Drake Model NB-7 Noise Blanker is a solid-state noise blanker to be used in  TR-7 and R-7  in Excellent shape, and working well. Simply remove the NB dummy board in your radio and pop this in, takes a few seconds. Unlike noise clippers or limiters commonly found in communication equipment, the NB-7 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 NB-7 is most effective on strong, periodic noise impulses such as ignition noise. The blanker is least effective on random noise. This noise is continuous in time and the information it masks cannot be recovered by either blanking or limiting techniques. However, loss of communications due to random noise is a rare occurrence, generally impulse noise is responsible for such situations.

       Low level signals masked by noise impulses without the noise blanker can be copied when the blanker is used. The NB-7 is a must for the mobile operator because one  can now blank ignition noise due to trucks and other cars as well as his own car. Buyer pays shipping for a well packed box.  Buy from me with confidence as I have excellent feedback.