Before I forget, thank you to everyone who has responded thusfar with ideas and suggestions. This one is a real head-scratcher, and I appreciate everyone bouncing ideas around with me.
If the problem is in fact originating with power line neutral distortion, what, if anything could I actually do about it, beyond what I've already done in running on battery power? I can't really move my 'shack' in this case. I did find the "squeaky wheel" at least. It was the end of one of the aluminum straps of an antenna mast chimney mount brushing against a copper ground wire in the wind. A pair of tin snips solved that problem. This bit was kind of fascinating-- if I held a copper wire against the aluminum strap, and position the antenna of the KX3 nearby, I could receive some broadcast AM station on the 51.123 MHz carrier I was transmitting from inside the house (it's pretty close to a multiple of 810kHz, so if I had to guess, it was likely KGO I was getting). I also found the noise gets a hell of a lot louder near the back gutter of the house (which runs parallel to the power lines that run through the back yard), though this could just be because the antenna of my KX3 was coupling to it. Yet to be determined is whether the noise is a local thing only affecting reception (e.g., some kind of passive intermod), or if in fact it becomes part of the signal I'm sending up to the ionosphere. To really figure that one out, I probably will need to make an actual distant AM contact and ask someone to tell me how it sounds... this may be no small feat with the way the sun is behaving lately, but I'll keep trying. Nick On Fri, 26 Apr 2019 at 19:18, Bob McGraw K4TAX <rmcg...@blomand.net> wrote: > I think Jim's concern, expressed earlier, about power line neutral > distortion components is valid. And it may be originating in "the big green > transformer" in the yard. > > Bob, K4TAX > > > Sent from my iPhone > > > On Apr 26, 2019, at 8:53 PM, Nicklas Johnson <n...@n6ol.us> wrote: > > > > Sorry for the additional email, but this is particularly interesting: it > > occurred to me that I'd never tried the reverse setup, so I put the KX3 > in > > transmit mode and 0.1W on AM in another room, and set the K3S on receive. > > And sure enough, the K3S immediately started picking up S40 of buzzing > > noise. However if I tune the K3S to an AM broadcast station or WWV, no > > buzz. So either both the K3S and KX3 are being affected on transmit in > the > > same way (which seems implausible but not impossible), or possibly > > something else is going on at my QTH. > > > > On the P3, I definitely see the noise when the KX3 is transmitting from > the > > other room. > > > > Now I wish I had a scope so I could see what the AM carrier generated by > > the KX3 and K3S looks like so I could tell if this is something that's > > happening inside the transmitter, or something that is happening because > of > > some outside influence mixing powerline noise with the AM carrier. The > > important thing to me is that the carrier I'm putting out there is > clean... > > if there's some local mixing that happens that means I can't listen to my > > own transmission without a buzz, I can live with that. > > > > One kind of curious thing is that there's also a superimposed "squeaky > > wheel" sound at random intervals detectable when the KX3 is transmitting > an > > AM carrier, and not otherwise, and also not when listening to WWV or AM > > broadcast, which vaguely seems to correlate with how windy it is at any > > given moment. Could all of this be a "rusty bolt" effect from something > in > > the vicinity? > > > > Nick > > > > > > > >> On Fri, 26 Apr 2019 at 18:11, Nicklas Johnson <n...@n6ol.us> wrote: > >> > >> A few more data points: > >> > >> Changing TX EQ, including cutting the first 4 bands all the way down to > >> -16 had no effect on the received signal. > >> > >> Plugging in some headphones, turning the TX Monitor up all the way, I > >> don't detect the hum in the TX monitor signal either in TX test mode, > >> transmitting into a dummy load, or even transmitting into the antenna > with > >> very low power. If I turn up the Line In level, I just hear expected > white > >> noise on the TX monitor. So at least as far along the path as the TX > >> monitor, there's no hum or buzz introduced. > >> > >> Switching the receiver (a KX3) to USB mode and using one leg of a > >> buddistick as an antenna so I can walk around, the noise received around > >> the house and outside is around S4 when transmitting about 100mW into > the > >> antenna, though it varies some as I walk around. > >> > >> I do have a set of power lines running through my back yard, and where I > >> live in San Mateo, you're always near somebody's wiring for something, > >> unfortunately... my neighbor's south wall is possibly as far as 8 feet > away > >> from my north wall, etc. > >> > >> It looks like two phases running along the top, then a transformer to > two > >> phases and a neutral along the bottom, to which people's houses are > >> connected. > >> > >> We also have underground utilities on our street, including a big green > >> transformer that sits in the corner of our front lawn. > >> > >> I think the next test will be to take the K3S and the KX3 some distance > >> away from all of these things and see if the hum goes away, and if it > does, > >> then figure out what thing the K3S needs to get away from in particular. > >> If it's the powerlines in my back yard or the transformer in my front > yard, > >> then that'll be a difficult problem. > >> > >> Nick > >> > >> > >> > >> On Fri, 26 Apr 2019 at 17:28, Bob McGraw K4TAX <rmcg...@blomand.net> > >> wrote: > >> > >>> Yes but the EQ is in the digital path. The EQ should be done there, > >>> preferably after the MIC input. The AM BW does not attenuate the end > like > >>> the SSB filter. > >>> > >>> I suggest -16 dB on the first 3 bands. > >>> > >>> Bob, K4TAX > >>> > >>> > >>> Sent from my iPhone > >>> > >>>> On Apr 26, 2019, at 6:38 PM, Nicklas Johnson <n...@n6ol.us> wrote: > >>>> > >>>> Flat, except I turned the first one down a few notches, which doesn't > >>>> really do much in my case because both the microphone and mixer that I > >>> use > >>>> (when they're actually connected) roll off below 150 and 80 Hz > >>>> respectively. It had previously been suggested to me that rolling off > >>> low > >>>> frequency cruft is a good idea for AM and SSB. > >>>> > >>>> Nick > >>>> > >>>>> On Fri, 26 Apr 2019 at 15:57, Bob McGraw K4TAX <rmcg...@blomand.net> > >>> wrote: > >>>>> > >>>>> I recall commenting earlier. What TX EQ values are being used for > AM. > >>> ? > >>>>> > >>>>> Bob, K4TAX > >>>>> > >>>>> > >>>>> Sent from my iPhone > >>>>> > >>>>>> On Apr 26, 2019, at 5:48 PM, Nicklas Johnson <n...@n6ol.us> wrote: > >>>>>> > >>>>>> My desk in this case sits adjacent a wall, and there's only a shower > >>> on > >>>>> the > >>>>>> other side of that wall. I did turn off everything in the vicinity > of > >>>>> the > >>>>>> desk and all the lights in the room (I've in fact heard a very > similar > >>>>> hum > >>>>>> from the switching power supply for my mixer, and my first thought > >>> was it > >>>>>> was this that was being picked up), but I didn't turn off the > >>> computer on > >>>>>> the other side of the room. In this case it will be easier to move > >>> the > >>>>> rig > >>>>>> outdoors with a battery than it will be to turn that computer off > for > >>> the > >>>>>> moment. It would have to be an impressively/obnoxiously strong > >>> magnetic > >>>>>> field from that side of the room to influence the transformers > inside > >>> the > >>>>>> rig 8 feet away, but it's worth trying and simple enough to rule it > >>> out. > >>>>>> > >>>>>> Nick > >>>>>> > >>>>>>> On Fri, 26 Apr 2019 at 14:51, Don Wilhelm <donw...@embarqmail.com> > >>>>> wrote: > >>>>>>> > >>>>>>> In addition to operating from a battery isolated from the solar > >>> system, > >>>>>>> I would recommend that you do a quick test - remove all cables from > >>> the > >>>>>>> K3S except the power cable and a coax to a dummy load. Power down > >>> all > >>>>>>> power supplies in your station, including any desk lamps. > >>>>>>> Go into Transmit by tapping the XMIT button. > >>>>>>> Is the hum still present? If not, then start connecting things to > >>> your > >>>>>>> K3S one at a time, doing the same test after each thing connected. > >>>>>>> > >>>>>>> Of course, if the hum is present with nothing connected, contact > >>>>>>> supp...@elecraft.com - but I cannot imagine a hum with harmonics > of > >>> 60 > >>>>>>> Hz being induced if you take away all the 60 Hz operated sources in > >>> the > >>>>>>> area. > >>>>>>> > >>>>>>> 73, > >>>>>>> Don W3FPR > >>>>>>> > >>>>>>> -- > >>>>>> *N6OL* > >>>>>> Saying something doesn't make it true. Belief in something doesn't > >>> make > >>>>> it > >>>>>> real. And if you have to lie to support a position, that position is > >>> not > >>>>>> worth supporting. > >>>>>> ______________________________________________________________ > >>>>>> 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 > >>>>>> > >>>>> > >>>>> > >>>> > >>>> -- > >>>> *N6OL* > >>>> Saying something doesn't make it true. Belief in something doesn't > >>> make it > >>>> real. And if you have to lie to support a position, that position is > not > >>>> worth supporting. > >>>> ______________________________________________________________ > >>>> 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 > >>>> > >>> > >>> > >>> > >> > >> -- > >> *N6OL* > >> Saying something doesn't make it true. Belief in something doesn't make > >> it real. And if you have to lie to support a position, that position is > not > >> worth supporting. > >> > > > > > > -- > > *N6OL* > > Saying something doesn't make it true. Belief in something doesn't make > it > > real. And if you have to lie to support a position, that position is not > > worth supporting. > > ______________________________________________________________ > > 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 > > > > > -- *N6OL* Saying something doesn't make it true. Belief in something doesn't make it real. And if you have to lie to support a position, that position is not worth supporting. ______________________________________________________________ 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
