A lot of NB success on power line noise has to do with what state the noise is in when it gets to you. If the source is near, and the waveform is not smeared, the K3 NB does very well. The problem comes when a source is rather distant, and is getting to you conducted over something like a mile of primary transmission line. Then the waveform can be smeared and lacks the crisp sharp peak that the circuitry and algorithms love and suppress so neatly. This also accounts for a lot of variation in reporting. A smeared noise waveform is very much harder to block out. Sometimes NR will do that better, but this is very much an individual situation variance.
In my case there is sometime an arc at a pole about 3/4 miles from here that belongs to the City of Apex power distribution. I don't hear it directly from there. I hear it from lines close to me up and down 64, which smears it. I also hear it from a line that runs beside Toll 540 at right angles to me and from the other direction. More smearing. I did find that with a certain combination of digital and IF NB, and sweeping the band, that there were a couple 3-4 kHz wide spots where the stuff nulled out pretty well. What was the difference? The change in frequency changed the wavelengths and unsmeared the result at those two spots enough that the NB could get it. So I worked a run frequency in the 160 contest in those two narrow ranges, where the NB actually had things down to the normal band noise level. So reports that don't mention anything about the nature of the noise and are at different locations can't be used to evaluate a noise blanker. Only a side by side comparison and knowing the nature of the noise. A "disadvantage" of sorts is the number of combinations possible on the K3. In a conversation with a complainant on the K3 NB, I asked if the full number of combinations had been tried. He said that was too many. He tried a few and gave up. When I pressed on that, he said that radios shouldn't have so many possibilities, that manufacturers should pick the right one and just have that come up when the NB is hit. When that Apex noise source started up before a contest, it took me a couple of hours fiddling before I realized that certain settings produced noise nulls in different places on the band. It took me a lot longer than that to figure out what was going on (the smearing or not). Without all the possible combinations, I would have either been lucky or not with what the radio gave me. And you can have a bad board. If that's it, your Elecraft service is top flight. Besides that your K3 NB can take out key clicks, and Elecraft is the only one I know of that can do that. 73, Guy K2AV On Tue, May 17, 2016 at 2:36 PM, ab2tc <ab...@arrl.net> wrote: > Don Wilhelm wrote > > The gentleman who was having problems has found the cause. He swapped > > the KNB3 from the sub to the mainRX. In other words, the KNB3 in his > > mainRX was not functioning properly. > > > > Yes, the NB does not do too much for power line noise > > <snip> > > > > Hi Don, > > That is not my experience at all. I sometimes have moderate power line > noise > and I find the DSP blanker, not IF, rather effective. I use settings > between > T2-5 to T2-7. The higher setting gives better suppression but distorts > audio > for moderately strong signals (S7). For a while I was using some additional > IF blanking but soon decided it had virtually no additional benefits. This > is on SSB with 300-2700Hz passband. > > AB2TC - Knut > > > > -- > View this message in context: > http://elecraft.365791.n2.nabble.com/NB-issue-tp7617459p7617525.html > Sent from the Elecraft mailing list archive at Nabble.com. > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to k2av....@gmail.com > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
