HP 3400A Service manual

OPERATING AND SERVICE MANUAL
RMS VOLTMETER
3400A
,J- MOO* »« VOLIWIt* -^
HEWLETT MPACKARD
J

HEWLETT-PACKARD
M
CERTIFICATION
Hewlett-Packard Company certifies that this instrument met its published
specifications at the time of shipment from the factory. Hewlett-Packard
Company further certifies that its calibration measurements are traceable to the
United States National Bureau of Standards, to the extent allowed by the
Bureau's calibration facility, and to the calibration facilities of other
International Standards Organization members.
WARRANTY AND ASSISTANCE
This Hewlett-Packard product is warranted against defects in materials and
workmanship for aperiod of one year from the date of shipment, except that
in the case of certain components, if any, listed in Section 1of this operating
manual, the warranty shall be for the specified period. Hewlett-Packard will, at
its option, repair or replace products which prove to be defective during the
warranty period provided they are returned to Hewlett-Packard, and provided
the proper preventive maintenance procedures as listed in this manual are
followed. Repairs necessitated by misuse of the product are not covered by this
warranty. NO OTHER WARRANTIES ARE EXPRESSED OR IMPLIED,
INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR APARTICULAR PURPOSE.
HEWLETT-PACKARD IS NOT LIABLE FOR CONSEQUENTIAL DAMAGES.
If this product is sold as part of aHewlett-Packard integrated instrument
system, the above warranty shall not be applicable, and this product shall be
covered only by the system warranty.
Service contracts or customer assistance agreements are available for
Hewlatt-Packard products.
For any assistance, contact your nearest Hewlett-Packard Sales and Service
Office. Addresses are provided at the back of this manual.

fMANUAL CHANGES
Model 3400A
RMS VOLTMETER
Manual Part No. 03400-90008
|New or Revised Item
ERRATA:
Page 5-3, Paragraph 5-12 d and f. Change reference from
0.707 volts to 0.707 millivolts.
Page 6-5/6-6, Figure 6-2. Change value of C403 to
0.1 uF.
Page 6-9/6-10, Figure 6-4. Change Part No. on A7
schematic to 03400-66510.
Page 7-3, Table 7-1. Change C403 to Part No. 0160-0269,
C:fxd 0.1 uF 500 V.
Page 7-4. Change C427 to a selected component, C427*.
Page 7-5. Change R403 and R404 to R403* and R404*.
Change R419* to Part No. 0683-3315, R:fxd 330 «±5%
1/4W.
Page 7-6. Change R426 and R429 to R426* and R429*.
CHANGE NO. 1: For All Serial Numbers.
Page 7-8. Add Part No. 1200-0077, lnsulator:transistor
mica, TQ =3to Miscellaneous Parts.
CHANGE NO. 2: For Serial No. 1218A14726 and
Greater.
Page 7-6. Change R207 to Part No. 0757-0848.
CHANGE NO. 3: For Serial No. 1218A16126 and
Greater.
Page 6-9/6-10, Figure 6-4. Change value of A7R708 to
24.
Page 7-4. Change CR704 to Part No. 1901-0701
.
Page 7-5. Change Q1 to Part No. 1853-0063 Tstr:Si PNP.
Page 7-7. Change R708 to Part No. 0683-2405 R:fxd
24 «±5%1/4W.
CHANGE NO. 4: For Serial Numbers 1218A16126 thru
1218A16425.
If C71 1,R701 or R702 require replacement, replace with
part number listed above. If unable to obtain above part
numbers, replace all three components with part numbers
specified in Table 7-1. This is necessary to maintain the
same oscillator frequency provided by the above
component values.
CHANGE NO. 5: For Serial Numbers 1218A18576 and
Greater.
Page 6-9/6-10, Fig. 6-4. Change T1 lead designation color
codes as follows:
OLD
Primary Side- YEL(L)
BLU
GRN(L)
VIO
NEW
BLK
BLK/GRN
BLK/YEL
BLK/RED
Secondary Side-RED(S) pin 16BLU
ORN(L)pin8 VIO
ALL OTHER SECONDARY COLOR CODES RE
MAIN THE SAME.
Page 7-2, Fig. 7-1. Change Index No. 6, Rear Panel, to
Part No. 03400-00205.
CHANGE NO. 6applies to serial numbers 1218A18776
'and greater.
Page 7-8, Miscellaneous. Delete Insulator, 1200-0043 and
1200-0077.
Add InsulatonTransistor, 0340-0580.
CHANGE NO. 7applies to serial numbers 1218A19076
and greater.
Page 6-3/6-4, A2 Schematic. Change A2C208 from
.01 mF to .02 mF.
Page 7-3, Table 7-1. Change the -hp- Part Number and
description of C208 to 0150-0024,0.02 mF-
CHANGE NO. 8applies to all serial numbers.
Page 1-0, Table 1-1. Change the POWER specification to:
115or 230 Vac ±10%, 48 to 66 Hz, 15VA max.
Page 6-5/6-6, Figure 6-2. Change R433 from 24 Kto
249 K.
C711 is 0170-0019 C:fxd 0.1 uF 200 VR701, R702 are
0757-0852 R:fxd 47.5 K1%.
Page 6-7/6-8, Figure 6-3. Change R617 from 1800 to
1.82 Kand R3* from 1200 to 1210.
10 October 1977 Supplement Afor 03400-90008

»qge 2MANUAL CHANCES Mode! 3400A
Page 6-9/6-10, Figure 6-4. Change R704 from 36 Kto
36.5 K.
Page 7-5 and 7-7, Table 7-1. Change the -hp- Part Num-
bers and descriptions as shown in Table MC-1
.
Table MC-1.
R3*
R433
R434, R435
R617
R703
0757-0734
0698-3217
0757-0739
0757-0738
0757-0765
1,21 kfi ±1%
24.9 kS2 ±1%1/4W
2000 nt1%1/4W
1.82 kn ±1%
36.5 kJ2 ±1-%
CHANGE NO. 9applies to all serial numbers.
Page 1-1. Add the following new paragraphs.
1-16. OPTIONS AVAILABLE.
1-17. Option 910. An additional Operating and
Service Manual may be ordered, part number
03400-90008.
CHANGE NO. 10 applies to Serial Number 1218A20341
and greater.
Page 7-5, Table 7-1. Change the part number of Q401,
402, 403 and 405 to 1853-0288.
Change the part number of Q404 and 406 to 1854-0354.
Page 7-6 and 7-7. Show the following reference designa-
tors as starred value components.
R403*
R404*
R426*
R429*
CHANGE NO. 11 applies to all serial numbers.
Delete all "RMS" designations throughout the entire man-
ual.
Page 73, Table 7-1.
Delete: P. C. Assy -ATTEN 03400-66501 1ea.
Add: P. C. Assy -ATTEN 03400-66511 1ea;
The P.C assemblies are completely interchangeable.
CHANGE NO. 16 (09-14845) applies to serial numbers
1218A21281 and greater.
Page 7-5.
Delete: Q2, Q3 XSTR-GE SP1822 1850-0038 2ea.
Add: Q2, Q3 XSTR PNP 2N5875 1853-0305 2ea.
Page 7-8, Table 7-1.
Delete: R731 R-F 5360 OHM .01 0698-3258 1ea.
R730 R-F 11.3 KOHM .01 0698-4121 1ea.
Add: R730 R-F 10.5 KOHM .01 0698-4477 1ea.
R731 R-F 5620 OHM .01 0757-0200 1ea.
'age 7-4, Table 7-1
.
Delete: CR706 DIO-S1 1910-0025 1ea.
Add: CR706 DIODE-SILICON 1910-0701 1ea.
CHANGE NO. 12 (09-14504) applies to all serial num-
bers.
Page 1-1, Table 1-2. Change item number 1under IDEN-
TIFICATION NUMBER from 10110A to 10110B.
CHANGE NO. 13 (09-14494) applies to serial numbers
1218A21041 and greater.
Page 7-3, Table 7-1. Change part number of C201 from
01 70-001 9to 01 60-2671.
CHANGE NO. 14 (09-14530) applies to all serial num-
bers.
Page 7-6, Table 7-1. Change part number of R104 from
121 00-01 28 to 5061-1101.
CHANGE NO. 15 (09-14840) applies to serial numbers
1218A21121 and greater.

^
OPERATING AND SERVICE MANUAL
(HP PART NO. 03400-90008)
MODEL 3400A
RMS VOLTMETER
SERIALS PREFIXED: 1140A*
*Appendix C, Manual Backdating Changes, adapts this
manual to instruments with serial numbers 0979A13725
and below, and serials prefixed: 322-, 401-, 528-,
and 714-.
Copyright Hewlett-Packard Company 1965
P.O. Box 301, Loveland, Colorado, 80537 U.S.A.
Printed: JUNE 1972

Table of Contents Model 3400A
TABLE OF CONTENTS
Section
I
Page
GENERAL INFORMATION 1-1
1-1. Introduction 1-1
1-3. Description and Purpose 1-1
1-8. Specifications 1-1
1-10. Instrument Identification 1-1
1-12. Equipment Supplied 1-1
1-14. Accessory Equipment Available ... 1-1
Section Page
HINSTALLATION 2-1
2-1. Introduction 2-1
2-3. Initial Inspection 2-1
2-5. Power Requirements 2-1
2-8. Installation 2-1
2-10. Combining Case(-hp- Models 1051A
or 1052A) 2-1
2-12. Adapter Frame (-hp- Part No.
5060-0797) 2-1
2-14. Repackaging for Shipment 2-1
Section Page
mOPERATING INSTRUCTIONS 3-1
3-1. Introduction 3-1
3-3. Controls and Indicators 3-1
3-5. Turn On Procedure 3-1
Operating Instructions 3-1
Applications 3-1
RMS Value of AC Signals with DC
Component 3-1
3-13. RMS Current 3-1
3-15. RMS AC-to-DC Converter 3-1
Section Page
IV THEORY OF OPERATION 4-1
4-1. Introduction 4-1
4-3. General Description 4-1
4-11. Detailed Description 4-1
3-7.
3-9.
3-11.
4-12.
4-15.
4-19.
4-22.
4-27.
4-37.
4-40.
4-48.
Input Attenuator Assembly Al ...4-1
Impedance Converter Assembly A2. 4-1
Second Attenuator Assembly A3. .4-2
Video Amplifier Assembly A4 ... 4-2
Photochopper Assembly A5,
Chopper Amplifier Assembly A6,
and Thermocouple Pair
(part of A4) 4-2
Power Supply Assembly A7 . . ..4-3
Regulator Operation 4-3
Neon Lamp Drive Oscillator .... 4-3
Section
VMAINTENANCE
5-1. Introduction
5-3. Test Equipment
5-5. Performance Checks
5-7. Accuracy, Linearity, and DC Out-
put Check
5-9. Frequency Response Check . . ..
5-10. Input Impedance Check
5-13. Crest Factor Check
5-14. Output Noise Check
5-15 Adjustment and Calibration
Procedures
5-17. Mechanical Meter Zero
5-19. Power Supply Checks
5-21. Low Frequency Calibration ...,
5-25. High Frequency Calibration ...
5-29. Troubleshooting Procedure
5-34. Checking Thermocouples TC401
andTC402
5-37. Thermocouple Replacement ....
5-39. Checking Photochopper Assembly
A5
5-41. Replacement of Neon Subassembly
-hp- Part No. 1990-0224 ... .
5-43. Servicing Etched Circuit Boards . . .
Page
5-1
5-1
5-1
5-1
5-1
5-2
5-2
5-3
5-4
5-4
5-4
5-5
5-5
5-6
5-6
5-7
5-14
5-15
5-15
5-16
Section Page
VI CIRCUIT DIAGRAM 6-1/6-2
6-1. Introduction 6-1/6-2
6-3. Schematic Diagrams 6-1/6-2
6-6. Parts Location Diagrams 6-1/6-2
Section
VII REPLACEABLE PARTS. .
7-1. Introduction
7-4. Ordering Information
7-6. Non- Listed Parts
Page
7-1
7-1
7-1
7-1
Appendix
ACODE LIST OF MANUFACTURERS
Appendix
BSALES AND SERVICE OFFICES
Appendix
CMANUAL BACKDATING CHANGES
LIST OF TABLES
Number Page
1-1. Model 3400A Specifications 1-0
1-2. Equipment Supplied 1-1
1-3. Accessory Equipment Available 1-1
5-1. Required Test Equipment 5-0
5-2. Accuracy, Linearity, and DC Output
Check Data 5-1
Number Page
5-3. Frequency Response Check 5-2
5-4. Power Supply Checks 5-5
5-5. Front Panel Symptoms 5-7
5-6. Troubleshooting Procedure 5-9
5-7. Factory Selected Components 5-16
7-1. Replaceable Parts 7-3

Model 3400A Table of Contents
LIST OP ILLUSTRATIONS
Number Page
1-1. -hp- Model 3400A RMS Voltmeter .... 1-0
3-1. Model 3400A Controls and Indicators . . 3-0
4-1. Block Diagram 4-0
5-1. Accuracy, Linearity and DC Output
Test Setup 5-2
5-2. Frequency Response Test Setup 5-2
5-3. Input Impedance Test Setup 5-3
5-4. Crest Factor Test Setup 5-4
5-5. Troubleshooting Tree 5-8
5-6. Input to Demodulator 5-9
5-7. Input to Demodulator (feedback loop open) 5-10
5-8. Output of Demodulator (feedback loop open) 5-10
5-9. Neon Drive Voltage 5-11
5-10. Collector of Q602 (feedback loop open) ..5-12
5-11. Base of Q604 (feedback loop open) .... 5-12
Number Page
5-12. Base of Q601 (feedback loop open) ... 5-13
6-1- Input Attenuator Al, Impedance
Converter A2, and Second Attenuator
A3 Schematic and Parts Location
Diagram 6-3/6-4
6-2. Video Amplifier A4, Schematic and
Parts Location Diagram 6-5/6-6
6-3. Photochopper Assembly A5, Chopper
Amplifier Assembly A6, and
Thermocouple pair Schematic and
Parts Location Diagram ..6-7/6-8
6-4. Power Supply A7, Schematic and
Parts Location Diagram .... 6-9/6-10
7-1. Modular Cabinet 7-2
iv

Section IModel 3400A
UM00» RMSVOLTMETtR /->.
oe
-10
VOLTS
.3
RANGE VOLTS
1
OB
-M .1 v/S10
-M 03 ^J L- io 20
-40 .01 -^ m30 JO
-so .003 'W100 «0
-60 .001 ——300 so
40 ^*
Table 1-1. Model 3400A Specifications
VOLTAGE RANGE: 1mV to 300 Vfull scale, 12
ranges.
DB RANGE: -72 to +52 dBm (0 dBm 1mW in
600 n).
FREQUENCY RANGE: 10 Hz to 10 MHz.
RESPONSE: Responds to rms value (heating value)
of input signal.
METER ACCURACY: %of Full Scale (20°C to
30°C)*
10 Hz 50 Hz 1MHz 2MHz 3MHz 10 MHz
±5% ±1% ±2% ±3% ±5%
AC-to -DC CONVERTER ACCURACY: %of Full
Scale (20°C to 30°C)*
10 Hz 50 Hz 1MHz 2MHz 3MHz 10 MHz
±5% ±0. 75% ±2% ±3% ±5%
OUTPUT: Negative 1Vdc into open circuit for
full-scale deflection, proportional to meter
deflection; 1mA maximum; nominal source
impedance lOOOfi.
OUTPUT NOISE: <1mV RMS.
CREST FACTOR: (ratio of peak-to-rms ampli-
tude of input signal): 10:1 at full scale (except
where limited by maximum input), inversely
proportional to meter deflection (e. g. ,20:1 at
half -scale, 100:1 at tenth-scale).
INPUT IMPEDANCE: 0. 001 Vto 0. 3Vrange;
10 Mfi shunted by <50 pF: 1. Vto 300 V
range; 10 MS2 shunted by <20 pF. AC -coupled
input.
AC OVERLOAD: 30 dB above full scale or 800 V
peak, whichever is less, on each range.
MAXIMUM DC INPUT: 600 Von any range.
RESPONSE TIME: For astep function, <5
seconds to respond to final value.
POWER: 115 or 230 V±10%, 48 to 440 Hz.
approximately 7watts.
WEIGHT: Net 71/4 lbs. (3, 3kg); shipping 10 lbs.
(5 kg).
OVERALL DIMENSIONS: 61/2" high; 51/8" wide;
11 11/16" deep.
•
Temperature Coefficient: ±0. 1% over range of Qoc to 20°C and 30°C to 55°C.
It
1-0

Model 3400A Section I
SCOPE OF MANUAL
This manual contains the information necessary for oper-
ating and servicing the standard Model 3400A RMS Voltmeter
and the Model 3400A/Option 01 RMS Voltmeter (DB scale
uppermost).
SECTION I
GENERAL INFORMATION
1-1. INTRODUCTION.
1-2. This section contains general information about
the Model 3400ARMS Voltmeter (Figure 1-1). In-
cluded are: description of instrument, purpose, in-
strument identification, equipment supplied and
accessory equipment available. Also included is a
table of instrument specifications.
number on your instrument does not agree with those
on the title page of this manual, change sheets supplied
with the manual will define the differences between your
instrument and the Model 3400A described in this man-
ual. Some serial numbers may have a letter separating
the two sections of the number. This letter indicates
the country in which the instrument was manufactured.
1-12. EQUIPMENT SUPPLIED.
1-3. DESCRIPTION AND PURPOSE.
1-4. The Model 3400A RMS Voltmeter measures the
actual root-means-square (RMS) value of ac voltages
between 100 microvolts and 300 volts. Frequency
range is from 10 Hz to 10 MHz. Full scale
measurements of nonsinusoidal waveforms with crest
factors (ratio of peak voltage to rms voltage) of 10
can be made.
1-5. Ac voltages are measured with aspecified full-
scale accuracy of ±1% from 50 Hz to 1MHz, ±2%
from 1MHz to 2MHz, ±3% from 2MHz to 3MHz,
and ±5% from 10 Hz to 50 Hz and 3MHz to 10 MHz.
Asingle front panel control selects one of 12 voltage
or decibel ranges.
1-6. The Model 3400A crest factor rating is 10:1
which enables full scale readings for pulses which
have a1% duty cycle. At l/10th of full scale, pulse
trains with 0. 01% duty cycle (100:1 crest factor) can
be accurately measured.
1-7. The Model 3400A provides adc output which is
proportional to the front panel meter reading. By
using this voltage to drive auxiliary equipment, the
Model 3400A functions as an rms ac-to-dc converter.
1-8. SPECIFICATIONS.
1-9. Table 1-1 contains the specifications for the
Model 3400A.
1-10 INSTRUMENT AND MANUAL
IDENTIFICATION.
1-11. Hewlett-Packard uses atwo-section serial num-
ber. If the first section (serial prefix) of the serial
1-13. The equipment supplied with each Model 3400A
is listed and described in Table 1-2.
Table 1-2. Equipment Supplied
IDENTIFICATION
NUMBER QUANTITY DESCRIPTION
10110A 1Adapter (BNC to
dual banana jack)
8120-1348 1Power Cord
03400-90008 1Operating and
Service Manual
1-14. ACCESSORY EQUIPMENT AVAILABLE.
1-15. The accessory equipment available is listed
in Table 1-3. For further information contact your
local -hp- Sales and Service Office. (See Appendix B
for office locations.
)
Table 1-3. Accessory Equipment Available
IDENTIFICATION
NUMBER DESCRIPTION
10503A Cable (Male BNC to male
BNC, 48 inches)
11001A Cable (Male BNC to dual
banana plug, 45 inches)
11002A Test Lead (dual banana plug
to alligator clips, 60 inches)
11003A Test Lead (dual banana plug to
probe and alligator clip, 60 in.
)
456A Current Probe
01768-4 1-1

Model 3400A Section II
SECTION II
INSTALLATION
2-1. INTRODUCTION.
2-2. This section contains information and instructions
necessary for installation and shipping of the-hp- Model
3400A RMS Voltmeter. Included are initial inspection
procedures, power requirements, installation infor-
mation, and instructions for repackaging for shipment.
2-3. INITIAL INSPECTION.
2-4. The -hp-Model 3400A RMS Voltmeter received a
careful mechanical and electrical inspection before
shipment. As soon as the Model 3400A is received,
verify that the contents are intact and as ordered.
Although the instrument should be free of mars and
scratches and in perfect electrical condition, it should
be inspected for any physical damge which may have
been incurred in transit. Also test the electrical
performance of the instrument using the procedures
given in paragraph 5- 5.If any physical damage or
electrical deficiency is found, refer to the warranty
on the inside front cover of this manual. Should
shipping of the instrument become necessary, refer
to paragraph 2-14 for repackaging and shipping
instructions.
2-5. POWER REQUIREMENTS.
2-6. The Model 3400A can be operated from any ac
source of 115- or 230- volts (±10%), at 48 to 440 cycles.
With the instrument disconnected from the ac power
source, move the slide switch (located on the rear
panel) until the desired line voltage value appears.
The ac line fuse is a0. 25 amp, fast blow type for 115-
or 230-volt operation. Power dissipation is approxi-
mately 7watts.
2-7. The Model 3400A is equipped with athree-prong
power cord. To protect operating personnel, it is
necessary to preserve the grounding feature of this
plug when using atwo contact ac outlet. Use athree-
prong to two-prong adapter and connect the green
pigtail lead on the adapter to ground.
2-8. INSTALLATION.
2-9. The Model 3400A is asubmodular unit suitable
for bench top use. However, when used in combination
with other submodular units it can be bench and/or
rack mounted. The -hp- combining case and adapter
frame are designed for this purpose.
2-10. COMBINING CASE (-hp- Models 1051A or 1052A).
2-11. The combining case is afull-module unit which
accepts various combinations of submodular units.
Being afull-module unit, it can be bench or rack
mounted and is analogous to any full-module instru-
ment.
2-12. ADAPTER FRAME (-hp- Part No.5060-0797).
2-13. The adapter frame is a rack frame that accepts
any combination of submodular units. It can be rack
mounted only. For additional information, address
inquiries to your -hp- Sales and Service Office. (See
Appendix Bfor office location.
)
2-14. REPACKAGING FOR SHIPMENT.
2-15. The following paragraphs contain ageneral
guide for repackaging for shipment. Refer to para-
graph 2-16 if the original container is to be used;2-17
if it is not. If you have any questions, contact your
local -hp- Sales and Service Office.
•NOTE-
If the instrument is to be shipped to
Hewlett-Packard for service or
repair, attach a tag to the instrument
identifying the owner and indicate 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, serial
number, and serial number prefix.
2-16. If original container is to be used, proceedas
follows:
a. Place instrument in original container if avail-
able. If original container is not available, one
can be purchased from your nearest -hp- Sales and
Service Office.
b. Ensure that the container is well sealed with
strong tape or metal bands.
2-17. If original container is not to be used, pro-
ceed as follows:
a. Wrap instrument in heavy paper or plastic
before placing in an inner container.
b. Use packing material around all sides of
instrument and protect panel face with cardboard
strips.
c. Place instrument and inner container in a
heavy carton or wooden box and seal with strong
tape or metal bands.
d. Mark shipping container with "DELICATE
INSTRUMENT, ""FRAGILE, "etc.
2-1

Section III Model 3400A
'
1. Direct reading meter: dc meter which indicates
rms voltage level of input signal.
2. Mechanical zero adjustment: screwdriver
adjustment for zero of direct reading meter.
3. LINE ON pilot lamp: neon lamp which
indicates when power is applied to instrument
and power switch is ON.
4. Power switch: two-position toggle switch which
applies 115- or 230- volts ac to instrument.
5. RANGE switch: 12-position rotary switch
which selects various attenuation ranges
available within Model 3400A.
6. INPUT connector: BNC jack which enables
application of input signal to instruments
measuring circuits.
7. 115/230-volt switch: two-position slide switch
which sets instrument to operate from either
a115- or 230-volt ac source.
8. Input power jack: three-prong jack which
enables application of line voltage to instru-
ments power supply circuits.
9. 115V/230V .25A FUSE: 0. 25 ampere fuse
which provides protection against line voltage
surges.
10. DC OUT jack: telephone-type jackwhich pro-
vides negative 1-volt dc out at full scale de-
flection, output is proportional to meter de-
flection. Output impedance is 1000 ohms.
Atelephone type plug for the DC OUT jack may
be purchased under -hp- Part No. 1251-0067.
I
Figure 3-1. Model 3400A Controls and Indicators t
3-0

Model 3400A Section m
SECTION III
OPERATING INSTRUCTIONS
t
3-1. INTRODUCTION.
3-2. This section consists of instructions and infor-
mation necessary for the operation of the -hp- Model
3400ARMS Voltmeter. This section contains identi-
fication of controls and indicators, turn-on pro-
cedures, and operating instructions. Also included
is adiscussion of the applications for the Model
3400A.
3-3. CONTROLS AND INDICATORS.
3-4. Each operating control, connector, and indicator
located on the Model 3400A is identified and described
in Figure 3-1. The description of each component is
keyed to an illustration of that component which is
included within the figure.
3-5. TURN ON PROCEDURE.
3-6. Toturnonthe Model 3400A, proceed as follows:
a. Set 115/230 switch (7, Figure 3-1) to correct
position for input line voltage.
b. Apply ac voltage to Model 3400A by plugging
power cord into input power jack (8) ac receptacle.
c. Operate power switch (4) to ON; ensure that
LINE indicator (3) lights.
NOTE
Allow five minutes for the Model
3400Ato warm up and stabilize
before making areading.
3-7. OPERATING INSTRUCTIONS.
DO NOT MEASURE SIGNAL ABOVE
80 VOLTS WITH 10 TO 1CREST
FACTOR. OTHERWISE, THE MAXI-
MUM INPUT RATING (800 VOLTS
PEAK) WILL BE EXCEEDED. WHEN
MEASURING SIGNALS UP TO 80
VOLTS RMS WITH A10 TO 1CREST
FACTOR, USE THE BNC TO DUAL
BANANA JACK, ACCESSORY 101 10A,
SUPPLIED WITH THE INSTRUMENT,
OR OTHER INPUT TEST LEADS AND
CONNECTIONS THAT WILL WITH-
STAND THE MAXIMUM INPUT OF
800 VOLTS PEAK.
3-8. To operate the Model 3400A as an rms volt-
meter proceed as follows:
a. Attach test lead to INPUT connector (6, Figure
3- 1). (See Table 1-3 for alist of test leads available.
)
b. Set RANGE switch (5) to 300 VOLTS position.
CAUTION
WHEN MEASURING AN AC SIGNAL
SUPERIMPOSED ON ADC LEVEL,
ALWAYS SET THE RANGE SWITCH
TO THE 300 VOLT POSITION.
AHIGH VOLTAGE TRANSIENT DUE
TO THE APPLICATION OF ADC
VOLTAGE WILL DAMAGE THE
INPUT CIRCUITRY.
c. Connect test lead to point to be measured.
d. Rotate RANGE switch counterclockwise until
meter (1) indicates on upper two thirds of scale.
3-9. APPLICATIONS.
3-10. The Model 3400A can be used in conjunction
with other test instruments to measure the rms
value of ac signal with adc component, measure rms
current and act as an rms ac-to-dc converter. For
additional information on special applications, contact
your -hp- Sales and Service Office.
3-11. RMS VALUE OF AC SIGNALS WITH DC
COMPONENT.
3-12. Since the 3400A is an ac device it will measure
only the rms value of the ac component. If it is nec-
essary to include the rms value of the dc component
when measuring asignal use a-hp-Model 412A DC
Voltmeter to measure the dc component. Substitute
the reading from the Model 412A and Model 3400A in
the following formula: The ac signal (up to 800V peak)
may be superimposed onadc level of up to 600 V.
rms 4ac 'dc
3-13. RMS CURRENT.
3- 14. To measure rms current, use an -hp- Model 456A
AC Current Probe. This probe clips around the
current conductor and provides an output voltage that
is proportional to the current being measured. Using
this method, rms currents of one milliampere to one
ampere can be measured.
3-15. RMS AC-TO-DC CONVERTER.
3-16. Since the Model 3400Ais provided with adc
output (10, Figure 3-1) which is proportional to the
meter deflection, it can be used as alinear rms ac
to dc converter. The dc output can be used to drive a
-hp- Model 3440A Digital Voltmeter for high resolu-
tion measurements and/or aMosely Model 680 Strip
Chart Recorder. External loading does not affect the
meter accuracy so that both the meter and dc output
can be used simultaneously. Aplug for DC OUT jack
may be purchased under -hp- Part No. 1251-0067.
3-1

Section IV Model 3400A
Ck
i
fc
4-0

Model 3400A Section IV
SECTION IV
THEORY OF OPERATION
i
4-1. INTRODUCTION.
4-2. This section contains the theory of operation
of the Model 3400A RMS Voltmeter. Included is a
general and detailed description of the theory of
operation.
4-3. GENERAL DESCRIPTION.
4-4. The Model 3400A comprises two attenuators, an
impedance converter, avideo amplifier, aphoto-
conductor chopper (modulator/demodulator), achop-
per amplifier, an emitter follower, athermocouple
pair, and adirect reading meter. (See Figure 4-1.)
4-5. Asignal being measured with the Model 3400A
is applied to input attenuator Al through the INPUT
jack, located on the Model 3400A front panel. The
input attenuator has an input impedance of over 10
megohms and provides two ranges of attenuation.
The output of the input attenuator is applied to imped-
ance converter A2. The impedance converter is a
non-inverting unity voltage gain amplifier. It presents
ahigh impedance to the input signal and provides a
low impedance output to drive the second attenuator
A3. The second attenuator provides 6ranges in a1,
3, 10 sequence. The two attenuators are switched to
provide 12 ranges of attenuation.
4-6. The output of the second attenuator is amplified
by video amplifier A4. The video amplifier is awide-
band, five stage amplifier. The overall gain of the
video amplifier is controlled by an ac feedback loop.
The ac output of the amplifier is applied to TC401;
one of the thermocouples of the thermocouple pair.
4-7. The dc output of TC401 is modulated by mod-
ulator A5. The modulator comprises two photocells
which are alternately illuminated by two neon lamps
which in turn are controlled by the oscillator located
on power supply assembly A7. The output of the
modulator is asquare wave whose amplitude is pro-
portional to the dc input level.
4-8. The square wave output of the modulator is
amplified by chopper amplifier A6. The chopper
amplifier is ahigh gain ac amplifier. Its output is
applied to demodulator A5. The demodulator output
is a dc level whose magnitude is proportional to the
amplitude of the ac input. The demodulator output is
applied to two direct coupled emitter followers. The
emitter follower is used to make the impedance trans-
formation from the high impedance output of the de-
modulator to the low impedance of the direct reading
meter Ml and TC402; the second thermocouple of the
thermocouple pair.
4-9. The thermocouple pair TC401 and TC402 acts
as asumming point for the ac output of the video
amplifier A4 and the dc output of the emitter followers.
The difference in the heating effect of these voltages
is felt as a dc input to modulator A5. This difference
input is amplified and is fed to TC402 and to meter
Ml. This amplified dc voltage represents the rms
value of the ac signal applied at the INPUT jack. By
using two "matched" thermocouples and measuring the
difference, the output to the modulator will be linear.
Using two thermocouples also provides temperature
stability.
4-10. The dc voltage driving meter Ml is also
available at the DC OUT jack, located at the rear of
the Model 3400A.
4-11. DETAILED DESCRIPTION.
4-12. INPUT ATTENUATOR ASSEMBLY Al.
4-13. The input attenuator assembly is acapacitive-
compensated attenuator which provides two ranges of
attenuation for the 12 positions of the RANGE switch.
See input attenuator schematic diagram illustrated on
Figure 6-1.
4-14. When the RANGE switch is positioned to one
of the six most sensitive ranges (. 001 to .3VOLTS),
the attenuator output voltage is equal to the input
voltage. When the RANGE switch is positioned to one
of six highest ranges (1 to 300 VOLTS), the input sig-
nal is attenuated 60 dB (1000: 1voltage division) by
the resistive voltage divider consisting of R101, R103,
and R104. Trimmer C102 is adjusted at 100 kHz, and
R104 is adjusted at 400 Hz to provide constant atten-
uation over the input frequency range.
4-15. IMPEDANCE CONVERTER ASSEMBLY A2.
4-16. The impedance converter assembly utilizes a
nuvistor tube cathode follower circuit to match the
high output impedance of the input attenuator to the
low input impedance of the second attenuator. The
cathode follower circuit preserves the phase relation-
ship of the input and output signals while maintaining
again of unity. See impedance converter assembly
schematic diagram illustrated on Figure 6-1.
4-17. The ac signal input to the impedance converter
is RC coupled to the grid of cathode follower V201
through C201 and R203. The output signal is devel-
oped by Q201 which acts as avariable resistance in
the cathode circuit of V201. The bootstrap feedback
from the cathode of V201 to R203 increases the
effective resistance of R203 to the input signal. This
prevents R203 from loading the input signal and pre-
serves the high input impedance of the Model 3400A.
The gain compensating feedback from the plate of
V201 to the base of Q201 compensates for any varying
gain in V201 due to age or replacement.
4-18. Breakdown diode CR201 controls the grid bias
4-1

Section IV Model 3400A
voltage on V201 thereby establishing the operating
point of this stage. CR202 and R211 across the base-
emitter junction of Q201 protects Q201 in the event of
afailure in the +75 volt power supply. Regulated dc
is supplied to V201 filaments to avoid inducing ac hum
in the signal path. This also prevents the gain of V201
changing with line voltage variations.
4-19. SECOND ATTENUATOR ASSEMBLY A3.
4-20. The second attenuator is aresistive divider
which attenuates the ac input signal while maintaining
alow impedance output for the following amplification
stages. See second attenuator assembly schematic
diagram illustrated in Figure 6-1.
4-21. The ac input signal is applied to aprecision
resistance voltage divider consisting of R302 through
R312. These resistors are arranged to give six
ranges of attenuation at 10 dB per range. The six
ranges of the second attenuator combined with the two
ranges of the input attenuator make up the 12 ranges
of attenuation (0. 001 to 300V), Trimmer capacitor
C303 (10 MHz 0. 3V ADJ) provides an adjustment for
frequency response at the higher frequencies.
4-22. VIDEO AMPLIFIER ASSEMBLY A4.
4-23. The video amplifier functions to provide con-
stant gain to the ac signal being measured over the
entire frequency range of Model 3400A. See video
amplifier assembly schematic diagram illustrated on
Figure 6-2.
4-24. The ac input signal from the second attenuator
is coupled through C402 to the base of input amplifier
Q401. Q401, aclass Aamplifier, amplifies and in-
verts the signal which is then direct coupled to the
base of bootstrap amplifier Q402. The output, taken
from Q402 emitter is applied to the base of Q403 and
fed back to the top of R406 as a bootstrap feedback.
This positive ac feedback increases the effective ac
resistance of R406 allowing agreater portion of the
signal to be felt at the base of Q402. In this manner,
the effective ac gain of Q401 is increased for the mid-
band frequencies without disturbingthe static operating-
voltages of Q401.
4-25. Driver amplifier Q403 further amplifies the
ac signal and the output at Q403 collector is fed to
the base circuit emitter follower Q404. The feedback
path from the collector of Q403 to the base of Q402
through C405 (10 MHz ADJ) prevents spurious oscil-
lations at high input frequencies. Adc feedback loop
exists from the emitter circuit of Q403, to the base
of Q401 through R425. This feedback stabilizes the
Q401 bias voltage. Emitter follower Q404 acts as a
driver for the output amplifier consisting of Q405 and
Q406; acomplimentary pair operating as a push-pull
amplifier. The video amplifier output is taken from
the collectors of the output amplifiers and applied to
thermocouples TC401. Again stabilizing feedback is
developed in the emitter circuits of the output ampli-
fiers. This negative feedback is applied to the emitter
of input amplifier Q401 and establishes the overall
gain of the video amplifier.
4-26. Trimmer capacitor C405 is adjusted at 10 MHz
for frequency response of the video amplifier. Diodes
CR402 and CR406 are protection diodes which prevent
voltage surges from damaging transistors in the
video amplifier. CR401, CR407, and CR408 are
temperature compensating diodes to maintain the zero
signal balance condition in the output amplifier over
the operating temperature range. CR403, abreak-
down diode, establishes the operating potentials for
the output amplifier.
4-27. PHOTOCHOPPER ASSEMBLY A5, CHOPPER
AMPLIFIER ASSEMBLY A6, AND THERMO-
COUPLE PAIR (PART OF A4).
4-28. The modulator/demodulator, chopper ampli-
fier, and thermocouple pair form aservo loop which
functions to position the direct reading meter Ml to
the rms value of the ac input signal. See modulator/
demodulator, chopper amplifier, and thermocouple
pair schematic diagram illustrated in Figure 6-3.
4-29. The video amplifier output signal is applied to
the heater of thermocouple TC401. This ac voltage
causes adc voltage to be generated in the resistive
portion of TC401 which is proportional to the heating
effect (rms value) of the ac input. The dc voltage is
applied to photocell V501.
4-30. Photocells V501 and V502 in conjunction with
neon lamps DS501 and DS502 form amodulator cir-
cuit. The neon lamps are lighted alternately between
90 and 100 Hz. Each lamp illuminates one of the
photocells. DS501 illuminates V501;DS502 illuminates
V502. When aphotocell is illuminated it has a low
resistance compared to its resistance when dark.
Therefore, when V501 is illuminated, the output of
thermocouple TC401 is applied to the input of the
chopper amplifier through V501. When V502 is illumi-
nated, aground signal is applied to the chopper amp-
lifier. The alternate illumination of V501 and V502
modulates the dc input at afrequency between 90 and
100 Hz. The modulator output is asquare wave whose
amplitude is proportional to the dc input level.
4-31. The chopper amplifier, consisting of Q601 through
Q603, is ahigh gain amplifier which amplifies the
square wave developed by the modulator. Power
supply voltage variations are reduced by diodes CR601
thru CR603. The amplified output is taken from the
collector of Q603 and applied to the demodulator
through emitter follower Q604.
4-32. The demodulator comprises two photocells,
V503 and V504, which operate in conjunction with
DS501 and DS502; the same neon lamps usedto illumi-
nate the photocells in the modulator. Photocells V503
and V504 are illuminated by DS501 and DS502, res-
pectively.
4-33. The demodulation process is the reverse of
the modulation process discussed in Paragraph 4-30.
The output of the demodulator is adc level which is
proportional to the demodulator input. The magnitude
and phase of the input square wave determines the
magnitude and polarity of the dc output level. This dc
output level is applied to two emitter follower output
stages.
i
%
4-2

Model 3400A Section IV
4-34. The emitter follower is needed to match the
high output impedance of the demodulator to the low
input impedance of the meter and thermocouple cir-
cuits. The voltage drop across CR604 in the collec-
tor circuit of Q605 is the operating bias for Q604.
This fixed bias prevents Q605 failure when the base
voltage is zero with respect to ground.
4-35. The dc level output, taken from the emitter of
Q606, is applied to meter Ml and to the heating
element of thermocouple TC402. The dc voltage de-
veloped in the resistive portion of TC402 is effectively
subtracted from the voltage developed by TC401. The
input signal to the modulator then becomes the differ-
ence in the dc outputs of the two thermocouples. When
the difference between the two thermocouples becomes
zero the dc from the emitter followers (driving the
meter) will be equal to the ac from the video amplifier.
4-36. Noise on the modulated square wave is sup-
pressed by feedback from emitter of Q606 through
C607 and C608 to the resistive element of TC402.
4-37. POWER SUPPLY ASSEMBLY A7.
4-38. The power supply assembly provides dc oper-
ating voltages for the tube and transistors used in the
Model 3400A. See power supply assembly schematic
diagram illustrated on Figure 6-4.
4-39. Either 115 or 230 volts ac is connected to the
primary of power transformer Tl through fuse Fl and
the POWER switch SI. Switch S2 (slide switch on
rear panel) connects Tl primary windings in series
for 230-volt operation or in parallel for 115-volt oper-
ation. Neon lamp DS1 lights to indicate LINE power
ON when ac power is applied and SI is closed.
4-40. REGULATOR OPERATION.
4-41. The series regulator acts as adynamic vari-
able resistor in series with the power supply output.
Acontrol amplifier senses changes in the output volt-
age by comparing the output with afixed reference
voltage. The control amplifier then supplies any out-
put voltage changes to the driver transistor, which in
turn changes the resistance of the series regulator to
oppose the change in output voltage. Diodes CR704,
CR713 and CR706 across the base emitter junction of
the series regulator provide overload current protection.
4-42. +75 VOLT SUPPLY.
4-43. The +75 volt supply consists of afull-wave
rectifier (CR701 and CR702) whose output is filtered
by CIA and C1B and regulated by series regulator Ql.
The +75 volt supply provides regulated +75 volts which
is used as the plate supply voltage for V201. Voltage
variation from the output is felt at Q702 base circuit
through C704, R715, and R716. The C703 and R709
network provides phase correction for power supply
stability. The regulation circuitry is in the negative
leg of the +75 volt supply, and uses the -17. 5volt
supply as areference.
4-44. -17. 5VOLT SUPPLY.
4-45. The regulated -17. 5volt supply consists of a
full-wave rectifier (CR711, and CR712) whose output
is filtered by C706 and C707 and regulated by Q2.
Breakdown diod ^R715 provides reference voltage
at the base of Q'. 1. Regulation operation is the same
described in Para^ °.ph 4-41.
4-46. -6. 3VOLT SUPPLY.
4-47. The regulated -6. 3volt supply consists of a
full -wave rectifier (CR716 and CR717) whose output
is filtered by C2 and regulated by Q3. Emitter follow-
er Q705 is connected to the -17. 5volt supply which
provides areference for the -6. 3volt supply. Series
regulator Q3 acts as adynamic variable resistor in
series with the output to oppose changes in output
voltage.
4-48. NEON LAMP DRIVE OSCILLATOR.
4-49. The neon lamp drive oscillator consists of
transistor Q706, diode CR718, resistors R701, R702,
R712, R713, and capacitor C711. Transistor Q706
is held on (conducting) by the base bias developed at
the junction of R712 and CR718. The collector current
of Q706 charges up capacitor C711 through R701 or
R702 depending upon the illuminated neon lamp on the
Chopper Amplifier Assembly A6. When the capacitor
reaches asufficient charge to fire the dark neon lamp,
the illumination of the neon lamps alternate and the
capacitor discharges through the previously dark neon
lamp. With the previously dark neon lamp illuminated,
the capacitor charges up in the opposite direction
until firing the previously illuminated neon lamp. The
cycle described above repeats at afrequency of 90 to
100 Hz as determined by the RC time constants of
R701and C711, and R702 and C711.
4-3

rSection VModel 3400A
Table 5-1. Required Test Equipment
INSTRUMENT
TYPE REQUIRED CHARACTERISTICS USE RECOMMENDED MODEL
DC Voltmeter Accuracy: ±0. 1% full scale
Voltage Range: lOmVto 100 VPerformance Checks
Adjustment and Calibration -hp- Model 3440A/3443A
Digital Voltmeter
Voltmeter
Calibrator
Voltage Range: 1mV to 300 Vrms
Frequency: 400 Hz Performance Checks
Adjustment and Calibration
Troubleshooting
-hp- Model 738B Volt-
meter Calibrator
Oscillator Frequency Range: 10 Hz to 10 MHz
Output: 1mV to 3V
Frequency Response: 0.25%
(expand scale)
Performance Checks
Adjustment and Calibration
Troubleshooting
-hp- Model 652A Test
Oscillator
Oscilloscope Sensitivity: 0. 005 v/cm
Bandwidth: dc to 20 MHz Adjustment and Calibration
Troubleshooting
-hp- Model 140A/
1402A/1420A
Pulse
Generator Pulse Width: variable to 10 /isec
Pulse Amp: ±10 volts peak, variable
Pulse Rate: 250 to 1000 pps
Performance Checks -hp- Model 214A
Pulse Generator
Frequency
Counter Range: 250 to 1000 Hz
Accuracy: ±1 count
Time Interval: 1/isec
Performance Checks -hp- Model 5233 L
Electronic Counter
Peak
Responding
Voltmeter
Voltage Range: 0. 5Vto 300 V
Accuracy: ±3% full scale Performance Checks -hp- Model 410C
Voltmeter
Average
Responding
Voltmeter
Voltage Range: 0. 001 to 300 V
Accuracy. 1% full scale Adjustment and Calibration
Troubleshooting -hp- Model 400E/EL
Voltmeter
Current
Supply/
Ohmmeter
Output: 5mA of current into 100ft
Ohm Range: 1ft to 10 Mft
Accuracy: ±5%
Troubleshooting -hp- Model 412A DC
Vacuum Tube
Voltmeter
RMS Respond-
ing Volt-
meter
Range: 1mV full scale Performance Checks -hp- Model 3400A
RMS Voltmeter
Resistor 200 kft, metal film, 1/4 W1% Performance Checks -hp- Part No. 0757-0782
Resistor 499 kft, metal film, 1/4 W1% Troubleshooting -hp- Part No. 0757-0327
Capacitor 1iiF Troubleshooting -hp- Part No. 0180-0269
50 ft Feedthru
Termination Resistor: fixed corap 50ft ±5%
1/4 WPerformance Checks -hp- Model 11048B
50ft Feedthru
BNC-T-
Adapter Performance Checks
Adjustment and Calibration -hp- Part No. 1250-0072
Adapter 410C to Dual Banana Performance Checks -hp- Model 11018A
Extender
Board 15 pin programmable Troubleshooting -hp- Part No. 5060-6038
I
5-0
t

Model 3400A Section V
SECTION V
MAINTENANCE
5-1. INTRODUCTION.
5-2. This section contains the information necessary
for maintenance of the Model 3400A RMS Voltmeter.
Included are performance checks, adjustment and
calibration procedures, and troubleshooting procedures.
5-3. TEST EQUIPMENT.
5-4. The test equipment required for the maintenance
of the Model 3400Ais listed in Table 5-1. If the re-
commended model is not available, use any substitute
that meets the required characteristics.
•NOTE
5-7.
Allow a30 -minute warmup period before
making performance checks. During the
performance checks, periodically vary
the Model 3400A line voltage ±10% with
apower line transformer to assure that
the instrument operates correctly at
various ac line voltages.
ACCURACY, LINEARITY, AND DC OUTPUT
CHECK.
5-5. PERFORMANCE CHECKS.
5-6. The Performance Checks are in-cabinet tests
that compare the Model 3400A with its given specifi-
cations. These checks may be used for incoming
inspection, periodic maintenance, and for specifica-
tion checks after arepair. APerformance Check
Test Card is provided at the end of this section for
recording the performance of the instrument during
the Performance Checks. The card may be removed
from the manual and used as a permanent record of
the incoming inspection or of aroutine performance
check. If the instrument fails to meet any of its
specifications, perform the Adjustment and Cal-
ibration Procedures outlined in Paragraph 5-15.
5-8. The accuracy, linearity, and dc output test set-
up is illustrated in Figure 5-1. AVoltmeter Calibrator
-hp- Model 738B and aDC Voltmeter -hp- Model
3440A/3443A) are required for this test.
Connect test setup illustrated in Figure 5-1.
Set Model 3400A RANGE switch to 0. 001
position.
Adjust Voltmeter Calibrator for 0.001 volt,
rms 400 Hz output; set the DC Voltmeter to
measure 1volt.
a.
b.
c.
d.
e.
If Model 3400A does not indicate within values
listed under "meter reading" in Table 5-2,
perform low frequency calibration procedure,
Paragraph 5-21. Record 3400A readings.
Dc output as indicated on dc voltmeter should
be within values listed under "3400A DC
output" in Table 5-2.
Continue to check accuracy, linearity, and
dc output using Table 5-2.
Table 5-2. Accuracy, Linearity, and DC Output Check Data
VOLTMETER
CALIBRATOR
OUTPUT (V)
3400A
VOLTAGE
RANGE (V)
3400A METER
READING
(V)
3400A DC
OUTPUT
(V)
0.001
0.003
0.01
0.03
0.1
0.3
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
3.0
10.0
30.0
100.0
300.0
0.001
0.003
0.01
0.03
0.1
0.3
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
3.0
10.0
30.0
100.0
300.0
0.000990 to 0.00101
0. 00297 to 0. 00303
0.00990 to 0.0101
0.0297 to 0.0303
0.0990 to 0.101
0.297 toO. 303
0.990 to 1.01
0.89 to 0.91
0.79 to 0.81
0.69 to 0.71
0.59 toO. 61
0.49 to 0.51
0.39 to 0.41
0.29 to 0.31
0.19 to 0.21
0.090 to 0. 11
2.97 to 3.03
9. 90 to 10. 10
29. 7to 30.
3
99.0 to 101.0
297. to 303.
0. 992 to 1. 008
0. 942 to 0. 957
0.992 to 1.008
0. 942 to 0. 957
0.992 to 1.008
0. 942 to 0. 957
0.992 to 1.008
0.892 to 0.908
0.792 to 0.808
0. 692 to 0. 708
0. 592 to 0. 608
0.492 toO. 508
0.392 to 0.408
0.292 toO. 308
0. 192 to 0. 208
0. 092 to 0. 108
0.942 to 0.957
0.992 to 1.008
0. 942 to 0. 957
0.992 to 1.008
0.942 to 0.957
5-1

Section VModel 3400A
t,
VOLTMETER CALIBRATOR
A/J738BR A/73400A
RMS VOLTMETER DIGITAL VOLTMETER
A/J3440A
•
°
®
V3443A
HIGH GAIN/
AUTO RANGE
UNIT
TO
D.C. OUT JACK
ON REAR
Figure 5-1. Accuracy, Linearity, and DC Output Test Setup
5-9. FREQUENCY RESPONSE CHECK.
•NOTE-
Connect 50fi feedthru termination
directly to 3400A INPUT to elimi-
nate loss in output cable at high
frequency.
a. Connect test setup illustrated in Figure 5-2.
b. Set Model 3400A RANGE switch and Test
Oscillator output attenuator to 1volt position.
c. Set Test Oscillator for 400 Hz output and ad-
just output amplitude for the reading obtained
in Paragraph 5-8 step don the Model 3400A.
d. Switch the Test Oscillator monitor switch to
expand mode and set aconvenient reference
level.
e. Adjust test oscillator output frequency to
values listed under "frequency" in Table
5-3; adjust oscillator output voltage to
maintain reference level set in step d. If
Model 3400A does not indicate within values
under "meter reading" in Table 5-3, perform
high frequency calibration procedures, Para-
graph 5-25.
Table 5-3. Frequency Response Check
FREQUENCY METER READING
15 Hz 0. 95 to 1. 05
45 Hz 0.95 to 1.05
100 Hz 0.99 to 1.01
900 kHz 0.99 to 1.01
1. 2MHz 0.98 to 1.02
1.8 MHz 0.98 to 1.02
2. 2MHz 0.97 to 1.03
2.8 MHz 0.97 to 1.03
3.2 MHz 0.95 to 1.05
9.8 MHz 0.95 to 1.05 '-.
5-10. INPUT IMPEDANCE CHECK.
5-11. RESISTANCE CHECK.
a. Connect the Test Oscillator, 50 ohm feedthru
and -hp- Model 3400A to position Ain Figure
5-3.
b. Set 3400A to 1volt range and Test Oscillator
to 400 Hz.
c. Adjust Test Oscillator output for 1volt in-
dication on Model 3400A.
TEST OSCILLATOR
•652A
hpZAQOA
RMS VOLTMETER
500 FEED-THRU
TERMINATION
/ipllOISB
—boCZDco- J
/
Figure 5-2. Frequency Response Test Setup
5-2

Model 3400A Section V
TEST OSCILLATOR
•652A
A/J3400A
RMS VOLTMETER
500 FEEO-THRU
TERMINATION
hpilOABB
—an too
®<§>
Figure 5-3. Input Impedance Test Setup
»
d. Connect Model 3400A to position Bin Figure
5-3. The 3400Ameter reading should change
less than 0.02 volts (2 minor divisions).
This corresponds to an input impedance of
10 megohms.
5-12. CAPACITANCE CHECK.
a. Connect Test Oscillator, 50 ohm feedthru
and Model 3400A to position Bin Figure 5-3.
Insert the resistor lead directly into the BNC
connector on the 3400A as an adapter adds
capacitances to the measurement.
b. Set 3400Ato 0. 001 volt range and Test Oscil-
lator to 400 Hz.
c. Adjust Test Oscillator output for full scale
indication on Model 3400A. Switch the Test
Oscillator Switch to Expand mode and set
aconvenient reference level.
d. Change Test Oscillator frequency to 16 kHz,
maintaining the reference level set in step c.
The Model 3400A reading should be greater
than 0. 707 volts. This corresponds to an
input shunt capacity of less than 50 pF.
e. Set Model 3400A Range switch to 1Vposition
and repeat step c.
f. Change Test Oscillator frequency to 40 kHz,
maintaining the reference level set in step c.
The Model 3400A reading should be greater
than 0. 707 volts. This corresponds to an
input shunt capacity of less than 20 pF.
5-13. CREST FACTOR CHECK.
a. Connect test setup as illustrated in Figure
5-4.
b. Set Model 3400A Range switch to 1volt
position.
.Adjust Pulse Generator for pulse output with
the following characteristics:
Pulse Rate -990 pps as indicated on
electronic counter.
Pulse Width -10 usee as indicated on
electronic counter in time
internal mode.
Pulse Amplitude -7. 07 volts as indicated
on Model 4IOC.
NOTE-
The 410C responds to the positive peak
above the average of the input waveform.
Since the Model 410C is calibrated to
read the rms value of asine wave a
correction factor is required to measure
pulse amplitude. The correction factor
under these conditions is:
E,
E410C
JPP
VT 1II
see waveform below
E„ T2
•n fi +
E410C
E410C -7'07V
T2
Ti
T2
Ep=Epp(l-D)
5-3