Tektronix CMC251 User Manual

User Manual

CMC251

1.3 GHz Frequency Counter
070-8527-03

Copyright  T ektronix, Inc. 1991. All rights reserved.
T ektronix 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.

T ektronix, Inc., P.O. Box 1000, Wilsonville, OR 97070–1000
TEKTRONIX and TEK are registered trademarks of T ektronix, Inc.

WARRANTY

Tektronix warrants that this product will be free from defects in materials and
workmanship for a period of one (1) year from the date of shipment. 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.

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, with shipping charges
prepaid. 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; or c) to service a
product that has been modified or integrated with other products when the effect of such
modification or integration increases the time or difficulty of servicing the product.

THIS WARRANTY IS GIVEN BY TEKTRONIX WITH RESPECT TO THIS
PRODUCT IN LIEU OF ANY OTHER WARRANTIES, EXPRESSED OR
IMPLIED. TEKTRONIX AND ITS VENDORS DISCLAIM ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR
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. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Getting Started 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Preparing the Frequency Counter for Use 2. . . . . . . . . . . . . . . . .

Front Panel 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Rear Panel 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Reference 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Making Frequency Measurements 9. . . . . . . . . . . . . . . . . . . . . . .

Frequencies Below 10 MHz 9. . . . . . . . . . . . . . . . . . . . . . . . .

Frequencies Below 100 MHz 10. . . . . . . . . . . . . . . . . . . . . . . .

Frequencies Between 80 MHz and 1.3 GHz 11. . . . . . . . . . . .

Making Period Measurements 11. . . . . . . . . . . . . . . . . . . . . . . . . .

Making Pulse-Width Measurements 13. . . . . . . . . . . . . . . . . . . . .

Remote Control of Pulse-Width Measurements 14. . . . . . . . .

Counting Events 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Remote Control of TOTAL Mode 16. . . . . . . . . . . . . . . . . . . .

Checking Instrument Operation 17. . . . . . . . . . . . . . . . . . . . . . . . .

Appendix A: Specifications 19. . . . . . . . . . . . . . . . . . . . . . . . . . .

Appendix B: Maintenance 25. . . . . . . . . . . . . . . . . . . . . . . . . . .

Cleaning 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Preparing for Shipment 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Troubleshooting 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

No Display with Power On 26. . . . . . . . . . . . . . . . . . . . . . . . .

Appendix C: Replaceable Parts 27. . . . . . . . . . . . . . . . . . . . . . .

Standard Accessories 27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Optional Accessories 27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CMC251 User Manual

i

T able of Contents

List of Tables

Table 1: A or B Channel Input 9. . . . . . . . . . . . . . . . . . . . . . .

Table 2: Selecting Features For Channel A

(1 Hz to 10 MHz) 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 3: Selecting Features For Channel A

(10 MHz to 100 MHz) 10. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 4: Gate Time Versus Resolution for Channel A 11. . . . .

Table 5: Gate Time Versus Resolution for Channel B 11. . . . .

Table 6: Period Measurements 12. . . . . . . . . . . . . . . . . . . . . . . .

Table 7: Resolution For Period Measurements 12. . . . . . . . . . .

Table 8: Pulse Width Measurements 13. . . . . . . . . . . . . . . . . . .

Table 9: Resolution for Pulse Measurements 14. . . . . . . . . . . .

Table 10: Warranted Characteristics 19. . . . . . . . . . . . . . . . . .

Table 11: Certifications and Compliances 23. . . . . . . . . . . . . .

Table 12: Typical Characteristics 23. . . . . . . . . . . . . . . . . . . . .

Table 13: Standard Accessories 27. . . . . . . . . . . . . . . . . . . . . . .

Table 14: Optional Accessories 27. . . . . . . . . . . . . . . . . . . . . . .

Table 15: Accessory Power Cords 28. . . . . . . . . . . . . . . . . . . . .

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CMC251 User Manual

General Safety Summary

Review the following safety precautions to avoid injury and prevent
damage to this product or any products connected to it.

Injury Precautions

Use Proper Power Cord

T o avoid fire hazard, use only the power cord specified for this
product.

Avoid Electric Overload

T o avoid electric shock or fire hazard, do not apply a voltage to a
terminal that is outside the range specified for that terminal.

Ground the Product

This product is grounded through the grounding conductor of the
power cord. T o avoid electric shock, the grounding conductor must
be connected to earth ground. Before making connections to the
input or output terminals of the product, ensure that the product is
properly grounded.

Do Not Operate Without Covers

T o avoid electric shock or fire hazard, do not operate this product
with covers or panels removed.

Use Proper Fuse

T o avoid fire hazard, use only the fuse type and rating specified for
this product.

CMC251 User Manual

iii

General Safety Summary

Do Not Operate in Wet/Damp Conditions

T o avoid electric shock, do not operate this product in wet or damp
conditions.

Do Not Operate in Explosive Atmosphere

T o avoid injury or fire hazard, do not operate this product in an
explosive atmosphere.

Product Damage Precautions

Use Proper V oltage Setting

Before applying power, ensure that the line selector is in the proper
position for the power source being used.

Provide Proper Ventilation

T o prevent product overheating, provide proper ventilation.

Do Not Operate With Suspected Failures

If you suspect there is damage to this product, have it inspected by
qualified service personnel.

Safety Terms and Symbols

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.

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CMC251 User Manual

General Safety Summary

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:

DANGER

High Voltage

Protective Ground

(Earth) T erminal

Certifications and Compliances

CSA Certified Power Cords

CSA Certification includes the products and power cords appropriate
for use in the North America power network. All other power cords
supplied are approved for the country of use.

CMC251 User Manual

ATTENTION

Refer to

Manual

Double

Insulated

v

General Safety Summary

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CMC251 User Manual

Getting Started

The Tektronix CMC251 Frequency Counter can make the following
frequency-related measurements:

H Frequency measurements up to 1.3 GHz
H Period measurements at rates up to 25 MHz
H Period averaging of up to 1000 events
H Pulse measurements up to 0.25 s
H Event counting

The 10 MHz internal time base (using a highly stabilized crystal
oscillator) provides a single-shot resolution of 100 ns. Measurement
results are displayed using an eight digit display, automatically
placing the decimal appropriately.

The CMC251 Frequency Counter has a locking, multiposition handle
that folds under the instrument. The instrument is delivered with a
115 V power cord, an installed fuse for 115 V operation, and this
manual.

CMC251 User Manual

1

Getting Started

Preparing the Frequency Counter for Use

Check the following items prior to operating the frequency counter
for the first time (see Figure 1 for locations of items 1 through 3):

1 23

Figure 1: Line Voltage Selectors, Power Input, and Fuse Locations

CAUTION. To prevent damage to the instrument, set the line voltage
selectors to the proper voltage setting and install the correct line
voltage fuse before operating the equipment.

1. Set the line voltage selectors to the input line voltage. These

selectors connect internal wiring for various line voltages. This

product is intended to operate from a power source that does not

supply more than 250 V

between either supply conductor and ground. For line voltage

ranges, refer to Appendix A: Specifications on page 19.

WARNING. To prevent electrical shock, unplug the power cord and
disconnect the signal input cable from any signal source before
checking or replacing the fuse.

2. Check that the correct line fuse is installed. The line fuse

provides protection if the equipment malfunctions or an overload

occurs. Refer to Appendix C: Replaceable Parts on page 27 for

fuse part numbers.

2

between the supply conductors or

RMS

CMC251 User Manual