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
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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

Model 339A Section I
Table 1-1. Specifications (Cont’d).
fundamental is removed for further analysis using
oscilloscope or low frequency spectrum analyzer.
Output Voltage: 1Vrms ±5% open circuit for full
scale meter indication, proportional to meter
deflection
Output Resistance: 1kfl ±5%,
VOLTMETER
Voltage Range:
1mV rms full scale to 300 Vrms full scale
(-60 dB to +50 dB full scale, meter calibrated in dBV
and dBm into 600 0)
Frequency Range:
10 Hz to 110 kHz
Accuracy (% of range setting
I
20 Hz to 20 kHz ±2%
Monitor Output:
Provides scaled presentation of input signal for further
analysis using oscilloscope or low frequency spectrum
analyzer.
Output Voltage: 1Vrms ±5% open circuit for full
scale meter indication, proportional to meter
deflection.
Output Resistance: 1kll ±5%.
RELATIVE INPUT LEVEL
Defection and Meter Indication
True rms detection for waveforms with crest factor s: 3.
Meter reads true rms volts, dB V, and dBm into 60011.
Input Impedance:
100 kl) *1.0% shunted by <100 pF Input High to
Low. OSCILLATOR
Provides aratio measurement relative to an operator
selected reference level with readout directly in dB Vor
dBm (600 11).
Voltage range, frequency range, accuracy
specifications, and monitor are the same as in
VOLTMETER mode. (Accuracy is relative to OdB set level
input.)
Frequency Range:
10Hz to 110kHz in 4overlapping decade ranges with 2
digit resolution Frequency vernier provides continuous
frequency tuning between 2nd digit switch settings.
Output Level:
Variable from <1mV to >3Vrms into 600 0with 10
dB/step LEVEL control and 10dB VERNIER adjustment.
OSC LEVEL position on function switch allows aquick
check of oscillator level without disconnecting leads to
device under test.
OFF position on Oscillator LEVEL control provides fast
signal-to-noise measurement capability. Oscillator
output terminals remain terminated in 60011.
Frequency Accuracy:
±2% of selected frequency (with FREQUENCY VERNIER
in CAL position).
Level Flatness:
20 Hz to 20 kHz
10Hz to 1 1 0kHz ±0.1 dB ±0.2 db
Distortion (> 600 0load, <3 Voutput,):
10 Hz to 20 kHz
20 kHz to 30 kHz
30 kHz to 50 kHz
<-95 dB (0.0018%) THD
<-85 dB (0,0056%) THD
<-80 dB (0.01%) THD
50 kHz to 110 kHz <-70 dB (0.032%) THD
Output Resistance:
60011 ±5%
AM DETECTOR
Frequency Range:
Carrier frequencies: 550 kHz to 1.6 MHz.
Modulation frequencies: 20 Hz to 20 kHz.
Distortion introduced by AM Detector Iwith 30 kHz filter
switched INI:
Up to 85% Modulation: <-36 dB (1.6%) THD
85% to 95% Modulation: <-30 dB (3%) THD
Input Level
Maximum: 60 Vpeak
Modulation signal level:
2.0 Vrms minimum
10 Vrms maximum
Monitor Output (with modulated RF earner applied to
AM Detector inputI:
1-3

Section 1
Model 339A
Table 1-1. Specificatons (Cont’d).
Distortion mode: Provides scaled presentation of
demodulated input signal after fundamental is
removed
Voltmeter and Relative Input mode: Provides scaled
presentation of demodulated input signal.
Output Voltage and Output Resistance are the same
as in Distortion mode.
Table 1-2. Typical Operating Characteristics.
GENERAL
Operating Environment
:
Weight:
Temperature 0°C to 50°C.
Humidity Range: <95%, 0°C to 40°C.
Net 8.2 kg (1 8lbs.): shipping 11.3 kg (25 lbs.).
Dimensions:
Storage Temperature: 426 mm wide x146 mm high x442 mm deep (16.75"
-40^0 to +6b°C. wide x5.75" high x17.4" deep).
Power:
100/120/220/240. -i-5%. -10%. 40 to 66 Hz, 200 mA
max.
Table 1-3. Recommended Test Equipments.
Instrument Critical Specification Recommended Model Use
AC Calibrator Frequency:
10 Hz -110 kHz
-hp- Model 745A
AC Calibrator PAT
Output Level:
1mV -300 Vrms
Level Accuracy:
±.2%
Output Impedance:
<50 Q
-hp- Model 746A
High Voltage
Amplifier
True RMS Frequency Range -hp- Model 3403C PT
Voltmeter 10 Hz -110 kHz
Voltage Range
1mV -10 Vrms
Measurement Accuracy:
±.5%
Measurement Resolution
.1% of full-scale
Crest Factor:
54
True RMS
Voltmeter
Pulse Generator Pulse Output
Amplitude:
10Vp-p
Pulse Width:
Variable, 1msec -10*isec
Repetition Rate:
100 Hz -10 kHz
-hp- Model 801 1A
Pulse Generator
P
Oscilloscope Bandwidth
DC -2MHz
Sweep Time
.1 Ms-.5 sec/div
Sensitivity:
.1 V/div.
-hp- Model 1221 A
Oscilloscope
PT
1-4

Model 339A Section I
Table 1-3. Recommended Test Equipments (Cont’d).
Instrument Critical Specification Recommended Model Use
Frequency Counter Frequency Range:
10 Hz -110 kHz
Frequency Resolution:
.1 %of reading
-hp- Model 5300A
Counter Mainframe
-hp- Model 5302A
Counter Module
P
Spectrum Analyzer Frequency Range:
10 Hz -330 kHz
Frequency Resolution:
.1 Hz
Input Amplitude:
1V
Dynamic Range:
50 dB
Measurement
Resolution:
x.1 dB
Minimum Bandwidth:
3Hz
-hp- Model 3044A
Spectrum Analyzer PA
Tuneable Notch
Filter
Frequency Range
10 Hz -110 kHz
Notch Depth:
3? -80 dB
i»*. j.i oor» A
-rip* iviuuci
Distortion
Measurement
Set
P
Low Distortion
Oscillator
Frequency Range:
10 Hz -110 kHz
Output Level:
3Vrms into 600 il
THD:
>-95 dB (10 Hz -20 kHz)
>-85 dB (20 kHz -30 kHz)
>-80 dB (30 kHz -50 kHz)
>-70 dB (50 kHz -110 kHz)
-hp- Model 239A
Oscillator PAT
DC Digital
Voltmeter
Input Range:
4Vdc
Measurement
Accuracy:
±.1%
Resolution:
.01% of full-scale
-hp- Model 3465A
Digital Voltmeter AT
Resistors 600 !l Resistive
Load
-hp- Accessory No.
11095A PA
600 il 1% Metal
Film
-hp- Part No.
0698-5405
60 kil 1%Metal
Film
-hp- Part No.
0698-5973 P
100 kil .1%
Metal Film
-hp- Part No
0698-4158
1kil 1%
Metal Film
-hp- Part No.
0757-0280
P=Performance Test
A-Adjustment Procedures
T-Troubleshooting

Model 339A Section II
SECTION II
INSTALLATION
2-1. INTRODUCTION.
2-2. This section of the manual contains information and
instructions necessary to install the Model 339A
Distortion Measurement Set. Also included are initial
inspection procedures, power and grounding require-
ments, environmental information, and packaging
instructions.
2-3. INITIAL INSPECTION.
2-4. This instrument was carefully inspected, both
mechanically and electrically, before shipment. It should
be free of mars and scratches and in perfect electrical
ordep. The instrument should be inspected upon receipt
for damage that might have occured in transit. 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 instrument has
been mechanically and electrically inspected. Procedures
for testing the electrical performance of the Model 339A
are given in Section IV of this manual. If the contents are
incomplete, if there is mechanical damage or defect, or if
the instrument does not pass the Performance Tests,
notify the nearest Hewlett-Packard Office. (A list of the-
hp- Sales and Service Offices is presented at the back of
this manual.) If the shipping container is damaged, or the
cushioning material shows signs of stress, notify the
carrier as well as the Hewlett-Packard Office. Save the
shipping materials for the carriers inspection.
2-5. PREPARATION FOR USE.
2-6. Power Requirements.
2-7. The Model 339A requires apower source of 100.
120, 220, or 240 Vac (+5% -10%), 48 Hz to 66 Hz single
phase. Maximum power consumption is 48 VA.
2-8. Line Voltage Selection.
2-9. Before connecting ac power to the Model 339A
make sure the rear panel line selector switches are set to
correspond to the available power line voltage and that
the proper fuse is installed, as shown in Figure 2-1. The
instrument is shipped from the factory with the line
voltage and fuse selected for 120 Vac operation.
2-10. Power Cable.
2-11. Figure 2-2 illustrates the standard configurations
used for -hp- power cables. The number directly below
each drawing is the -hp- part number for apower cable
equipped with aconnector of that configuration. If the
100 Volt! IZO Volts
NOMINAL OPERATING RANGE
VOLTAGE -10%. +5% of nominal FUSE
100 volts 90 to 105 volts
120 volts 108 to 126 volts 0.25 A
220 volts 198 to 231 volts
240 volts 216 to 252 volts
Figure 2-1. Line Voltage Selection.
appropriate power cable is not included with the
instrument, notify the nearest -hp- Sales and Service
Office and the proper cable will be provided.
2-12. Grounding Requirements.
2-13. To protect operating personnel, the National
Electrical Manufacturer's Association (NEMA)
recommends that the instrument cabinet and front panel
be grounded. The Model 339A is equipped with athree
Figure 2-2. Power Cord Configurations.

Section II
conductor power cable which, when plugged into an
appropriate receptacle, grounds the instrument.
2-14. Bench Use.
2-15. The Model 339Ais shipped with plastic feet and tilt
stands installed and is ready for use as a bench
instrument. The plastic feet are shaped to permit
“stacking” with other full-module Hewlett-Packard
instruments. The tilt stands permit the operator to elevate
the front of the instrument for operating and viewing
convenience.
2-16. Rack Mounting.
2-17. The Model 339A may be rack mounted by adding
rack mounting kit Option 908 or Option 909. Option 908
contains the basic hardware and instructions for rack
mounting; Option 909 adds front handles to the basic
rack mount kit. The rack mount kits are designed to
permit the instrument to be installed in astandard 19inch
rack.
2-18. ENVIRONMENTAL REQUIREMENTS.
WARNING ^
To prevent electrical shock orfire hazard,
do not expose the instrument to rain or
moisture.
2-19. Operating and Storage Temperature.
2-20. In order to meet the specifications listed in Table
1-1, the instrument should be operated within an am-
bient temperature range of 0°C to +50°C (+32°F to
+122°F).
2-21. The instrument may be stored or shipped where
the ambient temperature range is within -40°C to
+65°C (-40°F to +149°F). However, the instrument
should not be stored or shipped where temperature fluc-
tuations cause condensation within the instrument.
Model 339A
2-22. Humidity.
2-23. The instrument may be operated in environments
with relative humidity of up to 95%. However, the
instrument must be protected from temperature extremes
which cause condensation within the instrument.
2-24. Altitude.
2-25. The instrument may be operated at altitudes up to
4572 meters (15,000 feet).
2-26. REPACKAGING FOR SHIPMENT.
NOTE
If the instrument is to he shipped to Hewlett-
Packard for service or repair, attach atag to
the instrument identifying the owner and
indicating the service or repair to be
accomplished. Include the model number and
full serial number of the instrument. In any
correspondence, identify the instrument by
model number andfull serial number. Ifyou
have any questions, contact your nearest -hp-
Sales and Service Office.
2-27. The following is ageneral guide for repackaging
the instrument for shipment. If the original container is
available, place the instrument in the container with
appropriate packing material and seal well with strong
tape or metal bands. If the original container is not
available, proceed as follows:
a. Wrap the instrument in heavy paper or plastic
before placing it in an inner container.
b. Place packing around all sides of the instrument
and protect the front panel with cardboard strips or
plastic foam.
c. Place the instrument and inner container in aheavy
carton and seal with strong tape or metal bands.
d. Mark the shipping container “DELICATE
INSTRUMENT', “FRAGILE”, etc.

1. Meter indicates voltage level, distortion in dB or percent,
or VU (volume units) in dB.
2. Filters permit the user to eliminate unwanted frequencies
and noise from the measurement. The filters include a400 Hz
high-pass filter which is normally used to reject power-line
related noise, a30 kHz low-pass filter for use in making "proof
of performance" measurements at AM broadcast stations, and
an 80 kHz low-pass filter to eliminate high frequency noise.
3DISTORTION RANGE control selects the gain of the
distortion measurement circuits to the proper sensitivity for
measuring the applied signal.
4. INPUT RANGE control sets the input range of the
distortion and meter circuits to the proper sensitivity for
measuring the applied signal.
5. Input Range indicators indicate the direction the INPUT
RANGE control must be turned to select the correct range for
the signal applied.
6. FREQUENCY controls determine the fundamental
reiection frequency of the analyzer and the output frequency of
the oscillator.
Figure 3-1. Control. Connector and Indicator
Descriptions.
7. Frequency indicators indicate the direction the
FREQUENCY controls must be turned to bring the analyzer
circuits within "pull-in range" of the fundamental frequency of
the applied signal. This applies only when using an external
signal source.
8. OSCILLATOR OUTPUT terminals. Output impedance is
600 O.
9. OSCILLATOR LEVEL control changes the output level in
10 dB Vsteps from 3mV rms to 3Vrms into 600 n. The LEVEL
control also includes an OFF position which disconnects the
oscillator output and terminates the output terminals with a
600 0resistive load.
10. Oscillator LEVEL Vernier permits the output level to be
varied below the level selected by the LEVEL control. This
makes the oscillator output level continuously variable from
less than 1mV to greater-than 3rms into 600 fl.
11.OSCILLATOR FREQUENCY VERNIER. Frequency range
of the vernier permits the oscillator output frequency to be in-
creased above the frequency selected by the FREQUENCY
controls. Frequency range of the vernier is approximately equal
to one step on the center frequency control.
3-0
12. DISTORTION ANALY2ER (and voltmeter) terminals
provide connection for analyzer and voltmeter inputs.
13. ANALYZER (and voltmeter) INPUT/GND SELECT switch
selects Distortion ANalyzer input with either circuit or chassis
ground or AM DETECTOR input with chassis ground only.
14.AM DETECTOR input terminal provides connection for
amplitude modulated RF signals.
15. Ground Terminal provides connection to 339A Chassis.
16. METER RESPONSE switch selects normal or VU (volume
units) meter response.
17. RELATIVE ADJUST permits the user to set a convenient
reference level on the meter when using the voltmeter
RELative LEVEL FUNCTION.
18. FUNCTION control selects analyzer or voltmeter
functions.
19. MONITOR terminals permit the signal applied to the
meter circuitry to be monitored. The MONITOR output is 1V
rms for afull-scale meter deflection.
With an audio signal applied to the DISTORTION ANALYZER
input the MONITOR output will be:
DISTORTION FUNCTION -Distortion products of the applied
signal after the fundamental has been removed.
INPUT LEVEL -And RELative LEVEL FUNCTIONS. Scaled
presentation of the applied signal.
With amodulated RF signal applied to the AM DETECTOR input
the MONITOR output will provide:
DISTORTION FUNCTION -Scaled presentation of the
demodulated input signal with the fundamental removed.
INPUT LEVEL and RELative LEVEL FUNCTIONS -Scaled
presentation of the demodulated input signal.
The MONITOR terminals are disabled when using the
OSCillator LEVEL FUNCTION.
20. LINE switch applies ac power to the instrument.
21 .AC LINE connector provides connection for ac power.
22. AC VOLTAGE SELECTOR switches setthe instrument to
operate from 100 V, 120 V, 220 V, or 240 Vac power source.
23. FUSE protects the instrument circuits from excessive
current.

Model 339A Section 111
SECTION III
OPERATION
3-1. INTRODUCTION.
3-2. This section contains information and instructions
necessary for operation of the Model 339A Distortion
Measurement Set. Included is adescription of operating
characteristics, adescription of operating controls and
indicators, and functional checks to be performed by the
operator.
3-3. OPERATING CHARACTERISTICS.
3-4, General.
3-5. the Model 339A is designed to measure Total
Harmonic distortion (THD) of signals having a
fundamental frequency between 10 Hz and 110 kHz. the
analyzer section of this instrument measures total
harmonic distortion levels from 100% (0 dB) full-scale to
.01% (-80 dB) full-scale in nine ranges as selected by the
DISTORTION RANGE control, to simplify operation,
the analyzer section features both automatic “set level”
and automatic “nulling”.
3-6. The Auto Set Level feature automatically sets the
measurement reference level over a10 dB Vrange. If the
input signal is outside this range, an LED 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.
3-7. The Auto Nulling feature is fully automatic when
the 339A internal oscillator is used as the signal source.
When using an external signal source, an LED on the
front panel indicates which direction the FREQUENCY
controls must be rotated to be within the Auto Nulling
range.
3-8. The Model 339A includes an AM detector which
has acarrier frequency range of 550 kHzto 1.6 MHz. The
AM detector permits the measurement of THD of a
modulation signal.
3-9. The signal source used in the Mode! 339A is a
“bridged T” oscillator which provides alow distortion
sine-wave signal from 10 Hz to 110 kHz. The operating
frequencies of the oscillator and the analyzer notch filter
are set simultaneously. The output level of the oscillator
is variable from 1mV rms full-scale to 3Vrms full-scale
into a600 fl load.
3-10. The ac voltmeter section of the Model 339A
measures the true rms value of input voltages from 1mV
full-scale to 300 Vfull-scale in twelve ranges. Frequency
response of the meter section is 10 Hz to 110 kHz.
3-11. True RMS VS Average Responding
Detection.
3-12. Since the 339A employs atrue rms converter to
detect the measurement signal, it is less susceptible to
errors than average responding devices. Most average
responding meters are calibrated to indicate the rms
value of apure sine-wave. When reading apure sine-
wave, both the true rms and average responding meters
will give the correct indication. However, when reading
complex signals the average responding meter may be in
error. The amount or error depends upon the particular
signal being measured.
As an example; when measuring asquare-wave, the true
rms meter will give the correct indication of the rms
value. The average responding meter however, will read
11% high. The average responding meter is also affected
by signals with harmonic content. The amount of error
introduced by an average responding meter due to
harmonics is dependent upon the relative amplitude,
phase, and order of the harmonic. The third harmonic
usually causes the greatest amount of error. For example,
when measuring asignal with third harmonic content, an
average responding meter can be in error by +5% to -20%
depending upon the amplitude and phase of the
harmonic, relative to the fundamental frequency. Due to
the errors inherent in average responding meters, a
distortion analyzer which employs this type of detector
will also be subject to the same measurement errors.
These errors can cause indicated distortion readings to be
as much as 1.3 dB below the actual rms value for certain
combinations of second and third harmonics. The Model
339A is not affected by the errors associated with average
responding detectors and will provide more accurate
measurement indications.

Section III Model 339A
3-13. Turn-On and Warm-Up.
3-14. Before connecting ac power to the 339 A, be certain
the rear panel voltage selector switches are set to
correspond to the voltage of the available power line and
that the proper fuse is installed for the voltage selected.
For rated measurement accuracy, the 339A should be
allowed to “warm-up” for at least 15 minutes.
3-15. DISTORTION MEASUREMENT.
3-16. Distortion Measurement Using the 339A
Internal Oscillator.
3-17. The Model 339A Distortion Measurment Set is
designed to provide complete capability for measuring
Total Harmonic Distortion by combining an automatic,
high resolution distortion analyzer and alow distortion
signal source. Figure 3-2 illustrates the fundamental
application of the Model 339A. The figure shows the
equipment configuration and includes an operating
procedure for making THD measurements.
339A DISTORTION
MEASUREMENT SET DEVICE BEING TESTED
ANALYZER
INPUT
PRELIMINARY ADJUSTMENTS.
a. Set the OSCILLATOR LEVEL control to OFF.
b. Set the METER RESPONSE switch to NORMal.
cSet the ANALYZER INPUT/GND SELECT switch to Distortion ANalyzer. (Low input connected to chassis ground or floated as
desired.)
d. Set FILTER switches as desired.
e. Connect the 339A DISTORTION MEASUREMENT SET and the device to be tested as shown.
OSCILLATOR ADJUSTMENT.
fSet the FUNCTION switch to OSCillator LEVEL and adjust the OSCILLATOR LEVEL and LEVEL vernier controls for the desired
signal level as indicated on the meter (Change the METER INPUT RANGE switch as necesary to obtain the proper meter range.)
g. Set the FREQUENCY controls and FREQUENCY VERNIER for the desired output frequency. (Use afrequency counter if
frequency is critical.)
ANALYZER ADJUSTMENT
h. Set the FUNCTION switch to DISTORTION.
i. Select the proper input range by turning the METER INPUT RANGE control in the direction indicated by the INPUT RANGE
indicator lights. The proper input range has been selected when the INPUT RANGE control is set to the lowest range wic
extinguishes both indicator lights.
jAdjust the DISTORTION RANGE control to obtain an "on-scale" meter indication as near full-scale as possible.
kRead the amount of total harmonic distortion (THD) in dB by adding the dB figure on the DISTORTION RANGE control and the
dB reading of the meter, or the amount of THD in per-cent is indicated by the meter reading (second or third scale) relative to te
full-scale per-cent figure on the DISTORTION RANGE control.
Figure 3-2. Distortion Measurement Using 339A
Internal Oscillator.