HP 339A Service manual

hp
339
OPERATING AND SERVICE MANUAL
i
i
i
DISTORTION
MEASUREMENT SET
339A
Whpl HEWLETT
mLriM Packard

Whn1HEWLETT
mLrtm Packard
OPERATING AND SERVICE MANUAL
MODEL 339A
DISTORTION MEASUREMENT SET
Serial Numbers: 1730A01162 and Greater
IMPORTANT NOTICE
This manual applies directly to instruments with serial number
shown on this page. If changes have been made in the instrument
since this manual was printed, a"Manual Changes" supplement
supplied with this manual will define these changes. Be sure to
record this information in your manual. Backdating information
contained in Section VII adapts this manual to instruments having
serial numbers lower than those shown on this page.
^WARNINi^|
To help minimize the possibility of electrical fire
or shock hazards, do not expose this instrument
to rain or excessive moisture.
Manual Part No. 00339-90001
Microfiche Part No. 00339-90051
©Copyright Hewlett-Packard Company 1984
P.O. Box 69, Marysville, Washington 98270 U.S.A.
Reproduced with Permission, Courtesy of Agilent Technologies, Inc.
Printed: December 1979

Model 339A Table of Contents
TABLE OF CONTENTS
Section Page
1.
General Information 1-1
1-1. Introduction 1-1
1-4. Specifications 1-1
1-6. Instrument and Manual
Identification 1-1
1-10. Description 1-1
1-17. Options 1-2
1-19. Recommended Test
Equipment 1-2
Section Page
II. Installation 2-1
2-1. Introduction 2-1
2-3. Initial Inspection 2-1
2-5. Preparation For Use 2-1
2-6. Power Requirements 2-1
2-8. Line Voltage Selection 2-1
2-10. Power Cable 2-1
2-12. Grounding Requirements 2-1
2-14. Bench Use 2-2
2-16. Rack Mounting 2-2
2-18. Environmental Requirements .2-2
2-19. Operating and Storage
Temperature 2-2
2-22. Humidity 2-2
2-24. Altitude 2-2
2-26. Repackaging For Shipment 2-2
Section Page
III. Operation 3-1
3-1. Introduction 3-1
3-3. Operating Characteristics 3-1
3-4. General 3-1
3-11. True RMS vs Average
Responding Detection 3-1
3-13. Turn-On and Warm-Up 3-2
3-15. Distortion Measurement 3-2
3-16. Distortion Measurement Using the
339A Internal Oscillator 3-2
3-18. Distortion Measurement of an
External Source 3-3
3-20. AM Detector 3-3
3-22. Voltmeter Operation 3-3
3-24. Normal Voltmeter Operation 3-3
3-26. Relative Level Operation 3-4
3-28. Oscillator Level Operation 3-4
3-31. VU Measurements 3-4
3-33. Filters 3-4
3-35. Input Ground Select 3-4
3-37. Monitor Output 3-5
Section Page
III. 3-39. Oscillator Operation 3-5
3-40. Frequency Selection 3-5
3-42. Output Level 3-5
3-44. Operational Verification
Checks 3-5
3-46. Preliminary Procedure 3-5
3-48. Oscillator 3-5
3-50. AC Voltmeter 3-5
3-52. Distortion Analyzer 3-6
3-54. Filters 3-6
3-56. Operator’s Maintenance 3-7
3-57. Fuse Replacement 3-7
3-
59. Adjustment of Meter
Mechanical Zero 3-7
Section Page
IV. Performance Test 4-1
4-
1. Introduction 4-1
4-3. Equipment Required 4-1
4-5. Test Record 4-1
4-7. Calibration Cycle 4-1
4-9. Voltmeter Performance Tests 4-1
4-11. Full-Scale Accuracy and
Frequency Response Test 4-1
4-12. Meter Tracking and Monitor
Output Accuracy Test 4-2
4-13. RMS Accuracy
(crest factor) Test 4-4
4-14. Filter Accuracy Test 4-4
4-15. Oscillator Performance Tests 4-5
4-16. Output Level and
Flatness Test 4-5
4-17. Output Impedance Test 4-5
4-18. Oscillator Frequency Accuracy Test .4-6
4-19. Oscillator Total Harmonic
Distortion Test 4-7
4-20. Distortion Analyzer
Performance Tests 4-8
4-22. Fundamental Rejection and
Induced Distortion Test 4-8
4-24. Distortion Measurement
Accuracy Test 4-10
4-25. Residual Noise Test 4-11
4-
26. Input Impedance Test 4-11
Section Page
V. Adjustments 5-1
5-
1. Introduction 5-1
5-3. Equipment Required 5-1
5-5. Adjustment Locations 5-1
iii

Table of Contents Model 339A
TABLE OF CONTENTS (Cont’d)
Section Page
V. 5-7. Factory Selected Components .
.
5-1
5-9. Voltmeter Adjustments 5-1
5-10. Mechanical Meter Zero 5-1
5-12. Gain Adjustments 5-1
5-13. Oscillator Adjustments 5-2
5-14. Amplitude Adjustment 5-2
5-15. Frequency Adjustment 5-2
5-16. Analyzer Adjustments 5-2
5-17. Notch Filter Null Adjust 5-2
5-18. High Frequency Adjustment . .
.
5-4
Section Page
VI. Replaceable Parts
6-1. Introduction
6-4. Ordering Information
6-6. Non-Listed Parts
6-8. Parts Changes 6-1
/6-10. Proprietary Parts 6-2
Section Page
VII. Manual Changes ..7- 1/7-2
7-1. Introduction ..7- 1/7-2
7-3. Manual Changes ...7-1/7-2
7-6. Manual Change Instructions. .....7- 1/7-2
Section Pa8e
VIII. Service 8-1
8-1. Introduction 8-1
8-3. Safety Considerations 8-1
8-8. Recommended Test Equipment 8-1
THEORY OF OPERATION
8-10. General Description 8-1
8-22. Circuit Descriptions 8-2
8-23. Input Circuitry 8-2
O*>£ Amnlir.ar
0*^u. liijjut rvmpiuiwt ^
8-28. Input Overload Protection 8-3
8-30. Analyzer Circuitry 8-3
8-31. Notch Filter 8-3
8-33. Capacitance Neutralizer 8-5
8-35. Amplitude Error Detector 8-6
8-37. Phase Error Detector 8-6
8-39. Auto Set -Level Circuit 8-7
8-41. Meter Circuits 8-7
8-43. Oscillator Circuit 8-8
LIST OF TABLES
Table Page
1-1. Specifications 1-2
1-2. Typical Operating Characteristics 1-4
1-3. Recommended Test Equipments 1-4
4-1. Full-Scale Accuracy and Frequency
Response Test Limits
4-2. Meter Tracking and MONITOR
Output Accuracy Tests
4-3. Oscillator Output Limits
(Flatness Test) 4-6
4-4. Oscillator Frequency Accuracy Test 4-7
4-5. Oscillator Total Harmonic
Distortion Test 4-8
4-6. Fundamental Rejection and Induced
Distortion Test
4-
7. Distortion Measurement Accuracy Test .... 4-1
1
5-
1. Factory Selected Components 5-7
5-
2. Adjustable Components 5-7
6-
1. Standard Abbreviations 6-1
6-2. Code List Of Manufacturers 6-2
6-
3. Replaceable Parts 6-3
7-
1. Manual Changes by Serial Number 7-1/7-2
IV

Model 339A Table of Contents
TABLE OF CONTENTS (Cont’d)
LIST OF ILLUSTRATIONS
Figure ^a8c
2-1. Line Voltage Selection 2-1
2-
2. Power Cord Configurations 2-1
3-
2. Distortion Measurement Using
339A Internal Oscillator 3-2
3-3. Distortion Measurement of an
External Source 3-3
3-1. Control, Connector and
Indicator Descriptions 3-0
4-1. Full-Scale Accuracy and
Frequency Response Test ..
.
4-2. Meter Tracking and Monitor
Output Accuracy Test
4-3. R.MS Accuracy Test 4-3
4-4. Filter Accuracy Test 4-3
4-5. /Oscillator Output Level and
Flatness Test 4-5
4-6. Oscillaotr Output Impedance Test 4-6
4-7. Oscillator Frequency Accuracy Test 4-6
4-8. Oscillator Total Harmonic
Distortion Test 4-8
4-9. Logarithmic Addition of
Harmonic Components 4-8
4-10. Fundamental Rejection and
Induced Distortion Test 4-9
4-11. Distortion Measurement
Accuracy Test 4-10
4-12. Shielded Load Assembly 4-11
4-
13. Input Impedance Test 4-12
5-
1. Notch Filter Null Adjustments 5-3
Figure Pa8e
5-2. Notch Filter High Frequency Adjust . . . 5-5/ 5-6
5-
3. Adjustment Locations 5-7
6-
1. Mechanical Parts Locator 6-15/6-16
7-
1. Amplitude Control Circuit Change 7-1/7-2
8-1. Model 339ASimplified Block Diagram
8-2. Simplified Input Amplifier Schematic .
8-3. Simplified Notch Filter Schematic
8-4. Effect of Feedback
8-5. Simplified Capacitance Neutralizer
Schematic
8-6. Simplified Amplitude Error
Detector Schematic
8-7. Simplified Phase Error
Detector Schematic
8-8. Simplified Auto Set-Level Circuit ..
.
8-9. Simplified Meter Circuit Schematic .
8-10. Simplified Oscillator Circuit
8-11. Simplified Amplitude Control Circuit
8-12. AM Detector and Input
Switching
8-13. Input Attenuator and Input
Amplifier
8-14. Fundamental Rejection Circuit
8-15. Error Detector Circuits
8-6
8-7
8-8
8-8
8-9
8-11 /8-12
8-13/8-14
8-15/8-16
8-17
8-16. Auto Set-Level and Meter
Circuits
8-17. Oscillator Circuits
8-18. Power Supplies
8-19/8-20
8-21 /8-22
8-23/8-24
V

SAFETY SYMBOLS
General Definitions of Safety Symbols Used On Equipment or In Manuals.
h
r±- OR (-±r
rh OR
Instruction manual symbol: the product will be marked with this
symbol when it is necessary for the user to refer to the instruction
manual in order to protect against damage to the instrument.
Indicates dangerous voltage (terminals fed from the interior by
voltage exceeding 1000 volts must be so marked).
Protective conductor terminal. For protection against electrical
shock in case of afault. Used with field wiring terminals to in-
dicate the terminal which must be conne .Tr/Mind KfArP
gl UU1IU UCi Ol V
operating equipment.
Low-noise or noiseless, clean ground (earth) terminal. Used for a
signal common, as well as providing protection against electrical
shock in case of afault. Aterminal marked with this symbol must
be connected to ground in the manner described in the installation
(operating) manual, and before operating the equipment.
Frame or chassis terminal. Aconnection to the frame (chassis) of
!the equipment which normally includes all exposed metal struc-
tures.
Alternating current (power line).
Direct current (power line).
Alternating or direct current (power line).
WARNING |
1
iCAUTION 3
The WARNING sign denotes ahazard. It calls attention to apro-
cedure, practice, condition or the like, which, if not correctly per-
formed or adhered to, could result in injury or death to personnel.
The CAUTION sign denotes ahazard. It calls attention to an
operating procedure, practice, condition or the like, which, if not
correctly performed or adhered to, could result in damage to or
destruction of part or all of the product.
NOTE: The NOTE sign denotes important information. It calls attention
to procedure, practice, condition or the like, which is essential to
highlight.

Model 339A Section I
SECTION I
GENERAL INFORMATION
1-1. INTRODUCTION.
1-2, This Operating and Service Manual contains
information necessary to install, operate, test, adjust, and
service the Hewlett-Packard Model 339A Distortion
Measurement Set.
1-3 This section of the manual contains the performance
specifications and general operating characteristics of the
Model 339A. Also listed are available options and
accessories, and instrument and manual identification
information.
1-4. SPECiFiCATiONS.
1-5. Operating Specifications for the Model 339A are
listed in Table 1-1. These specifications are the
performance standards or limits against which the
instrument is tested. Table 1-2 lists general operating
characteristics of the instrument. These characteristics
are not specifications but are typical operating
characteristics included as additional information for the
user.
1-6. INSTRUMENT AND MANUAL IDENTIFI-
CATION.
1-7. Instrument identification by serial number is
located on the rear panel. Hewlett-Packard uses atwo-
section serial number consisting of afour-digit prefix and
afive-digit suffix separated by aletter designating the
country in which the instrument was manufactured. (A=
U.S.A.; G=West Germany; J=Japan; U=United
Kingdom.) The prefix is the same for all identical
instruments and changes only when amajor instrument
change is made. The suffix, however, is assigned
sequentially and is unique to each instrument.
1-8. This manual applies to instruments with serial
numbers indicated on the title page. If changes have been
made in the instrument since the manual was printed, a
yellow “Manual Changes” supplement supplied with the
manual will define these changes and explain how to
adapt the manual to the newer instruments. In addition,
backdating information contained in Section VII adapts
the manual to instruments with serial numbers lower
than those listed on the title page.
1-9. Part numbers for the manual and the microfiche
copy of the manual are also listed on the title page.
1-10. DESCRIPTION.
1-11. The Model 339A Distortion Measurement Set
combines alow distortion signal source, a high resolu-
tion distortion analyzer, an rms responding voltmeter
and aVU (volume units) meter in one unit.
1-12. The signal source used in the Model 339A is a
“bridged-T” oscillator which provides alow distortion
sine-wave signal from 10 Hz to 110 kHz. The output
amplitude is variable from 1mV rms to 3Vrms into a
600 ohm load and is maintained by an amplitude control
circuit which minimizes amplitude variations even when
fraonanr*\7 ranOM
CiUUlgmE, ll^uwiiv; *»***£,«-*,.
1-13. The distortion analyzer section of the 339A
contains atracking notch filter which is tuned to the
oscillator frequency. The analyzer measures total
harmonic distortion (THD) from 100% full-scale to .01%
full-scale in nine ranges and features both automatic “Set
Level” and automatic “Nulling” to greatly simplify
operation. The Auto Set Level feature automatically sets
the reference level over a10 dB range. If the input signal is
outside this range, aLED on the front panel indicates
whether the INPUT RANGE control setting must be
increased or decreased to be within the “pull-in” range of
the Auto Set Level. The Auto Nulling feature is fully
automatic when the 339Ainternal oscillator is used as the
signal source. When an external oscillator is used as the
signal source, an LED on the front panel indicates which
direction the FREQUENCY controls must be set to be
within the Auto Nulling range. Distortion characteristics
of the input signal can be monitored at the MONITOR
OUTPUT terminals with external equipment (oscillo-
scope, voltmeter, spectrum analyzer, etc.) to provide
additional analysis of the distortion products.
1-14. The Model 339 Ais equippped with an amplitude
modulation (AM) detector which has afrequency
response from 550 kHz to 1.6 MHz. The AM detector
permits the measurement of modulation distortion.
1-15. The 339A contains three active filters, one high-
pass and two low-pass, which enables the user to
eliminate unwanted frequencies and noise to permit
higher resolution measurements.
1-16. The ac voltmeter section of the 339A measures the
rms value of input voltage from 1mV full-scale to 300 V
full-scale in twelve ranges. In the VU meter mode, the
1-1

Section IModel 339A
meter response characteristics are changed to those of a
volume units meter.
1-17. OPTIONS.
1-18. The following options are available for use with the
Model 339A:
Option 907: Front Handle Kit
Option 908: Rack Mounting Kit
Option 909: Front Handle and Rack Mounting Kit
Option 910: Additional Operating and Service
Manual
1-19. Recommended Test Equipment
1-20. Equipment required to maintain the Model 339A is
listed in Table 1-3. Other equipment may be substituted if
it meets the critical requirements listed in the table.
Table 1-1. Specifications.
DISTORTION
Fundamental Frequency Range:
10 Hz to 110 kHz continuous frequency coverage in 4
ji_-—-.»t-> O<Hintf roenlutinn Dictnrtinn
UdOdUC idliyco Willi ^.-uiyu 1-
analyzer and oscillator are simultaneously tuned.
Distortion Measurement Range:
0.01 %full scale to 100% full scale (-80 dB to 0dB) in 9
Detection and Meter Indication:
True rms detection for waveforms with crest factor ^3.
Meter reads dB and %THD (Total Harmonic Distortion).
Meter response can be changed from NORMAL to VU
ballistics with afront panel switch.
Distortion Measurement Accuracy:
20 Hz to 20 kHz
10 Hz to 50 kHz
50 kHz to 110 kHz
±1 dB
+1. -2 dB
+1.5. -4 dB
The above specifications apply for harmonics
<330 kHz.
Fundamental Re/ection:
10 Hz to 20 kHz >100 dB
20 kHz to 50 kHz >90 dB
50 kHz to 110 kHz >86 dB
Distortion Introduced by Instrument (Input >1Vrms)
10 Hz to 20 kHz
20 kHz to 30 kHz
30 kHz to 50 kHz
50 kHz to 110 kHz
<-95 dB
<-90 dB
<-85 dB
<-70 dB
Residual Noise (Fundamental frequency setting <20 kHz, 80
kHz filter in. source resistance $1kCl shielded):
<-92 dB referenced to 1V.
Input Level for Distortion Measurements:
30 mV to 300 Vrms
(100 mV range minimum)
Input impedance:
100 kll rl .0% shunted by< 100 pF input High to Low
DC Isolation:
Input low may be connected to chassis ground or floated
30 Vto reduce the effects of ground loops on the
measurement.
Auto Set Level:
No set level adjustment required. Distortion
measurements are made directly over 10 dB range
selected by input range switch. Two LED annunciators
provide afast visual indication to change input range for
valid distortion measurement. Correct range isindicated
when both annunciators are extinguished.
Auto Null:
Using internal oscillators: No manual frequency tuning
necessary when using internal oscillator as signal
source Oscillator frequency controls simultaneously
tune the analyzer.
Using external frequency source: Two LED annunciators
provide aquick visual indication for the operator to in-
crease or decrease the analyzer frequency controls.
When the analyzer is rough tuned to within one least
significant digit of the fundamental frequency, the in-
dicator lights are extinguished and the 339A auto-null
circuitry takes over to provide afast accurate null
without tedious operator tuning.
input Filters (usable on all functions):
Low Pass
30 kHz -3dB point at 30 kHz, +2.6 kHz, -3kHz.
Provides band limiting required by FCC for proof-of-
performance broadcast testing.
80 kHz -3dB point at 80 kHz, +7kHz, -7.9 kHz.
Normally used with fundamental frequencies
<20 kHz to reduce the effect of higher frequency
noise present in the measured signal.
High Pass
400 Hz -3dB point at 400 Hz, +35 Hz, -40 Hz.
Normally used with fundamental frequencies
>1kHz to reduce the effect of hum components in
the input signal.
Monitor Output:
Provides scaled presentation of input signal after