Free-field microphone 4939

measurementexternally-polarizedhyperfrequency

Free-field microphone designed for high-level and high-frequency measurements over a frequency range of 4 Hz to 100 kHz. Using stainless steel diaphragm and protection grid, Type 4939 Microphone is built to withstand rough environments and can be used in high-temperature measurements up to 150°C (302°F). The microphone requires an external polarization voltage and must therefore be used with a classical preamplifier. Externally polarized microphones can be used at higher temperatures without severe changes in measurement sensitivity. High-level measurements High-frequency measurements Model work MICROPHONE BUILD AND STABILITY A laser-welded, stainless-steel diaphragm ensures superior long-term stability and mechanical robustness. Type 4939 will withstand the 1 m drop test required by IEC 60068-2-32. The microphone is assembled in a clean room, ensuring that the microphones maintain their inherent noise floor and high stability, even when used in environments with a combination of high humidity and high temperature. TEDS Microphones Type 4939 is available in a TEDS Microphone set with different variants of classical preamplifiers. The TEDS microphone is considered one unit and has been sealed in a clean environment. The TEDS is programmed with the loaded sensitivity of the actual cartridge and the data is therefore readily available in the transducer. CALIBRATION The sensitivity can be calibrated at 250 Hz by using Pistonphone Type 4228 with ¼-inch Adaptor DP 0775. The actuator response can be measured using Actuator UA 0033 with Adaptor DB 0264.