Tektronix P6021 Service manual

Instruction Manual

P6021
60 MHz Current Probe

070-0947-06

Warning

The servicing instructions are for use by qualified
personnel only. To avoid personal injury, do not
perform any servicing unless you are qualified to
do so. Refer to all safety summaries prior to
performing service.

www.tektronix.com

Copyright © Tektronix, Inc. All rights reserved.

Tektronix products are covered by U.S. and foreign patents, issued and pending. Information in this publication supercedes
that in all previously published material. Specifications and price change privileges reserved.

Tektronix, Inc., P.O. Box 500, Beaverton, OR 97077

TEKTRONIX and TEK are registered tradem arks of Tektronix, Inc.

POSIDRIV is a registered trademark of the Philips Screw Co.

WARRANTY

Tektronix warrants that the products that it m anufactures and sells will be free from defects in materials and
workmanship for a period of one (1) year from the date of purchase from an authorized Tektronix distributor. If
any such product proves defective during this warranty period, Tektronix, at its option, either will repair the
defective product without charge for parts and labor, or will provide a replacement in exchange for the defective
product. Batteries are excluded from this warranty.

In order to obtain service under this warranty, Customer must notify Tektronix of the defect before the expiration
of the warranty period and make suitable arrangements for the performance of service. Customer shall be
responsible for packaging and shipping the defective product to the service center designated by Tektronix,
shipping charges prepaid, and with a copy of customer proof of purchase. Tektronix shall pay for the return of the
product to Customer if the shipment is to a location within the country in which the Tektronix service center is
located. Customer shall be responsible for paying all shipping charges, duties, taxes, and any other charges for
products returned to any other locations.

This warranty shall not apply to any defect, failure or damage caused by improper use or improper or inadequate
maintenance and care. Tektronix shall not be obligated to furnish service under this warranty a) to repair damage
resulting from attempts by personnel other than Tektronix representatives to install, repair or service the product;
b) to repair damage resulting from improper use or connection to incompatible equipment; c) to repair any
damage or malfunction caused by the use of non-Tektronix supplies; or d) to service a product that has been
modified or integrated with other products when the effect of such modi fication or i ntegration increases the time
or difficulty of servicing the product.

THIS W ARRANTY IS GIVEN BY TEKTRONIX WITH RESPECT TO THE LISTED PRODUCTS IN
LIEU OF ANY OTHER W ARRANTIES, EXPRESS OR IMPLIED. TEKTRONIX AND ITS VENDORS
DISCLAIM ANY IMPLIED W ARRANTIES OF MERCHANTABILITY OR FITNESS FOR A
PAR TICULAR PURPOSE. TEKTRONIX’ RESPONSIBILITY TO REPAIR OR REPLACE DEFECTIVE
PRODUCTS IS THE SOLE AND EXCLUSIVE REMEDY PROVIDED TO THE CUSTOMER FOR
BREACH OF THIS WARRANTY. TEKTRONIX AND ITS VENDORS WILL NOT BE LIABLE FOR ANY
INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES IRRESPECTIVE OF
WHETHER TEKTRONIX OR THE VENDOR HAS ADVANCE NOTICE OF THE POSSIBILITY OF
SUCH DAMAGES.

Table of Contents

General Safety Summary iii...................................

Service Safety Summary v....................................

Contacting Tektronix vi.............................................

Operator Information 1......................................

Description 1.....................................................

Installation 1.....................................................

Operating Considerations 4..........................................

Service Information 7........................................

Warranted Characteristics 7..........................................

Typical Characteristics 9............................................

Circuit Description 12...............................................

Probe Performance 13...............................................

Performance Verification 15..........................................

P6021 Test Record 20...............................................

Adjustment Procedure 21............................................

Maintenance 24....................................................

Replaceable Electrical Parts 29.................................

Parts Ordering Information 29.........................................

Using the Replaceable Electrical Parts List 29............................

Replaceable Mechanical Parts 35...............................

Parts Ordering Information 35.........................................

Using the Replaceable Mechanical Parts List 35..........................

Index 41....................................................

P6021 Instruction Manual

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Table of Contents

List of Figures

Figure 1: The P6021 Probe and termination 2....................

Figure 2: Insertion Impedance of the P6021 5....................

Figure 3: Probe and termination input current vs.

frequency derating 8.....................................

Figure 4: Typical P6021 phase response 11.......................

Figure 5: Midband accuracy test setup 15........................

Figure 6: High frequency bandwidth test setup 18.................

Figure 7: Connecting the probe to the calibration fixture 22.........

Figure 8: Location of probe adjustments 23......................

Figure 9: Location of termination adjustments 23.................

Figure 10: Disassembling the probe 25...........................

Figure 11: P6021 probe component location 33....................

Figure 12: P6021 termination component location 33...............

Figure 13: P6021 exploded view 39..............................

List of Tables

T able 1: Warranted electrical characteristics 7...................

T able 2: Warranted environmental characteristics 7..............

Table 3: Maximum ratings 8..................................

Table 4: Certifications and compliances 9.......................

T able 5: Electrical characteristics 9............................

T able 6: Mechanical characteristics 10..........................

Table 7: Equipment list 14....................................

Table 8: Low frequency bandwidth measurements 17..............

Table 9: High frequency bandwidth measurements 19.............

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P6021 Instruction Manual

General Safety Summary

Review the following safety precautions to avoid injury and prevent damage to
this product or any products connected to it. To avoid potential hazards, use this
product only as specified.

Only qualified personnel should perform service procedures.

ToAvoidFireor

Personal Injury

Connect and Disconnect Properly. Do not connect or disconnect probes or test
leads while they are connected to a voltage source.

Observe All Terminal Ratings. To avoid fire or shock hazard, observe all ratings
and markings on the product. Consult the product manual for further ratings
information before making connections to the product.

Connect the ground lead of the probe to earth ground only.

Do not apply a potential to any terminal, including the common terminal, that
exceeds the maximum rating of that terminal.

Do Not Operate Without Covers. Do not operate this product with covers or panels
removed.

Avoid Exposed Circuitry. Do not touch exposed connections and components
when power is present.

Do Not Operate With Suspected Failures. If you suspect there is damage to this
product, have it inspected by qualified service personnel.

Do Not Operate in Wet/Damp Conditions.

Do Not Operate in an Explosive Atmosphere.

Keep Product Surfaces Clean and Dry.

P6021 Instruction Manual

iii

General Safety Summary

Symbols and Terms

Terms in this Manual. These terms may appear in this manual:

WARNING. Warning statements identify conditions or practices that could result
in injury or loss of life.

CAUTION. Caution statements identify conditions or practices that could result in
damage to this product or other property.

Terms on the Product. These terms may appear on the product:

DANGER indicates an injury hazard immediately accessible as you read the
marking.

WARNING indicates an injury hazard not immediately accessible as you read the
marking.

CAUTION indicates a hazard to property including the product.

Symbols on the Product. The following symbols may appear on the product:

CAUTION

Refer to Manual

Double

Insulated

Protective Ground

(Earth) Terminal

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P6021 Instruction Manual

Service Safety Summary

Only qualified personnel should perform service procedures. Read this Service
Safety Summary and the General Safety Summary before performing any service

procedures.

Do Not Service Alone. Do not perform internal service or adjustments of this
product unless another person capable of rendering first aid and resuscitation is
present.

To avoid electric shock, do not touch exposed connections.

P6021 Instruction Manual

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Service Safety Summary

Contacting Tektronix

Phone [phone]*

Address Tektronix, Inc.

Department or name (if known)
14200 SW Karl Braun Drive
P.O. Box 500
Beaverton, OR 97077
USA

Web site www.tektronix.com

Sales support 1-800-833-9200, select option 1*

Service support 1-800-833-9200, select option 2*

Technical support Email: [e-mail]

1-800-833-9200, select option 3*
1-503-627-2400

6:00 a.m. -- 5:00 p.m. Pacific time

* This phone number is toll free in North America. After office hours, pl ease leave a

voice mail message.
Outside North America, contact a Tektronix sales office or distributor; see the
Tektronix web site for a list of offices.

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P6021 Instruction Manual

Operator Information

Thank you for choosing a Tektronix current probe. This manual describes the
P6021 current probe with passive termination and provides information about
making measurements with the probe.

Description

The P6021 current probe converts an alternating current waveform to a voltage
that can be displayed and measured on an oscilloscope display. The probe
provides accurate current measurements over a wide range of frequencies and
allows you to measure current without breaking the circuit.

The P6021 probe is compatible with general purpose oscilloscopes having a
1MΩ input impedance. The P6021 probe comes with a passive termination that
matches oscilloscope and probe impedance, optimizes the probe performance,
and provides two sensitivity settings.

The P6021 probe comes with a 5-foot cable and termination.

Installation

This section describes both attaching the probe to an oscilloscope and using the
standard accessories with the probe.

To ensure the best performance from your probe and oscilloscope measurement
system, check that the probe and oscilloscope are appropriately matched. The
oscilloscope inputs should use BNC connectors and have an impedance of
1MΩ.

Figure 1 shows the probe and various parts referred to in this manual.

P6021 Instruction Manual

1

Operator Information

P6021 Probe

Termination

6” Ground Lead

Figure 1: The P6021 Probe and termination

Attaching the Probe and

Termination to an

Oscilloscope

Attach the probe to the termination as shown in Figure 1.

An alligator-style ground clip is supplied to improve EMI rejection at high
frequencies (2 MHz and above). Snap the ground lead to the probe transformer
post and attach the alligator clip directly to RF ground. This will reduce ringing
and help bypass capacitively-coupled RF currents that can flow into the probe
cable.

WARNING. To avoid injury or equipment damage, remove power from an
uninsulated wire before clamping the current probe around it. When the probe
slides are open, the exposed ferrite core pieces are not insulated. Also, never
disconnect the probe from the termination when the probe is connected to a live
conductor.

To avoid damaging the probe, do not disconnect the probe termination and leave
the P6021 clamped around the conductor when measuring high currents.
Leaving the probe cable unterminated can cause a high voltage to develop in the
secondary winding, which may damage the current probe transformer.

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P6021 Instruction Manual

Operator Information

Using the Standard

Accessories

Optional Accessories

Your P6021 is shipped with the following accessories:

H This instruction manual — Read these instructions to familiarize yourself

with the features, specifications, and operation of the P6021 current probe.

H 6-inch ground lead — Use the 6-inch ground lead to ground the shield

around the probe transformer at the probe end of the cable. This allows you
to move the ground connection closer to the circuit that you are measuring,
thereby improving high frequency response. The ground lead clips onto the
ground connector on the bottom of the probe as shown.

Please refer to the parts list in the section entitled Replaceable Mechanical Parts
for part numbers.

Your P6021 may be used with the following optional accessory:

H CT-4 Current Probe — The CT-4 is a robust clip-on transformer that

extends the current range of the P6021 up to 1000 amps (provided the
amp-second rating is not exceeded). The CT-4 has receptacles for current
probes in either 20:1 or 1000:1 step-down ratios.

P6021 Instruction Manual

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Operator Information

Operating Considerations

The information in this section will help you make effective use of your P6021
probe.

Features and Controls

Open

Closed

Locked

Ridge

Sensitivity
control

Probe
slide switch

H Sensitivity Control — The P6021 termination has a control that allows you

to select probe sensitivity. The switch has two positions: 2 mA/mV and
10 mA/mV. When the control is in the 2 mA/mV position, the oscilloscope
displays 1 mV for every 2 mA of current in the circuit under test. When the
control is in the 10 mA/mV position, the oscilloscope displays 1 mV for
every 10 mA of current in the circuit under test.

You can set vertical scale on the oscilloscope to any scale factor, as
determined by the signal amplitude. To calculate the overall vertical scale
factor for the oscilloscope, probe, and termination, multiply the termination
sensitivity control setting by the vertical scale factor of the oscilloscope. For
example, if the termination control is set to the 10 mA/mV position and the
oscilloscope to a vertical scale of 20 mV/division, the overall scale factor is
10 X 20, or 200 mA/division.

H ProbeSlideSwitch— The slide switch on the probe has three positions:

open, closed, and locked. Use your thumb to move the probe slide switch.
The switch is spring loaded so that it automatically moves from the open to
closed positions.

To Use the Prob e :

a. Pull the slide switch toward you, and hold the switch in position.

b. Place the conductor-under-test inside the exposed transformer core. The

arrow on the transformer end of the probe indicates conventional current
flow. If you place the probe on the conductor so that the arrow on the
probe matches conventional current flow through the conductor,
orientation of the displayed waveform will be correct.

c. Release the switch, allowing the probe to close.

d. Lock the slide switch. To lock the switch, push it firmly toward the

transformer (the switch will move only about 1/8th inch). Locking the
switch assures maximum contact between the two halves of the
transformer secondary. The conductor now becomes the primary of the
transformer. (When measuring current, always check that the probe slide
switch is moved completely forward into the locked position.)

WARNING. To prevent shock when measuring uninsulated conductors, keep your
hands and fingers behind the ridge on the probe head.

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P6021 Instruction Manual

Operator Information

Insertion Impedance

Minimizing Loading Effect

Increasing Probe

Sensitivity

When you insert a conductor into the probe, you add impedance to the circuit
you are measuring. This additional impedance affects signals; this is particularly
important if you are measuring fast rise times. Figure 2 illustrates the equivalent
circuit with the additional impedance introduced by the P6021.

1.7 nH2.8 H

.004 Ω

Figure 2: Insertion Impedance of the P6021

To minimize the loading effect of the probe, clamp it at the low or ground end of
a component lead when possible. This method also minimizes noise or stray
signal interference.

You can increase the current sensitivity of the probe by increasing the number of
times a conductor passes through it. For example, if the conductor loops through
the probe twice (a two-turn primary winding), the secondary current is doubled.

For example, suppose you set the termination sensitivity to 2 mA/mV and the
oscilloscope vertical scale to 10 mV/division. Ordinarily, this would result in the
equivalent of 2 X 10, or 20 mA/division. However, if the conductor is looped
through the probe twice, the vertical scale is divided by two, resulting in the
equivalent of 10 mA/division.

Looping the conductor twice effectively doubles vertical sensitivity; however,
impedance from the probe winding is also reflected into the circuit being
measured. This impedance is proportional to the square of the number of loops.
This additional impedance affects signals; this impedance is particularly
important when you are measuring high-frequency current waveforms or
waveforms with fast rise times.

P6021 Instruction Manual

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Operator Information

Probe Shielding

The P6021 is shielded to minimize the effect of external magnetic fields.
However, strong fields can interfere with the current signal being measured. If
you suspect that an external field is interfering with your measurement, remove
the probe from the conductor, but keep it in the same location as when you made
the suspect measurement. If a signal still appears on the oscilloscope, try to
measure the conductor current at a point farther from the location of the magnetic
field.

If you must measure current in the presence of a strong magnetic field, you can
minimize its interference by using two current probes and a differential-input
oscilloscope. To do so, follow these steps.

1. Connect the probes (with termination) to the positive and negative inputs of
the oscilloscope.

2. Clamp one probe around the conductor whose current you want to measure.

3. Place the other probe as close as possible to the first. Ensure that its slide

switch is completely closed, without a conductor inside it.

4. Set the oscilloscope to subtract the component of the signal that is common
to both probes.

5. Adjust the positions of the probes for best results. It may be difficult to
eliminate the undesirable signal completely, due to differences between the
probes or their terminations.

Droop

The flat-top response of any AC current probe displays a certain amount of
droop. This is caused by probe inductance loading the source impedance, causing
an L/R exponential decay. For short pulse widths, the response looks nearly flat.
The amount of droop can be calculated from the following relationship:

% Droop = 200 (π)Tf

where:

T=pulse duration in microseconds
f=lower 3 dB frequency of probe in Hertz

For example, to calculate the percent droop of a 100 s pulse measured with a
P6021 probe:

In the 10 mA/mV position, f=120 Hz

% Droop = 200 (π)Tf

= 200 (π) (100*10

--6

) (120)

= 0.075%

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P6021 Instruction Manual

Service Information

Warranted Characteristics

This section lists the various warranted characteristics that describe the P6021
Current Probe. Included are warranted electrical and environmental characteris­tics.

Warranted characteristics are described in terms of quantifiable performance
limits which are warranted.

The electrical characteristics listed in Table 1 apply under the following
conditions:

NOTE. The probe and instrument must be in an environment whose limits are
described in Table 2.

Table 1: Warranted electrical characteristics

Characteristic Information

Sensitivity setting 2 mA or 10 mA for each mV at oscilloscope input,

selected by termination sensitivity control

Midband accuracy

System bandwidth (--3 db)
(with BW>200 MHz oscilloscope)

2 mA/mV 450 Hz to 60 MHz

10 mA/mV 120 Hz to 60 MHz

±3%

Table 2: Warranted environmental characteristics

Characteristic Information

Temperature range

Operating --0 _ Cto+50_C(+32_F to +122 _F)

Nonoperating -- 4 0 _ Cto+65_C(--40_F to +149 _F)

Altitude

Operating To 2,000 m (6,561 ft), <300 V CAT I

To 4,572 m (15,000 ft), <150 V, CAT I

Nonoperating To 15,240 m (50,000 ft)

P6021 Instruction Manual

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