Cryogenic Noise Terminations

General Information


Maury cryogenic terminations are liquid nitrogen cooled loads which provide accurately known noise power at a well matched output port.. Used with ambient and/or heated terminations and a noise figure meter, these terminations provide cold reference temperatures needed for highly accurate noise figure or effective input noise temperature measurements. Because of the accuracy of the noise output, cryogenic terminations are often used as a noise standard for calibration of solid state noise generators.

The accuracy achieved by these terminations is possible because they utilize the the known temperature of boiling liquid nitrogen as a constant for calculating noise temperature. This mirrors the conceptual foundation of the noise standards used in virtually all national standards laboratories world-wide (e.g., NIST). Because of this measurements made with these terminations are traceable temperature and network calibration standards. Each unit is provided with a calibration report which includes VSWR and available output noise temperature data at specific frequencies. Option MT7250A series data module is available for calculating additional user-selected frequencies (see Maury data sheet 4E-020 for more information).


Cryogenic terminations require user-provided liquid nitrogen and dry helium gas at 2 psi. Maury's MT152A Pressurization System is available as an optional accessory to regulate the helium pressure. The terminations include a heater circuit which operates on 48 VDC powered by a universal input power supply that accepts line voltages of 100-240 VAC, 47-63 Hz. This design feature prevents ice from forming on the output connector and prevents the heat load of the device-under-test from affecting the output temperature.

Application Notes and Data Sheets


Technical Data - Model MT7118J - 7mm Coaxial Thermal Noise Termination


Technical Data - Model MT7250A Series Data Module (for calculating additional user-selected frequencies)


Technical Data - Model MT152A - Pressurizing System


Application Note - Applications of the Maury Noise Calibration Systems; Accuracy & Convenience in Noise Measurement

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