6 1 RESISTOR 4.64M 1% .125W F TC=0±100 28480 0699-0071
R25 0698-7273 2 1 RESISTOR 54.8K 1% .05W F TC=0±100 24546 C3-1/8-T0-3482-G
R26 0698-3903 7 RESISTOR 6,6K .1% .05W F TC=0±100 28480 0698-3903
R27 0698-3903 7 RESISTOR 6.6K .1% 05W F TC=0±100 28480 0698-3903
R28 0698-7265 2 1 RESISTOR 16.2K 1% .05W F TC=0±100 24546 C3-1/8-T0-1622-G
R29 0698-7260 7 RESISTOR 10K 1% .05W F TC=0±100 24546 C3-1/8-T0-1002-G
R30 0698-7267 4 1 RESISTOR 19.6K 1% .05W F TC=0±100 24546 C3-1/8-T0-1962-G
R31 0698-7220 9 RESISTOR 215 1% .05W F TC=0±100 24546 C3-1/8-T0-215R-G
R32 0698-7250 5 2 RESISTOR 3.83K 1% .05W F TC=0±100 24546 C3-1/8-T0-3831-G
R33 0698-7284 5 RESISTOR 100K 1% .05W F TC=0±100 24546 C3-1/8-T0-1003-G
R34 0696-7247 0 1 RESISTOR 2.87K 1% .05W F TC=0±100 24546 C3-1/8-T0-2871-G
R35 0698-7250 5 RESISTOR 3.63K 1% .05W F TC=0±100 24546 C3-1/8-T0-3831-G
R36 0696-7264 5 RESISTOR 100K 1% .05W F TC=0±100 24546 C3-1/8-T0-1003-G
R37 0698-7232 3 RESISTOR 681 1% .05W F TC=0±100 24546 C3-1/8-T0-681R-G
R38 0696-8812 7 2 RESISTOR 1 1% .125W F TC=0±100 28480 0696-6612
R39 0696-6812 7 RESISTOR 1 1% .125W F TC=0±100 28480 0696-6612
R40 0698-7229 8 RESISTOR 511 1% .05W F TC=0±100 24546 C3-1/8-T0-511R-G
R41 0698-7215 2 1 RESISTOR 133 1% .05W F TC=0±100 24546 C3-1/8-T0-133R-G
R42 0698-7232 3 RESISTOR 681 1% .05W F TC=0±100 24546 C3-1/8-T0-681R-G
T1 9100-0425 0 1 TRANSFORMER RF; WIND 9T PRI & 3T SEC 28480 9100-0423
U1 1826-0611 2 1 IC OP AMP GP DUAL 8-DIP-P 27014 LM2904N
U2 1826-0516 4 1 V REF 10.5 27014 LH0070-1H
U3 1826-0072 9 1 IC OP AMP LOW-BIAS-H-IMPD 10.99 07263 UA208M
XF1 1251-1556 7 2 CONNECTOR-SGL CONT SKT .018-IN-BSC-SZ 28480 1251-1556

V1 10811-60108 7 1

HP Part

Number

2260-0009 3 1 NUT-HEX-W/LKWR 4-40-THD .094-IN-THK 00000 ORDER BY

C
D

Qty

CRYSTAL-10MHZ W/R20 TEMP SET (REPAIR
ONLY)

Description

Mfr

Code

28480 10811-60108

Mfr Part Number

DESCRIPTION

33

Reference

D

Designation

HP Part
Number

MP1
MP2
MP3

MP4
MP5
MP6

MP7
MP8
MP9

1200-0868 5 1
0360-1244
3050-0588
0360-1682

10811-40002

2200-0103 2 SCREW 4-40 .250 28480
2190-0004
3050-0756
0340-0864

10811-60106 1 OVEN MASS ASS. W/THERMISTOR
10811-20202
10811-20203

0520-0166

10811-20206
10811-20211
10811-40001

3030-0827
2200-0101
7120-7912
7120-0331

10811-20205
10811-60107

1250-0911
2200-0164 4

7120-7911
7120-6299

05060-6116

Model 10811A/B

Table 6-1. Replaceable Parts (Continued)

C

Qty

10811A/B CIRCUIT BOARD MISCELLANEOUS PARTS

SOCKET-STRP 7-CONT DIP-SLDR

Description

0 3 TERMINAL-SPCL FEEDTHRU 28480 0360-1244
9 1 WASHER-FL NM NO. 6 145-IN-ID .23-IN-OD 28480 3050-0588
0 2 TERMINAL-STUD SGL-TUR PRESS-MTG 28480 0360-1682
4 1 FOAM SHEET-(BELOW OVEN CONTROLLER ASSY) 28480 10811-40002

10811A/B TRANSISTOR MOUNTING HARDWARE

2 WASHER, FLAT 28480 2190-0004
2 NYLON INSULATOR 28480 3050-0756
2 TRANSISTOR INSULATOR 28480 0340-0864

10811A/B MASS ASSEMBLY AND COVERS

1 MASS COVER W/XISTOR CUT-OUTS 28480 10811-20 202
1 MASS COVER W/TUNING CAP HOLE 28480 10811-20203
8 SCREW 28480 0520-0166

1 OUTER HOUSING (FOAMED) 28480 10811-20212
1 BOTTOM COVER 28480 10811-20211
1 FOAM COOKIE UNDER BOT COV 28480 10811-40001

2 SCREWS FOR P.C. CONNECTOR 28480 3030-0827

10811A MECHANICAL PARTS

10811A MISCELLANEOUS PARTS

3 SCREWS FOR BOTTOM COVER 28480 2200-0101
1 INFO LABEL 10811A 28480 7120-7912
1 INFO LABEL 10811-60101

10811B MECHANICAL PARTS
1 OUTER HOUSING (FOAMED) 28480 10811-20213
1 BOTTOM COVER COMPLETE 28480 10811-60107
1 EFC SHORTING CONNECTOR 28480 1250-0911

SCREW 4-40 .188 TOP 28480

10811B MISCELLANEOUS PARTS

1 INFO LABEL "FREQ ADJ." 28480 7120-7911
1 INFO LABEL HOUSING 28480 7120-6299
1 ADAPTOR MICON-BNC* 28480 05060-6116

*MICON TO BNC ADAPTOR NOT SUPPLIED.
PART NUMBER FOR REFERENCE ONLY.

Mfr

Code

Mfr Part Number

28480 1200-0868

2200-0103

28480

10811-60106

28480 7121-0331

2200-0164

34

Model 10811A/B

Table 6-2. Manufacturers Code List

MFR. NO. MANUFACTURER NAME ADDRESS ZIP CODE

00000 ANY SATISFACTORY SUPPLIER

03888 KDI PYROFILM CORP WHIPPANY, NJ 07981

04713 MOTOROLA SEMICONDUCTOR PRODUCTS PHOENIX, AZ 85062

07263 FAIRCHILD SEMICONDUCTOR DIV MOUNTAIN VIEW, CA 94042

24546 CORNING GLASS WORKS (BRADFORD) BRADFORD, PA 16701

25088 SIEMENS CORP ISELIN, NJ 08830

27014 NATIONAL SEMICONDUCTOR CORP SANTA CLARA, CA 95051

28480 HEWLETT-PACKARD CO CORPORATE HQ PALO ALTO, CA 94304

30983 MEPCO/ELECTRA CORP SAN DIEGO, CA 92121

51642 CENTRE ENGINEERING INC STATE COLLEGE, PA 16801

72982 ERIE TECHNOLOGICAL PRODUCTS INC ERIE, PA 16512

35

Model 10811A/B

Page Intentionally Left Blank

36

Model 10811A/B

SECTION VII

MANUAL CHANGES

7-1. INTRODUCTION

7-2. This section contains information necessary to adapt this manual to apply to older instruments.

7-3. MANUAL CHANGES

7-4. This manual applies directly to Model 10811 AlB Quartz Crystal Oscillators with serial prefix
number 2028.

7-5. NEWER INSTRUMENTS

7-6. As engineering changes are made, newer instruments may have serial prefix numbers higher
than those listed on the title page of this manual. The manuals for these instruments will be supplied with
"Manual Changes" pages containing the required information to update the manual. Replace affected
pages or modify existing manual information as described in the "Manual Changes" pages. See Section
VI of this manual for a description of board identification. If the series number etched or stamped on any
circuit board or circuit board assembly is higher than the above serial prefix number, "Manual Changes"
pages should accompany the manual.

7-7. If the "Manual Change" pages are missing from any HP manual, the information can be supplied
by any Hewlett-Packard Sales and Service Office listed at the back of this manual.

37

Model 10811A/B

Page Intentionally Left Blank

38

Model 10811A/B

SECTION VIII

SERVICE

8-1. INTRODUCTION

8-2. This section contains theory of operation, a detailed troubleshooting procedure, and a schematic

diagram.

8-3. SCHEMATIC DIAGRAM SYMBOLS AND REFERENCE DESIGNATORS

8-4. Figure 8-1 shows the symbols used in the schematic diagram. At the bottom of Figure 8-1, the

system for reference designators, assemblies, and subassemblies is shown.

8-5. REFERENCE DESIGNATORS

8-6. Theory of Operation

8-7. The overall theory of operation for the 10811A/B starts with paragraph 8-9. The detailed theory of

operation starts with

paragraph 8-13.

8-8. OVERALL BLOCK DIAGRAM THEORY

8-9. The 10811A/B Quartz Crystal Oscillator is an extremely stable, compact, low-power source of 10

MHz. The crystal, along with the oscillator, circuit buffer amplifier, and oven control circuits are all
mounted inside a thermally insulated housing.

8-10. A detailed block diagram of the 10811A/B oscillator is shown in

8-11. The 10811A/B oscillator is divided into three sections with each section connected by a .010-inch

thick flexible circuit. Three small circuit boards are bonded to the flexible circuit to provide support
in the areas where components are located. The arrangement allows the unit to be easily
disassembled and operated in the disassembled state on the service bench.

8-12. The three sections can be divided into the following subsections (

1. Main Oscillator

2. Automatic Gain Control
Voltage Reference (+5.7V and +6.4V)
Output Impedance Matching Buffer

3. Output Buffer Amplifier
Oven Controller

Figure 8-2.

Figure 8-2):

39

Model 10811A/B

40

Figure 8-1. Schematic Diagram Notes

• A GROUND POINT FOR
TESTING OSCILLATOR.
AGC,OUTPUT AMPLIFIER
AND VOLTAGE REFERENCE.

• B GROUND POINT FOR
TESTING OVEN
CONTROLLER.

• B GROUND POINT FOR
TESTING OVEN
CONTROLLER.

• A AND B GROUNDS MAY BE
TIED TOGETHER OR
FLOATED AT DIFFERENT
POTENTIALS EXTERNAL TO
THE OSCILLATOR.

Model 10811A/B

Figure 8-2. 10811A/B Overall Block Diagram

41

Model 10811A/B

8-13. MAIN OSCILLATOR THEORY OF OPERATION

8-14. The 10811A/B oscillator is a Colpitts-type crystal oscillator which uses the crystal as the series

inductor.
shows the basic equivalent components of the oscillator.

Figure 8-3A shows the basic block diagram of a Colpitts-type oscillator. Figure 8-3B

Figure 8-3A. Basic Colpitts- Type Oscillator

r

Figure 8-3B. Main Oscillator Schematic Design

8-15. Comparing Figure 8-3A and 8-3B, we find Y1 is the inductor, capacitor CA is C8 and CB is the

combination of C5, L2, C6, and L3. C5 is a dc blocking capacitor. Its reactance is very low, so the
combination of these components can be redrawn as in
overtone" crystal and is operated at 10 MHz. To keep the circuit from oscillating at the crystal's
fundamental, or at a different overtone, the mode suppression network of C5, L2, C6, L3 appears
capacitive only at frequencies between 9 MHz and 10.5 MHz. Below and above this frequency
range, the network appears inductive. This does not allow the proper phase shift around the loop
and thus suppresses oscillations at all frequencies other than 10 MHz. It should be noted that any
reactance in series with the crystal will cause a change in frequency.

Figure 8-4. The crystal Y1 is a "third

42

Model 10811A/B

Figure 8-4. Mode Suppression

8-16. Figure 8-5 show the equivalent crystal circuits with the tuning capacitor C1.

Figure 8-5. Frequency Tuning Circuit

8-17. C1 tuning capacitor is available from the top of the oscillator outer housing. The change in

reactance of C1 allows the oscillator's frequency to be varied over a 20 Hz (2 X 10

-6

) range. C9

and C4 are dc blocking capacitors.

8-18. ELECTRONIC FREQUENCY CONTROL (EFC)

8-19. To allow for a fine tuning control, a varactor (CR1) is added in parallel with C1 tuning capacitor.

Figure 8-6. The varactor's capacitance depends on the dc voltage applied to it (reverse bias).

See
The HC voltage range is +5 volts to -5 volts, giving a fine tuning range of ≈1 Hz (1 X10
one side of the varactor is tied to a reference (6.4V), a full +5 volts applied to the HC input will still
keep CR1 reverse biased. C2 and C3 are again dc blocking capacitors to keep the HC current
from flowing in to the crystal circuit. Note: if the HC input is not used, it must be connected to
ground to keep any noise from modulating the HC line and causing frequency changes.

-7

). Since

43

Model 10811A/B

Figure 8-6. EFC

8-20. AUTOMATIC GAIN CONTROL (AGC)

8-21. The output for the AGC (and output amplifiers, discussed later) is taken across capacitor C10,

and is applied to Q3. Since C10 is effectively in series with the crystal, the current passing
through the crystal also passes through C10. The voltage across C10 is therefore proportional to
the current through the crystal. As the output of the oscillator changes, the output of the peak
detector circuit changes. This change in the AGC voltage changes the voltage applied to the base
of Q1 and stops the impending output voltage change. A peak detector circuit formed by C12, CU,
CR4 and CR5 is used to develop a dc voltage to control the crystal current. This negative control
voltage forms the lower half of a voltage divider for the base of Q1 (R6 and R7). Controlling the
bias current and the gain of Q1. Thus AGC action controls the output signal level. (See

7).

Figure 8-

Figure 8-7. Automatic Gain Control (AGC)

8-22. By adjusting the AGC voltage with R6 the amplitude for the output (at the base of Q3) can be set.

R5 sets the AGC limit when R6 is at its minimum resistance.

44

Model 10811A/B

8-23. RF OUTPUT IMPEDANCE MATCHING AND OUTPUT BUFFER

8-24. The signal for the output amplifiers is taken from the same point as the AGC (across C10). The

voltage is buffered by Q5 which is an impedance matching stage. Resistors R14 and R15 set the
dc bias level while C14 allows the ac to bypass R14. The signal is then applied to the output
buffer stage of Q9. Resistor R40 provides the 50Ω source impedance when transformed by T1.
Typical gain from Q9 base to collector is approximately 2. See

Figure 8-8.

Figure 8-8. Output Amplifiers

8-25. VOLTAGE REFERENCES (5.7V AND 6.4V)

8-26. Constant current diode CR2 feeds 1 mA to zener diode CR3 providing 6AV dc for the EFC

varactor reference. R12 and C15 form a filter to attenuate noise from the zener diode. R13
provides current limiting for Q5 if the 5.7V line is shorted. See

Figure 8-9.

45

Model 10811A/B

Figure 8-9. Voltage References

8-27. OVEN HEATER AND CONTROLLER THEORY

NOTE
In the following theory of operation the term OVEN MASS will be used to
describe the cast aluminum block in which the crystal and crystal
electronics are located. The exploded view of the oscillator shows the
oven mass.

8-28. The purpose of the oven is to shield the oscillator crystal and electronics from normal ambient

temperature changes. The oven controller does this by maintaining a constant oven temperature
which is higher than the highest expected ambient temperature.

8-29. Three main blocks make up the oven circuits. See

1. Thermistor

2. Amplifier (controller)

3. Heaters

8-30. In the 10811A/B oven, a thermistor (RT1) is secured with epoxy into a hole in the oven mass. U3

is the amplifier and Q7 (not shown) and Q8 are the heaters. It is the thermistor that senses the
oven mass temperature. Since it is in one leg of the bridge circuit, when the mass temperature
changes slightly, a voltage change occurs across the bridge (RT1, R18, R19, R20, R21).
Amplifier U3 boosts this voltage change and then uses it to control the current through Q7 and Q8.
The current flowing through transistors Q7 and Q8 causes power dissipation in the form of heat,
and it is this heat that warms the oven mass. Therefore, when the mass temperature starts to
change, the heaters are told to adjust their power to cancel the impending temperature change.

Figure 8-10.

8-31. WARM-UP: GENERAL OPERATION. If the oscillator has been off for several hours, the mass

and thermistor will be at the ambient temperature. Assuming this is below the normal oven
operating temperature (80 to 84°C) the resistance at the thermistor RT1 is higher than that of R18
+ R20 and therefore V

> V2. This causes the output of U3 to be ≈ (Vcc - 1.5V) and supply base

1

current to Q8 through Q6. A separate circuit limits the collector current of Q8 and is described
later. As the oven mass warms up, the thermistor's resistance gets lower causing both V2 and V1
to lower (V2 lowers because Vo lowers due to RT1 getting smaller). V1 decreases at a faster rate
than V2 and eventually V

= V2 when RT1 = R20 + R18. At this time, the oven controller "cuts

1

back" and begins to operate in a linear mode, adjusting the collector current in Q8 (and therefore
the power dissipated in Q7 and Q8) to keep the oven precisely at its set temperature.

46

Model 10811A/B

Figure 8-10. Oven Control Circuits

8-32. The purpose of R17 is mainly to reduce the power dissipated in the thermistor which causes it to

self-heat above the oven operating temperature.

8-33. R38 and R39 in parallel provide a means of sensing the heater current, rH. During warm-up, the

voltage across them, VH, is used in the current limit circuit (described later). During normal, linear
operation, VH is essentially the feedback point for the oven controller loop.

8-34. Q6 is necessary primarily for the condition when the oscillator has been stored at -55°C. Since U3

(at -55°C) cannot supply enough base current for Q8, Q6 gives the added current gain required.

8-35. PRECISION VOLTAGE REFERENCE

8-36. U2 is a 10.0V voltage reference. It provides a stable voltage source for the bridge and U1. A

change in the bridge reference voltage changes the voltage across the thermistor and hence, the
power it dissipates. See

Figure 8-10.

8-37. OVEN CONTROLLER TURN-ON CURRENT LIMITING

8-38. Figure 8-11 shows the turn-on current limiting circuit. From an initial turn-on condition the

thermistor senses the oven temperature to be low. To correct this situation the amplifier attempts
to drive heavy amounts of current through Q7 and Q8 heaters. If allowed to continue this way,
excessive current will flow; much more than is practical or necessary for warm-up. Amplifier U1
and associated components limit the current during warm-up to a practical value. When Vcc is
applied to the oven, U1B forces VH to equal V3 by sinking the base current from Q6. By sensing
Vcc, the circuit transforms the heater transistors into what appears to be a fixed heater resistance
of 47Ω typical.

47

Model 10811A/B

Figure 8-11. Turn-on Current Limit Circuit

8-39. HEATER TRANSISTOR BALANCE

8-40. Because heater transistors Q7 and Q8 are not equally spaced from the crystal, it is necessary to

offset the power dissipation between the two transistors.
schematic of this circuit. Amplifier U1A references a voltage divider across Vcc (R25, R26) and a
divider referenced to the mid-point between the heater transistors. From this U1A controls the
base current of Q7 to insure the Voltage at the mid-point between the heater transistors is a
constant percentage of Vcc (V4 ≈ 0.57 Vcc ± 2%).

Figure 8-12 shows a simplified

48

Figure 8-12. Heater Transistor Balance Circuit.

Model 10811A/B

8-41. REPAIR AND TROUBLESHOOTING

8-42. Inspection

8-43. The 10811A/B should be inspected for indications of mechanical and electrical defects. Electronic

components that show signs of overheating, leakage, frayed insulation, and other signs of
deterioration should be checked and a thorough investigation of the associated circuitry should be
made to verify proper operation. Mechanical parts should be inspected for excessive wear,
looseness, misalignment, corrosion, and other signs of deterioration.

CAUTION

Proper static handling techniques must be employed when
servicing semiconductor products. The voltage susceptibility of all
IC and transistor families is well below levels commonly found in
service environments. Exercise care and observe standard static
precautions.

8-44. REPAIR

8-45. Printed Circuit Component Replacement

8-46. To prevent damage to the plating and the replacement component, apply heat sparingly, and

work carefully. See CAUTION below.

8-47. Replacing Integrated Circuits

8-48. Following are two recommended methods of replacing integrated circuits:

a. SOLDER GOBBLER. This is the best method. Solder is removed from board by a soldering

iron with a hollow tip connected to a vacuum source.

b. CLIP-OUT. Clip the leads as close to the component as possible. With a soldering iron and

long nose pliers, carefully remove the leads from each hole. Then clean the holes.

CAUTION

The flex circuitry used in the 10811A/B oscillator requires special
attention to soldering iron tip temperature and the length of time heat is
applied. A low wattage (≈25W) iron with a temperature control should be
used. The tip temperature should be held below 500°C. Care should be
taken to be sure that the iron is not held on the circuit longer than
necessary. Components should be removed by clipping the leads and
then gently removing them. Do not use force when removing
components. Following these precautions will insure that repairs can be
easily made without damaging the flex circuit. Also, components should
not be arbitrarily removed for troubleshooting or replacement unless
there is reasonable confidence in the component's failure.

49

Model 10811A/B

WARNING

THE OSCILLATOR'S INTERNAL OVEN MASS TEMPERATURE MAY
BE AS HIGH AS 85°C (185°F). TO AVOID SERIOUS BURNS DO NOT
REMOVE OSCILLATOR CIRCUITS AND/OR OVEN MASS ASSEMBLY
FROM THE OUTER CAN UNTIL THE OSCILLATOR HAS
SUFFICIENTLY COOLED (APPROXIMATELY ONE HOUR WITH
BOTTOM COVER AND FOAM INSULATOR REMOVED). THE OUTER
HOUSING TEMPERATURE IS NOT A RELIABLE INDICATION OF THE
INTERNAL TEMPERATURE.

8-49. The troubleshooting is arranged to allow the technician to quickly find the defective component(s)

without unnecessary removal of components.

8-50. TROUBLESHOOTING

8-51. Failures in the 10811A/B can be divided into two sections:

1. Failure of the oscillator's circuits.

2. Failure in the oven controller circuits.

8-52. Failures in the oscillator circuits can be divided into the following problems:

1. No output.

2. Output amplitude is too low or high.

3. Output is distorted (contains excessive harmonics).

4. Output is off frequency (high or low).

5. Output has excessive noise or frequency stability does not meet specifications.

8-53. Poor frequency stability can be difficult to troubleshoot, and many times the oscillator is not at

fault. Environmental conditions can affect stability and should be ruled out first.

8-54. Failures in the oven circuitry can be divided into the following problems:

1. No oven current (heat).

2. Excessive oven current (>600 mA).

3. Oven does not cut back after warm-up (this will open the thermal fuse if allowed to continue).

4. Oven does not regulate at the proper temperature. (This can be the cause for poor frequency
stability).

8-55. Since the main oscillator and oven control power supply inputs are separate from each other, the

defective circuit can be operated without applying power to the complete oscillator.

8-56. Determine which section is defective (oven or oscillator circuit), then proceed as described in the

following troubleshooting section. The two circuits can be investigated separately.

1. Remove top cover and insulator described in:
a. 10811A
b. 10811B

paragraphs 8-59.
paragraphs 8-59, step 4.

50

Model 10811A/B

CAUTION

With the cover and foam insulator removed to thermal fuse cannot protect the oven circuit from thermal runaway. Caution should be used at all times.

8-57. DISASSEMBLY FOR TROUBLESHOOTING AND REPAIR

8-58. Perform steps 1 through 3 for the 10811A oscillator and steps 4 and 5 for the 10811B oscillator.

Once these steps are completed, follow steps 6 through 10 for both oscillators.

8-59. For the 10811A Oscillator:

Step 1. Remove the three screws securing the bottom cover to the outer housing, and remove
bottom cover.

Step 2. Remove the two screws securing the pc edge connector to the outer housing.
Step 3. Remove the foam sheet to expose the oven controller circuit board.

If troubleshooting the oven controller, stop here and go to
trouble is in the oscillator circuit.

For the 10811B oscillator:

Step 4. Remove the four screws securing the cover to the outer housing.
Step 5. Disconnect the flexible circuit attached to the cover from the 7-pin connector mounted to

the oven controller circuit board.

If troubleshooting the oven controller, stop here and go to
is in the oscillator circuit.

The following steps will be performed for both oscillators.

Step 6. Using a long, small diameter tool, remove the complete oscillator assembly by inserting
the tool into the tuning capacitor access hole (labeled FREQ. ADJUST) and pushing on the
capacitor until the circuit can be grasped and removed freely.

paragraph 8-69. Go to Step 6 only if the

paragraph 8-69. Continue only if the trouble

CAUTION

10811A Only

Do not remove the circuits by pulling on the edge connector or
flexible circuit. Damage to the flexible circuit may occur.

Step 7. Using a Pozidriv screwdriver
to the oven mass. Remove the washers and transistor insulators.

When reassembling the oven mass the heater transistor screws must
be tightened to a torque of 44 Newton meters (5 in.-Ibs.)

, remove the two screws securing the heater transistors

NOTE

Step 8. Tilt the oven controller assembly back and remove the foam insulator between the oven
controller assembly and the oven mass. Be careful not to break the two black thermistor wires
attached to the oven controller assembly.

Step 9. Remove the eight screws (four each side) securing the covers to the oven mass
assembly.

Step 10. Use two of the screws from each cover (removed in Step 9) to secure the boards to the
mass for troubleshooting.

51

Model 10811A/B

8-60. Go to

procedure.

paragraph 8-84, Oscillator Troubleshooting. When reassembling unit, reverse the above

8-61. SPECIAL TEST CONNECTOR FOR 10811A

8-62. The following paragraphs describe a special 15-pin connector for use in troubleshooting,

alignment and testing of the 10811A. The connector provides the following (See

a. Two separate input leads for the oscillator circuits power and the oven heaters and controller

circuits.
b. 10 MHz output through a female BNC.
c. Oven monitor output for connection to a voltmeter.
d. HC input connection to ground.

Figure 8-13):

Figure 8-13. 10811A/B Special Test Connector

8-63. The following parts are required to construct the special test connector:

a. 15-pin pc board connector (HP part number 1251-0494).
b. 6 banana plugs (HP part number 1251-0124).
c. BNC female connector with ground lug and nut.
BNC connector 1250-0083

Ground lug 0360-0024
lock washer 2190-0016
Nut 2950-0001

52

d. Approximately 6-feet of 24-gauge wire.
e. Labels for banana plugs.

8-64. To construct the connector:

a. Solder the center pin of the BNC connector to pin 1(A) of the printed circuit connector; this is

the 10MHz output signal.
b. Bend the BNC ground lug to align with pin 2(B) of the printed circuit connector.
c. Solder one end of a 2-foot length of wire to pin 2(B) of the printed circuit connector.

Also solder the BNC ground lug to pin 2(B). This is the oscillator circuit common.
d. Solder one end of a 2-foot length of wire to pin 3(C) of the printed circuit connector.

This is the oscillator (+) supply.
e. Connect a jumper wire between pins 5(E) and 6(F). This terminates the HC input.
f. Solder one end of a 2-foot length of wire to pin 11(M). This is oven monitor output.
g. Solder one end of a 2-foot length of wire to pin 14(R) of the printed circuit connector.

This is the oven (+) supply.
h. Solder one end of two 2-foot lengths of wire to pin 15(S) of the printed circuit connector.

This is the oven common.
i. Twist together one of the two wires connected to pin 15(S) and the wire connected to pin

14(R). These are the oven controller power supply inputs.
j. Twist together the remaining wire connected to 15(S) and the wire connected to pin 11(M).

This is the oven monitor output.
k. Twist together the two wires connected to pins 2(B) and 3(C). These are the oscillator supply

input.
l. Connect one banana plug to the free end of each wire.
m. Label each banana plug as follows:

Wire connected to: Label as:
pin 2(B) oscillator supply (-)
pin 3(C) oscillator supply (+)
pin 11 (M) oven monitor (+)
pin 14(R) oven supply (+)
pin 15(S) two wire oven supply (-)

oven monitor (-)

n. Inspect the connector for poor solder joints, bent or damaged pins. Double check the labeling

of the banana plugs to be sure the polarity markings are correct. If the voltages are

connected the wrong way, damage to the 10811A may occur.

Model 10811A/B

8-65. SPECIAL CABLE FOR THE 10811 B.

8-66. A micon to BNC adaptor cable is available for the 10MHz output signal. Order HP Part Number

05060-6116 (see

Figure 8-13).

8-67. SPECIAL PARTS REPLACEMENT CONSIDERATIONS

8-68. Several mechanical parts and components must be replaced as a pair or require special

consideration. They are:
a. Oven mass assembly and thermistor: If the thermistor (RT1) is found to be defective, the

thermistor and oven mass assembly must be replaced as one item, HP Part Number 10811-

60106. Do not attempt to replace the thermistor alone.

53

Model 10811A/B

b. Crystal and Temperature Set Resistor: The replacement crystal for Y1 will be accompanied

by the required temperature set resistor (R20) for the oven. This resistor must be installed
with the new crystal. The crystal and R20 can be ordered using HP Part Number 10811-

60108. If the temperature set resistor is found to be defective only, it must be replaced with
the same value and tolerance. If the temperature set resistor (R20) is unreadable, the value
required can be determined by finding the oven temperature value marked on the crystal (Y1).
The required resistor can then be determined from

Table 8-1. When Y1 is replaced, the nut

which secures it to the oven mass should be tightened to a torque of 44 newton-metres (5 in.­Ibs.). This will insure maximum heat transfer without overstressing the crystal package.

c. 10811B Bottom cover: If any part of the 10811B bottom cover is found to be defective, the

complete bottom cover must be replaced (HP Part Number 10811-60107). Once the
insulating foam is attached to the bottom cover, feedthroughs and terminals cannot be
replaced without impairing the heat insulating abilities of the bottom cover. Do not attempt to

repair the cover or replace the flex circuit.

Table 8-1. Temperature Set Resistor List.

OVEN TEMP °C

RESISTOR VALUE PART NUMBER

80.0 1.33K 0698-7239

80.1 1.29K 0698-6981

80.2 1.25K 0698-6973

80.3 1.21K 0698-7238

80.4 1.18K 0698-3512

80.5 1.15K 0698-4469

80.6 1.10K 0698-7237

80.7 1.07K 0698-4196

80.8 1.04K 0698-6970

80.9 1.00K 0698-7236

81.0 968 0698-0096

81.1 931 0698-4465

81.2 909 0698-7235

81.3 866 0698-3495

81.4 825 0698-7234

81.5 787 0698-4014

81.6 750 0698-7233

81.7 715 0698-3700

81.8 681 0698-7232

81.9 649 0698-4460

82.0 619 0698-7231

82.1 600 0757-1100

82.2 562 0698-7230

82.3 511 0698-7229

82.4 500 0698-5852

82.5 464 0698-7228

82.6 422 0698-7227

82.7 383 0698-7226

82.8 348 0698-7225

82.9 316 0698-7224

83.0 287 0698-7223

83.1 261 0698-7222

83.2 215 0698-7220

83.3 196 0698-7219

83.4 162 0698-7217

83.5 121 0698-7214

83.6 100 0698-7212

83.7 61.9 0698-7207

83.8 34.8 0698-7201

83.9 0 jumper

84.0 0 jumper

54

Model 10811A/B

d. Oven heater transistors Q7 and Q8: The replacement transistors for Q7 and Q8 have formed

leads for easy installation (Part Number 10811-80001). Holding screws for Q7 and Q8 must

also be torqued to a specific force of 44 newton-metres (5 in.-Ibs.). There are several

available Pozidriv

torquing screwdrivers.

8-69. OVEN CONTROLLER TROUBLESHOOTING

8-70. General

8-71. The oven controller section consists of three major circuits and a 10V voltage reference for

increased stability of sensitive circuits.
ponents involved in their operation.

8-72. The temperature sense circuit monitors the temperature of the oven mass and reduces the power

drawn by the oven heater transistors when the oven mass has reached operating temperature.
After power cut-back, this circuit monitors the oven mass temperature and controls the power in
the heaters to maintain the constant temperature. The thermistor (RT1) has a negative
temperature coefficient. At room temperature the thermistor resistance is approximately 100K
ohms, while at operating temperature (-82°C) the resistance is approximately 9K ohms. Shorting
the thermistor to oven common makes the oven mass appear too hot to the temperature sense
circuit. This in turn causes the temperature sense circuit to shut off power to the oven heaters.
This technique is used in the troubleshooting procedure.

8-73. The warm-up current limit circuit controls the maximum current the oven may draw during warm-

up (380 to 490 mA with 20V dc oven input). This circuit is only active during the warm-up phase
of the oven circuit operation.

Figure 8-14 shows the major circuits and active com-

Figure 8-14. Oven Controller Block Diagram

55

Model 10811A/B

8-74. Normal Operation

8-75. When the oven is tested under normal conditions (-25°C ambient temperature) it will initially draw

380 to 490 mA. After 5 to 10 minutes the oven current will start to drop. Over the next 10 to 15
minutes the oven current will fall to the 60 to 150 mA range where it will stabilize. The oven circuit
should not oscillate.

WARNING

DO NOT OPERATE THE OVEN CIRCUITS WHEN THE OVEN MASS IS
OUTSIDE OF THE OSCILLATOR INSULATED HOUSING. DOING SO
WILL OVERHEAT THE OSCILLATOR CIRCUITS INSIDE THE OVEN
MASS AND CAUSE PERMANENT DAMAGE. ALL OVEN TEST POINTS
ARE A V AILABLE WITH THE OVEN MASS AND OVEN CONTROLLER
CIRCUIT INSIDE THE HOUSING.
WHEN OSCILLATOR COVER AND INSULATOR ARE REMOVED
THERMAL FUSE WILL NOT PROTECT CIRCUIT FROM OVER­HEATING. APPLY OVEN POWER ONLY WHEN ACTUALLY MAKING
MEASUREMENTS FOR TROUBLESHOOTING OR AS DIRECTED IN
TROUBLESHOOTING TREE,

TABLE 8-2.

8-76. TROUBLESHOOTING

8-77. Table 8-2 is a troubleshooting' tree for the oven circuits. The troubleshooting procedure separates

the different functional circuits by monitoring the oven supply current during different operating
conditions. For example, if the warm-up current is excessive, this indicates a trouble in the warm­up current limit circuit, or the current control and heater circuit. If shorting the thermistor reduces
the current being drawn from the power supply, this indicates the current control circuit is
operating and the problem is most likely in the warm-up current limit circuit.

8-78. As with most troubleshooting trees this is intended to be a guide to the trouble area. It is not a

substitute for technical skill in isolating the faulty components.

8-79.

Table 8-3 (next to schematic diagram) gives normal circuit voltages during warm-up, operation,

and when thermistor RT1 is shorted to ground. Use this table during troubleshooting.

8-80. Troubleshooting Cautions

8-81. When oven current is excessive, turn on the power supply only long enough to make the

necessary measurements. Do not leave power on if the oven is drawing excessive current. With
the housing cover and foam insulator removed, the thermal fuse (F1) cannot protect the circuits in
the oven mass from overheating and damage.

8-82. Flex Damage

8-83. If a tear in the flex circuit occurs, the tear can continue until a trace is broken. To stop a tear, use

a pair of scissors and cut around the tear. DO NOT CUT A SHARP CORNER as this will cause a
stress concentration allowing the tear to start again. A hole-punch may also be used. Punch a
hole in the flex so as to remove the forward end of the tear.

56

Model 10811A/B

Table 8-2. Oven Controller Troubleshooting Tree

57

Model 10811A/B

8-84. OSCILLATOR TROUBLESHOOTING

8-85. The oscillator circuits are relatively simple and straightforward. The following paragraphs will

briefly describe the major circuit areas, a troubleshooting outline, and some helpful suggestions to
make the troubleshooting process easier. The oscillator consists of four sections. They are:

1. Oscillator Q1, Q2, and associated circuitry.

2. AGC Q3, CR4, CR5, and R6.

3. Output circuit Q5, Q9.

4. 5.7V power supply CR2, CR3, and Q4.

The oscillator is the signal source. Its output level is controlled by the AGC. The 5.7V power
supply provides an extra-stable clean voltage source for the oscillator circuits. The output circuits
provide a high level signal capable of driving a 50 to 1K ohm load.

8-86. NORMAL OPERATION

8-87. The output of the oscillator circuit at Q2(C) is a 10 MHz undistorted sine wave; with an amplitude

of approximately 2.8V p-p. The AGC voltage (measured at CR5-C13 junction) is approximately -

1.5V. The 10 MHz signal passes through Q5 to Q9(B) at about the same level. The voltage gain
of amplifier Q5 (base to collector) is approximately 2 with a 50-ohm load on the output. The
output of transformer T1 is approximately 1.5V p-p. All10 MHz signals found in the 10811A/B will
be undistorted sine waves unless otherwise noted in

Table 8-4 (next to the schematic diagram).

8-88. OSCILLATOR TROUBLESHOOTING TECHNIQUES

8-89. When troubleshooting the oscillator section, remove the oven mass from the housing and the

covers from the oven mass as described in
use special connector described in
oscillator circuit common in 10811B. Set the power supply current limit to 60 mA. Do not apply

power to the oven circuits!

8-90. Initial troubleshooting and probing should be done on the backside of the boards (trace side)

while they are secured to the oven mass (see
more easily handled. When the fault is isolated to a few components, the unit may then be
disassembled for final troubleshooting and repair.

8-91. Helpful Hints

1. Most points in the oscillator circuits cannot be measured with a dc voltmeter. The reactance
of the voltmeter probe and leads will load the circuit and give false readings. Instead, use an
oscilloscope with a high input impedance probe for these measurements.
section normal voltages) indicates when a dc voltmeter can be used.

2. Before reinstalling the oven mass into the housing, adjust the output amplitude (with R6) to

0.53V into a 50-ohm load. Although this value is slightly below normal, the output will
increase slightly when the unit is reassembled and is at normal operating temperatures.

3. If a tear in the flex circuit occurs, go to

paragraph 8-59. Connect 12V to the oscillator section;

paragraph 8-61 for 10811A, connect power to T1(1) and

paragraph 8-59, step 10). This way the circuits are

Table 8-4 (oscillator

paragraph 8-82 for repair instructions.

58

Model 10811A/B

8-92. TROUBLESHOOTING INFORMATION

8-93. Symptoms of failures in the oscillator sections will generally fall into one of the following

categories:

1. No output.

2. Output amplitude is low or high.

3. Output is distorted (contain excessive harmonics).

4. Excessive drift of output frequency.

5. Time domain frequency stability (short-term stability) does not meet specifications.

8-94. Troubleshooting of these faults will be discussed in the following paragraphs.

8-95. NO OUTPUT. This is usually easy to repair by simple signal tracing. Localized faultfinding (to

actual defective component) can be somewhat more difficult if the problem is in the main
oscillator circuit (Q1, Q2, and AGC). If the fault appears to be in the oscillator section and does
not yield to normal troubleshooting techniques, measure the AGC voltage at the junction of CR5­C13 (see Note 7 on
problem may be a defective quartz crystal (Y1). To verify this possibility, obtain a 10 µH (HP Part
No. 9100-2265) and a 12 µH inductor (9100-2242). Use the HP numbered parts as these have
been tested in the circuit. On the oscillator board, remove the red and blue wires connecting the
crystal to the board. Place the 12 µH inductor in place of these wires. With 12V applied to the
circuit, adjust the FREQ ADJUST (C1), and amplitude control (R6) for a good sine wave signal.

At some settings of C1 and/or R6, intermittent oscillations may appear. Some minor adjustment of C1 and/or R6 should clear this. If this fails, replace the 12 μH inductor with the 10 μH inductor and repeat the C1/R6 adjustment.

If replacing the crystal with an inductor produces oscillation, this is a very good indication of a
defective crystal. When replacing crystal Y1, read
ations. If the circuit will still not oscillate, the problem is most likely one of the oscillator circuit
elements.

8-96. OUTPUT AMPLITUDE HIGH OR LOW. Many times this can be cured by the adjustment of R6 as

described in
monitor the signal at Q6(C) with an oscilloscope and set R6 to obtain an amplitude of 2.8V p-p.
Then check Q5 and Q9 stages. If the R6 adjustment isn't effective, you should suspect the AGC
circuitry (Q3, CR4, CR5, C5, C6, R5, R6, R7, or Q1).

paragraph 5-14. If the correct amplitude cannot be obtained with this adjustment,

Table 8-4, Oscillator Normal Voltages). If this voltage appears normal, the

NOTE

paragraph 8-68(b), Special Parts Consider-

8-97. OUTPUT DISTORTION. Check the distortion with a spectrum analyzer (see

procedure). If the distortion products are harmonically related to 10 MHz, trace the signal to the
distorting stage. If the distortion is not harmonically related to the 10 MHz output:

1. Check the mode suppression components of L2/C5 and/or L3/C6. These components
suppress oscillations at all frequencies other than 10 MHz.

2. Check for spurious oscillations from the amplifier stages and oscillator transistors.

8-98. EXCESSIVE DRIFT OF OUTPUT FREQUENCY. When a quartz crystal oscillator has not been

operated for a long period of time, or if it has been subjected to severe thermal or mechanical
shock, the oscillator may take some time to stabilize. In most cases, the crystal will drift and then
stabilize at or below the specified rate within a few days after being turned on. In isolated cases,
depending on the amount of time the oscillator has been off and the environmental conditions it
has experienced, the 10811A/B may take up to 1 week to reach the specified aging rate. This
should be taken into consideration if the drift rate of the unit is out of specifications. If the unit has
had sufficient time to stabilize but is still out of specification, the most likely cause of excessive
drift is a defective crystal (Y1). If Y1 is to be replaced, read
causes are unstable C3 and/or C8.

paragraph 8-68(b). Other possible

Table 4-2 step 2. for

59

Model 10811A/B

8-99. TIME DOMAIN STABILITY (SHORT-TERM STABILITY) OUT OF SPECIFICATION. Mea-

surement of time domain stability is somewhat difficult and exacting. If the 10811A/B fails this test,
be sure no signal sources other than the test reference are operating near the measurement
system, as these can cause interference with the measurement. Other sources of error are
vibration, nearby electrical equipment, poor shielding, or motors that can radiate signals into the
10811A/B. The failure to connect the HC input (to ground) can cause poor frequency stability as
can a noisy voltage being used for the EFC control. If another oscillator is available (known to be
good), verify the accuracy of the measurement system. This could save considerable
troubleshooting time.

8-100. Two other possibilities external to the oscillator are the oven and oscillator power supplies. These

must be stable in order for the circuits to function properly. See

Table 1-1, Specifications, and

paragraph 2-6 for power supply noise requirements.

8-101. When troubleshooting this condition, carefully monitor the output waveform. Check for distortion

or intermittent distortion, small amplitude variations (there should be none), or spurious
oscillations on the output signal. Use a spectrum analyzer for this test (see

Table 4-2, step 3).

These symptoms can be more readily traced than small frequency fluctuations.

8-102. Almost any of the circuits can cause poor short-term stability. However, the most probable cause

is crystal Y1. Other possible causes are the oven controller circuit (keeps changing temperature)
or defective frequency determining components (CR1, C1, C3, C8, or instability in the 5.7V
supply). Q1 and Q2 are also good suspects. Instability can also be caused by the AGC circuit, but
this is usually visible as output amplitude variations or instability on the output waveform.

8-103. To check oven stability, allow the 10811A/B to operate normally away from drafts or sudden

temperature changes. Allow the unit to warm up for at least 1-hour then connect a sensitive
recorder or digital voltmeter to the OVEN MONITOR OUTPUT. Once the oven has stabilized, the
monitor voltage should not vary more than 100-200 µV when measured over 3- to 4-minute
periods. Causes of oven instability are temperature sensing elements RT1, U2, U3, and
associated components.

60

Table 8-3. Oven Circuit Voltages·

Model 10811A/B

VOLTAGE POINT

Q6B 1.6 2. .25

Q6C 11.4 11.4 11.4

Q6E 1. 1.3 0
Q7B 12.5 12.7 11.9

Q7C 20. 20. 20.

Q7E 11.4 11.4 11.4
Q8B 1. 1.3 0

Q8C 11.4 11.4 11.4

Q8E .07 .23 0

U1 Pin 1 8.9 1.8 8.9
U1 Pin 2 .07 .23 0
U1 Pin 3 .2 .23 .2
U1 Pin 5 4. 4.1 3.8
U1 Pin 6 4. 4.1 3.8
U1 Pin 7 3.3 4.8 1.5

U2 Pin 2 10. 10. 10.
U3 Pin 6 3.5 19.0 .5

OVEN AT OVEN COLD (JUST RT1

OPERATING TEMP. AFTER TURN-ON) GROUNDED

*Voltage readings taken with oven supply voltage of 20V dc and insulating foam and cover removed.
Voltages are approximate and will vary slightly from unit-to-unit.

Table 8-4. Oscillator Section Normal Voltages (see Notes 1, 2, 3)

VOLTAGE

POINT

C3/R3 1 to 4 - Note 8

CR5/C13 - -1.5 Notes 4 and 7

CR3(C) 0 6.3 Note 4

Q1(B) 1 .75 Note 8
Q1(C) 0 5.5 Note 4
Q1(E) .9 .03 Note 8

Q2(B) 0 2.7 Note 4
Q2(C) 2.7 5.6 Note 8
Q2(E) .06 2 Notes 4 and 5

Q3(B) 2.7 5.6 Note 8
Q3(C) 0 11.8 Note 4
Q3(E) 2.4 4.9 Notes 4 and 6

Q4(B) 0 6.3 Note 4
Q4(C) 0 10.3 Note 4
Q4(E) 0 5.6 Note 4

Q5(B) 2.7 3.1 Note 8
Q5(C) 0 11.8 Notes 8 and 9
Q5(E) 2.8 2.6 Note 8

Q9(B) 2.8 2.8 Note 8, 9
Q9(C) 5.1 11.8 Note 8, 9
Q9(E) 2.5 1.9 Note 8

AC (p-p) DC

NORMAL

VOLTAGES

REMARKS

NOTES:

1. All voltages taken with 12V oscillator supply.

2. Voltages are approximate and will vary slightly from unit-to-unit.

3. All ac voltages are sine waves except Q2(E) and Q3(E).

4. This dc voltage may be measured with a standard dc voltmeter. All other voltages should be measured with an
oscilloscope and high impedance probe to minimize circuit loading.

5. Waveform is

6. Waveform is slightly flattened on the bottom.

7. This is the AGC voltage. Value shown is nominal with oscillator operating. If the oscillator is not oscillating, the
AGC voltage will be -+2.5V.

8. Measure both ac and dc voltages with an oscilloscope and a high impedance probe to minimize circuit loading.

9. AC voltage at Q9(C) measured with 50-ohm load on the output.

61

Model 10811A/B

Page Intentionally Left Blank

62

Model 10811A/B

63

Model 10811A/B

64

Figure 8-15. Oven Controller Schematic Diagram

Model 10811A/B

65