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TM 11-6625-1576-15
DEPARTMENT OF THE ARMY TECHNICAL MANUAL




ORGANIZATIONAL, DS, GS, AND DEPOT
MAINTENANCE MANUAL
DISTORTION ANALYZER
HEWLETT-PACKARD MODELS
333A AND 334A




HEADQUARTERS, DEPARTMENT OF THE ARMY
MAY 1967
TM 11-6625-1576-15




WARNING

DANGEROUS VOLTAGES

EXIST IN THIS EQUIPMENT

Be careful when working on the power supply and

on the 115-volt ac line connections.

DO NOT TAKE CHANCES !
This manual contains copyrighted material originally
prcpared by the Hewlett-Packard Co.
TM11-6625-1576-15

HEADQUARTERS
TECHNICAL MANUAL )
) DEPARTMENT OF THE ARMY
NO. 11-6625-1576-5 ) Washington, D.C., 1 9 M a y 1 9 6 7

Organizational, DS, GS, and Depot Maintenance

DISTORTION ANALYZER, HEWLETT-PACKARD MODELS 333A AND 334A


Section Page

I GENERAL INFORMATION . . . . . . . . . 1-2.1
1-A.1 Scope . . . . . . . . . . . . . . . . .1-2.1
l-A.2 Index of Publications. . . 1 - 2 . 1 Section V (Cont `d) Page
l-A.3 Forms and Records . . . . . . . . . . . 1 - 2 . 1 5-9. Fundamental Rejection Check . . 5-1
l-1. Description . . . . . . . .1-3 5-10. Second Harmonic Accuracy Check 5-2
1-6. Accessory Features . . . . . . . .1-3 5-11. Distortion Introduced by Instru-
1-8. Options Available . . . . . . . . .1-3 ment Check and Automatic
1-11. Modifications . . . . . . . . . . . . . . . . . . . . . . . . 1-3 Control Loop Operation . . . . 5-2
5-12. Frequency Calibration Accuracy
Section Page Check . . . . . . . . . . . . 5-3
II INSTALLATION . . . . . . . . . . . . . .2-1 5-13. Input Resistance Check . . . . . . 5-4
2-1. Introduction . . . . . . . . . . . . . .2-1 5-14. Input Shunt Capacitance Check . . 5-4
2-3. Inspection . . . . . . . . . . . . . . 2-1 5-15. Minimum Input Level Check . . . 5-4
2-5. Power Requirements . . . . . . . . . . 2-1 5-16. DC Isolation Check . . . . . . . . 5-4
2-7. Three-Conductor Power Cable . . . 2-1 5-17. Voltmeter Accuracy Check . . . . 5-5
2-10. Installation . . . . . . . . . . . . . . 2-1 5-18. High Pass Filter Check . . . . . . 5-5
2-12. Bench Installation . . . . . . . . . 2-1 5-19. Voltmeter Frequency Response
2-14. Rack Installation . . . . . . . . . . 2-1 Check . . . . . . . . . . . . . . . . 5-6
2-16. Repackaging for Shipment . . . . . . 2-1 5-20. Residual Noise Check . . . . . . . 5-6
5-21. AM Detector Check (Model 334A
Section Page only) . . . . . . . . . . . . . . . 5-6
III OPERATING INSTRUCTIONS . . . . . . . 3-1 5-22. Adjustment and Calibration
3-1. Introduction . . . . . . . . . . . . . 3-1 Procedure. . . . . . . . . . . . . . . 5-7
3-4. Controls and Indicators . . . . . . . 3-1 5-25. Meter Mechanical Zero Set . . . . 5-7
3-6. Adjustment of Mechanical Zero . . . 3-1 5-27. Power Supply and Bias
3-8. General Operating Information . . . 3-1 Adjustments. . . . . . . . . . . 5-7
3-9. Input Connections . . . . . . . . . 3-1 5-28. A3R16 and A3R30 Distortion
3-11. Voltmeter Characteristics . . . . . 3-1 Adjust. . . . . . . . . . . . . . 5-9
3-14. Use of Output Terminals . . . . . . 3-1 5-29. Bridge Balance Adjustment (C3) . 5-9
3-16. Operating Procedures . . . . . . . . 3-2 5-30. Voltmeter Gain Adjustments . . . 5-10
3-18. Distortion Measurement . . . . . . 3-2 5-31. Voltmeter Frequency Response
Adjustment . . . . . . . . . . . 5-10
Section Page 5-32. Sensitivity Switch Calibration . . . 5-10
IV THEORY OF OPERATION . . . . . . . . . . 4-1 5-33. Troubleshooting Procedures . . . . 5-11
4-1. Overall Description . . . . . . . . 4-1 5-39. Bottom Shield Removal . . . . . . 5-11
4-3. Block Diagram Description . . . . . 4-1 5-41. Servicing Etched Circuit Boards . 5-11
4-4. Distortion Measuring Operation . . 4-1 5-44. Servicing Rotary Switches . . . . 5-13
4-6. Distortion Measurement in AM
. Carriers . . . . . . . . . . . . . 4-1
4-8. Voltmeter Operation . . . . . . . . 4-1 Section Page
4-10. Schematic Theory . . . . . . . . . . 4-1 VI SCHEMATIC DIAGRAMS 6-1
4-11. Impedance Converter Circuit . . . 4-1 6-1. Schematic Diagrams 6-1
4-14. Rejection Amplifier Circuit . . . . 4-2
4-36. High Pass Filter . . . . . . . . . . . 4-5
4-38. Meter Circuit . . . . . . . . . . . . 4-5
4-46. Power Supply Circuit . . . . . . . . . . 4-7
4-51. RF Detector Circuit (334A only) . l 4-7
Section Page
V MAINTENANCE. . . . . . . . . . . . . 5-1
5-l. Introduction. . . . . . . . . . . 5-1
5-2. Test Equipment Required . . . . . 5-1
5-5. Performance Checks. . . . . . . . . 5-1
i i i
TM 11-6625-1576-15
Model 333A/334A Section 1
Figure 1-1 and Table 1-1




Figure 1-1. Model 333A Distortion Analyzer
Table 1-1. Specifications




1-1
TM 11-6625-1576-15
Section I Model 333A/334A
Table 1-1

Table 1-1. Specifications (Cont `d)




1-2
TM 11-6625-1576-15

SECTION I
GENERAL INFORMATION

1-A.1 Scope


This manual includes installation and operation instructions and
covers operator's, organizational, direct support (DS), general support
(GS), and depot maintenance. It describes Hewlett-Packard (Federal support
Code 80537) Distortion Analyzer Models 333A and 334A (fig. l-l). A
basic issue items list for this equipmnent is not included as part of
this manual.




1-A.2 Index of Publications


Refer to the latest issue of DA Pam 310-4 to determine whether there
are new editions, changes, or additional publications pertaining to the
equipment. DA Pam 310-4 is an index of current technical manuals,
technical bulletins, supply manuals (types 7, 8, and 9), supply bulletins,
lubrication orders, and modification work orders that are available through
publications supply channels. The index lists the individual parts (-10,
-20, - 35P, etc) and the latest changes to and revisions of each equipment
publication.


l-A.3 Forms and Records


a. Reports of Maintenance and Unsatisfactory Equipment. Use equip-
ment forms and records in accordance with instructions in TM 38-750.


b. Report of Damaged or Improper Shipment. Fill out and forward
DD Form 6 (Report of Damaged or Improper Shipment) as prescribed in
AR 700-58 (Army), NAVSANDA Publication 378 (Navy), and AFR `71-4
air Force).


c. Reporting of Equipment Manual Improvements. Report of errors,
omissions, and recommendations for improving this manual by the
individual user is encouraged. Reports should be submitted on DA Form
2028 (Recommended Changes to DA Publications) and forwarded direct
to Commanding General, U. S. Army Electronics Command,
ATTN: AMSEL-MR-NMP-AD, Fort Monmouth, New Jersey 07703.




1-2.1
TM 11-6625-1576-15

Model 333A/334A Section I
Paragraphs l-l to l-13




1-1. DESCRIPTION. band, and lower than 1% distortion can be measured
at the same level of the carrier up to 65 Mc.
1-2. The Hewlett-Packard Models 333A and 334A
Distortion Analyzers are solid state instruments for 1-6. ACCESSORY FEATURES.
measuring distortion and ac voltages. The Models 1-7. The accessory available with the 333A and 334A
333A and 334A include two control loops that auto- Distortion Analyzers is a voltage divider probe, -hp-
matically tune both legs of a bridge circuit which re - Model No. 1000lA. The features of the probe are:
jects the fundamental when the rejection circuit is
initially set within the range of the loops. A high im - a. 10 megohms shunted by 10 pf, giving 10:1
pedance detector which operates from 500 Kc to greater attenuation.
than 65 Mc provides the capability" of monitoring the b. DC to 30 Mc bandwidth.
distortion of the amplitude modulation on an rf carrier.
c. 2% division accuracy.
1-3. Distortion levels of O. 1% to 1OO% full scale are d. 600 v peak input.
measured in seven ranges for any fundamental fre -
quency of 5 cps to 600 Kc. Harmonics are indicated up e. 5 ns rise-time.
to 3Mc. The high sensitivity of these instruments re- 1-8. OPTION.
quires only O. 3 v rms for the 100% set level reference.
The distortion characteristics can be monitored at the 1-9. Option 0l is a standard -hp- Model 333A or 334A
OUTPUT connectors with an oscilloscope, a true rms with a special meter and meter amplifier, compen-
voltmeter, or a wave analyzer. The instruments are sated to permit response to VU (volume units)
capable of an isolation voltage of 400 volts above chassis characteristics.
ground.
1-11. Modifications
1-4. The voltmeter can be used separately for general
purpose voltage and gain measurements. It has a fre - 1-12, Specification C10-334A is a standard
quency range of 5 cps to 3 Mc (20 cps to 500 Kc for 300 334A Distortion Analyzer modified by placing
pv range) and a voltage range of 300 pv to 300 v rms the INPUT and OUTPUT terminals on the rear
full scale. panel of the instrument. The rear terminals
1-5. The AM detector included in the Model 334A is are binding post connectors and are in
a broadband dc restoring peak detector consisting of a parallel with the front panel terminals.
semiconductor diode and filter circuit. AM distortion Due to the rear terminal leads, the shunt
levels as low as O. 3% can be measured on a 3 v to 8 v capacitance of the instrument is increased
rms carrier modulated 30% in the standard broadcast by 20pF .




1-3
TM 11-6625-1576-15
Model333A/334A Section II
Paragraphs 2-1 to 2-19


SECTION II
INSTALLATION

2-1. INTRODUCTION. 2-14. RACK INSTALLATION.
2-2. This section contains information and instruc- 2-15. The Model 333A/334A may be rack mounted by
tions necessary for the installation and shipping of the using the 5" RackMount Kit (-hp- Part No. 5060-0775).
Models 333A/334A Distortion Analyzers. Included Instructions for the conversion are included with the
are initial inspection procedures, power and grounding kit. The rack mount for the Model 333A/334A is an
requirements, installation information, and instruc - ELA standard width of 19 inches. when mounted in a
tions for repackaging for shipment. rack using the rack mount kit, additional support at
the rear of the instrument should be provided if vibra
2-3. INSPECTION. tion or similar stress is likely.
2-4. This instrument was carefully inspected both
mechanically and electrically before shipment. It 2-16. REPACKAGING FOR SHIPMENT.
should be physically free of mars or scratches and in
perfect electrical order upon receipt. To confirm 2-17. The following paragraphs contain a general guide
this, the instrument should be inspected for physical for repackaging of the instrument for shipment. Refer
damage in transit. Also check for supplied accessories, to Paragraph 2-18 if the original container is to be
and test the electrical performance of the instrument used; 2-19 if it is not.
using the procedure outlined in Paragraph 5-5.



2-5. POWER REQUIREMENTS.
2-6. The Model 333A/334A can be operated from any
ac source of 115 or 230 volts (+10%), at 50- 1000 cps.
With the instrument disconnected from the ac power
source, move the slide (located on the rear panel) un-
til the desired line voltage appears. The instrument
can be battery operated by connecting two 28-50 V
batteries (rated 80 milliamperes) to the battery ter-
minal on the rear panel. Power dissipation is 10 watts
maximum.
2-7. THREE-CONDUCTOR POWER CABLE.
2-18. If original container is to be used, proceed as
2-8. To protect operating personnel, the National follows:
Electrical Manufacturers' Association (NEMA) recom-
mends that the instrument panel and cabinet be grounded. a. Place instrument in original container if avail-
All Hewlett-Packard instruments are equipped with a able.
three -conductor power cable, which when plugged in-
to an appropriate receptacle, grounds the instrument
The offset pin on the power cable three-prong connec-
tor is the ground wire. b. Ensure that container is well sealed with strong
tape or metal bands.
2-9. To preserve the protection feature when operat-
ing the instrument from a two-contact outlet, use a 2-19. If original container is not to be used, proceed
three-prong to two-prong adapter and connect the as follows:
green pigtail on the adapter to ground.
a. Wrap instrument in heavy paper or plastic be-
2-10. INSTALLATION. fore placing in an inner container.
2-11 The Model 333A/334A is fully transistorized; b. Place packing material around all sides of in-
therefore, no special cooling is required. However, strument and protect panel face with cardboard strips.
the instrument should not be operated where the am-
bient temperature exceeds 55 C (191 F). c. Place instrument and inner container in a heavy
2-12. BENCH INSTALLATION. carton or wooden box and seal with strong tape or
metal bands.
2-1% The Model 333A/34A is shipped with plastic
feet and tilt stand in place, ready for use as a bench d. Mark shipping container with "DELICATE
instrument. INSTRUMENT," ""RAGILE," etc.
2-1
TM 11-6625-1576-15

Section III Model 333A/334A
Figure 3-1




Figure 3-1. Front and Rear Panel Description
3-0
TM 11-6625-1576-15
Model 333A/334A Section III
Paragraphs-3-l to 3-15


SECTION III
OPERATING INSTRUCTIONS

3-1. INTRODUCTION. applied. Table 3-1 shows the deviation of the meter
indication of a sine wave partly distorted by harmonic..
3-2. The Models 333A and 334A Distortion Analyzers As indicated in the table, harmonic content of less
measure total harmonic distortion from 5 cps to 600 than approximately 10% results in very small errors.
Kc. Harmonics up to 3 Mc are included. The sharp
elimination characteristics, >80 db, the low level of Table 3-1
instrument induced distortion, and the meter accuracy
of the 333A and the 334A result in accurate measure- Effect of Harmonics on Voltage Measurements
ment of low level harmonic content in the input signal. Input Voltage True Meter
Characteristic RMS Value Indication
3-3. An RMS voltmeter is inherent in the 333A and
334A, The voltmeter provides a full scale sensitivity Fundamental = 100 100 100
of 300 u volts rms (residual noise <25 u volts). The Fundamental +10% 100. s 100
voltmeter frequency range is from 5 cps to 3 Mc ex- 2nd harmonic
cept on the 0. 0003 volt range, which is from 20 cps to
500 Kc. Fundamental +20% 102 100-102
2nd harmonic
3-4. CONTROLS AND INDICATORS. Fundamental +50% 112 100-110
3-5. Figure 3-1 illustrates and describes the function 2nd harmonic
of all front and rear panel controls, connectors, and Fundamental +10% 100.5 96-104
indlcators. The description of each component is 3rd harmonic
keyed to a drawing included within the figure.
Fundamental +20% 102 94-108
3-6. ADJUSTMENTS OF MECHANICAL ZERO. 3rd harmonic
3-7. The procedure for adjustment of mechanical Fundamental +50% 112 90-116
zero is given in Section V, Paragraph 5-25. 3rd harmonic
3-8. GENERAL OPERATING INFORMATION. NOTE
This chart is universal in application
3-9. INPUT CONNECTIONS. since time errors are inherent in
3-10. Signal source can be connected to the 333A and all average-responding type voltage-
334A through twisted pair leads or a shielded cable measuring instruments.
with banana plug connectors. Keep all test leads as
short as possible to avoid extraneous pickup from 3-13. In distortion measurements where the fundamen-
stray ac fields, When measuring low-level signals, tal frequency is suppressed and the remainder of the
battery operation is recommended to avoid ground signal is measured, the reading obtained on an average-
loops. Another method for avoiding ground loops is responding meter may deviate from the true total rms
by connecting only one instrument in a test setup value. When residual wave contains many inharmoni-
directly to power line ground through a NEMA (three- cally related sinusoids, the maximum error in the dis-
tortion reading is about 11% low for distorilon levels
prong) connector, Connect all other instruments to below 10%.
the power source through a three-prong to two-prong
adapter and leave the pigtail disconnected. Both the Measured Maximum Error Total
333A and 334A have a dc isolation of