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General Description
The 9-NB is a solid state noise blanker to be used in the TR-6 transceivers.
The purpose of the 9-NB noise blanker is to blank out noise pulses which otherwise prevent reading a wanted signal. The 9-NB was designed to perform this function with a perfection previously unknown in amateur radio equipment. This was achieved by designing optimum blanking performance without compromising.
Unlike noise clippers or limiters commonly found in communication equipment, the 9-NB is an advanced noise blanker which actually mutes the receiver for the duration of the noise pulse. Between noise pulses full receiver gain is restored. (The receiver AGC is affected only by the desired signal strength, not by the noise at the antenna.)
The 9-NB is most effective on strong, periodic noise pulses such as ignition noise or noise generated by power lines. The blanker is less effective on random noise (e.g., atmospheric or contact noise.) This noise is continuous in time and the information it masks cannot be recovered by either blanking or limiting techniques.
Low-level signals masked by noise pulses without the noise blanker can be copied when the blanker is used. The 9-NB is a must for the mobile operator because he can now blank ignition noise generated by other cars as well his own car.
Thank to Ken WA4WQL
