Another thought: The K3 has two noise blankers. The hardware blanker does see a broad input frequency range (so it can suppress very fast-rise-time noise pulses), and as with similar blankers, you have to keep the NB threshold high enough to not cause intermod.
Try using just the DSP blanker, which is post-crystal-filter. Or a touch of each. This can be very effective on disparate noise sources. Wayne > On Jul 27, 2018, at 6:59 PM, Richard Beerman <rbee...@att.net> wrote: > > Wonder if anyone else has encountered this on 2 Meters? I am using a 12 ele > K1FO yagi - about q12 dB gain on 2. That enters the shack where it is > connected to a Downeast Microwave 50 Watt transverter with about 17 dB gain > on receive. The output of the transverter is connected to transverter input > on my old K-3. For the longest time, I was receiving loud QRM from what I > initially thought were power line noise bursts. But, I became suspicious > because these bursts were about a second or so in duration consistently. > During this time, I was testing my setup for meteor scatter using the MSK 144 > software found in the current WSJT-X suite. These loud bursts created huge > red images on the monitor watching in 144.150 MHz, the MSK144 calling > frequency. > > I got suspicious that these signals were not simple electrical pole shorting > noise. So, I connected a whip to my old TS-790S rig and tuned it to 144.390 > MHz, the North American APRS frequency. WALAAAAA, the signals on my monitor > connected to a K-3 tuned to 144.150 MHz corresponded perfectly to the WPRS > signals on 144.390 MHz, some 240 kHz away! The preamp on the K-3 was off. > There were no other receiving preamps in line at the time. Later, I turned on > an external 2 Meter preamp and all that happened was that the APRS signals > were larger at 144.150 MHz. > > It appears that the front end of my K-3 simply folds up in the presence of > strong signals that are WAY off the receiving frequency. I can tell you that > connecting the same antenna/transverter to a Kenwood TS 590SG, there were no > traces of the APRS signals. And connecting the TS-790S to the K1FO likewise > produced no APRS QRM at 144.150. To me, with the presence of a number of > strong APRS signals on 144.390 makes this K-3 extremely unusable on 2 Meters. > I was running the K-3 noise blanker to handle the rest of the noise here but > likewise, I also had noise blankers running on the two Kenwood radios as > well. > > Any suggestions are welcome. Dick W5AK > ______________________________________________________________ > 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 n...@elecraft.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
