Re: [Elecraft] KX3: nearby noise post-mortem
My guess would be that the local oscillator of the KX3 (which is on the rx qrg) is emitted via the shield of the coax cable (common mode?) received by the charger's usb cable, modulated with the 60Hz by non-linearities in the charger and than re-emitted (maybe by the wiring a a whole) and then received by your antenna. If you turn on the 8khz shift, the re-emitted hum-modulated signal is 8khz away from your rx qrg and if you dissconnect the shield, the antenna that transmits the local oscillator is missing. Maybe a current mode choke close to the KX3 and one at the antenna's feed point will stop this from happen. Did you try to switch on and off the isolator amplifier in the KX3? The mechanism is called Ortssenderproblem (local station problem) in german and means that every rf signal is detected by the wiring in the house, modulated by the 60Hz hum by the non-linearities and then re-emitted. With my indoor antenna and a funcube SDR, all signals consist of one direct and one re-emitted part and almost all signals I find are either 50 or 100 Hz modulated (sidebands about 40 dB down). I can even see the local oscillator of my battery powered KX3 (weak) and the 100 Hz sidebands. When I got my KX3, I connected it to a piece of wire lying on the floor for initial testing and was having the same problem, but switching on the ISO amp in the menu solved it for me as did the 8khz feature and turning on the 10dB preamp. Normally the antenna is far away from the wiring and the re-emitted signal is much weaker than the original signal, but if the only signal is the local oscillator, this is possibly not true and the fraction re-emitted by the wiring is stronger than the original local oscillator. Greetings Ralf, DL6OAP __ 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
Re: [Elecraft] KX3: nearby noise post-mortem
Nick, The wire should run outside. It can and should be buried. It does not have to be down very far, but deep enough it will not be damaged by the lawn mower or shovels if you should dig in that area. A perimeter wire around the house would not be a bad idea either, it can divert a lightning surge such that it does not punch a hole in the foundation. If you are also using the wire for that kind of protection, it should have a ground stake each place where the wire makes a turn - lightning likes to move in a straight path. 73, Don W3FPR On 2/10/2014 12:29 AM, Nicklas Johnson wrote: That's a really good point, and in fact I have it on my 'to do' list to get the bonding done correctly. It's complicated by the ground rods being on the opposite side of the house, and the utilities running underground without an exposed ground stake by the utility box outside. I think code also won't let me run conduit under the house in the crawl space, so it has to go around the outside of the house, and then somehow safely/correctly enter the utility box and connect to the utility ground bus. I wonder if code allows the conduit to run through a garage, and if it'll be okay to run up the wall about 8' to get through it and be out of the way or if it's okay to run it along the roof line rather than along the ground (I think along the ground would be preferable)... ... Maybe it'll be best to hire someone to handle that part. Definitely agree it needs to be done, and I've already been planning it out / waiting for a tax refund. Nick On February 9, 2014 9:01:09 PM PST, Don Wilhelm w3...@embarqmail.com wrote: Nick, I suspect your antenna ground stakes were not connected to the utility entry ground rod with a #6 or larger copper wire. The earth creates resistance between the antenna ground stake(s) and the AC ground in your home. __ 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
Re: [Elecraft] KX3: nearby noise post-mortem
Now that you mention it, I did notice the buzz went away when I turned on the preamp, but I thought it was just my imagination or that the static had just become sufficiently loud that my own hearing wasn't responding to it anymore. Nick On 10 February 2014 03:02, Ralf Wilhelm r...@super-deutschland.net wrote: When I got my KX3, I connected it to a piece of wire lying on the floor for initial testing and was having the same problem, but switching on the ISO amp in the menu solved it for me as did the 8khz feature and turning on the 10dB preamp. Normally the antenna is far away from the wiring and the re-emitted signal is much weaker than the original signal, but if the only signal is the local oscillator, this is possibly not true and the fraction re-emitted by the wiring is stronger than the original local oscillator. -- *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
Re: [Elecraft] KX3: nearby noise post-mortem
Hi Nick, Turning on the preamp increases the isolation between the local oscillator and the antenna port. I also wasn't sure if my buzz went away when I turned on the preamp (I couldn't hear it any more) but I used the spectral display of the MixW-Software and the microphone of my laptop to check and I found it didn't go completely away (was still visible in the waterfall) but got much weaker... Greetings Ralf, DL6OAP Am 10.02.2014 um 15:52 schrieb Nicklas Johnson Now that you mention it, I did notice the buzz went away when I turned on the preamp, but I thought it was just my imagination or that the static had just become sufficiently loud that my own hearing wasn't responding to it anymore. Nick On 10 February 2014 03:02, Ralf Wilhelm r...@super-deutschland.net wrote: When I got my KX3, I connected it to a piece of wire lying on the floor for initial testing and was having the same problem, but switching on the ISO amp in the menu solved it for me as did the 8khz feature and turning on the 10dB preamp. Normally the antenna is far away from the wiring and the re-emitted signal is much weaker than the original signal, but if the only signal is the local oscillator, this is possibly not true and the fraction re-emitted by the wiring is stronger than the original local oscillator. -- 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
Re: [Elecraft] KX3: nearby noise post-mortem
Interesting, and if I may ask a potentially-dumb question, what do we really mean when we use the word isolation in this context, and how does it provide the benefit of keeping the buzz out of the detector (or to ask the question in the reverse, how does the buzz get in, in the absence of additional isolation)? Nick On 10 February 2014 08:40, Ralf Wilhelm r...@super-deutschland.net wrote: Hi Nick, Turning on the preamp increases the isolation between the local oscillator and the antenna port. I also wasn't sure if my buzz went away when I turned on the preamp (I couldn't hear it any more) but I used the spectral display of the MixW-Software and the microphone of my laptop to check and I found it didn't go completely away (was still visible in the waterfall) but got much weaker... -- *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
Re: [Elecraft] KX3: nearby noise post-mortem
The problem with all receivers using a local oscillator (direct conversion or superhet) is that they emit a small part of the local oscillator power via the mixer to the antenna port (maybe a typical number of L.O. to R.F. Port Isolation of a mixer is 40 dB or something like that). In a superhet, the local oscillator's frequency is far away from the rx frequency and the front end filtering keeps the oscillator signal from leaving the RX. In a direct conversion RX, the oscillator is on the same frequency as the RX. So basically, you have a very little transmitter that is always exactly on your rx frequency. In principle, this signal can be reflected by some structure and get back into the receiver (which would cause a d.c. offset) or in your (and my) case, it can be absorbed by the wiring, modulated by the 60/120 Hz in one of the power supplies and than be re-emitted by the wiring before being received via the antenna. In this case, you receive a carrier plus 60 Hz sidebands, but the carrier is at zero beat so you only hear the sidebands. The additional isolation (the oscillator signal tries to pass the amp in the wrong direction) of the preamp makes the emitted fraction of the local oscillator power maybe 20 dB weaker so that is buried in the atmospheric noise. 73, Ralf, DL6OAP Am 10.02.2014 um 17:49 schrieb Nicklas Johnson n...@n6ol.us: Interesting, and if I may ask a potentially-dumb question, what do we really mean when we use the word isolation in this context, and how does it provide the benefit of keeping the buzz out of the detector (or to ask the question in the reverse, how does the buzz get in, in the absence of additional isolation)? Nick On 10 February 2014 08:40, Ralf Wilhelm r...@super-deutschland.net wrote: Hi Nick, Turning on the preamp increases the isolation between the local oscillator and the antenna port. I also wasn't sure if my buzz went away when I turned on the preamp (I couldn't hear it any more) but I used the spectral display of the MixW-Software and the microphone of my laptop to check and I found it didn't go completely away (was still visible in the waterfall) but got much weaker... -- 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
Re: [Elecraft] KX3: nearby noise post-mortem
Makes sense. And that's why the RX SHFT also works, because then the reflected signal is shifted away from the RX frequency by the same amount as the shift. That was a great explanation, and I thank you for it! Another solution in my case, then, might be to just move the antenna further away from the house so the local oscillator's signal isn't mixed with and reflected by the house wiring (and/or whatever may be plugged into it). I noticed that I didn't have the same problem with the inverted-V dipole up on the roof, I imagine in part because it's so much further away from the house wiring (and the house). Nick On 10 February 2014 09:40, Ralf Wilhelm r...@super-deutschland.net wrote: The problem with all receivers using a local oscillator (direct conversion or superhet) is that they emit a small part of the local oscillator power via the mixer to the antenna port (maybe a typical number of L.O. to R.F. Port Isolation of a mixer is 40 dB or something like that). In a superhet, the local oscillator's frequency is far away from the rx frequency and the front end filtering keeps the oscillator signal from leaving the RX. In a direct conversion RX, the oscillator is on the same frequency as the RX. So basically, you have a very little transmitter that is always exactly on your rx frequency. In principle, this signal can be reflected by some structure and get back into the receiver (which would cause a d.c. offset) or in your (and my) case, it can be absorbed by the wiring, modulated by the 60/120 Hz in one of the power supplies and than be re-emitted by the wiring before being received via the antenna. In this case, you receive a carrier plus 60 Hz sidebands, but the carrier is at zero beat so you only hear the sidebands. The additional isolation (the oscillator signal tries to pass the amp in the wrong direction) of the preamp makes the emitted fraction of the local oscillator power maybe 20 dB weaker so that is buried in the atmospheric noise. -- *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
Re: [Elecraft] KX3: nearby noise post-mortem
You have written earlier that you could pull the coax plug half out (disconnecting the shield) and that this also helped. So maybe you have common mode current on the coax which would also increase the coupling to the wiring (because not only the antenna itself but also the coax would emit the local oscillator). Since this could also increase the risk of r.f.i. when you transmit I would recommend that you add a common mode current choke (a few windings of the coax?) close to the rig - and a second one near the antenna perhaps... Greetings Ralf, DL6OAP Am 10.02.2014 um 18:49 schrieb Nicklas Johnson n...@n6ol.us: Makes sense. And that's why the RX SHFT also works, because then the reflected signal is shifted away from the RX frequency by the same amount as the shift. That was a great explanation, and I thank you for it! Another solution in my case, then, might be to just move the antenna further away from the house so the local oscillator's signal isn't mixed with and reflected by the house wiring (and/or whatever may be plugged into it). I noticed that I didn't have the same problem with the inverted-V dipole up on the roof, I imagine in part because it's so much further away from the house wiring (and the house). Nick On 10 February 2014 09:40, Ralf Wilhelm r...@super-deutschland.net wrote: The problem with all receivers using a local oscillator (direct conversion or superhet) is that they emit a small part of the local oscillator power via the mixer to the antenna port (maybe a typical number of L.O. to R.F. Port Isolation of a mixer is 40 dB or something like that). In a superhet, the local oscillator's frequency is far away from the rx frequency and the front end filtering keeps the oscillator signal from leaving the RX. In a direct conversion RX, the oscillator is on the same frequency as the RX. So basically, you have a very little transmitter that is always exactly on your rx frequency. In principle, this signal can be reflected by some structure and get back into the receiver (which would cause a d.c. offset) or in your (and my) case, it can be absorbed by the wiring, modulated by the 60/120 Hz in one of the power supplies and than be re-emitted by the wiring before being received via the antenna. In this case, you receive a carrier plus 60 Hz sidebands, but the carrier is at zero beat so you only hear the sidebands. The additional isolation (the oscillator signal tries to pass the amp in the wrong direction) of the preamp makes the emitted fraction of the local oscillator power maybe 20 dB weaker so that is buried in the atmospheric noise. -- 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
Re: [Elecraft] KX3: nearby noise post-mortem
You can never completely achieve isolation, but as a practical matter Isolation is adequate when feed through of the offending signal is no longer a problem because the circuits involved can handle the magnitude of interference that is present. So the magnitude is subjective. The buzz heard is probably a beat between two oscillators an when the magnitude is reduced to the point you are not offended by it it is gone. Willis 'Cookie' Cooke, TDXS DX Chairman K5EWJ Trustee N5BPS, USS Cavalla, USS Stewart From: Nicklas Johnson n...@n6ol.us To: Ralf Wilhelm r...@super-deutschland.net Cc: elecraft elecraft@mailman.qth.net Sent: Monday, February 10, 2014 10:49 AM Subject: Re: [Elecraft] KX3: nearby noise post-mortem Interesting, and if I may ask a potentially-dumb question, what do we really mean when we use the word isolation in this context, and how does it provide the benefit of keeping the buzz out of the detector (or to ask the question in the reverse, how does the buzz get in, in the absence of additional isolation)? Nick On 10 February 2014 08:40, Ralf Wilhelm r...@super-deutschland.net wrote: Hi Nick, Turning on the preamp increases the isolation between the local oscillator and the antenna port. I also wasn't sure if my buzz went away when I turned on the preamp (I couldn't hear it any more) but I used the spectral display of the MixW-Software and the microphone of my laptop to check and I found it didn't go completely away (was still visible in the waterfall) but got much weaker... -- *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 __ 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
Re: [Elecraft] KX3: nearby noise post-mortem
I think that is very likely to be the case, yes. It's worth noting that it is a somewhat badly unbalanced antenna at the moment. Normally it would have a set of el-cheapo tape measures attached as radials, but the weather and time have not been kind to them, so they're not currently attached... the only ground is the actual earth ground at the base of the antenna. So I won't be even a tiny bit surprised to find no shortage of common-mode problems on the shield. I think I keep a spare length of coax around here somewhere that can be readily wound around a coffee can to make a common-mode choke when needed. Will be interesting to see if that is enough to clear up the detection problem, too. Nick On 10 February 2014 10:18, Ralf Wilhelm r...@super-deutschland.net wrote: You have written earlier that you could pull the coax plug half out (disconnecting the shield) and that this also helped. So maybe you have common mode current on the coax which would also increase the coupling to the wiring (because not only the antenna itself but also the coax would emit the local oscillator). Since this could also increase the risk of r.f.i. when you transmit I would recommend that you add a common mode current choke (a few windings of the coax?) close to the rig - and a second one near the antenna perhaps... -- *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
Re: [Elecraft] KX3: nearby noise post-mortem
Check your light bulbs, especially if using CFL or LED. I have had both emitting bad noise. Shutting them off rid my whole station of the issue. Bill K9YEQ -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Nicklas Johnson Sent: Sunday, February 9, 2014 10:11 PM To: mzil...@roadrunner.com; elecraft Subject: Re: [Elecraft] KX3: nearby noise post-mortem I should have mentioned this specifically, but I was operating the KX3 strictly from batteries at the time. Connecting a 13.8V source to it (one that was plugged into the house power) didn't really change whether the 'buzz' was present or not. The only thing that changed it was either unplugging the offending power supply, or de-energizing that circuit in the house (by tripping the breaker). I guess it's not impossible that the thing was putting off a lot more energy than I thought, and I was picking up a lot of common-mode noise on the cable shield-- a lot more than I thought I would/should. Good ideas though. Nick On 9 February 2014 20:05, Matt Zilmer mzil...@roadrunner.com wrote: Hi Nick, After reading your reply, I think I have an idea. I've had the same problem in a mobile setting, where good grounds are scarce and there is a lot of transient noise around. If -somehow- the noise put off by the charger were to get onto the 12V line into the KX3, you might get this effect. I don't see how this could happen though. -- *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 __ 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] KX3: nearby noise post-mortem
Hi all, I'm trying to make sure that I understand something kind of weird that I ran across today; I hate resolving a problem without fully appreciating everything that was causing it. Since 10M was pretty active today, I thought I'd pop on, and since the ground was nice and wet, I thought I'd give my Home Depot ground-mounted vertical a go. (It's a vertical made entirely out of things you'd find in Home Depot's plumbing, lumber, and window departments. I didn't have the tape-measure radials connected today, just the ground stakes around it.) Midway through the day I started picking up what looked and sounded like a 60Hz + harmonics buzz. I did not have a power supply connected to the KX3, and I pulled all the other connectors from the computer to make sure I wasn't getting some kind of ground loop hum. No dice. To make matters more interesting if I backed the antenna connector halfway off, such that the ground was no longer connected, the hum disappeared. I started worrying that I was having some trouble with the local utility, but decided I'd better rule out something in the house first. Through the course of troubleshooting, I came to find the culprit was a USB phone charger on the other side of the wall from the antenna, with the USB cable stretched out across the floor. Unplugging it or disconnecting the USB cable mostly made the noise go away (but not entirely, though there are so many different power supplies and things inside the house, there could be multiple sources of noise, too). I mostly sorted the problem by winding the proximal end of the USB cable about 6 times through a ferrite core, though a small amount of noise remained just by virtue of the thing being plugged in at all. Then I noticed that tuning up or down a few Hz had no effect at all on where the noise showed up in the waterfall, which got me wondering if it was a noise getting picked up in decoding. I set the RX SHFT setting to 8.0, and indeed, the noise disappeared entirely. I don't completely understand the why part of what happened here... that is to say, why did it change based on whether the ground side of the antenna was connected or not, and why did changing the RX SHFT get rid of it? (Also I note that the ground is particularly wet and conductive today, which may or may not be a factor in why I noticed it today.) Any thoughts? Nick -- *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
Re: [Elecraft] KX3: nearby noise post-mortem
Hi Nick, RX SHFT is normally used to cancel the effects of AM detection of very strong signals that blow by the mixer and enter the detector - overload. Since enabling RX SHFT cured this 60Hz+harmonics problem, it seems likely that you were copying a strong signal with little or no modulation. You may have been hearing the transmitter's power supply ripple. Is your QTH near a broadcast station or military facility? I've come across a similar problem once in a while when operating portable. Usually, the signal comes out as station audio that can't be tuned away from. A couple years ago, I had exactly the same symptoms (never could explain the _what_ part) and RX SHFT was what I used to solve it. It also works well on the OM down the street that operates with all gain controls set to 11. :) 73, matt W6NIA On Sun, 9 Feb 2014 17:06:13 -0800, you wrote: Hi all, I'm trying to make sure that I understand something kind of weird that I ran across today; I hate resolving a problem without fully appreciating everything that was causing it. Since 10M was pretty active today, I thought I'd pop on, and since the ground was nice and wet, I thought I'd give my Home Depot ground-mounted vertical a go. (It's a vertical made entirely out of things you'd find in Home Depot's plumbing, lumber, and window departments. I didn't have the tape-measure radials connected today, just the ground stakes around it.) Midway through the day I started picking up what looked and sounded like a 60Hz + harmonics buzz. I did not have a power supply connected to the KX3, and I pulled all the other connectors from the computer to make sure I wasn't getting some kind of ground loop hum. No dice. To make matters more interesting if I backed the antenna connector halfway off, such that the ground was no longer connected, the hum disappeared. I started worrying that I was having some trouble with the local utility, but decided I'd better rule out something in the house first. Through the course of troubleshooting, I came to find the culprit was a USB phone charger on the other side of the wall from the antenna, with the USB cable stretched out across the floor. Unplugging it or disconnecting the USB cable mostly made the noise go away (but not entirely, though there are so many different power supplies and things inside the house, there could be multiple sources of noise, too). I mostly sorted the problem by winding the proximal end of the USB cable about 6 times through a ferrite core, though a small amount of noise remained just by virtue of the thing being plugged in at all. Then I noticed that tuning up or down a few Hz had no effect at all on where the noise showed up in the waterfall, which got me wondering if it was a noise getting picked up in decoding. I set the RX SHFT setting to 8.0, and indeed, the noise disappeared entirely. I don't completely understand the why part of what happened here... that is to say, why did it change based on whether the ground side of the antenna was connected or not, and why did changing the RX SHFT get rid of it? (?Also I note that the ground is particularly wet and conductive today, which may or may not be a factor in why I noticed it today.) Any thoughts? Nick? __ 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
Re: [Elecraft] KX3: nearby noise post-mortem
In this case the 'transmitter' was the switching power supply in a USB cell phone charger plugged into an outlet in relatively close proximity to the antenna (other side of the wall of the house). The charger plugged in by itself put off a little noise. With the USB cable plugged into it and stretched out across the floor, it put off a lot more noise (until I added a ferrite to it). Unplugging the charger or switching off the circuit breaker to that side of the house also would make the noise go away (for the most part... but there are a lot of random little cheap switching power supplies in the house that get picked up to some degree). I'm a little stumped about how the noise put off by these little things could be so strong as to blow past the mixer and get into the detector, unless it's just the close proximity to the antenna (probably 2-3 feet). There's little question that it was, though, given its lack of movement when changing QRG (and this was USB) and the fact that it went away by changing RX SHFT. Extra weird is that it seemed to be getting picked up by the ground connection (or maybe the cable shield). Nick On 9 February 2014 18:37, Matt Zilmer mzil...@roadrunner.com wrote: Hi Nick, RX SHFT is normally used to cancel the effects of AM detection of very strong signals that blow by the mixer and enter the detector - overload. Since enabling RX SHFT cured this 60Hz+harmonics problem, it seems likely that you were copying a strong signal with little or no modulation. You may have been hearing the transmitter's power supply ripple. Is your QTH near a broadcast station or military facility? I've come across a similar problem once in a while when operating portable. Usually, the signal comes out as station audio that can't be tuned away from. A couple years ago, I had exactly the same symptoms (never could explain the _what_ part) and RX SHFT was what I used to solve it. It also works well on the OM down the street that operates with all gain controls set to 11. :) 73, matt W6NIA -- *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
Re: [Elecraft] KX3: nearby noise post-mortem
Hi Nick, After reading your reply, I think I have an idea. I've had the same problem in a mobile setting, where good grounds are scarce and there is a lot of transient noise around. If -somehow- the noise put off by the charger were to get onto the 12V line into the KX3, you might get this effect. I don't see how this could happen though. When I isolated the KX3 from the vehicle electrical system, the various annoying buzzes, hums and clicks disappeared. So yes, I think your problem might be something like this, or maybe grounding. Since the KX3 is designed to work from batteries (er, high-quality power sources), anything else might have the effect you described. Incidentally, in my mobile setup, turning on RX SHFT caused all the odd vehicle electrical system noises to vanish. So your problem might be something similar, but without the vehicle involved... 73, matt W6NIA On Sun, 9 Feb 2014 19:28:05 -0800, you wrote: In this case the 'transmitter' was the switching power supply in a USB cell phone charger plugged into an outlet in relatively close proximity to the antenna (other side of the wall of the house). The charger plugged in by itself put off a little noise. With the USB cable plugged into it and stretched out across the floor, it put off a lot more noise (until I added a ferrite to it). Unplugging the charger or switching off the circuit breaker to that side of the house also would make the noise go away (for the most part... but there are a lot of random little cheap switching power supplies in the house that get picked up to some degree). ?I'm a little stumped about how the noise put off by these little things could be so strong as to blow past the mixer and get into the detector, unless it's just the close proximity to the antenna (probably 2-3 feet). There's little question that it was, though, given its lack of movement when changing QRG (and this was USB) and the fact that it went away by changing RX SHFT. Extra weird is that it seemed to be getting picked up by the ground connection (or maybe the cable shield).? ? Nick? On 9 February 2014 18:37, Matt Zilmer mzil...@roadrunner.com wrote: Hi Nick, RX SHFT is normally used to cancel the effects of AM detection of very strong signals that blow by the mixer and enter the detector - overload. Since enabling RX SHFT cured this 60Hz+harmonics problem, it seems likely that you were copying a strong signal with little or no modulation. You may have been hearing the transmitter's power supply ripple. Is your QTH near a broadcast station or military facility? I've come across a similar problem once in a while when operating portable. Usually, the signal comes out as station audio that can't be tuned away from. A couple years ago, I had exactly the same symptoms (never could explain the _what_ part) and RX SHFT was what I used to solve it. It also works well on the OM down the street that operates with all gain controls set to 11. :) 73, matt W6NIA Matt Zilmer, W6NIA -- Give me six hours to chop down a tree and I will spend the first four sharpening the axe. -A. Lincoln __ 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
Re: [Elecraft] KX3: nearby noise post-mortem
I should have mentioned this specifically, but I was operating the KX3 strictly from batteries at the time. Connecting a 13.8V source to it (one that was plugged into the house power) didn't really change whether the 'buzz' was present or not. The only thing that changed it was either unplugging the offending power supply, or de-energizing that circuit in the house (by tripping the breaker). I guess it's not impossible that the thing was putting off a lot more energy than I thought, and I was picking up a lot of common-mode noise on the cable shield-- a lot more than I thought I would/should. Good ideas though. Nick On 9 February 2014 20:05, Matt Zilmer mzil...@roadrunner.com wrote: Hi Nick, After reading your reply, I think I have an idea. I've had the same problem in a mobile setting, where good grounds are scarce and there is a lot of transient noise around. If -somehow- the noise put off by the charger were to get onto the 12V line into the KX3, you might get this effect. I don't see how this could happen though. -- *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
Re: [Elecraft] KX3: nearby noise post-mortem
I'm puzzled by all of this, Nick. I'll think on it. 73, matt W6NIA On Sun, 9 Feb 2014 20:11:13 -0800, you wrote: I should have mentioned this specifically, but I was operating the KX3 strictly from batteries at the time. Matt Zilmer, W6NIA -- Give me six hours to chop down a tree and I will spend the first four sharpening the axe. -A. Lincoln __ 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
Re: [Elecraft] KX3: nearby noise post-mortem
Nick, I suspect your antenna ground stakes were not connected to the utility entry ground rod with a #6 or larger copper wire. The earth creates resistance between the antenna ground stake(s) and the AC ground in your home. Now, that USB phone charger power supply connects to at least the AC neutral, which is in turn connected to the grounding point at the entry panel. There is a lot of wire there to carry noise. That noise can be induced as a voltage between your antenna ground and the electrical system ground due to the resistance between the different ground points. That circuit includes your coax shield, and is then carried onto the board ground and enclosure of the KX3. I strongly suspect that is the reason the noise was not heard when you removed the coax shield from the KX3 is because the KX3 board and enclosure grounds were then isolated from that 'sneak' circuit. This is one minor reason that all ground rods should be connected to the utility ground - in this case it was a noise producing inconvenience, but in case of a fault in your home electrical system, a dangerous voltage could develop between the two ground points. Bottom line - connect all grounds to the utility entry ground for safety purposes, and hopefully it can also reduce noise generated by devices in your home in your received signal. Such ground rod connections are a requirement of the National Electrical Code because it can be a safety hazard. If the two grounds are more than 100 feet apart, then they do not have to be connected for safety (according to NEC, but consider that if your coax shield is connected to that remote ground stake and runs into your home, the same safety consideration exists between your coax shield and any AC grounding point, so in the case of antenna ground rods, they should be connected no matter what the distance. NEC requires they be connected using #6 or larger wire. Certainly with the price of copper, it is expensive to connect the ground rods, but what is the safety of your family or anyone who may be in your home worth? 73, Don W3FPR On 2/9/2014 8:06 PM, Nicklas Johnson wrote: and I pulled all the other connectors from the computer to make sure I wasn't getting some kind of ground loop hum. No dice. To make matters more interesting if I backed the antenna connector halfway off, such that the ground was no longer connected, the hum disappeared. I started worrying that I was having some trouble with the local utility, but decided I'd better rule out something in the house first. Through the course of troubleshooting, I came to find the culprit was a USB phone charger on the other side of the wall from the antenna, with the USB cable stretched out across the floor. Unplugging it or disconnecting the USB cable mostly made the noise go away (but not entirely, though there are so many different power supplies and things inside the house, there could be multiple sources of noise, too). __ 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
Re: [Elecraft] KX3: nearby noise post-mortem
That's a really good point, and in fact I have it on my 'to do' list to get the bonding done correctly. It's complicated by the ground rods being on the opposite side of the house, and the utilities running underground without an exposed ground stake by the utility box outside. I think code also won't let me run conduit under the house in the crawl space, so it has to go around the outside of the house, and then somehow safely/correctly enter the utility box and connect to the utility ground bus. I wonder if code allows the conduit to run through a garage, and if it'll be okay to run up the wall about 8' to get through it and be out of the way or if it's okay to run it along the roof line rather than along the ground (I think along the ground would be preferable)... ... Maybe it'll be best to hire someone to handle that part. Definitely agree it needs to be done, and I've already been planning it out / waiting for a tax refund. Nick On February 9, 2014 9:01:09 PM PST, Don Wilhelm w3...@embarqmail.com wrote: Nick, I suspect your antenna ground stakes were not connected to the utility entry ground rod with a #6 or larger copper wire. The earth creates resistance between the antenna ground stake(s) and the AC ground in your home. __ 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
