Eric, First do a test to see if your NB is working at all. Remove the antenna, turn on the Preamp, then tap on the case of Q21 with a screwdriver. The taps will create impulse noise in the receiver which should be blanked when NB1 or NB2 is turned on. Be careful to differentiate between the clicks from the impulse noise and the rush of 'antenna/band noise' that happens because the screwdriver shaft can act as an antenna.
If you find the NB is responding to that test, but it still does not help with your noise source, you can try widening the gate time a bit - try adding an additional .001 uF capacitor in parallel with C11 (just soleder ti to the solder pads for a test - if that helps, you can either leave the parallel cpacitor in place or change C11 to .002 uF. Other values may help as well, so some experimentation may be of help. If the noise gate is widened too much you will begin to notice "holes" on the received signal. 73, Don W3FPR eric norris wrote: > I built my K2 some months back with the KNB2 option. The noise blanker has > never been effective against any type of noise. The MCU recognizes the > blanker, it draws the proper amount of current, but just doesn't seem to do > anything. Before drinking the Kool-Aid (TM) I was pretty much a Kenwood man > and was used to ineffective noise blankers so I ended up blowing it off. I > recently built a K1, and the NB in it works FB. This got me thinking, and > besides Elecraft would never release a NB that was useless--it violates the > Tao of Elecraft. Yesterday I built another KNB2 (any excuse) and installed > it in my K2. Same result! I checked all the solder joints, component > values, RF board mods. It makes no difference whether it is NB1, NB2, HI or > LO, the preamp is on or off--nothing. No change in S-meter reading, no > change in audio. Any ideas, oh mighty brains? > > Thanks, Eric WD6DB(lost in noise) > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ------------------------------------------------------------------------ > > > No virus found in this incoming message. > Checked by AVG - www.avg.com > Version: 8.5.409 / Virus Database: 270.13.70/2329 - Release Date: 08/27/09 > 08:11:00 > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
