QuadTech 1657 RLC User Manual

1657 RLC Digibridge®

Instruction Manual

Foun 1657-0120-07/B1

®QuadTech, Inc., 1992

5 Clock Tower Place, 210 East

Maynard, Massachusetts, U.S.A. 01754

January, 1997

Tel. [phone]

800-253-1230 (Sales)
800-253-1230 (Service)

Fax. [phone]

The material in this manual is for informational purposes only and is subject to change, without notice.
QuadTech assumes no responsibility for any error or for consequential damages that may result from the
misinterpretation of any procedures in this publication.

Contents

Instruction Manual Changes

Specifications

Warranty

Introduction -Section 1

Installation -Section 2
Operation -Section 3
Theory -Section 4
Service and Maintenance -Section 5

~ Product will be marked with this symbol (ISO#3684) when it is necessary for the user to refer
to the instruction manual in order to prevent injury or equipment damage.

Parts Lists and Diagrams -Section 6

These two supplementary pages contain information of improvements or modifications not
documented in the current manual. All references to GenRad in the manual now apply to
QuadTech, Inc.

Page -Specifications (Power & Mechani cal)

Power should be 90 -250V AC, 50 -60 Hz. Voltage switching is automatic and no
longer selected by rear panel switch. 60 Watts maximum.

Weight should be 10 lbs. (4.5 kg) net, 15 lbs. (6.8 kg) shipping.
Environment reads, Altitude < 2000m, Installation Category 1, Pollution Degree 1

Page - Table of Contents (Parts List and Diagrams -Section 6)

Power supply board (1657-4720) layout and diagram (page 6-13) replaced by Power

supply assembly part number 700011 (no diagrams, repair by module exchange)

Page 1-4 -Figure 1-2, Rear Panel Controls and Connectors

Rear view should show new power supply assembly (PN 700011) without line-voltage

switch.

Page 1-4 -Table 1-2, Rear Panel Connectors and Controls

Ref No. 2R -& Fuse is 6/10A, 250V, 3AG Type, Slow Blow. Replace only with

the same type and rating. To replace, remove fuse drawer by pressing up on release tab.
Ref No. 3R -Line-voltage switch has been deleted, power input is from 90 -250V AC

Page 1-4 -Table 1-3, Accessories

A quantity of two spare fuses are supplied, 6/10A, 250V, 3AG Type, Slow Blow

(QuadTech part number 5330-1100)

Page 2-1 -Safety Inspection

Before operating the instrument inspect the power inlet module on the rear of the unit to

ensure that the properly rated fuse is in place, otherwise damage to unit is possible. Fuse is
6/l0A, 250V, 3AG Type, Slow Blow.

The 1657 is shipped with a standard U.S. power cord, QuadTech PN 4200-0300 (with Belden
SPH-386 socket or equivalent, and 3 wire plug confonning to IEC 320) or an approved
international cord set. Make sure the instrument is only used with these or other approved
international cord sets, which ensures the instrument is provided with connection to protective
earth ground.

In all installations the instrument should be positioned with consideration for ample air flow to the
side and rear panel ventilation holes. An open space around the instrument of at least 3 inches
(75mm) is recommend. The surrounding environment should be free from excessive dust to
prevent contatnination of electronic circuits.

Page 2-1 -Power-Line Connection

Power line switch for 115V or 230V operation has been removed, switching is
automatic for voltages between 90 -250V AC.

Page 2-2 -Figure 2-2

Figure 2-2 does not apply. Only certified line cords which comply with IEC 227 or
IEC 245 should be used.

Page 3-2 -Paragraph 3.1 Basic Procedure, step a

Power line switch for 115V or 230V operation has been removed, switching is

automatic.

Page 5-1 -Paragraph 5.2, Instrument Return

Contacts for QuadTech are: Sales 800-253-1230

Service 800-253-1230
Technical Assistance 978-461-2100

Page 5-2 & Page 5-3 -Caution Note

Power line switch for 115V or 230V operation has been removed, switching is
automatic.

Page 5-7 -& Paragraph 5.6.1 & Figure 5-3, Disassembly

Power Supply Assembly shown has been replaced by Power Supply Assembly PN

700011.

Page 5-10 -Instrument Cleaning Instructions

Monthly (more or less depending on usage) the built-in test fixture should be cleaned
with a soft brush and isopropyl alcohol. Avoid getting excess alcohol on instrument paint
surfaces, otherwise damage to the finish can result. For additional instrument cleaning
instructions refer to paragraph 5.7.1 (Care of the Test Fixture) and paragraph 5.7,2 (Care of the
Display Panel).
Power Supply Assembly shown in Figure 5-8 has been replaced by Power Supply

Assembly PN 700011.

Page 5-12 - Paragraph 5.8.2, Power Supply

Trouble Analysis procedure does not apply to new Power Supply Assembly P/N 700011.

Page 6-2 - Figure 6-2, Rear View

Rear view should show new power supply (PN 700011) without line-voltage switch

Page 6-3 - Mechanical Parts List, Rear

Items 1 - 4 (power connector, fuse extractor post, line voltage switch & cover) deleted on new assembly

Page 6-12 & Page 6-13 - Parts and Diagrams

Power Supply Board and Parts List shown, PN 1657-4720 has been replaced by
Power Supply Assembly, PN 700011. The 700011 Assembly must be repaired by module exchange.

Measurement Mode: Measures R series or parallel; L and Q series or parallel; C
and D series or parallel. All measurement modes are pushbutton selectable.

Displays: LED-type numerical display with automatically positioned decimal points
and illumination of units. For R LC, five digits (99999) and simultaneously for DQ,
four digits (9999).

Ranges: Pushbutton selection with automatic front-panel guidance. Three basic ranges
(best accuracy, see table) of 2 decades each, for each parameter. Automatic extensions
to min and max, as tabulated.

Measurement Speed: Greater than 3 measurements per second.

/

Test frequencies: Pushbutton selection between 2. Accuracy re panel
legends: +2%, -.01%. Actual frequencies: for 1657-9700, 1020.0 Hz +/- .01% (panel
legend "1 kHz") and 120.00 Hz +/- .01%;
for 1657.9800,1000.0 and 100.00 Hz +/- .01%.

Applied Voltage: 0.3 V rms maximum.

Accuracy: For R, L, and C: +/- 0.2% of reading in basic ranges, if quadrature
component is small (D < 0.1, Q > 10, etc). See table. D accuracy: +/- .001 in basic
ranges, for D < 0.1 (otherwise, see table). Q accuracy: +/-.01 in basic ranges, for Q < 1
(otherwise, see table).

Environment: TEMPERATURE: 0° to 50°C operating, -40° to +75°C
storage. HUMIDITY: 0 to 85% R.H., operating.

Supplied: Power cord, axial-lead adaptors, instruction manual.

Power: 90 to 125 or 180 to 250 V, 50 to 60 Hz. Voltage selected
by rear-panel switch. 25 W maximum.
Mechanical: Bench mounting. DIMENSIONS: (wxhxd): 375x112x343 mm
(14.8x4.4x13.5 in.). WEIGHT: 5.6 kg (12.3 lb) net,l0 kg (22 lb) shipping.

Patent applied for.

SERVICE POLICY

QuadTech policy is to maintain product repair capability for a period of five (5) years after original
shipment and to make this capability available at the then prevailing schedule of charges.

Table of Contents

1.1 PURPOSE 1-1

.

d

ifi

1.2 GENERAL DESCRIPTION 1-1

1.3 CONTROLS, INDICATORS, AND CONNECTORS 1-1

1.4 ACCESSORIES 1-1

1.1 PURPOSE. in keeping with the long-life circuitry inside. Glass-epoxy
The 1657 Digibridge digital impedance meter embodies circuit boards interconnect and support high-quality com

use of a microprocessor and other LSI circuitry to ponents to assure years of dependability.
provide excellent performance at low cost. Adaptability to any common ac power line is assured by

A few clearly labeled pushbuttons and the versatile the removable power cord and the convenient line-voltage
built-in test fixture make this instrument a model for con- switch. Safety is enhanced by the fused, isolating power
venience. Measurement results are clearly shown with dec- transformer and the 3-wire power connection. A compre
imal points and units, which are automatically presented to hensive functional description is given in Theory, Section 4
assure correctness. Display resolution is 5 digits for R, C, Electrical and physical characteristics are listed in Specifi
and L (4 for D or Q) and the basic accuracy is 0.2%. cations at the front of this manual, dimensions in Installa

Long-term accuracy and reliability are assured by the tion, Section 2. Controls are described below, and their use
measurement system. It makes these accurate analog in Operation, Section 3.
measurements over many decades of impedance without a
single calibration or "trimming" adjustment (not even in 1.3 CONTROLS, INDICATORS, AND CONNECTORS.
original manufacture). .

The built-in test fixture, with a pair of plug-in adaptors, Figure :-1 shows the front panel conrols and indicators.
receives any common component part (axial-lead or radial- Table 1-1 identifies them with descriptions and functions.
lead) so easily that insertion of the DUT is a one-hand Similarily, Figure 1-2 shows the rear panel and Table 1-2 identifies

operation. True 4-terminal connections are made automat

t

.

ically. Extender cables and other accessories are available

.

I

.

ent

es and describes the rear panel controls and connec

I

and describes the rear panel controls and connectors.

for measurements at a distance from the Digibridge.

1.4 ACCESSORIES.
Gen Rad makes several accessories that enhance the use

1.2 GENERAL DESCRIPTION. fulness of this instrument. Two extender cables facilitate
Convenience is enhanced by the arrangement of test making connections to those devices and impedance stan

fixture on the front ledge, with push buttons farther for- dards that do not readily fit the built-in test fixture. A
ward and display behind. The display panel is inclined and remote test fixture (used with BNC adaptor and cable
recessed to enhance visbility of digital readouts and mode assembly) provides convenience and relatively easy main
indicators. These indicators serve to inform and guide the tenance, and saves wear on the built-in test fixture. All of
operator as he operates the simple controls. these test-fixture accessories provide for true 4-terminal

The instrument stands on a table or bench top. The connections (and guard) to the device being measured,

sturdy metal cabinet is attractively and durably finished, without appreciable reduction in measurement accuracy.

Other useful accessories are offered, such as standards for
checking the performance of the Digibridge. Refer to
Table 1 -3 and Section 5.

INTRODUCTION 1-1

1-2 INTRODUCTION

INTRODUCTION 1-3

1-4 INTRODUCTION

2.1 UNPACKING AND INSPECTION.

If the shipping car ton is damaged, ask that the carrier's
agent be present when the in stru ment is unp ack ed. Insp ect the in str ument
for damage (scratches, dents, broken parts, etc.). If the instrument is
damaged or fails to m eet sp ecific ations, notify th e carr ier and th e neares t
GenRad field
office. (See list at back of this manual). Retain the shipping carton and the
padding material for the carr ier's inspect ion.

2.2 DIMENSIONS Figure 2-1.

The instrument is supplied in the bench configuration,
i.e., in a cabinet with resilient feet for placement on a table. The overall
dimensions are given in the figure.

2.3 POWER-liNE CONNECTION.

The power transformer primary windings can be switched, by means of
the line voltage switch on the rea r p anel, to ac. commodate ac line voltages
in either of 2 ranges, as labeled, at a frequency of 50 or 60 Hz, nominal.
Using a small screwdriver, set this switch to match the measured voltage of
your power line.

I f your I ine voltage is in the lower r ange, connect the 3-wire power

cable (P/N 4200-9625) to the power connector on the rear panel (Figure 1-2)
and then to the power line.

The instrument is fitted with a power connector that is in conformance
with the Intern ational Electrot echnical Commis sion publication 320. The 3
flat contacts are surrounded by a cylindrical plastic shroud that reduces the
possibility of electrical shock whenever the power cord is being unplugged
from the instrum ent. In addition, the center ground pin is longer, which
means that it mates first and disconnects last, for user protection. This panel
connector is a standard 3-pin grounding-type receptacle, the design of which
has been accepted world wide for electronic instru. mentation. The connector
is rated for 250 V at 6 A. The receptacle accepts power cords fitted with the
Belden type SPH- 386 connector.

The associ ated power cord f o r use with tha t receptacle, fo r line voltages

up to 125 V, is Gen Rad part no. 4200-9625.
It is a 210-cm (7 ft), 3-wire, 18-gage cable with connector bodies molded
integrally with the jacket. The connector at the power-line end is a stackable
hammerhead design that conforms to the "Standard for Grounding Type
Attachment Plug Caps and Receptacles ," ANSI C73. 11-1966, which
specifies limits of 125 V and 15 A. This power cord is
listed by Underwriters Laboratories, Inc., for 125 V, 10 A.

If the fuse must be replaced, be sure to use a "slow blow" fuse of the
current and volta ge ratings shown on the rear panel, regard less of the line
voltage.

INSTAllATION 2-1

If your line voltage is in the higher ra nge selectable b y the line voltage
switch, use a power cord of the proper rating (250 V, 15 A) that mates
with both instrument and
your receptacle. It is possible to replace the "hammerhead" connector on the
power cord that is supplied with a suitable connector. Be sure to use one
that is approved for 250 V, 15 A. A typical configuration is shown in Figure
2-2.

2.4 LINE-VOLTAGE REGUlATION

The accura cy of measurements accomplished with precision electronic
test equipment operated f r om ac line
sources can often be seriously degraded by fluctuations in primary input
power. line-voltage variations of +/-15% are commonly encountered, even
in laboratory environments.
Although most modern elect ron i c inst rumen ts in corp orat e some d egree of
regulation, possible power.source problems should be considered for
every instr umentation setup. Th e use of line-volta ge regulators b etween
power lines and the
test equipment is recommended as the only sure way to rule out the effects
on measuremen t data of variations in line voltage.

2.5 TEST-FIXTURE CONNECTIONS.

2.5.1 Test Fixture on the Digibridge.

Because an unusually versatile test fixture is provided on the front shelf
of the instrument, no test-fixture connection is generally required. Simply
plug the device to be measured (DUT) into the test fixture, with or without
its adaptors. For details, refer to paragraph s 3.1, 3. 2. Accessories can be
attached to exte nd and adapt the test fixt ur e, as described bel ow.

2.5.2 Remote Test Fixture.

Connection of the DUT at a remot e test fixture requires proper adaptors
and cable connections from the Digibridge. Obtain the following
accessories. (See Table 1-3.)

BNC Adaptor 1689-9601
BNC Cable Assembly 1689-9602, or equivalent
Remote Test Fixture 1689-9600, or equivalent

handler or special fixture.

This remote test fixture functions like the one supplied on the
Digibridge. True "Kel vin" conn ections are m ade at the point s of contact
with the DUT leads. Install as
follows:

a. Remove any adaptors, if present, from the test

fixture.

b. Plug the BNC adaptor into the basic test fixture with th e BNC
connectors facing forward. lock the connection with the 2 captive thumb
screws. (The screws must be

seated to complete the ground connection.)

c. Connect the cable assembly to the adaptor on the Digibridge and to
the remote test fixture as indicated in Table 2-1.

NOTE

User provided cables and/or remote test
fixtures can be us e d, particularly if the
DUT is to be handled automatically.
See paragraph 3.7 for comments on cable
and fixture capacitance.

2.5.3 The 1657-9600 Extender Cable (Banana Plugs).

The accessory extender cable 1657-9600 is available to connect to
DUTs that are multiterminal, physically large, or otherwise unsuited for
the built-in test fixture. This cable is particularly convenient for connecting
multiterminal components with binding posts that accommodate banana
plugs. Use the following procedure to install the extender cable on the
instrument.

a. Remove the ad aptors, if pr esent, from the t est

fix tu re.

b. Plug the single-connector end of the extender cable into the
Digibridge test fixture so that its blades enter both slots and the cable lies
away from the di splay panel. lock the connector with the two captive
thumb screws.

c. Note the color coding of the five banana plugs. Be sure that the
"low" terminals (both potential and current) connect to one end of the
DUT and the "high" terminals to the other end. Connect guard to a shield if
any, but not to either end of the DUT.

2-2 INSTAllATION

P-(potential, low) = Black/white
I-(current, low) = Black
P+(potential, high) = Red/white

I+(current, high) = Red
Guard = Black/green

2.5.4 The 1688-9600 Extender Cable
("Type 874" Connectors).

The accessory extender cable 1688-9600 can be used to connect a
DUT that is multiterminai, physically large, or otherwise unsuited for the
built-in test fixture. This
low-capacitance cable is used, for example, to connect type-874
connected impedance sta n dards or a special
test fixture. Make connections as follows:

a. Remove the ad aptors, if pr esent, from the t est fixture.

b. Plug the single-connector end of the extender cable into the
Digibridge test fixture s o that its blades enter both slots and the cable lies
away from the display panel. Lock the connector with the two captive
thumb screws.

c. Using the branched end of the cable, connect to the DUT with
careful attention to the following color code.

The cable tips are type 874 coaxial connectors, which
mate with a broad line of components and adaptors.

Notice that the 2 wires with red must connect to the same end of the
DUT, through a coaxial tee if the DUT is a 2-terminal device; the 2
wires labeled with black, connect to the other end, similarly. Connect
the outer (shield) contacts to the shield or case of the D U T only if it
is isolated fr om both ends of th e D U T.

EXTENDER CABLE COLOR CODE

RED AND RED: 1+, current driv e to

"high" end of DUT.

RED AND WHITE: P+, potential connection

to same.

BLACK AND BLACK' I-, cur rent return at

DUT "low".

BLACK AN D WHITE: P- , p o t ential

connection to same.

OUTER CONTACTS: G, guard connection

to shield or case.

2.6 EXTERNAL BIAS. Figure 2-3.

WARNING

To minimize electrical shock hazard, limit

bias to 30V.

Bias voltage is present at connectors, test

fixtures and on capacitors under test.

Capacitors remain charged after measurement.
Do NOT leave instrument unattended with bias

applied.

Full bias voltage appears on test lea ds, bias-voltagesource terminals,
and on the leads of the component being measured. Capacitors that have
been charged are dangerous until properly discharged; the user must fo llow
safe procedures to assure discharge. For safety, all personnel operating the
instrument with bias must be aware of the hazards, follow safe procedures,
and never leave the equipment una ttended with bias voltage applied.

2.6.1 Basic Bias Connections.

In order to measure a capacitor with dc bias voltage

applied, connect an external voltage source, as follows:

a. Attach the rem o te test fixtur e or an extender cable as described in

paragraph 2.5. Observe the color coding explained there.

INSTALLATION 2-3

b. Connect a suitable bias voltage source (see below)
in series with the 1+ connection, basically as shown in
the diagram, with the following details.

With the Remote Test Fixture. Disconnect the red coded BNC cable end
from the remote test fixture and connect one end of plain BNC cable there
instead.
Connect the red coded BNC cable end to the negative terminal of the bias
voltage source. Connect the remaining free end of the plain BNC cable to
the positive t erm inal of the bias voltage source. C onnect the DUT to
the test fixture in the usual way.

With 1657-9600 Ex tender Cable (Banana Plugs). Connect the red
banana plug to the negative terminal
of the bias voltage source. Connect a suitable banana
plug patch cord to the positive terminal. We designate
the free end of this patch cord as I++, as shown in the

diagram.

With 1688-9600 Ex tender Cable

("Type 874 Connectors").
Connect the "red and red" cable to t he negative termin al of the bias volta ge
source. Connect a suitable type-874 patch cable to the positive terminal.
We designate the
free end of this patch cable as I++, as shown in the diagram.

c. If either of the extender cables (not the rem ote test fixtu re) is used,
connect the DUT as follows. If capacitance is large (r ange 1), make 2
connections to each capacitor terminal (Kelvin connections). That is, I- and
P- to capacitor negative terminal; P+ and I++ to capacitor positive
terminal.

If the capacitance is smaller (range 2 or 3) the banana plugs can be

stacked or a tee used with type-874 connectors

and a single connection made to each capacitor terminal: I- /P- to the

negative terminal, P+/I++ to the positive.

To make 3-terminal (or 5-termina l) measu remen ts, also connect guard
(see paragraph 2.5) to the guard terminal, shield, case, or groun d of the
capacitor, provided that this is insulated from the 2 main terminals of the
capacitor. Do not connect guard to the case of a capacitor if the case is one
of its 2 main terminals.

2.6.2 Bias Voltage Source Description

The bias voltage source must satisfy several criteria:

1. Supply the desired terminal voltage (dc)

2. Serve as source for charging current.

3. Serve as source and sink for the measuring currents
(ac), which are 45, 0.45, and .0045 mA, peak, for measurements on ranges
1, 2, and 3, resp ectively.

4. Present a low, linear terminal impedance (< < 10 ohms)

at measuring frequency.

If the bias volta ge source is a regulated power supply
with the usual characteristic that it functions properly only as a source, not
a sink, then the following test setup is

recommended. Connect across the power supply a bleeder resistor that
draws dc current at least as great as the peak measuring current (item 3
above). In parallel with the bleeder, connect a 100-pF capacitor. (If the
power supply has exceptiona lly good transi ent response, the capacitor i s
not necessary.)

No single bleeder resistor will suffice for all bias conditions, so it may
be necessary to switch among several. Each resistance must be small
enough to keep the power supply regulator current unid irectional (as
mentioned above) for the smallest bias voltage in its range of usefulness.
Also the resistance and dissipation capacity must be large enough so that
neither the power supply is overloaded nor the resistor itself damaged for
the highest bias voltage in its range of applicat ion.

NOTE

For convenience, a suitable active current sink
can be used in lieu of bleeder resistors.

A discharge circuit is also required. (Do not depend on the above­mentioned bleeder resistor.) A dual discharge circuit is recommended.
Connect a clip lead with a 10-Q resistor in series and another plain clip lead
to the I-/Pjunction. Provide the loos e ends of these with insulated alligator
clips for us e when completing the discha r g e path across th e D U T. For a
recommended procedure, refer to para 3.6.

I f the measurement program warrants the exp ense of a test fixture for
biased-capacitor measurements, its functi on should be equivalent to that of
the circuit described above. It should be equipped with convenient
switching to remove the bias source, discharge through 10 Q, and finally to
short out the capacitor after measurement. For automated test setups, it is
also feasible to precharge the capacit o rs before they are attached t o the test
fixture and to discharge them after they h ave been removed.

CAUTION

To avoid damage t o the instrument, limit the bias voltage t o 30 V,
maximum, in any precharging
bias supply, used as mentioned above.

2.7 ENVIRONMENT.

The Digibridge can be operated in nearly any en vironment that is
comfortable f o r the operator. Keep the instrument and all connections to
the parts under test away from
electromagnetic fields that may interfere with measurements.

Refer to the Specifications at the front of this manual for temperature
and humidity tolerances. To safeguard the instrument during storage or
shipment, use protective packaging. Refer to S ection 5.

2-4 INSTAllATION

OPERATION 3-1

3.1 BASIC PROCEDURE. Figure 3-1.

For initial familiarization, follow this procedure care

fully. For details, refer to later paragraphs in Operation.

a. Before connecting the power cord, slide the linevoltage switch (rear
panel) to the position that corresponds to your power-line voltage. Power must
be nominally either 50 or 60 Hz ac, either 120 or 220 V. (Refer to
specifications at front of this manual.) The 1657-9700 can be run on 50 Hz but
with some loss of accuracy for 120-Hz measurements in high range
extensions. Similarly, the 1657-9800, if run

on 60-Hz power, experiences some extraneous noise in 100Hz

measurements in high range ext ensions.

If the fuse must be replaced, be sure to use a "slow

blow" fuse of the rating shown on the rear pan el.

b. Connect a typical device, whose impedance is to be

measured, as follows. (This device under test is denoted DUT.)

NOTE

Clean the leads of the DUT if th ey are notice
ably dirty, even though the tes t-fixture cont acts
will usually bite through a film of wax to pro
vide adequate connections.

Radial-lead DUT: I nsert the leads into the test.fixture
slots as shown in the photograph, Figure 1-1. For details of wire size a nd
spacing limits, refer to para 3.2.

Axial-lead DUT: Install the test-fixture adaptors, supplied, one in
each slot of th e test f ixtu re, a s shown in th e acc ompan ying figu re. Slid e
the adaptors together or apar t
so the body of the DUT will fit easily between them. Press the DUT down
so that the leads enter the sl ots in the adaptors as far as they g o easily. For
details of wire size and DUT size limits, refer to para 3.2.

NOTE

To remove each adaptor, lift with a gentle tilt
left or right. For a DUT with very short leads
it is important to orient each adaptor so its internal contacts
(which are off center) are close

to the DUT.

Other DUTs, Remote Connections, and Bias.

For connections via extender cables and remote
test fixtures, refer to the installa tion instructions of paragraph 2.5. For
connection of bias voltage and opera ting procedures wit h bias, refer to
paragraphs 2.6 and 3.6. For convenience, the typical color coding used in
extender ca bles is repeat ed below.

Red: I+, current connection to "high" end of DUT. ,

Red & white: P+potential connection to same.
Black: I-, current connection to low endof DUT. .

Black & white: P-, potential connection to same

Black & Green: G, guard connection to shield or case (if isolated
from the preceding terminals). Do not-connect G to the case of a capacitor
if the case serves as (or is connected to) one of its 2 main terminals.

Notice that the 2 red tips must connect to the same end of the DUT. The
terminals with white bands are potential connections; with no bands, current
terminals.

c. Set.the pushbu ttons according to the de sir e d me asur e

ment, as follows:

Power. Depress the POWER button so that it stays in the depressed
position. (To t urn the instrument off, push and release this button so that it
remains in the released position.)

Function. For resistance, depress R. For inductance, depress L/Q. For
capacitance, depress C/D. Be sure that one of these buttons is in the
depressed position.

Frequency. For measurement at 1 kHz, push and release the
FREQUENCY button until the 1-kHz light c omes on. For 120 (100) Hz, pus h
the same button s o that the 120-Hz (100.Hz) light comes on.

Parallel or Series. For series equivalent circuit, push and release the
PARALLEL/SERIES button until the SERIES light comes on. For parallel
equivalent circuit, push thi s button so that the PARALLEL light comes on.
(The choice is significant for lossy capacitors or inductors, not for lowloss
reactive components or non-reactive resistors.) For further explanation, refer
to para 3.5.

Range. Depress the middle (RANGE-2) button first and wat ch the
ADJUST RANGE lights. If the right-pointing arrow is lighted, depress
RANGE button at th e right. If the left-poi nting arrow is light ed, depress
RANGE button at the left. When neither arrow is lighted, the range you have
selected is correct. (Be surc that one of the RANGE buttons is in the
depressed position.) Additional comments on range choices are below.

d. Read the measurement on the main disp lays. The
R LC display is the principa l measurement, complete with decimal point and
units, which are indicated by the light spot behind MΩ, kΩ, Ω, H, mH, nF,
or uF.* The DQ display is D if the C/D FUNCTION button is in, Q if the
L/Q button is in.

e. After any change in DUT or measurement conditions, before looking

at the displays, notice the , ADJUS T RANGE

lights. Interpret them as follows:

Neither light. Correct range. (There are minor exceptions.)

Left Light. Wrong range; try next RANGE button to left.

Right Light. Wrong range; try next RANGE button to

right.

Both Lights. Overrange or invalid display. If FUNCTION is correc t
and RANGE is highest, the measurement is valid bu t because of an
overrange condition, the basic 0.2% accuracy cannot be guaranteed. (If you
switch to RANGE 2, one
of the lights will go out.) If bot h lights are lit on RANGE 2, either the
FUNCTION is inappropriate for the DUT or it is not properly connected.
For more details, refer to para 3.3.

*If the extender cable is used. it may be necessary to correct for its
capacitance.

3-2 OPERATION

3.2 CONNECTION OF THE DUT.

3.2.1 The Integral Test Fixture.

The test fixture provided on the front ledge of the Digi

bridge provides convenient, reliable, guarded 4-terminal connection to

any common radial-lead or axial-lead component.

If the slots of your test fixture have rounded ends, the

slots accommodate wires of any diameter from 0.25 mm (.01 in., AWG

30) to 1 mm (.04 in., AWG 18), spaced from 6 to 98 mm apart (0.23 to 3.9
in.) or equivalent strip conductors. Each "radial" wire must be at least 1 cm
long
(0.4 in.). However, if the slots of your test fixture have square ends, they
will accommodate wires spaced as close as 4 mm (0.16 in.) and each
"radial" wire must be at least
4 mm (0.16 in.) long. The divider between the test slots contains a shield, at
guard potent ial, with its edges exposed. Th e adaptors accomm odate wi res
of any diameter up to 1.5 mm (.06 in., AWG 15). The body of the DUT that
will fit between these adaptors can be 80 mm long and 44 mm diamet er
(3.1x1.7 in.) maximum. Each "axial" wire must be at least 3 mm long (0.12
in.).

For radial-lead parts, remove each adapt or from the test fixture by a
gentle pull upward, made easier by bending the adaptor left or right (never
forward or back). For axial-lead parts, insert the adaptors, one in the left
slot and the oth er
in the right slot of the test fixture, by pushing vertically downward. They
can be slid left and right to match the length of DUT to be measured. Notice
that the contacts inside the adaptor are off center; be sure to orient the
adaptors so the contacts are c lose to the body of the DUT, especially if it
has short or fragile leads.

Insert the DUT so one lead makes connection on the
left side of the test fixture, the other lead on the right side. Insertion and
removal are smooth, easy operations and connections are reliable if leads
are clean and straight.

Be sure to remove any obvious dirt from lead s b efore inserting them.
Be sure the contact pair inside each half of the test fixtu re is held open by a
single item ONLY, whether that is one lea d of an axial-lead DUT or one
adaptor, to obtain true "Kelvin" connections.

3.2.2 Test Fixture Accessories.

An accessory extender cable or adaptor, cable, and remote test fixture,
as described in Table 1-3, is needed
to connect any DUT that is multit erminal, physic ally

large, or otherwise unsuited for the built-in test fixture.
A cable is needed, for example, to connect impedance standards, a
remote test fixture, capacitors to be measured with bias, etc. For

connection to the instrument, refer to paragraph 2.5. For

measurements with bias,
refer to paragraphs 2.6 and 3.6. The color code for the branched end
of each cable is given in paragraph 3.1. To correct for cable
capacitance, refer to paragraph 3.7.

3.3 FUNCTION AND RANGE SELECTIONS.

3.3.1 Function Pushbuttons.

The selection of the principal parameter to be measured is almost self­explanatory. Depress the appropriate FU NCTION button: R, L/Q or C/D to
measure resistance, inductance, or capacitance. The instrument will tolerate,
to some degree, a poor choice of function, but accuracy is thereby reduced.
The readout will i n dicate a completely wrong choic e of function, as
explained below. Notice that the appearance of a device can be misleading.
(For example, a faulty induc tor can be essentially capacit ive or resistiv e;
a component part can be mislab eled or unlabeled.)

If both ADJUST RAN GE lights are on, the RANGE 2 button is in, the
RLC display is blank, and the DUT is properly connected, then the choice
of function is probably wrong. Most likely, if the L/Q button is in, the DUT
is capacitive; or if the C/D button is in, the DUT is inductive.

Observe the DQ display for an indication of poor choice of function
(though tolerable). Large D or small 0 may indicate that the "reactor" being
measured is practically a
resistor at the measuring frequency. If the C/D button is in and the D
reading is between 1 and 10 (or blank, as it will be for D> 10) it is
possible that the DUT is eno,ugh like a resistor to be measured best
with the R button in. Similarly, if the L/Q button is in and the Q reading
is
between zero and 1, it is possible that the DUT is enough like a resistor to
be measured best with the R button in. Notice that when the R button is in,
the DO display is always blank. On the other hand, any D or Q display is
valid, even if the "wrong" function has been selected. (The C or L display
can be blank.)

If the R button is in (a resistor is being m easured) the eas y way to
determine whether the DUT is reactive is to try making C/D and L/Q
measurements. If you obtain a valid C measurement with D < 1, the DUT is
capacitiv e. The smaller this D value, the less accurate the R measurement.
Similarly, if you obtain a valid L measurement with Q > 1, the DUT is
inductive. The larger this Q value the less accurate the R measurement. (See
para 3.4.)

3.3.2 Range Pushbuttons.

Range selecti o n is also nearly self-explanatory. Follow the ADJUST
RANGE lights. The left light means: "Push the next range button to the
left." The right-hand light
means: "Push the next range butt on to the right ." Continue unti l both light s
go out. The instrument will usually display a measurement (at reduced
accuracy) even though the range is not optimum. The following details
about range are best
understood with reference to para 3.4 (particu1arly the RLC basic accuracy
graph).

The RANGE buttons are placed in order of decreasing impedance, 3-2-

1. The "highest" range is therefore Range 1
for C/D; but it is Range 3 for Rand L/Q.

OPERATION 3-3

Each basic range is slightly more than 2 decades wide, from an R LC
display of 01900, with an automatic decimal
point change between the decades, to 19999. (The symbol 0 represents

a blanked zero. Initial zeroes to left of the decimal point are always blanked
out of the RLC display.) Each of the 3 ranges goes beyond its basic range,
with both upper and lower range extensions (shown by lighter lines in the
RLC basic accuracy graph). Several of these extensions are s eldom used
because they overlap "basic" portions of other ranges and because the
operator is alerted to this fact by an ADJUST RANGE light.

Each range in cludes 2 or 3 subranges, distinguished by th e automatic
decimal-point shift. The operator does NOT control them. Subranges are
detailed in Table 3-1. Notice, for example, if you select RANGE 1, C/D, 1
kHz, then there are 2 subranges: 19uF and 999uF. If a series of measure­ments is made with C increasing slowly above 19uF, the automatic
subrange ch ange takes place at 21. But with C decreasing , the change takes
place at 20. This hysteresi s eliminates a possible ca use of flickeri ng of the
display.

The "low" extension of each range goes from 01900 down to 00000,
without any change in decim al point, but wit h r educed accuracy. The
number of digits in this display is always adequate for the specified
accuracy. An y measurement in the low extensio n of either Ran g e 2 or the
highest range causes the appropriate ADJUST RANGE arrow to be lighted.
But there is no such light in the low extension of the lowest range ( because
there is no lower range to select).

the high extension of the highest range, both ADJUST RANGE arrows are
lighted (to indicate a useful "overrange" condition) .

The high extension of the top range for Rand C only, at 120 Hz (100
Hz) only, is a factor of 50, going from 19999, with an automatic d ecimal­point change, up to 99999, and finally to blank, with redu ced accuracy.
(Both ADJUST RANGE arrows are lighted as described above.)

A special case warrants explanation. (This is a minor exception to the

basic procedure of para 3.1.) It is possible

for both ADJUST RANGE lights to be out and yet the RANGE and

FUNCTION buttons to be incorrectly set.

This condition result's from either faulty connection to the DUT or a

numerically small negative Lor C measurement. Sometimes a loose or dirty

connection to the DUT causes

an erratic RLC display. A small negative L or C (wrong function
selected) causes a zero display. In either case, check connections at the test
fixture and try all 3 FUNCTIONS to see which is appropriate, R, L/Q, or
C/D.

The "high" extension of each range is a factor of 5 (with 2 exceptions),
going from 19999 up t o 99999, and finally to blank, without any change in
decimal point, but with reduced accuracy. Any measurement in the high
extension of either the lowest range or Range 2 causes the appropriate
ADJUST RANGE arrow to be lighted. However in

3-4 OPERATION

3.4 ACCURACY.

3.4.1 Graphs. Figures 3-2, 3-3, and 3.4

The following accuracy graphs supplement the statement of accuracy in

the speci fications, at the front of this manual.

Figure 3.2 shows that the R LC basic accuracy of 0.2% is realized over
6 decades of impedance if the correct range
is selected (as indicated by the ADJUST RANG E lights being out).

The reduction of accuracy is shown for all of the "low" and "high" range
extensions. This basic RLC accuracy is valid only for "pure" R. L, or C.
For the effect