Keithley Joins WiMAX Forum

Cleveland, Ohio - December 13, 2007 - Keithley Instruments, Inc. (NYSE:KEI), a leader in solutions for emerging measurement needs, announced today that it has become a member of the WiMAX Forum®. The WiMAX Forum is an industry-led, non-profit organization responsible for promoting and certifying interoperable WiMAX™ products. WiMAX technology enables wireless high-speed Internet access for laptops and other mobile devices over much longer distances than current wireless technologies such as Wi-Fi.

"Given our aggressive investments in expanding our RF measurement capabilities, our participation in this important industry forum is a natural extension of our commitment to the wireless communications test market," said Mark Hoersten, vice president, business management. "Wireless test in general and WiMAX technologies in particular are fast-moving platforms that require the very latest test solutions, so our participation in the Forum's activities will play a large role in ensuring our solutions are consistent with the very latest needs of the market."

Keithley has introduced a variety of new RF instrument platforms and software in recent years. Keithley's newest offering, the industry-leading 4X4 RF MIMO Test System, consists of the Model 2920 Vector Signal Generator with up to 80MHz of bandwidth and 100MSamples of arbitrary waveform generator memory and the Model 2820 Vector Signal Analyzer with 40MHz of signal bandwidth. Both units feature a 6GHz frequency range for testing nearly any wireless signal, including Mobile WiMAX, WLAN 802.11n MIMO, and a range of other standard signals such as GSM, EDGE, W-CDMA, and more.

For More Information For more information on Keithley's RF product family or any of its RF or general test solutions, contact the company at:

Telephone: 800-688-9951 440-248-0400

FAX: 440-248-6168

E-mail: publisher@keithley.com

Internet: www.keithley.com

Address: Keithley Instruments, Inc.

28775 Aurora Road

Cleveland, OH 44139-1891

About Keithley Instruments, Inc.

With more than 60 years of measurement expertise, Keithley Instruments has become a world leader in advanced electrical test instruments and systems from DC to RF (radio frequency). Our products solve emerging measurement needs in production testing, process monitoring, product development, and research. Our customers are scientists and engineers in the worldwide electronics industry involved with advanced materials research, semiconductor device development and fabrication, and the production of end products such as portable wireless devices. The value we provide them is a combination of precision measurement technology and a rich understanding of their applications to improve the quality of their products and reduce their cost of test.

"WiMAX Forum" is a registered trademark of the WiMAX Forum. "WiMAX," the WiMAX Forum logo, "WiMAX Forum Certified," and the WiMAX Forum Certified logo are trademarks of the WiMAX Forum. All other trademarks are the properties of their respective owners.

Products and company names listed are trademarks or trade names of their respective companies.

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