The IF setting of NB in the K3 is a traditional shut-down-the-IF blanker and will always exhibit that behavior. A strong enough signal will modulate it. Turning on PRE takes away from the headroom needlessly below 10 meters. Keep the ATT/PRE/RFGAIN low enough that ambient noise is moderately low. That's good medicine for a lot of things and proper operating for a K3.
Lower the ATT/PRE/RFGAIN: ATT on for 160 through 40, nothing for 20-15, PRE only for 10 and 6. Also on 160 and 80, setting RFGAIN to two or three oclock may help to set ambient noise moderately low. If this does not work, then try turning off IF blanking and use one of the DSP NB settings instead. Running PRE on the low bands is simply not needed unless you are using a low gain RX ant that needs a boost. Unless you are living in a low noise paradise :>) 73, Guy. On Fri, Feb 5, 2010 at 9:33 PM, vk4cmv <vk4...@gmail.com> wrote: > > The other day I was receiving a very loud (S9+10) Jt65a signal from a local > station and was noticing that his signal seemed to be modulated by a > commercial radio station. So I was just about to send him an email saying > that he had a problem, when I adjusted the RF gain, turned the ATT on and > turned the PRE off. His signal was now sweet. > > So I switched to another sound card - and still the same result after I had > reset the controls again. > > Then I remembered that I had set the NB on (dsp off) and IF to Wide 7 and > as soon as I had turned the NB off, his signal was copied just fine. What I > found was that setting the IF to Wide 7, Med 7 or Nar 7 gave rise to what > only can be described as intermodulation. > > The reason I use the NB at all is because my neighbour has one of these > solar pads that heats his swimming pool on his roof, and the pumps in it > generate this ta-pocketa-pocketa-pocketa noise (like an electric fence, but > faster) - and I just leave the NB one most of the time, because my > neighbours also own behemoth plasma TV sets :) > > So two questions: > 1) has anyone else noticed spurious intermodulation in DATA mode when the > IF NB is set to the 7 level - or have I got a fault?, and > 2) Is there a beginner's guide to help me understand how to use the NB > effectively - at the moment, I just spin the dials until the noise is gone. > > thanks, Julian VK4CMV > > > > > -- > View this message in context: > http://n2.nabble.com/K3-NB-and-Digital-Reception-tp4523714p4523714.html > Sent from the [K3] 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 > ______________________________________________________________ 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
