Model 7650 extensometers are primarily used on round specimens tested in bi-axial test machines capable of simultaneous axial and torsional loading. All models are capable of bi-directional displacement in both axes and may be used for strain-controlled fatigue testing under fully reversed load and strain conditions at frequencies up to 10 Hz.
All 7650 models mount rigidly on the load frame and incorporate slide mounting to bring the extensometer into contact with the specimen. The gauge length is set automatically before mounting on the test specimen, which allows for hot mounting after thermal equilibrium has been reached.
These units are specifically designed to minimize crosstalk between axes and to provide high accuracy, high resolution measurements. They incorporate capacitive sensors for low operating force and include electronics with programmable filtering and multi-point linearization for improved performance and accuracy. The overall design minimizes, and in many cases virtually eliminates, any influence from common lab environment vibrations.
These water-cooled extensometers are equipped with high purity alumina rods with conical rod tips for specimen contact when testing to 1200℃(2200°F). Silicon carbide rods are used for the 1600℃ (2900°F) high temperature option.

Features
• Hot mountable and retractable.
• Self-setting gauge length with fine adjustment feature.
• All models can measure in both tension and compression and may be used for cyclic testing at test frequencies up to 10 Hz.
• Standard units meet ASTM class B-1 requirements for accuracy (axial). A test certificate is included. ISO 9513 class 0,5 test certificates are available upon request.
• Ships fully calibrated with calibration that is traceable to NPL; voltage output may be user-specified (typically 0-10V).
• Excellent ambient vibration rejection; primary vibration mode >100 Hz typical
• Digital controller and power supply included. Provides high level DC voltage output with low noise. Easily interfaced to test controllers, data acquisition boards and chart recorders.
• Includes high speed analog and digital outputs.
• Web-based user interface for setup and data acquisition.
• Selectable analog and digital filter options from 2 Hz to 3 kHz.
• Built-in calibration reference and auto-zero features.
• Multiple extensometer calibration files may be loaded for use with one controller.
• Can be used with specimens at elevated temperatures while only requiring room temperature calibration.
• Quick-disconnect water cooling fittings and signal cables.
• Includes high quality foam lined case and a spare set of rods.