RX IQ USB Noise
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HI all
Me again, I have a problem with my setup and trying to work out what is wrong. I have a handy video, which shows my problem: https://www.youtube.com/watch?v=hZPYUVpqefI I hope somebody knows how to fix this, I've tried different USB hubs, different laptops even. I havent tried a different sound card though but then again I don't want to keep throwing money at a problem unless there is a less expensive way to fix this. Regards VK3FRAD ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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Hi,
This sounds like a 'hum loop' problem, the scourge of audio enthusiasts. In effect there are two earth connections between the KX3 and PC and it forms a small loop aerial where by it picks up mains interference. You could try running the cables from the KX3 to the PC very close together. It doesn't affect most people but I did get this problem a bit ago, but not with my KX3. The solution for me was to fit two small audio isolation transformers (one for each channel) in the IQ line, fitted in a small project box, and the problem went away. This has long been the recommended procedure for most audio lines between a PC and a rig. Hope this helps. Andrew G8BYB -----Original Message----- From: Elecraft [mailto:[hidden email]] On Behalf Of Enzo Adrian-Reyes Sent: 31 August 2016 08:43 To: Elecraft List Subject: [Elecraft] RX IQ USB Noise HI all Me again, I have a problem with my setup and trying to work out what is wrong. I have a handy video, which shows my problem: https://www.youtube.com/watch?v=hZPYUVpqefI I hope somebody knows how to fix this, I've tried different USB hubs, different laptops even. I havent tried a different sound card though but then again I don't want to keep throwing money at a problem unless there is a less expensive way to fix this. Regards VK3FRAD ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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Loop is absolutely the wrong way to view this problem, and transformers
are NOT the easiest or cheapest solution. The solution is 1) proper chassis-to-chassis BONDING between all of the equipment being interconnected and 2) get power for all of the interconnected equipment from the same mains outlet, or from outlets that share the same "green wire" (what is called the "protective earth" in Europe). 73, Jim K9YC . On Wed,8/31/2016 1:58 AM, Andrew Hebden wrote: > This sounds like a 'hum loop' problem, the scourge of audio enthusiasts. > In effect there are two earth connections between the KX3 and PC and it > forms a small loop aerial where by it picks up mains interference. You could > try running the cables from the KX3 to the PC very close together. > It doesn't affect most people but I did get this problem a bit ago, but not > with my KX3. The solution for me was to fit two small audio isolation > transformers (one for each channel) in the IQ line, fitted in a small > project box, and the problem went away. This has long been the recommended > procedure for most audio lines between a PC and a rig. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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This would be hard but I can see how that could happen.
The KX3 and the laptop use 2 prong connectors and this still happens, the macbook pro has a grounded power plug but this still happens. The stupid thing is they all share the same power board, so in theory they should all be sharing the same green wire. However The KX3 chassis is connected to a ground system independent than the electrical ground, the same way I thought hams connected their radio equipment to ground (through a ground rod). The problem I have is that I live near KVA power lines, and they induce a current on the shield of the coax, which if I dont ground the KX3 causes electrical build it which I can sense with my finger. So given what you have said the ground of the KX3 chassis is connected to the ground system for the radio, and this is causing the loop. However this means I cannot do what you suggest, as the ground in all the plugged elements is already connected to the green wire, except the KX3 whose power supply is a double isolated, except the chassis which is connected to the radio ground. I do not know how to solve this, my only work around for this would be to try to isolate the incoming current with arrestors at the entrance of the shack, but that might not get rid of this current. Regards On Thu, Sep 1, 2016 at 3:06 AM, Jim Brown <[hidden email]> wrote: > Loop is absolutely the wrong way to view this problem, and transformers > are NOT the easiest or cheapest solution. > > The solution is 1) proper chassis-to-chassis BONDING between all of the > equipment being interconnected and 2) get power for all of the > interconnected equipment from the same mains outlet, or from outlets that > share the same "green wire" (what is called the "protective earth" in > Europe). > > 73, Jim K9YC > > . On Wed,8/31/2016 1:58 AM, Andrew Hebden wrote: > >> This sounds like a 'hum loop' problem, the scourge of audio enthusiasts. >> In effect there are two earth connections between the KX3 and PC and it >> forms a small loop aerial where by it picks up mains interference. You >> could >> try running the cables from the KX3 to the PC very close together. >> It doesn't affect most people but I did get this problem a bit ago, but >> not >> with my KX3. The solution for me was to fit two small audio isolation >> transformers (one for each channel) in the IQ line, fitted in a small >> project box, and the problem went away. This has long been the recommended >> procedure for most audio lines between a PC and a rig. >> > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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You are concentrating on the "green-wire ground".
Instead concentrate on running a heavy wire or braid in parallel with your audio cables - it works. It may be difficult to get a chassis ground on the laptop but look for a jackscrew on one of the D-shell connectors. Worst case, run a wire around the shell of one of the audio cables at the laptop end and connect the bonding wire to that. What that bonding accomplishes is two things - it places the connected pieces of equipment at the same chassis potential, and secondly it provides a path for hum, buzz and noise from the chassis of one piece of equipment to the other. Consider that in most electronic gear, the connectors are "grounded" to the PC board(s) inside. Any hum, buzz and noise that is picked up by the shield of the connecting cables will be conducted onto the ground plane of the PC boards. The bonding wire conducts much of that garbage onto the outside outside of the equipment enclosure where it will be isolated from the working electronics. As far as the ground rod goes, I trust you have that ground rod connected (outside) to the utility entry ground rod with heavy wire - #6 but #4 is preferred. That is required not only to meet NEC requirements, but also for your personal safety. That ground is for AC mains and lightning safety - it is not a sink for hum, buzz and RF. 73, Don W3FPR On 8/31/2016 3:23 PM, Enzo Adrian-Reyes wrote: > This would be hard but I can see how that could happen. > The KX3 and the laptop use 2 prong connectors and this still happens, the > macbook pro has a grounded power plug > but this still happens. > > The stupid thing is they all share the same power board, so in theory they > should all be sharing the same green wire. > > However > > The KX3 chassis is connected to a ground system independent than the > electrical ground, the same way I thought hams connected their radio > equipment to ground (through a ground rod). The problem I have is that I > live near KVA power lines, and they induce a current on the shield of the > coax, which if I dont ground the KX3 causes electrical build it which I can > sense with my finger. > > So given what you have said the ground of the KX3 chassis is connected to > the ground system for the radio, and this is causing the loop. > However this means I cannot do what you suggest, as the ground in all the > plugged elements is already connected to the green wire, except the KX3 > whose power supply is a double isolated, except the chassis which is > connected to the radio ground. > > I do not know how to solve this, my only work around for this would be to > try to isolate the incoming current with arrestors at the entrance of the > shack, but that might not get rid of this current. > > Regards > > > On Thu, Sep 1, 2016 at 3:06 AM, Jim Brown <[hidden email]> wrote: > >> Loop is absolutely the wrong way to view this problem, and transformers >> are NOT the easiest or cheapest solution. >> >> The solution is 1) proper chassis-to-chassis BONDING between all of the >> equipment being interconnected and 2) get power for all of the >> interconnected equipment from the same mains outlet, or from outlets that >> share the same "green wire" (what is called the "protective earth" in >> Europe). >> >> 73, Jim K9YC >> >> ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by Enzo Adrian-Reyes
You are NOT grasping the problem or the suggested solution.
Please do yourself a favor and go read K9YC's white papers on bonding/grounding, noise reduction, EMI/RFI reduction, etc.... Just do it... ______________________ Clay Autery, KY5G MONTAC Enterprises (318) 518-1389 On 8/31/2016 2:23 PM, Enzo Adrian-Reyes wrote: > This would be hard but I can see how that could happen. > The KX3 and the laptop use 2 prong connectors and this still happens, the > macbook pro has a grounded power plug > but this still happens. > > The stupid thing is they all share the same power board, so in theory they > should all be sharing the same green wire. > > However > > The KX3 chassis is connected to a ground system independent than the > electrical ground, the same way I thought hams connected their radio > equipment to ground (through a ground rod). The problem I have is that I > live near KVA power lines, and they induce a current on the shield of the > coax, which if I dont ground the KX3 causes electrical build it which I can > sense with my finger. > > So given what you have said the ground of the KX3 chassis is connected to > the ground system for the radio, and this is causing the loop. > However this means I cannot do what you suggest, as the ground in all the > plugged elements is already connected to the green wire, except the KX3 > whose power supply is a double isolated, except the chassis which is > connected to the radio ground. > > I do not know how to solve this, my only work around for this would be to > try to isolate the incoming current with arrestors at the entrance of the > shack, but that might not get rid of this current. > > Regards > > > On Thu, Sep 1, 2016 at 3:06 AM, Jim Brown <[hidden email]> wrote: > >> Loop is absolutely the wrong way to view this problem, and transformers >> are NOT the easiest or cheapest solution. >> >> The solution is 1) proper chassis-to-chassis BONDING between all of the >> equipment being interconnected and 2) get power for all of the >> interconnected equipment from the same mains outlet, or from outlets that >> share the same "green wire" (what is called the "protective earth" in >> Europe). >> >> 73, Jim K9YC >> Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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