It has been my experience that the KNB2 is one of the least effective noise blankers that I've used on a current-production radio. At night, I have a high noise level produced by malfunctioning street lights (this has been true for the 10 years I've lived here), and the KNB2 is completely ineffective in blanking this noise while other radios such as my Ten-Tec Paragon II or Drake TR-7 eliminate it completely. As a result, I cannot use the K2 at night.
In an effort to understand why this is the case, I've looked at the received noise with a spectrum analyzer. I found that, while the noise sounds continuous across the amateur band, it actually has large peaks and valleys, in some cases varying up to 20 dB across the band. Other noise sources, such as electric motor noise (which the KNB2 blanks well, depending upon the pulse repetition rate) are typically of nearly equal-amplitude across the bandwidth of the RX front end. About a year ago I spent a lot of time trying to improve the performance of the KNB2, but my attempts were in vain, as any improvement in blanking effectiveness caused a corresponding decrease in performance in some other respect. I finally gave up this effort, in my opinion the entire KNB2 needs to be re-designed in order to meet the expectations of those of us who really need it. While I understand that there are folks on the reflector that claim the KNB2 does an excellent job of blanking this or that specific interference type, in general I've found that such instances are relatively rare. I have seen the KNB2 work very well, there's no doubt in my mind that it can under the proper conditions. However, I agree with those on the reflector who see the NB performance as a major impairment to an otherwise excellent receiver. As someone suggested, even if a portion of an updated NB had a surface-mount aspect, that wouldn't be any different than what we had with the KDSP2, and in my opinion, it's much more important. Until a better design comes along for the NB, my K2 will continue to sit unused in the evening when the blanker is needed. Scott N7NB _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
