NBSIR 88-3736

Reeearcli Information Center

JVatioaa! Bureau of Standards

Gaithersburg, Maryland 20899

MAY 3 1093

Electrical Performance Tests for

True-RMS Voltmeters

R. S. Turgel

O. B. Laug

T. E. Leedy

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Electronics and Electrical Engineering

Electrosystems Division

Gaithersburg, MD 20899

March 1988 .,t nc .

Stimulating America s Progress 1913-1988

Prepared for: U=S. Army Communications Electronics Command

Fort Monmouth, New Jersey 07703

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NBSIR 88-3736

ELECTRICAL PERFORMANCE TESTS FOR

TRUE-RMS VOLTMETERS

R. S. Turgel

O. B. Laug

T. E. Leedy

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Electronics and Electrical Engineering

Electrosystems Division

Gaithersburg, MD 20899

March 1988

Prepared for: U.S. Army Communications Electronics Command

Fort Monmouth, New Jersey 07703

U.S. DEPARTMENT OF COMMERCE, C. William Verity, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director
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ELECTRICAL PERFORMANCE TESTS FOR TRUE -RMS VOLTMETERS

Table of Contents

Abstract „ . . . 1

1. INTRODUCTION ........ . ... 1

2. BACKGROUND 2

3. AC VOLTMETER PRINCIPLES 4

3.1. General Considerations 4

3.2. Principles of Operation 5 3.2.1. AC to DC Conversion 5 3.2.2. Analog- to-Digital Conversion 6

4. VOLTMETER PERFORMANCE MEASUREMENTS 7 4.1. Input Characteristics 7 4.1.1. Input Impedance 7 4.1.2. Common Mode Rejection 8

4.1.3. Input Protection 9 4.2. AC Voltage Performance Tests 10

4.2.1. Range and Accuracy 10

4.2.2. Frequency Range . 13

4.2.3. True-RMS Detection 13

4.2.4. Crest Factor 15

4.2.5. Response Time 17

5. REFERENCES ... ........ ........ 18

APPENDIX A, True-RMS Voltmeter Specifications. ..... A-1

APPENDIX B, Test Procedures B-1

APPENDIX C, Computer Test Program C-1

APPENDIX D, List of Special Parts D-1

APPENDIX E, Equipment List for RMS Voltmeter Tests E-1

iii
ELECTRICAL PERFORMANCE TESTS FOR TRUE -RMS VOLTMETERS

List of Figures

Page

Fig. 1. Concept of dual-slope integration shown for ...... 7 Fig. 2 Test setup for measuring ac common mode rejection ratio, ..... 9

Fig. 3 Set-up to check for true-rms response .............. 14

Fig. 4. Crest-factor test waveform 16

iv
Electrical Performance Tests for True-RMS Voltmeters

R. S. Turgel, 0. B. Laug, T. E. Leedy

Electrosystem Division

Center for Electrical and Electronic Engineering

Abstract

Electrical performance test procedures for true-rms voltmeters were

developed by the National Bureau of Standards for the U. S. Army

Communications -Electronics Command. The report provides detailed,

step-by-step test procedures that are based on the specifications

supplied by the Army for the purpose of evaluating the bid samples

of this type of instrument. Examples of the data sheets and tables

for recording of interim data and the final results are given.

This report discusses the philosophy underlying each of the

measurement procedures with from a point of view of the basic

metrology required to perform the measurements. In addition, the

sources of measurement error are discussed.

Key Words: test procedures; true-rms voltmeter; rf voltmeter; and

voltmeter.

1. INTRODUCTION

This report describes test procedures that were developed by the National

Bureau of Standards (NBS) for the U.S. Army Communications -Electronics Command

(CECOM) , Ft. Monmouth, N.J., for testing the electrical performance of truerms responding voltmeters. The test procedures are based on meter performance

specifications supplied by CECOM, and will be used by the Army in their Test

Measurement and Diagnostic Equipment (TMDE) Modernization Program to evaluate

bid samples for this type of instrument. The report focuses only on the test

procedures for electrical performance that can be carried out without access

to the interior of the instruments under test. The Army performance

specifications, for the most part, represent performance levels attainable by

modern state-of-the-art commercial wide-band, true-rms ac voltmeters.

The main objective in developing the test procedures has been to provide

measurement techniques which are accurate, repeatable, and simple to perform.

Most importantly, the procedures must be technically sound so as to provide an unbiased and objective evaluation of competitive instruments. The test

equipment chosen has been selected not only to satisfy the requirements of

1
ELECTRICAL PERFORMANCE TESTS FOR TRUE -RMS VOLTMETERS

each individual test, but within the broader context of building a laboratory

at CECOM with an inventory of modern general-purpose test equipment that will

serve a wide range of bid sample testing needs. Thus, most of the test

equipment specified by make and model represent equipment that is a part, or will become a part, of the CECOM laboratory.

This report is divided into three sections: The first section gives a brief

overview of the Army's TMDE Modernization Program. The second section

contains general information on the principles of commercial wide -band, true- rms voltmeters. The third section discusses, in depth, the primary

performance measurements with emphasis on a preferred method and a consideration of error sources. The information in this last section is

intended to provide the theory and analysis to support the actual test

procedures given in Appendix B. The detailed step-by-step procedures in

Appendix B are intended for evaluation tests of bid samples by the Army to

assure conformance with the set of Army specifications given in Appendix A.

Also, included in Appendix B are samples of appropriate data sheets and tables

for recording interim and final results.

As part of the test procedures, a computer program for testing the voltmeter

efficiently is provided in Appendix C. Appendix D shows the design and

characteristics of specialized fixtures that are used in some of the

procedures, and Appendix E lists all the test equipment and accessories

required for the test procedures. Although the test procedures described in

this report were specifically developed for use by the Army TMDE Modernization

Program, many of the tests can be considered generic in nature and perhaps

could serve as the basis of an industry test standard for commercial, wideband, true-rms voltmeters.

2. BACKGROUND

The Department of the Army has undertaken a Test, Measurement, and Diagnostic

Equipment (TMDE) Modernization Program. The general goal of this program is

to provide TMDE for the Army, eliminate the proliferation of numerous types

and models of such equipment, and thus reduce the logistical burden.

Specifically, the intent of the TMDE Modernization Program is to:

1. Introduce a minimum ensemble of different types and models of up-to-date

TMDE into the Army inventory,

2. Replace multiple generic types of TMDE with a single new item, where

feasible

.

3. Periodically assess the Army TMDE inventory to identify individual or families of TMDE that require replacement.

2
ELECTRICAL PERFORMANCE TESTS FOR TRUE -RMS VOLTMETERS

The acquisition of new TMDE items progresses through a two-step

invitation-for-bid procedure. The first step begins with letter requests that

are released to potential offerors for bid samples. The offeror has a period

of 60 days to analyze the solicitation requirement and send bid sample

equipment to the Communications -Electronic Command (CECOM) , Ft. Monmouth, NJ

for testing. Equipment is evaluated for performance, useability,

maintainability, workmanship, ease of calibration, military suitability,

safety, and environmental capability. After the bid sample testing, only the

offerors with test equipment that meets the solicitation requirements are invited to submit bids.

The second step occurs when the bids are received, evaluated, and the lowest

responsive bidder is awarded the contract. This procedure is believed by the

Army to provide reliable and maintainable test equipment with superior

performance characteristics for support of weapons systems. Bid sample

equipment evaluation requires an established set of test procedures which can objectively determine conformance to specifications. Unlike some evaluations,

such as safety and workmanship which are more general and widely applicable,

test procedures for electrical performance are by necessity specific for each

requirement. That is, for each particular electrical performance

specification there must be a procedure. Although some equipment

manufacturers provide performance check procedures for purposes of incoming

inspection, or readjustment to specifications, there is a lack of generic test

methods applicable to various classes of equipment that can be directly and

objectively used by the Army. Therefore, before bid sample testing can

proceed, appropriate test procedures must be developed and validated. This

report describes the test procedures specifically developed by NBS for the

Army to perform bid sample testing of commercial high-frequency, true-rms

voltmeters

.

3
ELECTRICAL PERFORMANCE TESTS FOR TRUE -RMS VOLTMETERS

3. AC VOLTMETER PRINCIPLES

3.1. General Considerations

Voltmeters are one of the commonest tools of the electronic engineer and

technician. A decade ago, voltmeters for frequencies up to the order of

kilohertz were predominantly analog in nature and essentially consisted of an analog meter movement together with a manual switching network to implement

the various range capabilities of the meter. Generally, most analog

voltmeters were limited to the measurement of ac voltages with accuracies on

the order of 0.5 to 10 percent. The analog meters depended, generally, on the

measurand to provide the power necessary for the movement of a meter pointer.

Thus, older meters had relatively low input impedance, typically 1000 0/V, or

less, for operation at the lower audio frequencies. Consequently, in some applications, the input impedance could affect the accuracy of the voltage

readings obtained, since at least 500 fxA was needed to provide a full-scale

deflection of the meter. Most of the ac voltmeters, especially for higher

frequencies, including high- impedance input vacuum-tube voltmeters were

rectifier instruments responding to average or peak voltage, but calibrated to

read rms voltage for sinusoidal signals. If distortion was present, large

errors could be incurred with these instruments. With the development of

complex, miniaturized, low-power electronic circuitry, more sensitive and

accurate meters could be constructed, and, in turn, these meters filled the

need to service the newer electronic circuits being designed [1].

The digital voltmeter has largely replaced analog instruments and is generally

more accurate and more versatile. It can perform many additional functions

such as automatic ranging, data averaging, unit conversions (e.g., dB) , and

others. The basic functional blocks of the digital ac voltmeter include an ac-to-dc conversion stage followed by a form of analog- to-digital converter.

To measure the dc voltage resulting from the first stage, an integrating

analog- to-digital converter is generally used. This can be either a dualslope or voltage- to-frequency type. The integrating period is usually chosen

to minimize line- frequency interference.

The digital part of the circuitry in the voltmeter provides a means for making

logical decisions, such as automatic ranging ( auto- ranging) . With autoranging, the range setting is automatically or electronically selected to give

the best resolution possible, except that hysteresis is provided between the

up -range and down- range transitions to prevent hunting between ranges at the

transition points. Most ac voltmeters also automatically display the decimal

point and indicate the units of measurement as well. Many of the newer ac voltmeters make use of embedded microprocessors to provide features such as linearization of the response characteristic, correction for frequency

response, capability for making relative measurements between the present

reading and a previously stored value, or special displays such as "analog”

bar-graph readouts. Also, some voltmeters are able to store calibration data

in an internal memory and automatically correct the readings, making the

4
ELECTRICAL PERFORMANCE TESTS FOR TRUE -RMS VOLTMETERS

customary screwdriver adjustments of trimmers unnecessary. The elimination of

physical circuit adjustments tends to improve long-term stability.

Although the digital processing power embedded in modern ac voltmeters

distinguishes them from their older analog counterparts, the analog circuitry

which amplifies and conditions the input signals is still an important factor

in the overall measurement accuracy. With typical input impedances of 10 Mfl made possible by high-performance amplifiers, careful design of the range

changing attenuator is required to keep a flat frequency response over a wide

band. The high input impedance reduces source loading and makes possible

overload protection that was previously impractical. The input protection

typically consists of a metal-oxide varistor or zener diode circuit, possibly

in combination with fuses, which provides a voltage clamping action to prevent

high voltages or voltage transients from reaching the voltmeter's solid-state

circuitry. The major attribute of such clamping circuitry is speed of

operation and the ability to withstand high voltages without impairing the

accuracy of the instrument. In addition, the commercial ac voltmeter is also

designed to withstand vibration and mechanical shocks that are encountered in

field applications.

3.2. Principles of Operation

3.2.1. AC to DC Conversion

The specific principle of operation of an ac voltmeter is highly dependent on

the manufacturer's choice of technology and design decisions. In general, ac signals are measured by scaling and converting the ac voltage present at the

input of the ac voltmeter to a dc voltage level intended to be proportional to

the root-mean- square (rms) of the ac signal. The dc voltage is then digitized

and displayed as an ac-voltage amplitude.

The ac(rms) -to-dc conversion can be accomplished by several techniques. Most

voltmeters obtain the root-mean-square value either by squaring and averaging

of the input signal using an analog multiplier and averaging circuit, or by

using thermal converters which compare the heat dissipated by the ac signal to

that of an equivalent dc quantity.

The analog multipliers/dividers can employ either direct multiplication and

division using variations of the Gilbert (transconductance cell) multiplying

circuit [2], or can be based on logarithmic amplifiers. In either case, by

connecting the same ac signal to both "multiply" inputs and feeding the

averaged output back to the "divide" input, the arithmetic operation can compute the root -mean- square (rms) value of the input.

Both the transconductance type and the logarithmic amplifier type multiplier

are available as integrated circuits; some manufacturers also supply

specialized rms-computing integrated circuits.

5
ELECTRICAL PERFORMANCE TESTS FOR TRUE -RMS VOLTMETERS

An alternative means of rms-to-dc conversion is provided by thermal

converters. These devices employ a voltage -ranging resistor in series with a low-resistance heating element to which a temperature sensor (thermocouple) is

attached. The heating effect, and thus the dc voltage produced by the

thermocouple, is approximately proportional to the square of the input signal

current. To linearize the transfer characteristic, two similar thermoelements

are used, one energized with the unknown ac signal and the other with a dc

voltage which is adjusted in a servo loop until the thermoelement outputs are

equal. The advantage of the thermal technique is that the instrument has a relatively wide bandwidth, is insensitive to waveform distortion, and can tolerate large crest factors. The big disadvantage is a relatively slow

response time.

3.2.2. Analog- to-Digital Conversion

After the ac-to-dc conversion stage, most modern ac voltmeters use improved

integrating dual-slope (sometimes called ' quad- slope ' ) analog- to-digital

converters that correct for zero offset errors and operate on the charge

balance principle [3] [4] [5] [6], or the voltmeters use voltage to frequency

converters. The dual-slope technique is based on a linear charge -discharge

characteristic of a capacitor and arranged so that the discharge time, which

is proportional to the input voltage, is measured by counting a train of clock

pulses. In its simplest version, the input voltage is integrated by charging

a capacitor for a predetermined time. Then, a reference voltage is switched

to the integrating circuit and discharges the capacitor at a known rate until

a level corresponding to "zero" input is reached. Figure 1 shows the voltage

output of an idealized integrator for a typical measurement cycle. The time

for the second integration process (discharge time) is proportional the

average of the unknown signal over the predetermined integration period. The

intergration time is measured by counting pulses generated with a constant

clock frequency which is adjusted so that the count displayed on a readout

provides a value in the appropriate measurement units.

Dual-slope techniques are widely used since the method does not require highaccuracy resistor networks to achieve high-accuracy measurements. The basis

for accuracy resides in the precision reference source which is used during

the reference integration time. The components, other than the reference

source, are required to be stable only over the integration time in order for

the ac voltmeter to hold the specified accuracy. There are many variations to

the basic, dual-slope conversion technique. For example, additional circuitry

may be added to provide compensation for zero offset during each measurement

cycle. [7] [8] This zero compensation is accomplished by effectively shorting

the input to the analog- to-digital converter, measuring the offset voltage and

then subtracting it (in either an analog or digital manner) from the amplitude

of the input signal being measured. Additional techniques may also be used to

compensate for calibration errors, temperature errors, and frequency errors of

ac measurements.

6
ELECTRICAL PERFORMANCE TESTS FOR TRUE-RMS VOLTMETERS

Fig. 1. Concept of dual-slope integration shovm for two different input

voltages. (The slope of each signal integration curve is

proportional to the average of the corresponding input voltage.)

4. VOLTMETER PERFORMANCE MEASUREMENTS

4.1. Input Characteristics

The following sections describe the characteristics of the ac voltmeter input

and how to measure them. The characteristics generally specified are: the

input impedance, the common-mode rejection, the maximum input voltage and the

input over-voltage protection.

4.1.1. Input Impedance

The input characteristics of wideband, ac voltmeters are designed to minimize

disturbing the external circuit connected to the input terminals. Ideally,

the voltmeter input should have an infinite impedance (zero loading) for ac and dc voltage measurements. In actual practice, the input impedance of the

voltage measuring circuitry is typically a resistance of tens of megohms

shunted by a capacitance of tens of picofarads. Since the capacitive

reactance decreases with frequency, the effect of source loading by the input

impedance increases with frequency. At low frequencies the effect of the

input capacitance is usually negligible.

7
ELECTRICAL PERFORMANCE TESTS FOR TRUE -RMS VOLTMETERS

Measurement Technique

The input impedance is determined using a commercial digital LCR meter to

measure the input resistance and capacitance directly. This instrument is

generally a self-balancing bridge which can determine the resistance and

capacitance of an impedance across the input terminals. These quantities can

be determined without additional equipment or calculations.

Sources of Measurement Error

The errors associated with using a direct-reading LCR meter are attributable

to uncertainties associated with the accuracy of the of the LCR meter and the

stray capacitance of the leads connecting the LCR meter to the voltmeter under

test. The basic calibration accuracy of the LCR meter used in the procedure

is specified by the manufacturer to be

0.2 % of reading + 1 digit

for capacitance measurements, and

0.3 % of reading + 2 digits

for resistance measurements. The total errors associated with the LCR meter,

considering the ranges used and the number of digits displayed, are ± 2.1 pF

and 50 kO for the measurement of parallel capacitance and resistance,

respectively.

4.1.2. Common Mode Rejection

Common-mode rejection is the degree to which the ac voltmeter measurement of

the voltage drop across the input terminals remains unaffected by the presence

of a "common" ac voltage at both terminals with respect to ground. This

characteristic is particularly important for meters that are grounded by

connection to the power line.

Measurement Technique

For the line-operated true-rms voltmeter, the calibrator is connected to the

shorted input terminals and to chassis ground on the unit-under- test (UUT) as shown in Figure 2. Two measurements are made to determine the common-mode

rejection (CMR) ; the first reading, , on the unit-under- test is taken with

the calibrator voltage set at or near zero, and the second reading, , is

taken with the calibrator set to the specified common-mode voltage, The

is necessary to establish the reading of the voltmeter under conditions of

"zero" input. Because of the wide -band response of the meter, noise and other

stray signals will result in a non-zero reading even though there is no intended input voltage. The common-mode rejection, in units of decibels, is

then calculated using the following equation:

8
ELECTRICAL PERFORMANCE TESTS FOR TRUE-RMS VOLTMETERS

( Vi - vf

CMR - 20 log

0 VCM

This procedure can be carried out at the specified frequencies and repeated at

other frequencies, (The most commonly encountered power- line frequencies are

50, 60, and 400 Hz.)

Fig. 2 Test setup for measuring ac common mode rejection ratio.

Sources of Measurement Error

The predominant source of measurement error is the voltmeter-under- test . If

the common-mode voltage is small, the meter may not have sufficient resolution

to provide more than a two-digit reading. Another, though usually negligible

source of error, is the small but finite output voltage of the calibrator when

its nominal output is assumed to be "zero." Since this voltage term, , is

squared in the calculation, its effect is normally small. (If V is equal to

10% of

^ it will produce only a 1% error [0.09 dB)).

^

4.1.3. Input Protection

The input protection circuitry of the ac voltmeter permits the unit to survive

voltage overloads without damage. This characteristic is important since the

ac voltmeter may accidentally be subjected to high voltages when the range

switch is set to a low-voltage range.

9
ELECTRICAL PERFORMANCE TESTS FOR TRUE -RMS VOLTMETERS

Measurement Technique

The ability of the input circuity to withstand an overload condition is tested

by applying to the voltmeter-under- test the specified overload voltage on all

ranges. The overload protection tests are based on the tests for a maximum

nondestructive input signal specified by the manufacturer as described in ANSI

C39.6-1983 (paragraph 6.13)^. The meter passes the test if, after application

of the specified voltage for the specified time (five minutes, if the

specification is for continuous application) , the meter still meets is rated

accuracy requirements

.

Sources of Measurement Error

The input protection tests are designed as pass/fail tests. As such, there is no source of meaningful measurement error. The uncertainty of the applied

voltage, supplied by a high-accuracy meter calibrator, is negligible for this

test

.

4.2. AC Voltage Performance Tests

As pointed out in Section 3., measurement of ac quantities is usually a twostage process. In the first stage, the ac voltage is converted to an equivalent dc voltage, and in the second stage the dc voltage is digitized and

displayed. In the first stage of the process, the accuracy of the ac-dc

conversion circuitry is frequency dependent, and the range resistor network

may be both frequency and amplitude dependent. In the second stage, the dc

voltage- to-digital-output circuitry is independent of the frequency, but can introduce amplitude errors due to the non-linearities and incorrect reference

voltages in the converter. Tlierefore , it is necessary to determine the

performance of the ac meter at various combinations of frequencies and voltage

levels o

4.2.1. Range and Accuracy

Using the accuracy specifications as a guide, test points are selected over

the frequency and amplitude ranges of the unit-under- test . Generally, test

points are chosen along the upper or lower limits, or both, associated with a specified accuracy on a frequency- amplitude plot. Additionally, intermediate

points may also be chosen so that at least one point is checked on each

amplitude range of the unit-under- test at one or more frequencies.

American National Standard for Electrical Instrumentation - Digital

Measuring Instruments, ANSI C39.6-1983, published by the American National

Standards Institute, 1430 Broadway, New York, NY 10018.

10
ELECTRICAL PERFORMANCE TESTS FOR TRUE -RMS VOLTMETERS

Measurement Technique

No single measurement technique is adequate to check the accuracy over the

entire frequency band of the true rms -voltmeter at all voltage levels. Three

different methods are recommended for voltage measurement:

1. Over the frequency range from 10 Hz to 1 MHz, and for

amplitudes from 1 mV to 1000 V, a meter calibrator (with an associated high-voltage amplifier) can check the voltmeter

directly.

2. Above 1 MHz, and for voltages from IV to 100 V, an uncalibrated test signal source is used, and a calibrated

thermal converter is connected in parallel with the voltmeter

input. The voltage source is then adjusted until the output of

the calibrated thermal converter indicates that the desired

voltage level has been reached. The voltage source is then

effectively calibrated and the actual meter reading can be

compared against the calibration voltage.

3. For voltages below IV, at all frequencies, the calibration

voltage is obtained from a micropotentiometer. A

micropotentiometer is essentially a thermoelement used as an

rms current measuring device. The current passes through a special shunt resistor that has a very low ac-dc difference and

the voltage drop across the shunt becomes a calibrated output

voltage. Typically, the current is 10 mA and shunts are in

the range from 0.01 to 10.0 0 so that output voltages from

100 /iV to 100 mV can be obtained.

Note: Thermal converters or micropotentiometers are assigned an ac-dc

difference by the manufacturer or an independent calibration

laboratory based on intercomparisons with similar devices with

known or computable ac-dc difference. The value of this ac-dc

difference is usually stable over long periods of time.

However, the operating characteristic that links the current

through a thermoelement with the output voltage of the

temperature sensing device (thermocouple) is subject to drift.

Therefore, before use in either method 2 or method 3 above, a preliminary calibration against a known dc or low-frequency ac reference standard is necessary.

Sources of Measurement Error

A source of error with electrical and electronic measuring instruments of any

kind are currents that bypass the measuring circuit through ground loops or other stray paths. While it is relatively simple to avoid such stray currents

11
ELECTRICAL PERFORMANCE TESTS FOR TRUE -RMS VOLTMETERS

with proper insulation when measuring dc, for ac the problem is more complex

because of capacitive and inductive coupling. This is especially true for the

true-rms voltmeter. Careful circuit design, grounding, and shielding are necessary to avoid this type of error. Each set-up has to be considered

individually, and general rules can serve only as broad guidelines.

At low audio frequencies inductive coupling predominates, while capacitive

coupling becomes more important with increasing frequencies. Any measuring

circuit that produces a change in the reading when the operator comes near or touches part of the case or outside of a connecting cable is liable to give an incorrect measurement result. This is true even if care is taken not to touch

or approach the equipment. A rearrangement of the measuring circuit, and in

particular of the ground connections and shielding, is then advisable.

For performance tests on the true-rms ac voltmeter for signals above 10 MHz,

the characteristic impedance of the connecting cables and connectors becomes

important because of reflections at connectors and all other cable junctions.

Careful placement of critical circuit components is necessary to be sure that

the set-up measures the desired quantity. For instance, for a broad-band ac voltmeter at frequencies as low as 20 MHz, a few inches of coaxial cable

between the high- impedance voltmeter input and the 50 Q terminating resistor

can make an appreciable difference in the voltmeter reading. Keeping leads as short as possible is desirable.

When calibrating thermoelements with dc, errors can arise if the dc reversal

difference in the thermoelement response is not taken into account.

Measurements should always be made with both polarities of dc applied, and the

average of the two readings should be used as a reference for subsequent ac measurements. Also, devices containing thermoelements (thermal converters and

micropotentiometers) tend to drift with changes in ambient temperature and

should, therefore, be protected from such temperature changes during the

measurement

.

To compute the uncertainty in the calibration voltage or current using method

1 (calibrator) above, only the specified error limits of the calibrator have

to be taken into consideration.

For method 2 (thermal converter), the following factors have to be considered:

i. Uncertainty in the reference voltage (Uj-) {which can be dc or low-frequency ac).

ii. Uncertainty in the thermal converter ac-dc difference or frequency response correction (u^,)

.

The total uncertainty in the calibrating voltage uj is then computed as

UT - 7(u| + ug) .

12
ELECTRICAL PERFORMANCE TESTS FOR TRUE -RMS VOLTMETERS

For method 3 (micropotentiometer) the same formula as that given in method 2

is used. The reference voltage in this case is the average of the two

polarities of dc voltage across the shunt resistor of the micropotentiometer

as measured by a calibrated dc microvoltmeter. The corresponding uncertainty,

Uj., is the uncertainty in making this dc measurement. The uncertainty, U(,, in

the frequency response is the uncertainty in the ac-dc difference of the

micropotentiometer at the measurement frequency.

4.2.2. Frequency Range

Determination of the upper and lower limits of the frequency range of a truerms responding voltmeter can be combined with the accuracy check of the unitunder- test by selecting test points at the upper and lower specification

limits of frequency and signal amplitude.

Measurement Technique

The test method is the same as for section 4.2.1, Range and Accuracy.

The tests for accuracy of the ac voltage ranges of the true-rms ac voltmeter

are performed over the specified frequency range including the end points of

the range. Instruments that do not exhibit the required accuracy at the

endpoints are considered to possess insufficient frequency range.

Consequently, no separate "frequency range" tests need to be performed.

Sources of Measurement Error

For a discussion of errors, see Range and Accuracy.

4.2.3. True-RMS Detection

The basis for this test is taken from lEC Publication 51 (which has superseded

ANSI C39.1. [9]) The ability of the unit-under- test to measure waveforms

using true-rms detection is tested with a nonsinusoidal waveform generated by

adding approximately 30% of third harmonic to a fundamental signal at 1 kHz.

A true-rms responding meter will give an indication for this non-sinusoidal

signal that is independent of the phase angle of the harmonic relative to the

fundamental. (Note that an average or peak responding meter will give

indications that will vary with the phase angle of the harmonic) . To

implement the test, a signal with a frequency that is somewhat greater than

three times the fundamental by a small fraction of a hertz, is superimposed on

the fundamental frequency. In this way the relative phase angle between the

two signals increases slowly so that in a time interval of the order of half a minute, the phase angle has swept from 0 to 360 .

13
ELECTRICAL PERFORMANCE TESTS FOR TRUE -RMS VOLTMETERS

Measurement Technique

The test signal is generated by two independent signal generators, with stable

frequencies, at least one of which should preferably be a synthesized waveform

generator with a frequency adjustment in steps of fractional hertz. The

choice of fundamental frequency for this test is arbitrary. For best results

it is convenient to chose a frequency in a range where the specified meter

error is smallest for both the fundamental and the third harmonic. The

harmonic component is generated at about 3.0001 times the fundamental

frequency so that the relative phase with respect to the fundamental sweeps

through one cycle at a rate slowly enough so that the maximum and minimum

meter response can be read. (With the ratio indicated, the phase of a 3-kHz

waveform will sweep through 360® in 10 seconds.) The amplitude of the

harmonic component should be set at about 20% (30% in the original ANSI

standard) of that of the fundamental to conform to the lEC test

specifications. To obtain good resolution on the readout of the meter, the

amplitudes of the two signals should be chosen so that the meter indicates a value near full-scale on the range when relative phases are such that the

combined signal is at a maximum. For instance, if the full-scale meter

indication is 1.999 V, then if the fundamental is 1.500 V and the harmonic

component is 0.450 (30%), the combined signal will not be greater than 1.950

volts; close to, but less than full-scale.

The simplest way to combine the two signals is to use a resistance network

that acts as a summing junction for the inputs from the two generators as shown in the figure 3.

Fig. 3 Set-up to check for true-rms response

14
ELECTRICAL PERFORMANCE TESTS FOR TRUE -RMS VOLTMETERS

Sources of Measurement Error

Since the measurement is concerned only with the constancy of the indicated

value within the response tolerance for the range, a calibrated ac voltage

source is not required. Even the signal frequencies need only be approximate

for this test. Uncertainty statements are therefore not applicable.

4.2.4. Crest Factor

A crest- factor test is an important performance measure of voltmeters

employing true-rms detection. The crest factor is the ratio of the maximum

value of a voltage waveform (the peak) to the effective or rms value. Crestfactor limitations introduce an error when measuring non- sinusoidal signals.

Typical true-nns voltmeter systems can accept signals at full scale with crest

factors of 4:1 or higher. When a crest factor specification does not contain

an accuracy degradation statement, it must be assumed that all accuracy

specifications are applicable for signals with the specified crest factor . High crest-factor signals inherently have a broad spectrum of harmonics, but

for a given crest factor the spectral distribution depends on the waveshape of

the signal. By careful choice of the waveshape of the test signal, it is

therefore possible to set an upper frequency limit for significant harmonic

components. For each given accuracy specification of the voltmeter response,

there is an upper and lower frequency limit, and it is advantageous for the

crest factor response determination to choose a test signal that has all of

its significant frequency components within those frequency limits. If some significant harmonic components fall into another accuracy specification

region, it becomes difficult to assess whether the voltmeter has passed or failed the test. Thus, unless the crest- factor test signal is carefully

chosen, consistent test results will not be obtained.

Measurement technique

A crest- factor measurement is made by applying a test waveform with the

specified crest factor to the voltmeter-under- test and comparing the

voltmeter's indication with the true-nns value of the test waveform determined

by independent means. A worst case condition is ensured by setting the rms value of the test waveform near the full-scale value of a range. For an autoranging voltmeter, an amplitude adjustment is required so that the test

waveform amplitude is close to the upper end of a range.

The bipolar triangle waveform, shown in figure 4, offers a good compromise

between ease of generation and mitigation of the higher order harmonics. In

the absence of any specified waveform, it is the test waveform used for the

procedure described in Appendix B.

15
ELECTRICAL PERFORMANCE TESTS FOR TRUE -RMS VOLTMETERS

Fig. 4. Crest factor test waveform

The crest factor of this waveform is given by

CF - (3T/r)^ . (1)

For a 4:1 crest factor, the ratio of T/t becomes 16/3. The average of the

test waveform is zero and therefore exercises the full peak-to-peak dynamic

range of the voltmeter-under- test. The test waveform of figure 4 is most

easily generated by an arbitrary waveform generator, but this method limits

the fundamental to audio frequencies. A more meaningful test for the

wideband, true-rms voltmeter should be performed at a fundamental test

frequency near mid-band, and at a frequency which is low enough to insure that

all the significant harmonics are within the specified frequency band. A test

fixture, which generates the waveform shown in figure 4 with a 4:1 crest

factor, has been specifically designed for the crest- factor test procedure.

The design was implemented using a few logic gates and an operational

amplifier. The details of the circuit can be found in Appendix D. The width

of the triangle pulse r is set to 3 /is and the interval T to 16 /is. The

output amplitude of the waveform generator is set to a nominal 1-volt rms

level. In the test procedure, a power amplifier boosts the output of the

crest factor generator to a nominal level of 100 volts rms and applies it to

the voltmeter-under- test at a full scale range setting of 100 volts.

Performing the crest factor test at high amplitudes will emphasize any slewrate limitations existing in the voltmeter under test. The magnitude spectrum

of the crest factor test waveform at the output of the power amplifier, Fig.

D-2, Appendix D, shows that all significant harmonic energy is well within the

bandwidth of the voltmeter.

Sources of Measurement Error

The main source of error for this measurement is the uncertainty with which

the measurement of the rms value of the crest- factor signal can be made.

Thermal converters offer the most accurate means of determining the rms value

of high crest- factor waveforms. Thermal converters respond inherently to the

rms value and have a flat frequency response over a wide range [10]. In the

16
ELECTRICAL PERFORMANCE TESTS FOR TRUE -RMS VOLTMETERS

accuracy specification region on a frequency -amplitude plot, where the

voltmeter accuracy is specified as ± 3%, the measurement uncertainty of the

crest- factor waveform using a thermal converter can be conservatively

estimated to be better than 0.1%. The sources of error and measurement

uncertainty are generally the same as those discussed in Section 4.2.1.

4.2.5. Response Time

The response- time determination establishes whether a voltmeter reading within

the specified accuracy limits can be obtained in the time interval specified.

Measurement Technique

The measurement of response time for instruments having only a visual readout

is necessarily somewhat subjective and dependent on operator reaction time.

The measurement is carried out with a bus controlled calibrator which applies

a voltage to the unit-under- test , and, after a programmed time delay

corresponding to the specified response time, the operator is signaled to read

the meter. If the reading falls within the accuracy limits applicable for the

range and frequency of the input, the test is deemed successful. Generally,

it is beneficial to repeat the test several times to check the consistency of

the result and to assure that the observer does not contribute excessive

random errors to the outcome of the test.

Sources of Measurement Error

The predominant source of error is the reaction time of the observer. With

practice, a skilled observer should be able to reduce the uncertainty in the

time interval between application of the input signal and noting of the

readout to ± 0.2 seconds. Additional timing delays introduced by the bus

controller, usually of the order of a few milliseconds, are negligible.

17
ELECTRICAL PERFORMANCE TESTS FOR TRUE -RMS VOLTMETERS

5. REFERENCES

[1] For an interesting discussion of analog meters, see Soisson, Harold E. , Electronic Measuring Systems, McGraw-Hill Book Company, Inc., New York,

1961, pp. 182-188.

[2] Gilbert, B. , "A precise four-quadrant multiplier with subnanosecond

response,” IEEE J. Solid-State Circuits, Vol. SC-3, pp. 365-373,

December 1968.

[3] Ammann, S. K. , Integrating Analog- to-Digital Converter, U. S. Patent

No. 3,316,5^7, April 25, 1967.

[4] Kime, Jr., R. C., The Charge -Balancing A-D Converter: An Alternative To

Dual-Slope Integration, Electronics

,

May 24, 1973.

[5] Grandbois ,G. , Pickerell, T. , Quantized feedback takes its place in

analog- to-digital conversion. Electronics, pp. 103-107, October 13, 1977.

[6] Hnatek, E. R. , A User's Handbook of D/A and A/D Converters, John Wile &

Sons, New York, 1976.

[7] Mattera, L. , Converter Stresses Stability, Electronics, p. 139-140,

February 19, 1976.

[8] Jones, L. T. , Ressmeyer, J. J., Clark, C. A., Precision DVM Has Wide

Dynamic Range and High System Speed, Hewlett-Packard Journal, Vol. 32,

No. 4, pp. 23-31, April 1981.

[9] Requirements for Electrical Analog Indicating Instruments, ANSI C39.1-

1981] superceded by:

Direct Acting Indicating Analogue Electrical Measuring

Instruments and their Accessories, lEC Publication 51 -1984

[10] Hermach, F. L. , AC-DC Comparators for Audio -Frequency Current and Voltage

Measurements of High Accuracy, IEEE Trans. on Instrum. & Meas .

,

Vol. IM-25, No. 4, pp. 489-494, December 1976.

18
ELECTRICAL PERFORMANCE TESTS FOR TRUE -RMS VOLTMETERS

APPENDIX A

PERFORMANCE SPECIFICATION FOR

THE ME-545 0/G TRUE -RMS VOLTMETER^

Reprinted from the U. S. Army specifications for the TMDE

modernization project.
ELECTRICAL PERFORMANCE TESTS FOR TRUE -RMS VOLTMETERS

10=1 Type of Response

Meter AC voltage measurement capability shall be true rms responding over

the entire voltage range, (para. 10.3).

10.1.1 DC Coupling

Meter shall have the capability of being dc coupled, for measuring AC

signals with DC components.

10.2 Frequency Range

Frequency response shall be at least 10 Hz to 20 MHz.

10.3 Voltage Range

Shall be from 100 micro-volts rms or less, to 300 volts rms or greater

except where limited by the volt-hertz product of para. 10.12.

10.3.1 Selectable Ranges

Meter shall provide no less than seven selectable ranges, with the lowest

full scale range no greater than 2 millivolts rms, and the greatest full

scale range at least 300 volts rms.

10.3.2 Ranging

Shall be auto -ranging, also shall have the capability of manually setting

the range. Shall provide at least 10% over- range, or 10% under- range when

manually auto -ranged.

10.3.3 Voltage Resolution

Display resolution in voltage mode shall be at least as specified herein:

READING RESOLUTION

for readings below 1.999 mV 1 microvolt

2.00 mV to 19.99 mV 10 microvolts

20.00 mV to 199.9 mV 100 microvolts

200 mV to 1999 mV 1 millivolt

2.00 V to 19.99 V 10 millivolts

20.0 V to 199.9 V 100 millivolts

200 V to 300 V 1 volt

A - 2
ELECTRICAL PERFORMANCE TESTS FOR TRUE -RMS VOLTMETERS

10.4 Display Type and Units

Shall have a digital display with 3 1/2 digits, or more, in the voltage

mode. Shall also have analog peak and null indicator. Analog peak and null

indicator shall show changes in voltage equal to, or greater than 5% of full

scale of range in use. The digital display shall have annunciators for volts,

millivolts, decibels relative, dBm, and polarity.

10.5 Decibel Measurements

Meter shall have a minimum span of 130 dB and comply with the

requirements herein.

10.5.1 Decibel Display and Resolution

Meter shall have at least 4-digit display with polarity indicator when in

the decibel mode, decibel resolution shall be at least 0.01 dB.

10.5.2 dBm Reference Impedance

In dB mode, reference impedance shall be selectable, with a minimum of

five selection: 50 ohms, 75 ohms, 124 ohms, 135 ohms, and 600 ohms.

10.6 Accuracy

Shall be at least as specified below over the operating temperature range

from 18 to 28 degrees Celsius, for ac-coupled measurements. AC + DC

measurement accuracy shall be within twice the tolerance for ac measurements

.

RF-DC transfer difference from dc to 100 MHz at a voltage level of

100 microvolts

Shall be within ± 0,2% of dc input level.

Accuracy for frequencies from 10 Hz to 49.99 Hz for all input levels

from 100 microvolts to 300 volts

Shall be within + 5% of true input level.

Accuracy for frequencies from 100 Hz to 99.9 kHz for all input

levels from 100 microvolts to 1 millivolt

Shall be within + 5% of true input level.

A - 3
ELECTRICAL PERFORMANCE TESTS FOR TRUE -RMS VOLTMETERS

Accuracy for frequencies from 100 kHz to 999.9 kHz for all input

levels from 100 microvolts to 1 x 10® volt-hertz.

Shall be within ± 5% of true input level.

Accuracy for frequencies from 1 MHz to 9.99 MHz for all input levels

from 100 microvolts to 1 x 10® volt-hertz.

Shall be within + 10% of true input level.

Accuracy for frequencies from 10 MHz to 19.99 MHz for all input

levels from 100 microvolts to 1 x 10® volt-hertz.

Shall be within + 15% of true input level.

Accuracy for frequencies from 10 Hz to 49.99 Hz for all input levels

from 100 microvolts to 300.0 volts and for frequencies from 50 Hz to

99.99 kHz; for all input levels from 1 millivolt to 300 volts (200

volts from 20 kHz to 99.99 kHz).

Shall be within + 3% of true input level.

Accuracy for frequencies from 100 kHz to 999.9 kHz for all input

levels from 100 microvolts to 1 x 10® volt-hertz.

Shall be within + 5% of true input level.

Accuracy for frequencies from 1 MHz to 9.99 MHz for all input levels

from 100 microvolts to 1 x 10® volt-hertz.

Shall be within + 10% of true input level.

Accuracy for frequencies from 10 MHz to 19.99 MHz for all input

levels from 100 microvolts to 1 x 10® volt-hertz.

Shall be within + 15% of true input level.

10.7 Response Time

Shall be 3 seconds or less to rated accuracy.

A - 4
ELECTRICAL PERFORMANCE TESTS FOR TRUE -RMS VOLTMETERS

Shall be within + 3% of true input level.

10.8 Crest Factor

Meter shall handle crest factors of 4:1 for all input levels below 100

volts, increasing for downscale measurements.

10.9 Input Connector

Input connector of meter shall be selectable by a front panel switch,

allowing the outer connector to be floating from chassis ground or to be

connected to chassis ground. Connector type shall be BNC type female.

10.11 AC Common Mode Rejection

Shall be greater than 60 dB up to 400 Hz.

10.12 Maximtim Input Protection

Shall be at least 420 volts peak (300 volts rms) on all ranges, and shall

be at least 1 x 10® volts -hertz on all ranges above 1 volt.

10.13 Input Impe danc e

Input impedance shall be 1 megohm or greater, shunted by 50 picofarads

capacitance or less.

10.14 DC Output

The meter shall have rear panel dc output. Output connector shall be BNC

type female or dual banana female.

A - 5
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ELECTRICAL PERFORMANCE TESTS FOR TRUE-RMS VOLTMETERS

APPENDIX B

TEST PRODEDURES FOR

THE ME-545 0/G TRUE-RMS VOLTMETER
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

Note

The material in this Appendix has been prepared for use by the Department of

the Army, CECOM, Fort Monmouth, New Jersey. Certain commercial equipment is

identified with each test procedure listed. This identification does not

imply endorsement by the National Bureau of Standards, nor does it imply that

the equipment identified is necessarily the best available for the purpose.

B - 2
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

Table of Contents

Page

List of Figures ............... .... 4

List of Tables 5

10.1 Type of Response . B-6

10.1.1 DC Coupling B-10

10.2 Frequency Range ...... ..... B-13

10.3 Voltage Range B-14

10.3.1 Selectable Ranges ......... B-15

10.3.2 Ranging B-17

10.3.3 Voltage Resolution . B-20

10.4 Display Type and Units B-24

10.5 Decibel Measurements B-26

10.5.1 Decibel Display and Resolution B-28

10.5.2 dBm Reference Impedance B-30

10.6 Accuracy B-32

10.7 Response Time B-65

10.8 Crest Factor B-68

10.9 Input Connector B-73

10.11 AC Common Mode Rejection B-75

10.12 Maximum Input Protection B-78

10.13 Input Impedance B-81

10.14 DC Output B-84

B - 3
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

List of Figures

Page

Fig. 10.1a Set-Up for Type-of -Response Test . 7

Fig. 10.1b Waveforms for Type of Response Test 8

Fig. 10.1.1 Set-Up for testing DC Coupling 10

Fig. 10.3.2a Set-Up for Voltage Range Test 17

Fig. 10.3.2b Set-Up for Voltage Range Test for voltages above 100 volts . 17

Fig. 10.3.3a Set-Up for Voltage Resolution Test ............ 21

Fig. 10.3.3b Set-Up for the Resolution Test for voltages above 100

volts 21

Fig. 10.5 Set-Up for the Decibel Test 26

Fig. 10.5.1 Set-Up for Decibel Resolution Test 28

Fig. 10.6.1 Set-Up for Micropotentiometer DC Calibration 35

Fig. 10.6.2 Set-Up for 100 /iV AC Measurements 38

Fig. 10.6.3 Set-Up for the Accuracy Test with the Calibrator 48

Fig. 10.6.4 Set-Up for the Accuracy Test with the Calibrator and

Amplifier . 49

Fig. 10.6.5 Set-Up for the 100-Volt Accuracy Test

using a Thermal Converter ......... 52

Fig. 10.6.6 Set-Up for Low-Voltage Accuracy Test

using a Thermal Converter 56

Fig. 10,7.1 Set-Up for Response Time Test ......... 66

Fig. 10.8 Set-Up for the Crest Factor Test ..... ... 71

Fig. 10.11.1 Test setup for measuring the common mode rejection. .... 75

Fig. 10.12 Test setup for measuring maximum input protection. .... 78

Fig. 10.13 Test setup for measuring input impedance 81

B - 4
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

List of Tables

Page

Table 10.1 Type-of -Response Test ................ 9

Table 10.1.1 DC Coupling Test ................... 12

Table 10.3.1 Selectable Ranges ..... 16

Table 10.3.2 Ranging 19

Table 10.3.3.1 Voltage Resolution 20

Table 10.3.3.2 Voltage Resolution . . 23

Table 10.4 Display Type and Resolution . 25

Table 10.5 Decibel Measurement 27

Table 10.5.1 Decibel Measurements 29

Table 10.5.2 dBm Reference Impedance ..... ..... 31

Table 10.6a Accuracy Test, Data Sheet, Micropotentiometer

Measurements. 62

Table 10.6b Accuracy Test, Data Sheet. Calibrator 63

Table 10.6c Accuracy Test, Data Sheet, Thermal Converter. .... 64

Table 10.7 Response Time, Data Sheet, ( 3 Seconds) ....... 67

Table 10.8 Crest Factor 72

Table 10.9 Input Connector 74

Table 10.11 Common Mode Rejection 77

Table 10.12 Maximum Input Protection . 80

Table 10.13 Input Impedance 83

Table 10.14 DC Output 85

B - 5
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

10.1 Type of Response

Specification :

Meter AC voltage measurement capability shall be true rms responding over the

entire voltage range, (para. 10.3).

The test checks whether the meter is true-rms responding. The basis for

this test is taken from ANSI 39.1 and consists of adding approximately 30%

third harmonic to a fundamental signal at 1 kHz. A true-rms responding meter

will give the same indication for this non-sinusoidal signal independent of

the phase angle of the harmonic relative to the fundamental. (Note: an average

or peak responding meter will give indications that are dependent on the phase

angle of the harmonic.) To implement the test, a signal with a frequency that

is greater than three times the fundamental by a small fraction of a hertz, is

superimposed on the fundamental frequency. In this way the relative phase

angle between the two signals increases slowly so th^at in a ^time interval of

about one minute the phase angle has increased from 0 to 360 .

Test Condition :

The fundamental frequency (1 kHz) is generated with the Wavetek Model 275

Arbitrary Waveform Generator, and the harmonic component is produced using the

Hewlett-Packard Model 3325A Function Generator.

Equipment :

I terns

Function Generator

Arbitrary Waveform Generator

Oscilloscope

Cable with BNC connectors

BNC tee connector

Special Resistor Junction Box

Model

Hewlett-Packard 3325A or equivalent

Wavetek 275 or equivalent

Tektronix 465 or equivalent

Special part (NBS)

Procedure

:

Set up the equipment as shown in figure 10.1a. Connect the output of

the function generator and of the arbitrary waveform generator to the resistor

terminations of the special resistor junction box. Attach a BNC tee to the

third connector of the junction box, and connect one end of the tee to the UUT

and the other to the oscilloscope.

B - 6
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

To set up the Wavetek Model 275, push the front-panel controls in the

following sequence;

1 . Power

2. STAT Check Display as indicated in Wavetek Instruction Manual,

page 2-4.

3. OUT-ON, 1, EXEC Display reads "OUTPUT 0N(1)"

(This command connects the signal to the output terminal)

Steps 1 to 3 set up the Wavetek Function Generator to its default values

of 1 kHz and 5 V.

The next three steps will set up the Hewlett-Packard Model 3325A

Synthesizer to approximately 3 kHz and 1.5 V jnns

4. Turn on power switch

5. FREQ, 3, kHz

6. AMPTD, 1.5, V rms.

This should produce an image of a distorted sine wave on the

oscilloscope. Since the frequency setting of the Wavetek Model 275 may not be

exactly 1 kHz, a fine adjustment of the frequency of the Hewlett-Packard Model

3325A Synthesizer may be necessary. To adjust the frequency, proceed as follows

7. FREQ, Left arrow in the "Modify" field. (This turns on additional

digits on the display)

8. Push left arrow repeatedly until the zero to left of the decimal

point is blinking.

B - 7
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Push the "up" or the "down" arrow until the pattern on the

oscilloscope is almost stationary.

If the adjustment is too fine, use the "left" arrow once more, then

use the "up" or "down" arrows.

If the adjustment is too coarse, use the "right" arrow instead of

the "left" arrow and proceed as before.

If the frequency fine adjustment has been done correctly, the image on the oscilloscope screen should vary slowly from one waveform,

shown in figure 10.1b, to the other and back again. The time for the

pattern to return to its original shape should take approximately 10

seconds

.

While the waveform pattern is changing slowly, observe the output

reading of the digital voltmeter-under- test (UUT) , and enter into

the data sheet the highest and lowest readings obtained. The

difference between the two readings should be within +3%.

Fig. 10.1b Waveforms for Type of Response Test
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

Table 10.1 Type-of-Response Test

High Reading

(Volts)

Low Reading

(Volts)

Difference

(Volts)

Uncertainty Specification

Limits

±1 Isd* ± 3%

least significant digit on display

B - 9
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

10,1.1 DC Coupling

Specification :

Meter shall have the capability of being dc coupled, for measuring ac signals

with dc components.

This test checks whether the digital voltmeter under test (UUT) correctly

combines dc signals and ac signals. The Hewlett-Packard Model 3325A Function

Generator (or equivalent) is used as signal source. This signal generator

provides means for adding a dc offset (maximum 443 mV)

.

Equipment :

I terns Model

Function Generator Hewlett-Packard 3325A or equivalent

DC millivoltmeter Fluke 8506A or equivalent

Oscilloscope Tektronix 465 or equivalent

Cable with BNC connectors

50 -ohm BNC adapter

BNC tee connector

BNC to dual banana adapter

Procedure

:

1.

Connect the output of the Hewlett-Packard Model 3325A Function

Generator to the digital voltmeter under test (UUT) using a 50-ohm

BNC adapter at the voltmeter input terminal and also to the input of

the dc millivoltmeter. Set the UUT to its "ac+dc" mode, and set the

millivoltmeter to its 1-volt dc range.

\50 O BNC ADAPTER

Fig. 10.1.1 Set-Up for testing DC Coupling

2. Set the frequency to 1 kHz.

3. Set the amplitude to 30 mV rms

.

B - 10
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

4. Set the dc offset to 0.00 V.

6. Read the meter and record the ac reading on the data sheet.

7. Set the dc offset to 0.040 V.

8. Read the UUT and record the ac+dc reading on the data sheet,

Table 10.1.1.

9. Read the dc millivoltmeter and record the dc reading on the data

sheet,

10.

Compute what the meter should read using formula below;

reading(ac+dc) = 7{ (ac rdg in mV)^ + (dc reading)^}

B - 11
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

Table 10.1,1 DC Coupling Test

AC

Reading

(mV)

[Step 6]

AC+DC

Reading

(mV)

[Step 8]

DC

Reading

(mV)

[Step 9]

Computed

Reading

(mV)

[Step 10]

Uncertainty

(mV)

Specification

0.08 ± 6%

B 12
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

10.2 Frequency Range

Specification :

Frequency response shall be at least 10 Hz to 20 MHz.

Compliance with the frequency range specifications is implicit if the

digital voltmeter-under- test (UUT) passes the tests for accuracy (see 10.6).

A special test is therefore not necessary.

B - 13
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

10,3 Voltage Range

Specification :

Shall be from 100 micro-volts rms or less, to 300 volts rms or greater except

where limited by the volt-hertz product of para. 10.12.

The limits of the are determined as part

voltage range of the digital voltmeter under test (UUT)

of the Accuracy test (see 10,6 ).

B - 14
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

10.3.1 Selectable Ranges

Specification:

Meter shall provide no less than seven selectable ranges, with the lowest full

scale range no greater than 2 millivolts rms , and the greatest full scale

range at least 300 volts rms.

Procedure

1. Consult the manufacturer's literature concerning the number and upper

limits of the selectable ranges available.

B - 15
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Table 10.3,1 Selectable Ranges

Measurement

Description

Measurement

Data

Estimated

Measurement

Uncertainty

Specificat]

Min.

.on Limits

Max.

Units

Number of

ranges N/A 7

Lowest

range N/A 2 mV

Highest

range N/A 300 V

B - 16
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

10.3.2 Ranging

Specification :

Shall be auto- ranging , also shall have the capability of manually setting the

range. Shall provide at least 10% over-range , or 10% under-range when manually

auto - ranged

.

This test determines whether in the automatic mode sufficient hysteresis

has been provided so that the instrument will not hunt between ranges when the

input voltage is near the range transition voltage.

Equipment :

Items Model

AC Calibrator Fluke 5200A or equivalent

Power amplifier Fluke 5205A or equivalent

Cable with BNC connectors 3 feet or less, each.

Dual banana plug to BNC

adapter

Procedure

1. Connect the ac voltage calibrator (Fluke Model 5200) to the digital

voltmeter under test (UUT) using a dual banana plug-to-BNC adapter

and a cable with BNC connectors. Use the set-up shown in Fig.

10.3,2b for tests greater than 120 volts.

TO BNC ADAPTER

Fig. 10.3.2a Set-Up for Voltage Range Test

Fig. 10.3.2b Set-Up for Voltage Range Test for voltages above 100 volts
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

2. Set the amplitude to zero, and set the frequency of the calibrator

to 1 kHz

,

3. Set the UUT to autoranging.

4. Increase the voltage of the calibrator so that a reading on the

lowest range is obtained.

5. Slowly increase the voltage further until the UUT switches to the

next higher range. Note, but do not record the approximate

transition voltage.

6. Starting from somewhat below the approximate transition voltage,

again increase the voltage, but more slowly than before, until the

meter changes range. Observe the indicated voltage at each step

and record the voltage on the data sheet corresponding to the step

just before the meter changes to the next higher range. The

changing of the range occurs when the analog voltage indicator

changes from near full-scale deflection downscale to zero or near

zero

.

If the transition voltage cannot be determined exactly on the first

try, repeat step 6, allowing the meter to settle a little longer

after each step increase of the input voltage.

7. Starting from somewhat above the transition voltage, decrease the

input voltage, using a procedure similar to that of step 6, until

the meter shifts to a lower range. Record on the data sheet the

indicated voltage after the downshift has occurred.

8. Repeat steps 6 and 7 for each range of the meter.

B - 18

II
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Table 10.3.2 Ranging

Transition

Up -Range

Transition

Down-Range

Difference Uncertainty

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

Specification

Limits

+ 10 %

+ 10 %

10 %

+ 10 %

+ 10 %

+ 10 %

-I- 10%

+ 10 %

-t- 10%

+ 10 %

B - 19
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

10.3.3 Voltage Resolution

Specification :

Display resolution in voltage mode shall be at least as specified herein

READING RESOLUTION

for readings below 1.999 mV 1 microvolt

2.00 mV to 19.99 mV 10 microvolts

20.00 mV to 199.9 mV 100 microvolts

200 mV to 1999 mV 1 millivolt

2.00 V to 19.99 V 10 millivolts

20.0 V to 199.9 V 100 millivolts

200 V to 300 V 1 volt

Test Points :

Table 10.3.3.1

T . P . No

.

Test Voltage Voltage Increment Frequency

1. 1. 998 mV rms 0 001 mV rms 10 00 kHz

2. 19. 98 mV rms 0 010 mV rms 10 00 kHz

3. 199. 8 mV rms 0 100 mV rms 10 00 kHz

4. 1. 998 V rms 0 001 V rms 10 00 kHz

5. 19. 98 V rms 0 010 V rms 10 00 kHz

6. 199. 8 V rms 0 100 V rms 10 00 kHz

7. 298 V rms 1 000 V rms 10 00 kHz

B - 20
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

EQulpment :

Items

AC Calibrator

Power amplifier

Cable with BNC connectors

Dual banana plug to BNC

adapter

Procedure

Model

Fluke 5200A or equivalent

Fluke 5205A or equivalent

3 feet or less, each.

It is important to read the entire procedure before beginning the test.

All equipment should be warmed up following the manufacturers' specification

before any measurements are made.

1.

Connect the ac voltage calibrator (Fluke Model 5200) to the digital

voltmeter under test (UUT) using a dual banana plug-to-BNC adapter

and a cable with BNC connectors.

TO BNC ADAPTER

Fig. 10.3.3a Set-Up for Voltage Resolution Test

Fig. 10.3.3b Set-Up for the Resolution Test for voltages above 100 volts.

2. Set the output amplitude on the ac calibrator to approximately

1.99 mV.

3. Set the signal frequency to 10 kHz.

B - 21
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

4. Using the values given in Table 10,3.3.1, repeat the procedure in

step 5 to step 9 below for Test Points 1, to 7

.

5o Set the meter to "Auto - Range ,

6. Adjust the signal amplitude until the meter reads the value

given for Test Point voltage.

7. Set meter to "Manual" range (or "Range Hold").

8. Increase the signal voltage by a step of exactly the

Incremental voltage given in Table 10.3.3.1.

9. Note and enter the meter reading on the data sheet

Table 10.3.3.2.

10.

Calculate the differences between the value of the meter reading

obtained in step 9 and the Test Point Voltage. (This establishes

the resolution on the range selected) . Note the units of the Test

Point Voltage and the specification limits .

B - 22
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Table 10.3.3.2 Voltage Resolution

Uncertainty

±0.01 /xV

±0.1 /iV

±1.0 /xV

±0.01 mV

±0.1 mV

±1.0 mV

±0.01 V

Test Point Meter Rdg. Difference

1.998 mV

19.98 mV

199.8 mV

1.998 V

19.98 V

199.8 V

298 V

Specification

Limits

1 fiV

10 /xV

100 /xV

1 mV

10 mV

100 mV

1 V

B - 23
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

10.4 Display Type and Units

Specification :

Shall have a digital display with 3 1/2 digits, or more, in the voltage mode.

Shall also have analog peak and null indicator . Analog peak and null indicator

shall show changes in voltage equal to, or greater than 5% of full scale of

range in use. The digital display shall have annunciators for volts,

millivolts , decibels relative , dBm, and polarity.

Procedure

:

1 . Check digital voltmeter under test (UUT) by visual inspection.
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Table 10.4 Display Type and Resolution

Measurement

Description

Measurement

Data

Estimated

Measurement

Uncertainty

Specificat:

Min.

Lon Limits

Max.

Units

Number of

digits N/A 3 1/2

Peak and

null indie. N/A Yes

Show changes > 5% of FS N/A Yes

Proper

annunciators N/A Yes

B - 25
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

10 o 5 Decibel Measurements

Specification :

Meter shall have a minimum span of 130 dB and comply with the

requirements herein.

Equipment :

Items Model

AC Calibrator Fluke 5200A or equivalent

Power amplifier Fluke 5205A or equivalent

Cable with BNC connectors 3 feet or less, each.

Dual banana plug to BNC

adapter

Procedure

:

The following test indicates the range of the voltage to decibel

conversion capability of the digital voltmeter under test (UUT)

.

1. Short the input to the meter.

2. Set the meter into the decibel (dB) mode.

3. Set the meter to auto-ranging, note the decibel (dB) reading, and

enter the value into the data sheet. Table 10.5.

4. Remove the short from the input and connect the meter to the ac voltage standard and amplifier with the frequency set to 1 kHz, as shown in figure 10.5.

Fig. 10.5 Set-Up for the Decibel Test.

5. Set the output from the ac voltage standard to 300 V.

6. Note the decibel reading with the voltage applied, and enter the

value into the data sheet. Table 10.5.

7. Subtract the value obtained in step 3 from the value obtained in

step 6, and enter this difference on line 3 of the data sheet. Table

10.5.

B - 26
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Table 10.5 Decibel Measurement

Measurement

Description

Measurement

Data

Estimated

Measurement

Uncertainty

Specificat]

Min.

Lon Limits

Max.

Units

Reading with

input shorted N/A •k-kieie kk-kk dB

Reading with

300 V applied N/A •k-k-kk kkkk dB

dB range N/A 130 dB

B - 27
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

10.5,1 Decibel Display and Resolution

Specification :

Meter shall have at least 4-digit display with polarity indicator when in the

decibel mode, decibel resolution shall be at least 0.01 dB

.

Eouinment :

Items Model

AC Calibrator Fluke 5200A or equivalent

Cable with BNC connectors 3 feet or less, each.

Dual banana plug to BNC

adapter

Procedure

The number of digits in the display of the digital voltmeter under test

(UUT) are determined by inspection,

1. Set the meter to the auto-ranging mode and to the decibel display

mode

.

2. Connect the ac voltage standard to the meter as shown in figure

10.5.1, and set the voltage to 1.00 volt.

TO BNC ADAPTER

Fig. 10.5.1 Set-Up for Decibel Resolution Test

3. Adjust the voltage up or down until the maximum number of digits are displayed,

4. Check the number of digits and the presence of a polarity indicator

and enter the appropriate answers in the data sheet, Table 10.5.1.

B. - 28
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Table 10.5.1 Decibel Measurements

Measurement

Description

Measurement

Data

Estimated

Measurement

Uncertainty

Specificat]

Min.

Lon Limits

Max.

Units

Number of

digits N/A 4

Polarity

indicator N/A Yes

Resolution

N/A 0.01 dB
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

10.5„2 dBm Reference Impedance

Specification :

In dB mode, reference impedance shall be selectable , with a minimum of five

selection: 50 ohms, 75 ohms, 124 ohms, 135 ohms, and 600 ohms.

Procedure

1. The number and values of the reference impedances are to be determined by

inspection.

B 30
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Table 10.5.2 dBm Reference Impedance

Measurement

Description

Measurement

Data

Estimated

Measurement

Uncertainty

Specificat]

Min.

Lon Limits

Max.

Units

Number of

ref, levels N/A 5

Levels

comply N/A Yes

B - 31
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

10.6 Accuracy

Specification :

Shall be at least as specified below over the operating temperature range from

18 to 28 degrees Celsius, for ac-coupled measurements, AC + DC measurement

accuracy shall be within twice the tolerance for ac measurements

.

Procedure

:

Note: Because of the wide frequency and voltage ranges covered by the

digital voltmeter under test (UUT) , accuracy tests are carried out using three

different methods.

From 10 Hz to 99.9 kHz, for voltages above 1 millivolt, test signals are obtained from a calibrated ac voltage standard, while at frequencies from

100 kHz to 20 MHz an uncalibrated signal source is used, and the voltage

applied to the meter is measured using thermal converters.

For measurements at a voltage level of 100 microvolts, regardless of the

signal frequency, a micropotentiometer is used.

The procedures that make use of the ac voltage calibrator have been

automated with a Hewlett-Packard Model 9836 computer as the controller for the

calibrator. Readings of the digital voltmeter under test (UUT) are read

visually and entered via the computer keyboard. The computer terminal

provides the necessary prompts to carry out the calibration.

For tests at frequencies at or above 100 kHz, a Hewlett-Packard Model

3325A Function Generator and a power amplifier (ENI Model A300-40PA) are used

as a signal source. For output voltages from 1.0 to 50.0 volts rms , the

output of the amplifier is connected directly to the input of the meter, and

for voltages above 50 volts a special step-up (output) transformer (ENI Model

AM5-5B) is used.

B - 32
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

PRELIMINARY DC CALIBRATION OF THE MICROPOTENTIOMETER

RF-DC transfer difference from dc to 100 MHz at a voltage level of

100 microvolts

Specification :

Shall be within 0.2% of dc input level.

Test Point : 100 pV rms at

Equipment :

Items

DC calibrator

10-mA Micropotentiometer

0.01 ohm standard resistor

DC millivoltmeter

Thermal converter output

cable attached)

Procedure

dc

Model

Fluke 5440B or equivalent

Ballantine 440-10

Ballantine 440-02

Fluke 8506A or equivalent (2 required)

Special cable with dual Banana plug

It is important to read the entire procedure before beginning the test. All

equipment should be warmed up following the manufacturers' specification

before any measurements are made.

WARNING: Thermoelements are easily damaged

by even moderate over-voltage.

Do not leave connected except when

actually carrying out test.

1. Attach the 0.01 ohm standard resistor to the output port of the

micropotentiometer housing.

2. Connect the equipment as shown in figure 10.6.1. Attach a BNC (female)

to type N (male) adapter to the input connector of the

micropotentiometer. Attach a dual banana plug (male) to type N

(female) adapter to a type N - N (male -male) adapter, and connect the

adapters to the output connector (standard resistor) of the

micropotentiometer. Connect the combination to the input of one of

the millivoltmeters

3. Connect the output of the thermal converter to the other dc

B - 33
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

millivoltmeter using the attached thermal converter output cable. Set

the millivoltmeter to the 1-volt range.

4. Set the dc calibrator to an amplitude of approximately 0.15 volts, and

then fine-adjust the calibrator voltage until the micropotentiometer

output reads 100 microvolts. NOTE WARNING! Walt for about one minute

until the voltage reading settles, and then read and record on the data

sheet the output voltage of the thermoelement of the micropotentiometer

on the other millivoltmeter.

Note

:

To achieve the required accuracy, the dc millivoltmeter must

be used in the averaging mode .

5. Reverse the polarity of the dc supplied by the calibrator and repeat

step 4. Then proceed to step 6.

6. Calculate the average of the two thermoelement output voltages by

adding the two numerical values recorded on the data sheet, ignoring

the sign, and dividing the sum by two.

7. Disconnect the dc voltage calibrator immediately after making the

measurement to prevent possible damage to the thermoelement. Carefully

disassemble the setup so that the micropotentiometer and its associated

resistor can be used to make ac measurements. Note warning!

B - 34
TEST PROCEDURES FOR ME-545()/G TRUE- RMS VOLTMETER

fluke 8506A

thermal RMS OMM

Fig. 10.6,1 Set-Up for Micropotentiometer DC Calibration

B 35
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

Accuracy for frequencies from 10 Hz to 49,99 Hz for all input levels from

100 microvolts to 300 volts

Specification :

Shall be within ± 5% of true input level.

Test Point : 100 /iV rms at 10.0 Hz

Equipment :

Items Model

Function generator

10-mA Micropotentiometer

0.01 ohm standard resistor

DC millivoltmeter

Thermal converter output

cable

Hewlett-Packard 3325A or equivalent

Ballantine 440-10

Ballantine 440-02

Fluke 8506A or equivalent

Attached to micropotentiometer, free end

dual Banana plug

Procedure :

It is important to read the entire procedure before beginning the test. All

equipment should be warmed up following the manufacturers' specification

before any measurements are made.

WARNING: Thermoelements are easily damaged

by even moderate over-voltage.

Do not leave connected except when

actually carrying out test.

1. Attach the 0.01 ohm standard resistor to the output port of the

micropotentiometer housing.

2. Connect the equipment as shown in figure 10.6.2. Attach a BNC (female)

to type N (male) adapter to the input connector of the

micropotentiometer. Attach a BNC (male) to type N (female) adapter to a type N - N (male-male) adapter, and connect the adapters to the

output connector (standard resistor) of the micropotentiometer.

Connect the combination to the input of the UUT,

3. Connect the output of the thermal converter to the dc millivoltmeter

using a thermal converter output cable. Set the millivoltmeter to the

1-volt range.

B - 36
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

4. Set the function generator to a frequency of 10.0 Hz, and set the

amplitude to 0.4 millivolts . This will prevent applying an overvoltage

to the thermoelement.

5. Connect the output of the function generator to the input of the

micropotentiometer using any . shielded cable (e.g. RG 58-U) with BNC

connectors

6. Slowly increase the output voltage of the function generator, while

watching the reading of the dc millivoltmeter , until the reading

reaches the voltage determined during the dc calibration of the

micropotentiometer. An ac voltage of 100 /j,V is then being applied to

the UUT.

7. Consult the manufacturer's instructions for operation of the UUT in the

100- fiV range, and make the prescribed adjustments such as setting the

averaging time constant, switching a filter into the circuit, etc.

8. When the reading of the UUT has settled, note and record it on the data

sheet

9. Disconnect the function generator immediately after making the

measurement to prevent possible damage to the thermoelement. Note

warning

B - 37
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

FLUKE 8506A

THERMAL RMS OMM

RESISTOR /OUTPUT (MALE TO MALE) CONNECTOR

Fig. 10.6.2 Set-Up for 100 /iV AC Measurements

B - 38
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Accuracy for frequencies from 100 Hz to 99.9 kHz for all input levels from

100 microvolts to 1 millivolt

Specification :

Shall be within ± 5% of true input level.

Test Point : 100 /iV rms at 10.0 kHz

Equipment :

Items Model

Function generator

10-mA Micropotentiometer

0.01 ohm standard resistor

DC millivoltmeter

Thermal converter output

cable

Hewlett-Packard 3325A or equivalent

Ballantine 440-10

Ballantine 440-02

Fluke 8506a or equivalent

Attached to micropotentiometer, free end

dual Banana plug

Procedure

It is important to read the entire procedure before beginning the test. All

equipment should be warmed up following the manufacturers' specification

before any measurements are made.

WARNING: Thermoelements are easily damaged

by even moderate over-voltage.

Do not leave connected except when

actually carrying out test.

1. Attach the 0.01 ohm standard resistor to the output port of the

micropotentiometer housing.

2. Connect the equipment as shown in figure 10.6.2. Attach a BNC (female)

to type N (male) adapter to the input connector of the

micropotentiometer. Attach a BNC (male) to type N (female) adapter to

a type N - N (male -male) adapter, and connect the adapters to the

output connector (standard resistor) of the micropotentiometer.

Connect the combination to the input of the UUT.

3. Connect the output of the thermal converter to the dc millivoltmeter

using a thermal converter output cable. Set the millivoltmeter to the

1-volt range.

B - 39
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

4. Set the function generator to a frequency of 10.0 kHz, and set the

amplitude to 0.4 millivolts . This will prevent applying an overvoltage

to the thermoelement.

5. Connect the output of the function generator to the input of the

micropotentiometer using any shielded cable (e.g. RG 58-U) with BNC

connectors

6. Slowly increase the output voltage of the function generator, while

watching the reading of the dc millivoltmeter , until the reading

reaches the voltage determined during the dc calibration of the

micropotentiometer. An ac voltage of 100 /iV is then being applied to

the UUT.

7. Consult the manufacturer's instructions for operation of the UUT in the

100-/iV range, and make the prescribed adjustments such as setting the

averaging time constant, switching a filter into the circuit, etc.

8. When the reading of the UUT has settled, note and record it on the data

sheet

9. Disconnect the function generator immediately after making the

measurement to prevent possible damage to the thermoelement. Note

warning

B - 40
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Accuracy for frequencies from 100 kHz to 999.9 kHz for all input levels from

100 microvolts to 1 x 10® volt-hertz.

Specification :

Shall be within ± 5% of true input level.

Test Point: 100 uV rms at 999.9 kHz

Model

Fluke 5200A or equivalent

Hewlett-Packard 3325A or equivalent

Ballantine 440-10

Ballantine 440-02

Fluke 8506A or equivalent

Attached to micropotentiometer, free end

dual Banana plug

Procedure

Equipment :

Items

AC calibrator

Function generator

10-mA Micropotentiometer

0.01 ohm standard resistor

DC millivoltmeter

Thermal converter output

cable

It is important to read the entire procedure before beginning the test. All

equipment should be warmed up following the manufacturers' specification

before any measurements are made.

WARNING: Thermoelements are easily damaged

by even moderate over-voltage.

Do not leave connected except when

actually carrying out test.

1. Attach the 0.01 ohm standard resistor to the output port of the

micropotentiometer housing.

2. Connect the equipment as shown in figure 10.6.2. Attach a BNC (female)

to type N (male) adapter to the input connector of the

micropotentiometer. Attach a BNC (male) to type N (female) adapter to a type N - N (male -male) adapter, and connect the adapters to the

output connector (standard resistor) of the micropotentiometer.

Connect the combination to the input of the UUT.

3. Connect the output of the thermal converter to the dc millivoltmeter

using a thermal converter output cable. Set the millivoltmeter to the

1-volt range.

B - 41
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

4. Set the function generator to a frequency of 999.9 kHz, and set the

amplitude to 0.4 millivolts . This will prevent applying an overvoltage

to the thermoelement.

5. Connect the output of the function generator to the input of the

micropotentiometer using any shielded cable (e.g. RG 58-U) with BNC

connectors

6. Slowly increase the output voltage of the function generator, while

watching the reading of the dc millivoltmeter , until the reading

reaches the voltage determined during the dc calibration of the

micropotentiometer. An ac voltage of 100 /xV is then being applied to

the UUT.

7. Consult the manufacturer's instructions for operation of the UUT in the

100-/xV range, and make the prescribed adjustments such as setting the

averaging time constant, switching a filter into the circuit, etc.

8. When the reading of the UUT has settled, note and record it on the data

sheet

9. Disconnect the function generator immediately after making the

measurement to prevent possible damage to the thermoelement. Note

warning

B - 42
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Accuracy for frequencies from 1 MHz to 9.99 MHz for all input levels from

100 microvolts to 1 x 10® volt-hertz.

Specification :

Shall be within ± 10% of true input level.

Test Point : 100 pV rms at 9.99 MHz

Equipment :

Items Model

Function generator

10-mA Micropotentiometer

0.01 ohm standard resistor

DC millivoltmeter

Thermal converter output

cable

Hewlett-Packard 3325A or equivalent

Ballantine 440-10

Ballantine 440-02

Fluke 8506A or equivalent

Attached to micropotentiometer, free end

dual Banana plug

Procedure

It is important to read the entire procedure before beginning the test. All

equipment should be warmed up following the manufacturers' specification

before any measurements are made.

WARNING: Thermoelements are easily damaged

by even moderate over-voltage.

Do not leave connected except when

actually carrying out test.

1. Attach the 0.01 ohm standard resistor to the output port of the

micropotentiometer housing.

2. Connect the equipment as shown in figure 10.6.2. Attach a BNC (female)

to type N (male) adapter to the input connector of the

micropotentiometer. Attach a BNC (male) to type N (female) adapter to a type N - N (male -male) adapter, and connect the adapters to the

output connector (standard resistor) of the micropotentiometer.

Connect the combination to the input of the UUT.

3. Connect the output of the thermal converter to the dc millivoltmeter

using a thermal converter output cable. Set the millivoltmeter to the

1-volt range.

B - 43
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

4. Set the function generator to a frequency of 9.99 MHz, and set the

amplitude to 0.4 millivolts . This will prevent applying an overvoltage

to the thermoelement.

5. Connect the output of the function generator to the input of the

micropotentiometer using any shielded cable (e.g. RG 58 -U) with BNC

connectors

6. Slowly increase the output voltage of the function generator, while

watching the reading of the dc millivoltmeter , until the reading

reaches the voltage determined during the dc calibration of the

micropotentiometer. An ac voltage of 100 /iV is then being applied to

the UUT.

7. Consult the manufacturer's instructions for operation of the UUT in the

100 -/iV range, and make the prescribed adjustments such as setting the

averaging time constant, switching a filter into the circuit, etc.

8. When the reading of the UUT has settled, note and record it on the data

sheet

9. Disconnect the function generator immediately after making the

measurement to prevent possible damage to the thermoelement. Note

warning!

B - 44
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Accuracy for frequencies from 10 MHz to 19.99 MHz for all input levels from

100 microvolts to 1 x 10® volt-hertz.

Specification :

Shall be within ± 15% of true input level.

Test Point : 100 /iV rms at 19.99 MHz

Equipment :

Items Model

AC calibrator

Function generator

10-mA Micropotentiometer

0.01 ohm standard resistor

DC millivoltmeter

Thermal converter output

cable

Fluke 5200a or equivalent

Hevlett- Packard 3325A or equivalent

Ballantine 440-10

Ballantine 440-02

Fluke 8506A or equivalent

Attached to micropotentiometer, free end

dual Banana plug

Procedure

It is important to read the entire procedure before beginning the test. All

equipment should be warmed up following the manufacturers' specification

before any measurements are made.

WARNING: Thermoelements are easily damaged

by even moderate over-voltage.

Do not leave connected except when

actually carrying out test.

1. Attach the 0.01 ohm standard resistor to the output port of the

micropotentiometer housing.

2. Connect the equipment as shown in figure 10.6.2, Attach a BNC (female)

to type N (male) adapter to the input connector of the

micropotentiometer. Attach a BNC (male) to type N (female) adapter to

a type N - N (male -male) adapter, and connect the adapters to the

output connector (standard resistor) of the micropotentiometer.

Connect the combination to the input of the UUT,

3. Connect the output of the thermal converter to the dc millivoltmeter

using a thermal converter output cable. Set the millivoltmeter to the

1-volt range.

B - 45
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

A. Set the function generator to a frequency of 19,99 MHz, and set the

amplitude to 0.4 millivolts . This will prevent applying an overvoltage

to the thermoelement.

5 . Connect the output of the function generator to the input of the

micropotentiometer using any shielded cable (e.g. RG 58/U) with BNC

connectors

6. Slowly increase the output voltage of the function generator, while

watching the reading of the dc millivoltmeter , until the reading

reaches the voltage determined during the dc calibration of the

micropotentiometer. An ac voltage of 100 fiV is then being applied to

the UUT.

7. Consult the manufacturer's instructions for operation of the UUT in the

100-/iV range, and make the prescribed adjustments such as setting the

averaging time constant, switching a filter into the circuit, etc,

8. When the reading of the UUT has settled, note and record it on the data

sheet

9. Disconnect the function generator immediately after making the

measurement to prevent possible damage to the thermoelement. Note

warning

B - 46
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Accuracy for frequencies from 10 Hz to 49.99 Hz for all input levels from

100 microvolts to 300.0 volts and for frequencies from 50 Hz to 99.99 kHz for

all input levels from 1 millivolt to 300 volts (200 volts 20 kHz to 99.99

kHz)

Specification :

Shall be within ± 3% of true input level.

1.,0 mV rms at 10,,00 Hz

300..0 V rms at 10,.00 Hz

1,.0 mV rms at 50,.00 Hz

300,.0 V rms at 50,.00 Hz

1,.0 mV rms at 10,.0 kHz

10,,0 mV rms at 10,.00 kHz

100,,0 mV rms at 10..00 kHz

1,,0 V rms at 10,.00 kHz

10,.0 V rms at 10,.00 kHz

300,.0 V rms at 10..00 kHz

1,.0 mV rms at 99,.99 kHz

200,.0 V rms at 99,.99 kHz

Equipment : Items

AC calibrator

Power amplifier

Instrument Controller

(IEEE-488 Bus)

IEEE-488 cable

Dual banana to BNC adapter

Cable with BNC connectors

Model

Fluke 5200A or equivalent

Fluke 5205A or equivalent

Hewlett-Packard 9836 or equivalent

Procedure

It is important to read the entire procedure before beginning the test. All

equipment should be warmed up following the manufacturers' specification

before any measurements are made.

B. - 47
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

WARNING: This procedure uses lethal voltages during the test

Care should be taken to avoid injury or shock.

1. Link the instrument controller (computer) to the calibrator and the

power amplifier using the IEEE-488 cable. Also, connect the power

amplifier to the calibrator with the special purpose cable supplied by

the manufacturer.

For tests with voltages between 1 volt and 100 volts, use the equipment

as shown in figure 10.6.3. Connect the calibrator to the to the input

of the UUT directly using the cable with BNC connectors and the dualbanana adapter.

For tests with voltages above 100 volts, connect the UUT to the power

amplifier using the cable attached to the power amplifier and an adapter to make the connection as shown in figure 10.6.4. (The program

will provide the necessary prompts.)

TO BNC ADAPTER

Fig. 10.6.3 Set-Up for the Accuracy Test with the Calibrator

B 48
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Fig. 10.6.4 Set-Up for the Accuracy Test with the Calibrator and Amplifier

2.

Insert the 5 1/4 in. floppy disk labelled "TMDE4A" into the right-hand

disk drive of the computer (controller) . The program requires that HPBasic 2.1 and AP 2.1 (or later versions) are first loaded into the

computer.

3. Type LOAD "MENU" on the computer keyboard.

4. Press EXECUTE.

5. Press RUN and follow directions shown on the computer display.

6. Enter the results of the measurement shown on the printout into the

data sheet, Table 10.6b.

B - 49
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

Accuracy for frequencies from 100 kHz to 999.9 kHz for all input levels from

100 microvolts to 1 x 10® volt-hertz.

Specification :

Shall be within ± 5% of true input level.

Test Point : 100.0 V rms at 999.9 kHz

Equipment :

Items Model

AC Calibrator

Function Generator

Power Amplifier

28 -volt dc power supply

Output Transformer

100-volt thermal converter

DC millivoltmeter

Oscilloscope

Thermal converter output

cable

Cable with BNC connectors

RG 214/U cable with type "N"

connectors (3 required)

Type "N" tee (2 required)

BNC (male) to "N" (female)

(4 required)

Dual banana to "N" adapter

Coaxial relay

Relay control box

Fluke 5200A or equivalent

Hewlett-Packard 3325A or equivalent

ENI A300-40PA (modified)

Kepco JQE 25-lOM or equivalent

ENI AM-5B Serial No. 103

Ballantine 1394A-100 (modified)

Fluke 8506A or equivalent

Tektronix 465 or equivalent

Type MS connector MS3102A- 10SL-3P (3-pin

male) to dual Banana plug

3 feet or less, each.

Hewlett-Packard 8761A

Special part

B 50
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Procedure :

It is important to read the entire procedure before beginning the test. All

equipment should be warmed up following the manufacturers' specification

before any measurements are made.

WARNING: Theraoelements are easily damaged

by even moderate over-voltage.

Do not leave connected except when

actually carrying out test.

1. Connect the equipment as shown in figure 10.6.5. Attach the BNC (male)

to N (female) adapter to a type "N" (male) to "N" (male) adapter and

then to a type "N” tee, and connect the combination to the input of

the UUT.

2. Attach the coaxial relay to the thermal converter and port 1 of the

coaxial relay to the type "N" tee.

3. Attach a BNC (male) to "N" (female) adapter to both input and output

terminals of the output transformer.

4. Make sure the amplifier power supply is turned off . Then use a RG

214/U cable to connect the output of the power amplifier to the input

of the transformer and another RG 214/U cable to connect the

transformer to the tee leading to the UUT and thermal converter.

5. Make sure that the output voltage from the ac calibrator is zero . Then

connect the output of the ac calibrator to port 2 of the coaxial switch

using the dual banana to "N" adapter and a RG 214/U cable.

6. Connect the output of the 100-volt thermal converter to the dc

millivoltmeter using a thermal converter output cable. Set the

millivoltmeter to the 1-volt range. Set the coaxial switch to "Port 2"

by momentarily depressing button No. 2 on the switch control box.

7. Set the frequency of the ac calibrator to 1 kHz, and bring the output

voltage up slowly to 100 volts rms while observing the dc

millivoltmeter reading and making sure the reading does not exceed 8

millivolts

8. With the ac calibrator set to 100.0 V and when the reading on the dc

B - 51
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

4;l FLUKE 5200A

crest’ FACTOR CALIBRATOR

TYPE "N to type N (male to male)

Fig. 10.6.5 Set-Up for the 100-volt Accuracy Test

using a Thermal Converter

B - 52
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

millivoltmeter has settled (about 5 to 10 minutes after setting frequency and

amplitude; step 7), note and record the millivoltmeter reading on the data

sheet, Table 10. 6. c.

9. Turn on the power supply to the rf power amplifier and adjust it to 28

volts dc. The quiescent current should be approximately 6.5 amperes.

Note warning!

WARNING: Do not turn on the rf power amplifier

if the cooling fan is not operating.

Do not obstruct air flow to the heat

sink. After switching off the power

supply, leave fan on until the heat

sink is at room temperature.

11. Set the frequency of the function generator to 999.9 kHz and the

amplitude to 1 mV rms . Increase the output voltage until the UUT reads

approximately 100.0 V rms.

12. Set the increment control on the function generator so that the least

significant digit can be incremented (0.001 mV).

13. Set the coaxial switch to "Port 1" and, using the increment or decrement control (up or down arrows) of the function generator, slowly

adjust the output voltage until the dc millivoltmeter reading settles

to the same voltage as that obtained when using the 1 kHz signal from

the ac calibrator . The dc voltage reading will take 20 to 30 seconds

to settle, and it may not be possible to get exactly the same reading

as before because of limited resolution in the adjustment of the

function generator. Generally, the dc millivolt readings should agree

within + 0.002 mV.

14. When the millivoltmeter reading agrees within the tolerance with the

reading obtained when measuring the 1-kHz reference signal, note and

record on the data sheet. Table 10.6c, the reading on the UUT

(including the units) as well as the millivoltmeter reading.

15. Set the coaxial switch back to "Port 2," and check whether the reading

has changed. If the reading has changed by more than 0.002 mV, repeat

steps 11 to 13. If it has not changed, the test is completed.

16. Set the function generator voltage to 0.4 millivolts (it cannot be set

to zero) to power down the equipment, and set the ac calibrator to zero

output. Turn off the power amplifier.

B - 53
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Accuracy for frequencies from 1 MHz to 9.99 MHz for all input levels from

100 microvolts to 1 x 10® volt-hertz.

Specification :

Shall be within ± 10% of true input level.

Test Point: 10.00 V rms at 9.99 MHz

Equipment :

Items Model

AC Calibrator

Function Generator

Power Amplifier

28 -volt dc power supply

10-volt thermal converter

DC millivoltmeter

Oscilloscope

Thermal converter output

cable

Cable with BNC connectors

RG 214/U cable with type "N"

connectors (3 required)

Type "N" tee (2 required)

50 -ohm "N" adapter

BNC (male) to "N" (female)

(2 required)

Dual banana to "N" adapter

Coaxial relay

Relay control box

Fluke 5200A or equivalent

Hewlett-Packard 3325A or equivalent

ENI A300-40PA (modified)

Kepco JQE 25-lOM or equivalent

Ballantine 1394A-10 or equivalent

Fluke 8506A or equivalent

Tektronix 465 or equivalent

Type MS connector MS3102A- lOSL- 3P (3-

pin male) to dual Banana plug

3 feet or less, each.

Special part

Hewlett-Packard 8761A

Special part

Procedure

It is important to read the entire procedure before beginning the test. All

equipment should be warmed up following the manufacturers' specification

before any measurements are made.

B - 54
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

WARNING: Thermoelements are easily damaged

by even moderate over-voltage.

Do not leave connected except when

actually carrying out test.

1. Connect the equipment as shown in figure 10.6.6. Attach the BNC (male)

to N (female) adapter to the 50-ohm "N-N" adapter, then to a type "N"

tee, and connect the combination to the input of the UUT.

2. Attach the coaxial relay to the thermal converter and port 1 of the

coaxial relay to the type "N" tee.

3. Attach a BNC (male) to "N" (female) adapter to a t3rpe "N" tee, and

connect the combination to one of the inputs of the oscilloscope.

4. Make sure the amplifier power supply is turned off . Then use a RG

214/U cable to connect the output of the power amplifier to the tee at

the oscilloscope and another RG 214/U cable to connect the oscilloscope

to the tee leading to the UUT and thermal converter.

5. Make sure that the output voltage from the ac calibrator is zero . Then

connect the output of the ac calibrator to port 2 of the coaxial switch

using a dual banana to ”N” adapter and a RG 214/U cable.

6. Connect the output of the thermal converter to the dc millivoltmeter

using a thermal converter output cable. Set the millivoltmeter to the

1-volt range. Set the coaxial switch to "Port 2" by momentarily

depressing button No. 2 on the switch control box.

7. Set the frequency of the ac calibrator to 1 kHz, and bring the output

voltage up slowly to 10 volts rms while observing the dc millivoltmeter

reading and making sure the reading does not exceed 8 millivolts .

8. Turn on the oscilloscope and set it to display a 10-volt, 10-MHz signal

(5 volts/div; 0.2 microsecond/div, lOx magnification, dc coupled).

B - 55
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

FLUKE S200A

AC CALIBRATOR

Fig. 10.6.6 Set-Up for Low-Voltage Accuracy Test

using a Thermal Converter

B 56
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER 9.

Turn on the power supply to the rf power amplifier and adjust it to 28

volts dc. The quiescent current should be approximately 6.5 amperes.

Note warning!

WARNING: Do not turn on the rf power amplifier

if the cooling fan is not operating.

Do not obstruct air flow to the heat

sink. After switching off the power

supply, leave fan on until the heat

sink is at room temperature.

10. Set the frequency of the function generator to 9.99 MHz and the

amplitude to 1 mV rms. Increase the output voltage until the UUT reads

approximately 10.0 V rms.

11. Observe the amplifier output waveform on the oscilloscope for parasitic

oscillations, clipping, or other distortion. If distortion or oscillation is observed, shut off the amplifier immediately and

investigate the cause.

12. Set the increment control on the function generator so that the least

significant digit can be incremented (0.001 mV).

13. With the ac calibrator set to 10.000 V, and when the reading on the dc

millivoltmeter has settled (about 5 to 10 minutes after setting

frequency and amplitude; step 7), note and record the millivoltmeter

reading on the data sheet.

14. Set the coaxial switch to "Port 1" and, using the increment or decrement control (up or down arrows) of the function generator, slowly

adjust the output voltage until the dc millivoltmeter reading settles

to the same voltage as that obtained when using the 1 kHz signal from

the ac calibrator . The dc voltage reading will take 20 to 30 seconds

to settle, and it may not be possible to get exactly the same reading

as before because of limited resolution in the adjustment of the

function generator. Generally, the dc millivolt readings should agree

within + 0.002 mV.

15. When the millivoltmeter reading agrees within the tolerance with the

reading obtained when measuring the 1-kHz reference signal, note and

record on the data sheet. Table 10.6c, the reading on the UUT

(including the units) as well as the millivoltmeter reading.

16. Set the coaxial switch back to "Port 2," and check whether the reading

has changed. If the reading is unchanged, the test is completed. If

the reading has changed by more than 0.002 mV, repeat steps 11 to 16

and revise the reading on the data sheet. Table 10.6c.

B - 57
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

17. Set the function generator voltage to 0.4 millivolts (it cannot be set

to zero) to power down the equipment, and set the ac calibrator to zero output

B - 58
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Accuracy for frequencies from 10 MHz to 19.99 MHz for all input levels from

100 microvolts to 1 x 10® volt-hertz.

Specification :

Shall be within ± 15% of true input level.

Test Point : 5.00 V rms at 19.99 MHz

Equipment :

Items Model

AC Calibrator

Function Generator

Power Amplifier

28 -volt dc power supply

5 -volt thermal converter

DC millivoltmeter

Oscilloscope

Thermal converter output

cable

Cable with BNC connectors

RG 214/U cable with type "N"

connectors (3 required)

Type "N" tee (2 required)

50-ohm "N" adapter

BNC (male) to "N” (female)

(2 required)

Dual banana to "N" adapter

Coaxial relay

Relay control box

Fluke 5200a or equivalent

Hewlett-Packard 3325A or equivalent

ENI A300-40PA (modified)

Kepco JQE 25-lOM or equivalent

Ballantine 1394A-5 (modified)

Fluke 8506a or equivalent

Tektronix 465 or equivalent

Type MS connector MS3102A- lOSL- 3P (3-pin

male) to dual Banana plug

3 feet or less, each.

Special part

Hewlett-Packard 8761A

Special part

B - 59
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

Procedure

It is important to read the entire procedure before beginning the test. All

equipment should be warmed up following the manufacturers' specification

before any measurements are made.

WARNING: Thermoelements are easily damaged

by even moderate over-voltage.

Do not leave connected except when

actually carrying out test.

1. Connect the equipment as shown in figure 10.6.6. Attach the BNC (male)

to N (female) adapter to the 50-ohm "N-N" adapter, then to a type "N"

tee, and connect the combination to the input of the UUT.

2. Attach the coaxial relay to the thermal converter and port 1 of the

coaxial relay to the type "N" tee.

3. Attach a BNC (male) to "N" (female) adapter to a type "N" tee, and

connect the combination to one of the inputs of the oscilloscope.

4. Make sure the amplifier power supply is turned off . Then use a RG

214/U cable to connect the output of the power amplifier to the tee at

the oscilloscope and another RG 214/U cable to connect the oscilloscope

to the tee leading to the UUT and thermal converter.

5. Make sure that the output voltage from the ac calibrator is zero . Then

connect the output of the ac calibrator to port 2 of the coaxial switch

using a dual banana to "N" adapter and a RG 214/U cable.

6. Connect the output of the 5-volt thermal converter to the dc

millivoltmeter using a thermal converter output cable. Set the

millivoltmeter to the 1-volt range. (10 mV will then be displayed as 0.010000 V). Set the coaxial switch to "Port 2" by momentarily

depressing button No. 2 on the switch control box.

7. Set the frequency of the ac calibrator to 1 kHz, and bring the output

voltage up slowly to 5 volts rms while observing the dc millivoltmeter

reading and making sure the reading does not exceed 8 millivolts .

8. Turn on the oscilloscope and set it to display a 5-volt, 20-MHz signal

(2 volts/div; 0.1 microsecond/div, lOx magnification, dc coupled).

9. Turn on the power supply to the rf power amplifier and adjust it to 28

volts dc. The quiescent current should be approximately 6.5 amperes.

Note warning!

B - 60
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

WARNING: Do not turn on the rf power amplifier

if the cooling fan is not operating.

Do not obstruct air flow to the heat

sink. After switching off the power

supply, leave fan on \mtil the heat

sink is at room temperature.

10. Set the frequency of the function generator to 19.99 MHz and the

amplitude to 1 mV rms. Increase the output voltage until the UUT reads

approximately 5.0 V rms.

11. Observe the amplifier output waveform on the oscilloscope for parasitic

oscillations, clipping, or other distortion. If distortion or oscillation is observed, shut off the amplifier immediately and

investigate the cause.

12. Set the increment control on the function generator so that the least

significant digit can be incremented (0.001 mV).

13. With the ac calibrator set to 5.000 V, and when the reading on the dc

millivoltmeter has settled (about 5 to 10 minutes after setting

frequency and amplitude; step 7), note and record the millivoltmeter

reading on the data sheet. Table 10.6c.

14. Set the coaxial switch to "Port 1" and, using the increment or decrement control (up or down arrows) of the function generator, slowly

adjust the output voltage until the dc millivoltmeter reading settles

to the same voltage as that obtained when using the 1 kHz signal from

the ac calibrator . The dc voltage reading will take 20 to 30 seconds

to settle, and it may not be possible to get exactly the same reading

as before because of limited resolution in the adjustment of the

function generator. Generally, the dc millivolt readings should agree

within + 0.002 mV.

15. When the millivoltmeter reading agrees within the tolerance with the

reading obtained when measuring the 1-kHz reference signal, note and

record on the data sheet the reading on the UUT (including the units)

as well as the millivoltmeter reading.

16. Set the coaxial switch back to "Port 2," and check whether the reading

has changed. If the reading is unchanged, the test is completed. If

the reading has changed by more than 0.002 mV, repeat steps 11 to 16

and revise the reading on the data sheet. Table 10.6c.

17. Set the function generator voltage to 0.4 millivolts (it cannot be set

to zero) to power down the equipment, and set the ac calibrator to zero output

B - 61
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Table 10.6a Accuracy Test, Data Sheet, Micropotentiometer Measurements.

Test Point Measurement

Num. Value

Data

Units

Estimated

Uncertainty

Measurement

Specification Limits

Min. Max.

Calibr.

mV

Value

+100 fiV dc ± 0.8 /iV **

-100 fiV dc ± 0.8 fiV

100 fiV 10.00 Hz ± 3 /^V

95 mV 105 mV

100 fiV 10.00 kHz ± 2 HV95 mV 105 mV

100 fiV 999.9 kHz ± 3 mV95 mV 105 mV

100 /iV

9.99 MHz ± 3 mV

90 mV 110 mV

100 /iV

19.99 MHz ± 3 mV

85 mV 115 mV

B - 62
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

Table 10.6b Accuracy Test, Data Sheet, Calibrator.

Test Point Measurement Data Estimated Specification Limits

Measurement Min. Max.

Num. Value Units Uncertainty

1.00 mV 1.05 mV 0.95 mV

10.00 Hz ±0.0002 mV

300.0 V 315 V 285 V

10.00 Hz ±0.06 V

1.00 mV 1.03 mV 0.97 mV

50.00 Hz ±0.0002 mV

300.0 V 309 V 291 V

50.00 Hz ±0.06 V

1.00 mV 1.03 mV 0.97 mV

10.0 kHz ±0.0002 mV

10.0 mV 10.3 mV 9.7 mV

10.0 kHz ±0 . 002 mV

100.0 mV 103 mV 97 mV

10.0 kHz ±0 . 02 mV

1.00 V 1.03 V 0.97 V

10.0 kHz ±0.0002 V

10.0 V 10.3 V 9.7 V

10.0 kHz ±0.002 V

300.0 V 309 V 291 V

10.0 kHz ±0.06 V

1.00 mV 1.03 mV 0.97 mV

99.9 kHz ±0.0002 mV

200.0 V 206 V 194 V

99.9 kHz ±0.04 V

B - 63
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Table 10. 6c Accuracy Test, Data Sheet, Thermal Converter.

Test Point Measurement

Num. Value

Data

Units

Estimated

Measurement

Uncertainty

Specification

Limits

Min . Max

Millivoltmeter

Reading

100.0 V

1 kHz

St"***'*"*'***'*'*' ***

(± 0.1%)

*****•*••*•*•***

100.0 V

999.9 kHz ± 0.2 V

95 V 105 V

10.00 V

1 kHz

*••***•**••***•*•* ***

(± 0.1%)

A"******'***'*

10.00 V

9.99 MHz ± 0.03 V

9 V 11 V

5.00 V

1 kHz

'k'f:-k~k'k'k-k-k-ic-k'k ***

(± 0.1%)

************

5.00 V

19.99 MHz ±0.02 V

4.25 V 5.75 V

B - 64
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

10.7 Response Time

Shall be 3 seconds or less to rated accuracy.

Specification :

Shall be within ± 3% of true input level.

Test Points: 100,,0 mV rms at 1,.00 kHz

1,.0 V rms at 1 .00 kHz

10,.0 V rms at 1,.00 kHz

100,,0 V rms at 1,.00 kHz

Equipment :

Items

AC calibrator

Instrument Controller

(IEEE-488 Bus)

IEEE-488 cable

Dual banana to BNC adapter

Cable with BNC connectors

Model

Fluke 5101B or equivalent

Hewlett-Packard 9836 or equivalent

WARNING: This procedure uses lethal voltages during the test

Care should be taken to avoid injury or shock.

1. Connect the calibrator to the to the input of the UUT using the cable

with BNC connectors and the dual -banana adapter, as shown in

figure 10.7.1. Link the instrximent controller (computer) to the

calibrator using the IEEE-488 cable.

B - 65
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

"I\

\

V

CONTROLLER

UUT

o

Fig. 10.7.1 Set-Up for Response Time Test

DUAL BANANA /

TO BNC ADAPTER

2. Insert the 5 1/4 in. floppy disk labelled "TMDE4A" into the right-hand

disk drive of the computer (controller) . The program requires that HPBasic 2.1 and AP 2.1 (or later versions) are first loaded into the

computer.

3. Type LOAD "MENU" on the keyboard of the computer.

4. Press EXECUTE.

5. Press RUN and follow directions shown on the computer display.

6. Record the results shown on the printout into the data sheet,

Table 10.7

B. - 66
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

Table 10,7 Response Time, Data Sheet, ( 3 Seconds)

Test Point Measurement

Num. Value

Data

Units

Estimated

Measurement

Uncertainty

Specification Limits

Min. Max.

100,0 mV

1.00 kHz ± 0.2 s*

103 mV 97 mV

1.00 V

1,00 kHz ± 0.2 s*

1.03 V 0.97 V

10.0 V

1.00 kHz ± 0.2 s*

10.3 V 9.7 V

100.0 V

1.00 kHz ± 0.2 s*

103 V 97 V

* Estimate in the uncertainty of the time interval is based on spread of results obtained by a skilled observer.

B - 67
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

10,8 Crest Factor

Specification :

Meter shall handle crest factors of 4:1 for all input levels below 100 volts,

increasing for downscale measurements

Test Point : 90,0 V nns at 60 kHz (nominal)

Equipment :

I terns Model

AC Calibrator

Power Amplifier

100 -volt thermal converter

DC millivoltmeter

Thermal converter output

cable

Cable with BNC connectors

(2 required)

RG 142/U cable with type "N"

connectors (2 required)

Type ”N" tee

BNC (male) to "N" (female)

Dual banana to ”N" adapters

(2 required)

"N" to "N" adapter (male)

Coaxial relay

Relay control box

4:1 Crest Factor Waveform

Generator

Fluke 5200A or equivalent

Fluke 5205 or equivalent

Ballantine 1394A-100 (modified)

Fluke 8506A or equivalent

Type MS connector MS3102A-10SL-3P (3-pin

male) to dual Banana plug

3 feet or less, each.

Hewlett-Packard 8761A

Special part (NBS design)

Special part (NBS design)

B 68
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Procedure :

It is important to read the entire procedure before beginning the test. All

equipment should be warmed up following the manufacturers' specification

before any measurements are made.

WARNING: Thermoelements are easily damaged

by even moderate over-voltage.

Do not leave connected except when

actually carrying out test.

1. Connect the equipment as shown in figure 10.8. Attach the BNC (male)

to N (female) adapter to a type "N" (male) to "N" (male) adapter and

then to a type "N" tee, and connect the combination to the input of

the UUT.

2. Attach the coaxial relay to the thermal converter and port 1 of the

coaxial relay to the type "N" tee.

3. Attach dual banana plug to "N" adapters to one end of each of the two

RG-142 cables. Connect the other end of one of the cables to the "tee",

and connect the free end of the other cable to port 2 of the coaxial

relay.

4 . Make 'sure that the output voltage from the power amplifier is zero , then plug the cable from the "tee" into the output terminal of the

power amplifier.

5. Connect the output of the 100-volt thermal converter to the dc

millivoltmeter using a thermal converter output cable. Set the

millivoltmeter to the 1-volt range. Set the coaxial switch to "Port 1"

by momentarily depressing button No. 1 on the switch control box.

6. Make sure that the output voltage from the ac calibrator is zero . Then

connect the output of the ac calibrator to port 2 of the coaxial switch

using the dual banana to "N" adapter and a RG 142/U cable.

7. Set the instrument under test to the manual range mode. Then, set the

UUT to a range that has a full scale value of 100 volts rms . If the

UUT does not have a manual range setting with a full scale value of 100

volts rms, see the note on page 65.

8. Connect the special crest factor waveform generator to the input of the

power amplifier, and observe the millivoltmeter reading. The reading

should not exceed 8 millivolts . When the reading has settled, record

the UUT reading and the millivoltmeter reading on the first line of the

data sheet. Table 10.8.

B - 69
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

9.

Set the coaxial switch to "Port 2" by momentarily depressing button

No. 2 on the switch control box.

10. Set the frequency of the ac calibrator to 60 kHz, and bring the output

voltage up slowly while observing the dc millivoltmeter reading and

making sure the reading does not exceed 8 millivolts. When the

millivoltmeter reading approaches the reading determined in step 8,

wait and let the reading settle.

11. Adjust the calibrator voltage until the dc millivoltmeter reading

settles to the same voltage as that obtained when using the crest

factor generator and amplifier (step 8). The dc voltage reading may

take 20 to 30 seconds to settle, and it may not be possible to get

exactly the same reading as before because of limited resolution in the

adjustment of the calibrator. Generally, the dc millivolt readings

should agree within + 0.002 mV.

12. When the millivoltmeter reading has settled and agrees to within the

tolerance with the reading obtained in step 8, enter the calibrator

voltage and the new millivoltmeter reading in the second line of the

data sheet. Table 10.8.

13. Set the coaxial switch back to "Port 1," and check whether the

millivoltmeter reading has changed. If the reading has changed by more than 0.002 mV, repeat steps 11 to 13. If it has not changed, the test

is completed. The test is successful if the difference between the UUT

UUT reading and the calibrator voltage does not exceed the stated

tolerance

Note

Although the crest factor test can be performed with the UUT in the

autorange mode, operation in this mode does not insure that the applied

voltage will be near the full-scale value. The test is more meaningful

if the rms amplitude of the crest factor signal applied to the UUT is

at, or just below, the full-scale voltage of the measuring range.

If the UUT does not have a range with a full-scale value of 100 volts

rms, set the meter to its next lower range and reduce the output

voltage of the crest- factor waveform generator so that the rms output

from the power amplifier is about 10% below the nominal value of the

range selected. To reduce the output voltage of the crest- factor

waveform generator, an attenuator is inserted between the output

terminals of the waveform generator and the input terminals of the

power amplifier. In its simplest form, the attenuator can be

constructed using two resistors with resistances of the order of 1 kfi to 10 kfl. Adjustment and verification of the desired output voltage

level can be obtained using the Fluke 8506 Digital Multimeter.

B - 70
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

4:i FLUKE S200A

AC calibrator waveform FLUKE 850«A generator THERMAL RMS DMM

(NBS» OUTPUT e

OUTPUT t

o

1

^thermo* ELEMENT

UUT

\ —Di*. WPUT ^SWITCH ?

>R6-M WITH BNC

CONN ON BOTH ENDS

ADAPTER

TYPE "n" ADAPTER

TYPE V TO TYPE *N" (MALE TO male)

TO BNC

Fig. 10.8 Set-Up for the Crest Factor Test

B 71
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Table 10,8 Crest Factor.

Test Point Calibrator Voltage U U T Estim. Specification MillivoltMeas

Limits meter

Num. Value Units Reading UncertMin . MaxReading

90.0 V* ±3% of Cali60 kHz brator volts

'kicicic-kirkirk'k A"***'*"*"*"*"*** 60 kHz ±0.1%

*

See Note if attenuator is used.

B - 72
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

10.9 Input Connector

Specification :

Input connector of meter shall be selectable by a front panel switch, allowing

the outer connector to be floating from chassis ground or to be connected to

chassis ground. Connector type shall be BNC type female.

Procedure

1. The existence of the input connector is to be determined by inspection.

2. Connect an ohmmeter between the BNC outer shell and a grounded point on

the chassis.

3. Switch the front panel switch to the grounded position. Read and record

the resistance.

4. Switch the front panel switch to the ungrounded position. Read and

record the resistance.

B - 73
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Table 10.9 Input Connector

Measurement

Description

Measurement

Data

Estimated

Measurement

Uncertainty

Specificat]

Min,

Lon Limits

Max,

Units

Connector

of BNC type N/A Yes

Resistance

grounded N/A ohms

Resistance

floating N/A ohms

B - 74
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

10.11 AC Common Mode Rejection

Specification :

Shall be greater than 60 dB up to 400 Hz.

Equipment :

Items Model

AC Calibrator Fluke 5200A or equivalent

Procedure

1,

Connect the equipment as shown below.

Fig. 10.11.1 Test setup for measuring the common mode rejection.

2. Initially, set the UUT controls as follows:

Function: AC VOLTAGE

Range Mode: MANUAL - most sensitive range

3. Set the output level of the calibrator to 0.100 mV rms and 400 Hz.

4. Set the calibrator to OPERATE position. Read and record the value

displayed on the UUT as V^.

NOTE: If the UUT indicates underrange, enter zero for Vj^.

5. Set the output level of the calibrator to 0.420 V rms and 400 Hz. Set

the calibrator to OPERATE and record the value displayed by the UUT on

the data sheet as V2

.

NOTE: If the UUT indicates an overrrange, set the range switch to its

next highest position and repeat steps 4 and 5.

B - 75
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

6 . Calculate the common mode rejection (CMR) according to the formula

CMR — 20 logj^Q-

( V| - Vf )

0.42

and record this value on the data sheet, Table 10.11.

NOTE: Assure that the units in the above equation are consistent.

B - 76
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Table 10.11 Common Mode Rejection

Measurement

Description

Measurement

Data

Estimated

Measurement

Uncertainty

Specificat]

Min.

Lon Limits

Max.

Units

Vl N/A V

V2 N/A V

CMR ± 0.5 60 dB

B - 77
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

10.12 Maximum Input Protection

Specification :

Shall be at least 420 volts peak (300 volts RMS) on all ranges, and shall be

at least 1 x 10^ volt-hertz on all ranges above 1 volt.

Equipment :

I terns Model

Meter Calibrator Fluke 5101B or equivalent

Wall Clock Commercial item

Procedure

:

WARNING: This procedure uses lethal voltages during the test.

Care should be taken to avoid injury or shock.

1.

Connect the equipment as shown below.

OUT

Fig. 10.12 Test setup for measuring maximum input protection.

2. Set the UUT controls as follows:

Function: AC VOLTAGE

Range Mode : MANUAL

3. Apply 300 volts ac at 1 kHz from the meter calibrator to the input of the

UUT. Note the time on the wall clock.

4. After 2 minutes has elapsed, note any evidence of smoking, arcing, or
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

10.13 Input Impedance

Specification :

Input impedance shall be 1 megohm or greater, shunted by 50 picofarads

capacitance or less.

Equipment :

I terns Model

Digital LCR meter Hewlett-Packard 4262A or equivalent

Isolation Transformer Topaz 91002-22 or equivalent

Three-wire -female to two-wire-male adapter Order by description

Procedure

1, Connect the equipment as shown below.

To

120 V

60 Hz

Fig. 10.13 Test setup for measuring input impedance.

Note: This procedure requires that the chassis of

the UUT be ungrounded with respect to earth ground.

Assure that adequate safety precautions are observed.

2. Set the UUT controls as follows:

Function: AC VOLTAGE

Range Mode : AUTORANGE

B - 81
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

3.

Set the controls on the LCR meter as follows:

DC Bias OFF

PRL

C

Circuit Mode

Function

Test Signal 1 kHz

LCR Range

DQ Range

Trigger

AUTO

AUTO

INT

4. Disconnect the cable to the input of the UUT.

5. Read and record on the data sheet the value of the cable capacitance as indicated by the LCR meter.

6. Reconnect the cable to the input of the UUT.

7. Read and record on the data sheet the value of the sura of the cable and

input capacitance as indicated by the LCR meter.

8. Subtract the value of the capacitance obtained in step 5 from the value

of the capacitance obtained in step 7. Record this difference on the

data sheet.

9. Press the R/ESR button on the LCR meter.

10. Read and record on the data sheet the value of the input resistance

indicated on the LCR display.

B - 82
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Table 10.13 Input Impedance

Measurement

Description

Measurement

Data

Estimated

Measurement

Uncertainty

Specificat]

Min.

Lon Limits

Max.

Units

Cable Cap. ± 0.2 PF

Cable + Input ± 0.2 pF

Input Cap

± 0.2 0 50 pF

Input Resist. ± 0.004 1 Mn

B - 83
TEST PROCEDURES FOR ME-545()/G TRUE-RMS VOLTMETER

10.14 DC Output

Specification :

The meter shell have rear panel dc output. Output connector shall be BNC type

female or dual banana female.

Procedure

1 . The existance of the dc output connector is

inspection.

to be determined by

B - 84
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

Table 10.14 DC Output

Measurement

Description

Measurement

Data

Estimated

Measurement

Uncertainty

Specificat]

Min.

Lon Limits

Max.

Units

Connector

on rear pnl. N/A Yes

Connector

proper type N/A Yes

B. - 85
V*. ’

• c. -•

^

fr

I . ' ---

'ii

i' 5. y.

f’r

'^-r » ' .'

' fil f, ; ; 0 :' V .., Us

I »•-*• , f . t

• o:-

e.t 1

i

'.'/ \.a: A\?:

*' '•' * •- r

’ c s!../3^ h

- :'> 'i
TEST PROCEDURES FOR ME-545()/G TRUE -RMS VOLTMETER

APPENDIX C

SOFTWARE FOR THE AUTOMATIC TESTS FOR

THE ME-545 0/G TRUE-RMS VOLTMETER

C - 1
10 20

3040

50

60

70

80

90100 110

120

130

140

150

160 170

180

190 200

210

220

221

230

231

240

250

260

270

280

290

300

310

320

330

340

350

351

360

361

370

380

390

400

410

420

430

440

450

460

470

480

490

500

510

520

530

540

550

560

570

580 590

600

610

620

630

Appendix C - Software Listing for True-RMS Voltmeter (ME-545()/G)

*************** menu **********************

MAIN PROGRAM TO TEST ME-5450/G TRUE RMS VOLTMETER.

VOL=TMDE4A. PROGRAM NAME - MENU. KJL

VERSION 1.0

Printer“701

CLEAR 7 OUTPUT 2; "SCRATCH KEY"&CHR$ ( 255 )&CHR$ ( 88 ) ;

! CLEAR SOFTKEYS

OFF KEY PRINTER IS CRT PRINT CHR$(12) ! Roll the screen to clear PRINT ”*********************** MAIN MENU **************************'* PRINT

PRINT "PROGRAM SELECTIONS FOR TESTS OF ME-5450/G TRUE RMS VOLTMETER"

Timedate: PRINT PRINT BEEP

DIM Yes_no$tl] ,Date$[15] ,Time$[10] PRINT "DATE : "; DATES ( TIMEDATE

PRINT "TIME : TIMES ( TIMEDATE

Yes_noS”""

INPUT "ARE DATE AND TIME CORRECT? ( Y/N )

! " , Yes_no$

IF Yes_noS='"" THEN 180 IF Yes_noS“"Y" OR Yes_noS“"y" THEN Headings BEEP

INPUT "ENTER DATE AS 25 JUN 1986",DateS BEEP

INPUT "ENTER TIME AS 16 : 09 : 21" . TimeS

SET TIMEDATE DATE ( DateS )+TIME (TimeS

GOTO Timedate

!tlk*#*'********^^**#*******************^**********^#********#*******#*^

f Headings: ! BEEP

Yes noS“""

INPUT "DO YOU WANT A PRINTED TEST HEADING? ( Y/N )

. " , Yes_noS

IF Yes_noS-"" THEN 350

IF Yes_noS-"N" OR Yes_noS-"n" THEN Ok BEEP

INPUT "OPERATOR NAME",NameS

BEEP

INPUT "MANUFACTURER NAME",MfgS

BEEP

INPUT "MODEL NUMBER" , ModelS

BEEP

INPUT "METER SERIAL NUMBER" , SernumberS

PRINT PRINT CHRS(12) BEEP

PRINT "**************** ME-5450/G TRUE RMS VOLTMETER ACCEPTANCE TESTS *****************" OUTPUT Printer ;CHRS( 12) ! FORM FEED FOR EXTERNAL PRINTER OUTPUT Printer;"*************** ME-545-0/G TRUE RMS VOLTMETER ACCEPTANCE TESTS**************

PRINT OUTPUT Printer ;CHRS( 10) ! LINE FEED FOR EXTERNAL PRINTER

OUTPUT Printer ;CHRS( 10) ! LINE FEED FOR EXTERNAL PRINTER

PRINT "OPERATOR: ";NameS

OUTPUT Printer;" OPERATOR: ";Name$

PRINT "MANUFACTURER: ";MfgS

OUTPUT Printer;" MANUFACTURER: ";MfgS PRINT "MODEL: "; ModelS

OUTPUT Printer;" MODEL: ";ModelS PRINT "SERIAL NUMBER: "; SernumberS

OUTPUT Printer;" SERIAL NUMBER; "; SernumberS

PRINT

C - 2
Appendix C - Software Listing for True-RMS Voltmeter (ME-5A5()/G)

6A0 PRINT DATE$(TIMEDATE)&" "&TIMES ( TIMEDATE

650 OUTPUT Printer;" "&DATES ( TIMEDATE )&" "&TIME$ (TIMEDATE

660 PRINT

670 OUTPUT Printer ;CHR$( 10) ! LINE FEED FOR EXTERNAL PRINTER

680 PRINTER IS CRT

690 PRINT "PAUSED. PRESS <CONTINUE> WHEN READY."

700 PAUSE

710 !

730 ! 7A0 OkrPRINT CHR$(12)

750

760

770

780

790

800

810

820

830

8A0

850

860

.870 880

890

900

910

920 930

9A0

950

960

970

980

990

1000

1020

30

AO

5060

70

8090100

110 Start :Addr«702

120 DIM Pass$[l]

130 Prlnter“701

lAO PRINTER IS CRT

150 PRINT CHR$(12) ! Roll the

160 BEEP

170 PRINT " Enter the type of test desired;"

180 PRINT " " 190 PRINT " (1) AC VOLTAGE RESPONSE TIME"

200 PRINT " (2) RETURN TO MAIN MENU."

210 PRINT

220 PRINT " Enter 1 or 2" 230 INPUT Choice

2A0 IF Cholce-1 THEN 330

250 IF Cholce-2 THEN LOAD "MENU"

260 PRINT

270 PRINT " IMPROPER CHOICE ! ! Try Again

280 BEEP

290 WAIT 2.0

300 GOTO Start

BEEP

PRINT " PRINT

PRINT

PRINT " PRINT

PRINT " PRINT

PRINT

PRINT " INPUT Choice

tPRINT

PRINT "

Run the test for

1. AC VOLTAGE ( 5200A/5205A)

2. RESPONSE TIME (5101B)

ENTER THE NUMBER OF CHOICE

WAIT -- Loading program number ";Cholce

Improper Choice'*

Improper choice'

IF Cholce<0 THEN PRINT " IF Cholce<0 THEN WAIT 2.0

IF Cholce<0 THEN GOTO Ok

IF Cholce=l THEN LOAD "VOLTS"

IF Cholce=2 THEN LOAD "RESP"

IF Cholce=0 THEN Ok

IF Cholce>2 THEN PRINT " IF Cholce>2 THEN WAIT 2.0

IF Cholce>2 THEN GOTO Ok END*************** kesp **********************

!

Program to test AC response time for meters In the voltage mode.

PROGRAM - RESP. VOL-TMDEAA. VERSION 1.1 KJL.

C - 3
310

320

330

340

350

360

370

380

390

400

410

420

430

440

450

460

470

480

490

500

510

520

530

540

550

560

570

580

590

600

610

620

630

640

650

660

670

680

690

700 710

720

730

740

750

760

770

780

790

800

810

820

830

840

841

850

860

861

870

880

890

900

901

910

920

921

930

Appendix C - Software Listing for True-RMS Voltmeter (ME-545()/G)

I

I

I Start of the AC Voltage Section

I OUTPUT Addr;"CC"

PRINT CHR$(12) ! Roll Screen to Clear

1 Time-3. 0 ! RESPONSE TIME INTERVAL IN SECONDS

Numberof tests-4 ! Number of tests to be performed

I RESTORE 420 ! DATA-VOLTAGES 01 kHz. TO BE USED IN THE TEST DATA 0.10, 1.0, 10.0, 100.

I FOR N-1 TO Numberoftests ! Loop each test READ D(N) ! Read output level NEXT N

I BEEP 3000, .6 PRINT "*********** ENSURE THAT METER IS SET TO RESPOND TO AC VOLTAGE •*********"

PRINT

PRINT

PRINT " CONNECT METER TO FLUKE 5101B CALIBRATOR!!!!!"

PRINT

PRINT

PRINT " At the sound of the tone, mentally note the voltage reading on the meter." PRINT

PRINT " This test will consist of Numberoftests ; "tests .

PRINT

PRINT "********** PRESS <CONTINUE> WHEN READY! **«**'»****" PRINT

PAUSE PRINT CHR$(12)

FOR Test-1 TO Numberoftests

IF Test-1 THEN OUTPUT Printer;" AC VOLTAGE RESPONSE TIME TESTS"

Ac_voits; OUTPUT Addr ; D ( Test )

; "V" OUTPUT Addr;","

OUTPUT Addr;"1000H," ! TEST FREQUENCY - 1 kHZ

PRINT CHRS(12)

PRINT

PRINT " Test ";Test;" of "; Numberof tests ;

PRINT BEEP

PRINT " PROGRAMMED VOLTAGE WILL BE -"; D (Test ); "volts

PRINT

PRINT " PRESS <ENTER> WHEN READY" PRINT

PRINT " WATCH THE METER NOW!!!"

INPUT AS PRINT PRINT " AC VOLTAGE TESTS"

OUTPUT Addr;"N"

WAIT Time

Enter_acvolts : BEEP 3000,. 15 PRINT Meter_reading$-""

PRINT "ENTER THE OBSERVED READING AT THE TIME OF THE TONE" INPUT Meter_reading$

IF Meter_reading$-"" THEN Enter_acvolts

PRINT

PRINT " READING ENTERED - " ;Moter_reading$

PRINT BEEP Yes_no$-"

PRINT "IS THE READING ENTERED CORRECTLY? (Y/N)" INPUT Yes_noS

IF Yes_no$-"" THEN 900

IF Yes no$-"N" OR Yes no$-"n" THEN Enter acvolts

C - 4
Appendix C - Software Listing for True-RMS Voltmeter (ME-5A5()/G)

940 OUTPUT Addr;" CC"

950 PRINT

960 BEEP

961 Yes noS*""

970 PRINT "DO YOU WISH TO RE-TEST THIS VOLTAGE? (Y/N)

980 INPUT Yes_no$

981 IF Yes_no$“"" THEN 960

990 IF Yes~no$="Y " OR Yes_no$«"y" THEN Ac_volts

1000 GOSUB Record

1010 NEXT Test

1020 OUTPUT Addr;"CC " 1030 PRINT

1040 BEEP 500, .4 1050 PRINT "ALL" ;Numberoftests ; "TESTS COMPLETED!

1060 PRINT

1070 PRINTER IS Printer

1080 PRINT

1090 PRINT TAB (25)," ALL" ; Numberoftests ; "TESTS COMPLETED!

1100 PRINT

1110 PRINT TAB (10)," TIME INTERVAL - "; Time ;

seconds"

1120 PRINT

1130 PRINT TAB (10)," TEST FREQUENCY - 1 kHz."

1140 PRINT

1150 PRINTER IS CRT

1160 PRINT "WAIT 5 SECONDS"

1170 WAIT 5 1180 GOTO Start

1190 1 1200 ! *******PRINT ROUTINE HERE**************

1210 ! 1220 Record; ! 1230 PRINTER IS CRT

1240 PRINT

1250 PRINT "ENTERED READING , Meter_r eadingS

1260 ! BEEP 400, .4 1270 ! PRINT "WAIT 2 SECONDS"

1280 PRINTER IS Printer

1290 PRINT

1300 PRINT TAB (10), "PROGRAMMED VOLTAGE - ";D(Test)," METER READING - " ;Meter_reading$

1310 PRINTER IS CRT

1320 RETURN

1330 END

t **#*#*##*#***** VOLTS ********************

20 ! 30 ! PRG-VOLTS. FRI 05 SEPT 86. KJL.

40 ! VERSION 2.1. DISC VOLUME - TMDE4A.

50 ! 60 ! 70 Start: CLEAR 7 80 ! 90 GOSUB Initialize

100 ! 110 ! Test Data Definition Section

120 ! 130 ! 140 ! 150 ! AC Voltage Test Data

160 ! 170 Test_points“12

180 Actest length“7 ! Number of AC Voltage Tests

190 ! 200 \ Voltage !# Freqs ! *** Frequencies

210 DATA 0.001, 4, 10, 50, 10000.

99900

220 DATA 0.010, 4, 0, 0, 10000.

0 230 DATA 0.100, 4, 0, 0, 10000.

0 240 DATA 1.000, 4 , 0, 0, 10000. , 0 250 DATA 10.00, . 0, 0, 10000.

0

C - 5
260

270

280

290

300

310

320

330

340

350

360

370

380

390

400 410

420 430

440

450

460

470

480

490

500

510

520

530

540

550

560

570

580

590

600

610

620

630

640

650

660

670

680

690

700

710

720

730

740 750

760

770

780

790

800

810

820

830

840

850

860

870

880

890

900

910

920

Appendix C - Software Listing for True-RMS Voltmeter (ME-545()/G)

DATA 200.00, 4, 0. 0, DATA 300.00, 4, 10, 50.

I

tFOR N=1 TO Actest_length

READ Vac(N.l)

READ Vac(N,2)

FOR M-1 TO Vac(N,2) READ Vac(N,M+2)

NEXT M

NEXT N PRINT

PRINT

PRINT

1

! End of Test

,

0., 99900.

10000 ., 0

Loop each Vac Test Read the Voltage into Vac(*)

Read the number of frequency pts.

Loop the frequency points

Read the frequency points

Data Definition Section

t

!

I

I Start of ac test sequence

Restart : CLEAR 7 BEEP

PRINT

PRINT "SET METER TO RESPOND TO AC VOLTAGE!"

PRINT PRINT "PRESS <CONTINUE> WHEN READY!"

PRINT

PAUSE

ITest-1 ! COUNTER SET FOR FIRST TEST AT FIRST RFEQUENCY

FOR Freqnum-1 TO 4 ! Loop up to 4 freqs / voltage

FOR T=1 TO Actest_iength ! Loop voltages

OUTPUT 2;Clear$;

Volts-Vac(T, 1) Freq-Vac (T , Fr eqnum+2

IF Freq-0 THEN 1070 BEEP

PRINT "AC test number" ; Test ; "of Test_points ! Displays test sequence

PRINT "PROGRAMMED FREQUENCY - ",Freq PRINT "PROGRAMMED VOLTAGE » ", Volts

GOSUB Volt_hertz! Volts*Freq<-lE8

GOSUB Volts

GOSUB Entry

GOSUB Record

! Next_test:Test-Test+l ! ADVANCE COUNTER FOR NEXT VOLTAGE TEST AT THE SPECIFIED FREQ.

Next_voltage : NEXT T Next_freq : NEXT Freqnum

CLEAR 7 OUTPUT 2 ; Clears

BEEP 550, .5 PRINTER IS Printer

PRINT

PRINT TAB (15), "ALL VOLTAGE TESTS AT ALL FREQUENCIES COMPLETED!"

PRINT PRINTER IS CRT PRINT

PRINT "ALL VOLTAGE TESTS AT ALL FREQUENCIES COMPLETED!"

PRINT BEEP Yes_no$“"”

INPUT "DO YOU WISH TO REPEAT THE TEST? ( Y/N )

! " , Yes_noS

IF Yes_no$-"" THEN 860

IF Yes_no$-"Y" OR Yes_no$-"y" THEN GOTO Restart

PRINT PRINT "WAIT 5 SECONDS!"

C - 6
Appendix C - Software Listing for True-RMS Voltmeter (ME-545()/G)

930 WAIT 5 940 LOAD "MENU”

950 ! ***Alk**********A********A*W********A*A#****A******4r*4r*4r*'**4r**A***1^*****

960 ! Start of Subroutines

970 ! ***********************************************************************

980 Volts: ! 990

1000

1010

1020

1030

1040

1050

1060

1070

1080

1090

1100

1110

1120

1130

1140

1150

1160

1170

1180

1190

1200

1210

1220

1230

1240

1250

1260

1270

1280

1290

1300

1310

1320

1330

1340

1350

1360

1370

1380

1390

1400

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1440

1450

1460

1470

1480

1490

1500

1510

1520

1530

1540

1550

1560

1570

1580

1590

Checkout**!

!Addr~Addr-^0 ! Get HP address from IEEE address

I

!

I

! --- START OF THE AC VOLTAGE TEST

OUTPUT Addr;"*" ! Reset

PRINT

IF T“1 THEN PRINT TABXY C 10 , 5 ), "CONNECT TEST METER TO 5200A CALIBRATOR!

IF T=1 THEN BEEP

PRINT

IF T=1 THEN PRINT TAB ( 10 ), "PRESS <CONTINUE> WHEN READY!"

IF T-1 THEN PAUSE

IF Freq“0 THEN Next_voltage

PRINT WAIT .5 V$=VAL$ (Volts)

OUTPUT Addr;V$ ! Append the voltage value

OUTPUT Addr;"V" ! Add the V WAIT .5 F$=VALS(Freq)

OUTPUT Addr;F$ ! Append the frequency

OUTPUT Addr;"H"

WAIT .5 IF Volts>119.9999 THEN Highv

OUTPUT Addr;"F0X0N" ! Go to operate condition

IRETURN

Entry: !

!

! This subroutine records the operator's entry of the UUT reading

! and checks for the validity of response. In addition, it uses the

! numerical entry to determine the range the meter is set to, i.e.

! volts, millivolts, etc.

IPRINT PRINT BEEP

Meter_reading$**"" PRINT "ENTER THE READING DISPLAYED ON THE TEST METER."

PRINT

INPUT Meter_readingS ! The operator’s entry of reading

IF Meter_reading$**" " THEN 1410

ValidS*"" ! Clear the flag for bad entry

Convert: ! Convert Meter_reading$ to Volts

!Decade“-3

FOR D«-6 TO +6 ! Go through the ranges to determine

Reading**VAL(Meter_reading$)*(10''D) ! the meter's range

IF ABS(Reading/Volts-l)<.3 THEN Decade-D

NEXT D Range_check: ! Check to assure that a reasonable range has been entered

IBEEP

IIF Decade“-6 THEN PRINT " Meter reading « " ;Meter_readingS ; " microvolts

C - 7
1600

1610

1620

1630

1640

1650

1660

1670

1680

1690

1700

1710

1720

1730

1740

1750

1760

1770

1780

1790

1800

1810

1820

1830

1840

1850

1860

1870

1880

1890

1900

1910

1920

1930

1940

1950

I960

1970

1980

1990

2000

2010

2020

2030

2040

2050

2060

2070

2080

2090

2100

2110

2120

2130

2140

2150

2160

2170

2180

2190

2200

2210

2220

2230

2240

2250

2260

Appendix C - Software Listing for True-RMS Voltmeter (ME-545()/G)

IF Decado--5 THEN PRINT " Reading entered - " ; Meter_readingS *• CHECK IT! " IF Decade=-4 THEN PRINT " Reading entered - ” ;Meter_reading$ •* CHECK IT! " IF Decade--3 THEN PRINT " Meter reading » " ; Meter_reading$ millivolts"

IF Decade-“2 THEN PRINT " Reading entered - " ;Meter_reading$ CHECK IT! " IF Decade--! THEN PRINT " Reading entered » " ;Meter_reading$ CHECK IT! " IF Decade-0 THEN PRINT " Meter reading - " ;Meter_reading$ volts"

IF Decade-+1 THEN PRINT " Reading entered - " ;Meter_reading$ CHECK IT! " IF Dec ade-+2 THEN PRINT " Reading entered - " ;Meter_readingS CHECK IT! " IF Dec ade-+3 THEN PRINT " Meter reading - " ;Meter_reading$ ** kilovolts"

IF Decade-+4 THEN PRINT " Reading entered - " ;Meter_reading$ CHECK IT! " IF Decade-+5 THEN PRINT " Reading entered - " ;Meter_reading$ CHECK IT! " IF Decade=+6 THEN PRINT " Reading entered - " ;Meter_reading$ CHECK IT!"

!

! If the operator’s entry Is more than 30 percent In error, question it. Error“ABS ( ( ( VAL (Meter_reading$ )*(10”'Decade))/Volts)-l)

IF Error>.3 THEN BEEP 400,1.5 WAIT .5 BEEP 500,1 PRINT

PRINT " ******* RECHECK THE READING! *******

END IF PRINT PRINT "ARE THE VALUE AND UNITS CORRECT?

INPUT ValidS

IF Valid$-"n" OR Vaiid$=»"N" THEN 1400

RETURN

Yes- <ENTER>; No - <N>"

I Check for valid entry

! Re-enter data

I************************************************************************

Record: !

!IF Decade=-6 THEN Meter_reading$=Meter_reading$&" uV"

IF Decade--3 THEN Meter_r eading$=Meter_r eadingS&" mV"

IF Decade-0 THEN Meter_reading$=Meter_r eading$&" V"

IF Decade-3 THEN Meter_r eading$=Meter_reading$&" kV" BEEP

PRINT F$-VAL$(Freq)

PRINT USING "3X,4A,3X,10A,3X,9A,3X,10A";"TEST", "PROGRAMMED"," METER ", "PROGRAMMED

PRINT USING "2X, 6A, 3X , 7A, 5X , 9A, 3X, lOA" ; "NUMBER" , "VOLTAGE" , "READING" , "FREQUENCY"

PRINT USING "2X,6A,3X,7A,5X,9A,3X,10A":" ---•/• " " PRINT USING " 4X, 2D, 3X, 5D. 4D, 3X, 9A, 4X, 6A" ; Test, Volts, Met er_roadlng$,F$

IF T-1 THEN Recordl PRINTER IS Printer

PRINT USING "16X,2D, lOX, 5D . 4D , IIX , 9A" ; Test , Volts , Met or_reading$

Return: PRINTER IS CRT

OUTPUT 2;Clear$; ! CLEARS SCREEN

RETURN

!I*********************************************************

f Recordl: !

PRINTER IS Printer

! PRINT CHR$(12) ! FORM FEED PRINT

IF Freq-0 THEN

PRINT USING "32X, 14A"; "FREQUENCY - DC" ELSEPRINT

PRINT USING "32X,12A,K,3A": "FREQUENCY - ",Freq," Hz." END IF PRINT

PRINT USING "15X, 4A, lOX, lOA, lOX, 9A" ; "TEST" , "PROGRAMMED" , " METER " PRINT USING " 14X , 6A, lOX , 7A , 12X , 9A" ; "NUMBER" , "VOLTAGE" , "READING" PRINT USING "14X, 6A, lOX, 7A, 12X, 9A" ; " "," "," "

C - 8
2270

2280

2290

2300

2310

2320

2330

2340

2350

2360

2370

2380

2390

2400

2410

2420

2430

2440

2450

2460

2470

2480

2490

2500

2510

2520

2530

2540

2550

2560

2570

2580

2590

2600

2610

2620

2630

2640

2650

2660

2670

2680

2690

2700

2710

2720

2730

2740

2750

2760

2770

2780

2790

2800

2810

2820

2830

2840

2850

2860

2870

2880

2890

2900

2910

2920

2930

Appendix C - Software Listing for True-RMS Voltmeter (ME-545()/G)

PRINT USING "16X.2D, lOX, 5D. 4D, 1 IX , 9A" ; Test , Volts , Meter_readlngS

BEEP PRINTER IS CRT

GOTO Return

Il^r******^**#*****#********^*^^*#**#*^*************************# 

! Initialize; 1

jAddr-703 ! IEEE-488 ADDRESS OF AC VOLTAGE CLIBRATOR

Prlnter-701 ! IEEE-488 ADDRESS OF EXTERNAL PRINTER ASSIGN gHplb TO 7 REMOTE gHplb

LOAD KEY "ABORTKEYS"

ON KEY 0 LABEL "TO GOSUB Abort

ON KEY 1 LABEL "SAFELY " GOSUB Abort

ON KEY 2 LABEL "ABORT " GOSUB Abort

ON KEY 3 LABEL "THE " GOSUB Abort

ON KEY 4 LABEL "RUNNING " GOSUB Abort

ON KEY 5 LABEL "PROGRAM " GOSUB Abort

ON KEY 6 LABEL "PRESS " GOSUB Abort

ON KEY 7 LABEL "ANY " GOSUB Abort

ON KEY 8 LABEL "SOFT- " GOSUB Abort

ON KEY 9 LABEL "KEY " GOSUB Abort PRINTER IS CRT DIM Clear$[2] ,Home$[2] .Scratch keyS t 13 ]

, Vac ( 50 . 9

DIM V$[20] ,H$[20] ,A$[3]

Clear$=CHR$(255)&CHR$(75) ! CLEAR THE CRT

Home$=CHR$(255)&CHR$(84) ! PLACE THE CURSOR IN THE UPPER LEFT TOP OF THE SCREEN. Scratch_keyS="SCRATCH KEY"&CHRS ( 255 )&CHR$ ( 88 ) ! ERASE THE SOFT-KEYS

GRAPHICS OFF

CONTROL 2,1;0 ! PRINTALL OFF

CONTROL 1,4 ;0 1 DISPLAY FUNCTIONS OFF

OUTPUT 2;Clear$;

RETURN

!I** *****************************************************

Hlghv: ! OPERATE THE FLUKE 5205 POWER AMPLIFIER

IBEEP 500, .4 V$=V$&"V"

F$=F$&"H"

IF F$-"0H" THEN Next_voltage

IF V$>"120V THEN 2730

IF V$-"120V" THEN 2730

IF V$<"120V" THEN V$="120V"

OUTPUT Addr;V$,H$."FOXlS"

PRINT BEEP 500, .4

! OUTPUT 2; Clears

PRINT "CONNECT METER TO 5205A POWER AMPLIFIER!"

PRINT

PRINT "PRESS <CONTINUE> WHEN READY"

PRINT PAUSE BEEP 500, .4 PRINT "LETHAL VOLTAGE PRESENT!!!!!"

PRINT DISP "LETHAL VOLTAGE PRESENT! !!!!!"

IF Freq<30 THEN WAIT 5 GOTO 2990

END IF

IF Freq<120 THEN WAIT 3 GOTO 2990 END IF

C - 9
2940

2950

2960

2970

2960

2990

3000

3010

3020

3030

3040

3050

3060

3070

3080

3090

3100

3110

3120

3130

3140

3150

3160

3170

3180

3190

3200

3210

3220

3230

3240

3250

3260

3270

3280

3290

3300

3310

3320

3330

3340

3350

3360

3370

3380

3390

3400

3410

3420

3430

3440

3450

3460

3470

3480

3490

3500

3510

3520

3530

3540

3550

3560

3570

3580

3590

3600

Appendix C - Software Listing for True-RMS Voltmeter (ME-545()/G)

IF Freq<1200 THEN WAIT 2 GOTO 2990

END IF WAIT .3 OUTPUT Addr;V$,H$,"F0XlN"

RETURN

I|**#**4r*********A*******#*****4r**A***4r**lft*1^4r*AA**A*

! Voit_hertz: !

IIF Volts*Freq<-l.E+8 THEN RETURN

ELSEPRINT

BEEP 500, .4 PRINT "VOLTAGE*FREQUENCY > 1E8" PRINT "CALCULATED PRODUCT , Voits*Freq, "WAIT" BEEP

END IF WAIT 5 GOSUB Volts

!i**************ft*****«**********ft*******««*«***a«*«

! Abort: !

I CLEAR 7 OUTPUT Addr;"»"

OUTPUT 2;ClearS; PRINT BEEP 500, .4 PRINT "RUN ABORTED! WAIT !", TIMES ( TIMEDATE )&" "&DATES ( TIMEDATE

PRINT WAIT 3 PRINTER IS Printer

PRINT " RUN ABORTED! "; TIMES ( TIMEDATE )&" "&DATES ( TIMEDATE

PRINT PRINTER IS CRT PRINT CHRS(12) ! CLEAR SCREEN

GOTO Restart

!

} Abortl: !

ICLEAR 7 PRINT BEEP 500, .4 PRINT "RUN ABORTED! WAIT !", TIMES ( TIMEDATE )&" "&DATES ( TIMEDATE

PRINT WAIT 3 PRINTER IS 701 PRINT " RUN ABORTED! "; TIMES (TIMEDATE )&" "&DATES ( TIMEDATE

PRINT PRINTER IS CRT

GOTO Start

I l********************************************«*AA**i>«

! End: !

IOUTPUT 2;ClearS: BEEP 500, .4 OFF KEY

PRINT

C 10
3610

3620

3630

3640

3650

Appendix C - Software Listing for True-RMS Voltmeter (ME-5A5()/G)

PRINT "ALL AC VOLTAGE TESTS COMPLETED! WAIT. WAIT 5 LOAD "MENU" BEEP 500, .A END

C-11
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APPENDIX D

LIST OF SPECIAL PARTS

D - 1
List of special parts

4:1 Crest Factor Waveform Generator

A circuit designed at NBS which generates a waveform for the crest- factor

test with a fundamental of “ 31 kHz and significant harmonic components

limited to “ 1 MHz. The circuit is shown in fig. D-1, and the spectrum

generated is shown in fig. D-2. [Fabricated at NBS]

50-ohm "N" adapter

A modified set of commercial N-type male and female connectors attached

to the ends of a short tube containing a disk- type, 50 -ohm shunt

resistor. [Fabricated at NBS]

Cable with dual Banana plug

A special cable supplied by the manufacturer (Fluke) with output and

sensing leads for a voltage standard. [Manufactured by Fluke]

Relay control box

A metal enclosure containing a 9-volt battery and two double-pole,

double -throw momentary push-button switches intended to control the

operation of the Hewlett-Packard co-axial relay. The circuit is shown in

fig. D-3. [Fabricated at NBS]

Resistor Junction Box

An enclosure containing two 3-kilohm tin-oxide resistors in series. The

two ends of the resistor chain and the center tap are brought out to the

center pins of three female BNC-type connectors. [Fabricated at NBS]

Step-up (output) transformer

A commercial signal transformer designed for use with the high-frequency

amplifier to step up the output voltage. [ENI Model AM5-5B]

D - 2
Fig. D-1, Circuit Diagram of Crest Factor Test Signal Generator

0

-10 -H

-20

-30 -|

-40 4

-50

-oO 4:

-70 -

-80

-90

-lOO

frequency spectrum of 4, I CREST Factor waveform

M JjJ.

27/8/83

1 1 1 ^ 1 1 1 F 1.0 2.0 1.0 4.0 i.O frequency iMHi)

Fig. D-2, Frequency Spectrum of Crest Factor Test Signal

D - 3
MOMENTARY PUSHBUTTON SWITCH

Fig. D-3, Circuit Diagram of Relay Control Box

Fig. D-4, Resistor Junction Box, 3 kfl. Assembly Drawing

D - 4
APPENDIX E

EQUIPMENT LIST FOR RMS VOLTMETER TESTS

E - 1
EQUIPMENT LIST for RMS VOLTMETER TEST^

Function Generator Hewlett-Packard 3325A or equival

Wall Clock, commercial item

To describe the system discussed adequately, commercial equipment

and parts are identified by the manufacturer's name and model

number. In no case does such identification imply a recommendation

or endorsement by the National Bureau of Standards, nor does it

imply that the material or equipment identified is necessarily the

best available for the purpose.

E - 2
1. For an interesting discussion of analog meters, see Soisson, Harold E.

Electronic Measuring Systems, McGraw-Hill Book Company, Inc., New York,

1961, pp. 182-188.

2. B. Gilbert, "A precise four-quadrant multiplier with subnanosecond

response," IEEE J. Solid-State Circuits, Vol. SC-3, pp . 365-373,

December 1968.

3.

S. K. Ammann, Integrating Analog- to-Digital Converter, U. S. Patent

No. 3,316,547, April 25, 1967.

4.

R, C. Kime, Jr., The Charge -Balancing A-D Converter: An Alternative To

Dual-Slope Integration, Electronics, May 24, 1973.

5.

G. Grandbois, T. Pickerell, Quantized feedback takes its place in analog

to-digital conversion. Electronics, pp. 103-107, October 13, 1977.

6.

E. R. Hnatek, A User's Handbook of D/A and A/D Converters, John Wile &

Sons, New York, 1976.

7.

L. Mattera, Converter Stresses Stability, Electronics, p. 139-140,

February 19, 1976.

8.

L. T. Jones, J. J. Ressmeyer, C. A. Clark, Precision DVM Has Wide Dynamic

Range and High System Speed, Hewlett-Packard Journal, Vol. 32, No. 4,

pp. 23-31, April 1981.

9.

Requirements for Electrical Analog Indicating Instruments, ANSI C39.1-

1981; superceded by:

Direct Acting Indicating Analogue Electrical Measuring Instrximents and

their Accessories, lEC Publication 51 -1984

10.

F. L. Hermach, "AC -DC Comparators for Audio -Frequency Current and Voltage

Measurements of High Accuracy," IEEE Trans, on Instrum. & Meas .

Vol. IM-25, No. 4, pp. 489-494, December 1976.

E - 3
NBS-114A iREv. 2 -ec) U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO.

NBSIR 88-3736

2. Performing Organ. Report No. Ill

3. Publication Date MARCH 1988

4. TITLE AND SUBTITLE

Electrical Performance Tests for True-RMS Voltmeters

5. AUTHOR(S)

R.S. Turqel , O.B. Laug, T.E. Leedy

6. PERFORMING ORGANIZATION (If joint or other than N BS, see instructions)

NATIONAL BUREAU OF STANDARDS

U.S. DEPARTMENT OF COMMERCE

GAITHERSBURG, MD 20899

7. Contract/Grant No.

8. Type of Report & Period Covered

9.

SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State. ZIP)

U.S. Army Communications Electronics Command

Fort Monmouth, New Jersey 07703

10.

supplementary notes

I I Document describes a computer program; SF-185, FIPS Software Summary, is attached.

li. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here)

Electrical performance test procedures for a true rms voltmeter were developed by

the National Bureau of Standards for the U.S. Army Communications-Electronics

Command. The report provided detailed, step-by-step test procedures that are based on the specifications supplied by the Army for the purpose of evaluating

the bid samples of this type of instrument. Examples are provided of the data

sheets and tables for recording of interim data and the final results.

This report discusses the philosophy underlying each of the measurement procedures

from a point of view of the basic metrology required to perform the measurements.

In addition, the sources of measurement error are discussed.

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

Army specifications; rf voltmeter; test procedures; true rms voltmeter; voltmeter

13. availability

I^X] Unlimited

I 1 For Official Distribution. Do Not Release to NTIS

1 1 Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

20402.

[7^ Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

129

15. Price

$18.95

USCOMM-OC 9043-P80

‘'if' I'

*'

*»

. -i"

-

: 'A. #®ii

Sr-

' /iS
IR 88-3737

CANCELLED

UNAVAILABLE FOR BINDING