Cal Test CT3688A User Manual

Active Differential Probe Kit, 200 MHz, 10x Small Signal ±20V

CT3688A

USER MANUAL

CAL TEST ELECTRONICS

CT3688A Active Differential Probe Kit, User Guide

© Cal Test Electronics. All rights reserved.

Cal Test Electronics products are covered by US and foreign patents, issued
and pending. Information on this publication supersedes all earlier versions.

Specications are subject to change without notice.

Made in Taiwan

SYMBOLS AND TERMS

The following symbols may appear on the product or in the documentation.

Caution Symbol (ISO 7000-0434) – Statements or instructions

that must be consulted in order to nd out the nature of the
potential hazard and any actions which must be taken.

Caution, possibility of electric shock Symbol (IEC 604027-

6042) - To identify equipment that has the risk of electric shock.

A statement calling attention to an operating procedure,

WARNING

CAUTION

WARNING

practice, or condition, which if not followed correctly, could result

in damage to or destruction of parts or the entire product.

A statement calling attention to an operating procedure,

practice, or condition, which if not followed correctly, could result
in injury or death to personnel.

DEFINITIONS

POLLUTION (P) – addition of foreign matter solid, liquid or gaseous (ionized

gases), that may product a reduction of dielectric strength or surface
resistivity.

• Degree 2 (P2) – only non-conductive pollution occurs except that
occasionally a temporary conductivity caused by condensation is
expected.

MEASUREMENT CATEGORY (CAT) – classication of testing and measuring

circuit according to the type of mains circuits to which they are intended to

be connected.

• MEASUREMENT CATEGORY other than II, III, or IV: - measuring
circuits that are not directly connected to the mains supplies.

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GENERAL SAFETY INFORMATION

Safety is compromised if instructions are not read, understood, and followed.

• Disconnect from all devices and sources before attaching test leads or
adapters.

• Check for damage before usage - Do not use if any part is damaged.

• Do not use in wet or explosive atmospheres.

CAUTION

CAUTION

WARNING

WARNING

WARNING

WARNING

WARNING

WARNING

Do not install substitute parts or perform any

unauthorized modication to the probe.

This probe is not authorized for use in contact with the

human body or for use as a component in a life-support
device or system.

Never exceed the maximum voltage or measurement
category of the probe and adapter assembly as

congured for usage.

Never remove the probe’s casing as this may expose you

to electric shock. If necessary, disconnect the inputs and

outputs of the probe before opening the case.

To avoid injury, remove jewelry such as rings, watches,
and other metallic objects. Do not touch exposed
connections and components when power is present.

Hazardous voltages may be present in unexpected

locations in circuitry being tested when a fault condition

in the circuit exists. Capacitors inside the instrument may
retain a charge even if the instrument is disconnected
from its source of supply.

Do not operate this probe from a power source that
applies more than the voltage specied.

This probe must be grounded by the shell of the BNC

connector through the grounding conductor of the power
cord of the measurement instrument. Before making
connections make sure the measurement instrument is
properly grounded. Whenever it is likely that the ground
protection is impaired, you must make the instrument

inoperative and secure it against any unintended
operation.

• If the probe is used in a manner not specied by this user guide, the
protections provided may be impaired.

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DESCRIPTION

Dierential probes allow safe, accurate measurement between two voltage
points where neither point is referenced to ground. The CT3688A oers a 200
MHz bandwidth and can test up to ±60 V (DC + AC peak). Compatible with
oscilloscopes from all major manufacturers, the probe can be battery operated
or powered directly from an oscilloscope using the included USB cable.

Features:

• Meets IEC 61010-031 safety standard

• Small compact size

• Up to ±20 V dierential

• High accuracy ±1%

• 200 MHz bandwidth (-3 dB)

• Excellent CMRR

• Kit comes in foam-lined plastic case and contains:

• Dierential probe

• (2) Sprung hook probes,1000 V, CAT III, 20 A (black & red)

• (2) Alligator clips, 300 V, CAT II (black & red)

• 9 V Battery

• USB Power Cable

This probe is tested prior to shipment. It is therefore ready for immediate use
upon receipt. An initial physical inspection should be made to ensure that no
damage has been sustained during shipment.

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C

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B

A

D

• A - Active Dierential Probe, 200 MHz, 10x Small Signal ± 20 V

• B - CT4441, Insulated Medium Alligator Clips, 300 V, CAT II Pair (Black &

Red)

• C - CT4122, USB Power Cable

• D - CT4386, Insulated Sprung Hook Probes, 1000 V CAT III, 20 A, Pair

(Black & Red)

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SPECIFICATIONS

All specications apply to the unit after a temperature stabilization time of about
20 minutes over an ambient temperature range of 25 °C ± 5 °C.

ELECTRICAL SPECIFICATIONS

Bandwidth (-3dB) 200 MHz

Rise Time (10%-90%) 1.75 ns

Attenuation Ratio 10x

Accuracy ±1%

CMRR (typical)

Maximum Dierential Input Voltage

(DC + AC peak)

Maximum Common Mode Input Voltage

(DC + AC peak)

Absolute Maximum Rated Input Voltage

(each side to ground)

Input Impedance 500 kΩ // 7 pF (each side to ground)

Output Voltage Swing ±2 V (driving 50 Ω oscilloscope input)

Oset (typical) ±2 mV

Noise (typical) 0.3 mVrms

Source Impedance 50 Ω

CT4122 USB Power Cable (included)

Power Supply

-80 dB @ 100 Hz

-50 dB @ 10 MHz

±20 V

±60 V

40 Vrms CAT I

or

9 V battery (included)

MECHANICAL SPECIFICATIONS

Weight 200 g

Dimensions (L x W x H) 111 mm x 22 mm x 14 mm

BNC Cable Length 120 cm

Input Leads Length 15 cm

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ENVIRONMENTAL SPECIFICATIONS

Operating Temp/Humidity -10°C to 40°C / Up to 85% RH

Storage Temp/Humidity -30°C to 70°C / Up to 85% RH

Pollution Degree Pollution Degree 2

Altitude

Speci cations are subject to change without notice. To ensure the most current
version of this manual, please download the current version from our website:

caltestelectronics.com

CE COMPLIANCE

Low-Voltage Directive (LVD) 2014/35/EU
Standard EN 61010-031:2015

Reduction of Hazardous Substances Directive (RoHS 2) 2011/65/EU
+ AMD 2015/863 ANNEX III Exemption 6(c)

DISPOSAL OF OLD ELECTRICAL & ELECTRONIC EQUIPMENT

(Applicable in the European Union and other European countries

with separate collection systems). This product is subject to Directive
2012/19/EU of the European Parliament and the Council of the
European Union on waste electrical and electronic equipment (WEEE),
and in jurisdictions adopting that Directive, is marked as being put on
the market after August 13, 2005, and should not be disposed of as
unsorted municipal waste. Please utilize your local WEEE collection
facilities in the disposition of this product and otherwise observe all

applicable requirements.

Operating: 3,000 m

Non-operating: 15,300 m

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VOLTAGE DERATING CURVE

The derating curve of the absolute maximum input voltage (either input to

ground) is shown as follows:

MAXIMUM INPUT VOLTAGE DERATING CURVE

100

60

Voltage (Vrms)

10

10 100 200 1000

Frequency (MHz)

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USING THE PROBE

Power Connection

Connect the USB power cable to the USB interface on the front of the
oscilloscope and then to the input on the probe. See gure below.

Only use center pin positive supply, USB cable included

CAUTION

WARNING

or optional 9 VDC/300 mA AC wall adapter (CT3723 not

included).

At the time of powering on the probe, the input leads

must not be connected to the device under test (DUT).

Never operate the probe with the case open.

If powering by 9 V battery, slide the cover o the back of the battery box and
plug the battery in, making sure to position the battery for proper polarity. After
inserting the battery, close the case. See gure below.

When the battery is low, the power indicator will start to icker and dim.

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INSPECTION PROCEDURE

1. Connect the BNC output connector to the vertical input of the
oscilloscope.

2. Power on the probe.

3. Set the oscilloscope input to DC coupling and 1V/div. Center the trace

on the display.

4. Set the attenuation setting on the oscilloscope to match the probe

(10x).

5. Connect the hook probes to the leads.

6. Connect the black hook probe to the ground connection on the
oscilloscope and the red hook probe to the test signal on the
oscilloscope (1 kHz for example).

7. A wave matching the test signal displayed on the screen of the
oscilloscope means the probe is working properly.

MAKING MEASUREMENTS

1. Connect the hook probes or alligator clips as needed to the leads.

2. Connect the probe to the oscilloscope with the BNC cable.

3. Switch the probe “ON.”

4. Set the attenuation setting on the oscilloscope to match the probe

(10x).

5. Set the input impedance setting on the oscilloscope to match the
probe (50Ω)

6. Connect to the circuit to be tested.

This probe is used to carry out dierential measurements

CAUTION

between two points on the circuit under test. This probe

is not for electrically insulating the circuit under test and
the measuring instrument.

CLEANING

Clean probe and accessories with cloth lightly moistened with water only. Dry

thoroughly before use.

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SERVICE & WARRANTY INFORMATION

Limited One-Year Warranty

Cal Test Electronics warrants this product to be free from defective material or
workmanship for a period of 1 year from the date of original purchase. Under
this warranty, Cal Test Electronics is limited to repairing the defective device
when returned to the factory, shipping charges prepaid, within the warranty

period.

Units returned to Cal Test Electronics that have been subject to abuse, misuse,
damage or accident, or have been connected, installed or adjusted contrary to

the instructions furnished by Cal Test Electronics, or that have been repaired by

unauthorized persons, will not be covered by this warranty.

Cal Test Electronics reserves the right to discontinue models, change

specications, price, or design of this device at any time without notice and
without incurring any obligation whatsoever.

The purchaser agrees to assume all liabilities for any damages and/or bodily
injury which may result from the use or misuse of this device by the purchaser,

his employees, or agents.

This warranty is in lieu of all other representations or warranties expressed or

implied and no agent or representative of Cal Test Electronics is authorized to

assume any other obligation in connection with the sale and purchase of this

device.

Service

If you have a need for calibration or repair services, technical or sales support,
please contact us:

22820 Savi Ranch Parkway

Yorba Linda, CA 92887

800-572-1028 or 714-221-9330

caltestelectronics.com

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