RFI resistant Monitor
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On Sun,4/10/2016 10:44 PM, KC6CNN wrote:
> I just found that when the monitor is on it adds 2 bars of noise to my > meter. It is also turning off when I operate on certain bands. I had exactly that experience with a Samsung that W4UAT gave me because it did that in his shack too. It also makes RF noise. The good news is that not all Samsung monitors are RFI dogs. I have two recent model Samsungs in my house and four in the shack. They are designed to run on power supplies labeled 14VDC, and the supply they sell you is a switching power supply that makes RF noise. I throw those power supplies away, cut the attached power cable and attach red/black PowePoles, and run them from either the 12V battery system in my shack or a small 12V lead-acid cell that I float-charge from a linear 12V wall wart. I also use ferrite common mode chokes on both the video cable that runs to the computer and the power supply cable "just in case" some RF trash is conducted to those cables, which the cables could radiate. All that, and a lot more, is discussed in this "in progress" article for the National Contest Journal. k9yc.com/KillingReceiveNoise.pdf 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 KC6CNN
Gerald, I’ve been on the RFI noise hunt for several weeks with my system. Added the SVGA with a very nice LG 23-inch LED monitor (M45 23M45D). Perfect size to fit above the K3S and P3. I’ve managed to lower my noise floor to typically well below S1, and do notice the LG producing a tiny high pitched noise from it’s switching power supply. I would use my 12V PowerWerx, but the LG switching PS produces something like 27 volts. I’m confident I can reduce the tiny noise some more.
David A., KK6DA, Los Angeles > On Apr 10, 2016, at 10:44 PM, KC6CNN <[hidden email]> wrote: > > Hello Everyone. > I am running a Samsung 21 inch monitor on my Elecraft P3 SVGA. > I just found that when the monitor is on it adds 2 bars of noise to my > meter. > It is also turning off when I operate on certain bands. > Does anyone know of a good monitor to combat RFI and Noise. > I have had some local hams tell me to cut the power cable and run it from my > Astron and take out the switching power supply that came with the Samsung > monitor. > Any suggestions and thoughts are appreciated. Oh PS I do have a bunch of > beads on the cable from P3 to monitor and on the power cable. > > Thanks > Gerald > KC6CNN > > > > > ----- > KC6CNN - Gerald > K1 # 0014 > K2 # 5486 > K3 # 6294 > KX3 # 757 > -- > View this message in context: http://elecraft.365791.n2.nabble.com/RFI-resistant-Monitor-tp7616198.html > Sent from the Elecraft 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:[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] David Ahrendts [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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In reply to this post by Jim Brown-10
One thing I have noticed over the years is that the near-field noise is present with most any modern electronics. The switching frequency is between 200-300kHz and can be easily sniffed with a pocket AM radio (harmonics of that fundamental switching frequency are easily spotted with an AM radio). When I bring my CCrane Pocket Radio in the near field at the operating position, I can’t tune in the semi-local 600 KCOL out of Greely, CO. If I back up a few feet the noise level drops considerably and the station is audible again. The CC Pocket Radio has a fairly good front end with somewhat good selectivity but is still overloaded with IBOC noise.
I have battery chargers, an old Dell 1501 laptop, an external HD with switcher, the list goes on. Common mode noise and strong near-field noise is the bane of my ham radio existence in this RFI rich environment. Myron WV0H Printed on Recycled Data From: Jim Brown Sent: Monday, April 11, 2016 12:14 AM To: [hidden email] Subject: Re: [Elecraft] RFI resistant Monitor On Sun,4/10/2016 10:44 PM, KC6CNN wrote: > I just found that when the monitor is on it adds 2 bars of noise to my > meter. It is also turning off when I operate on certain bands. I had exactly that experience with a Samsung that W4UAT gave me because it did that in his shack too. It also makes RF noise. The good news is that not all Samsung monitors are RFI dogs. I have two recent model Samsungs in my house and four in the shack. They are designed to run on power supplies labeled 14VDC, and the supply they sell you is a switching power supply that makes RF noise. I throw those power supplies away, cut the attached power cable and attach red/black PowePoles, and run them from either the 12V battery system in my shack or a small 12V lead-acid cell that I float-charge from a linear 12V wall wart. I also use ferrite common mode chokes on both the video cable that runs to the computer and the power supply cable "just in case" some RF trash is conducted to those cables, which the cables could radiate. All that, and a lot more, is discussed in this "in progress" article for the National Contest Journal. k9yc.com/KillingReceiveNoise.pdf 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] ______________________________________________________________ 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 KC6CNN
Gerald,
I'm using a pair of AOC monitors. The 27" is the computer display; model E2752She Current cost $159, I bought it from http://www.bhphotovideo.com/ It was $139 when I bought it. Its easily worth the $159. It plugs into the wall socket, has been running 3 hours now and is cool to the touch. The P3 monitor is AOC 23" 12367F I paid something like $115 for it at Best Buy. It's easily worth much more. Runs on a 12V supply that looks like a laptop PS. It is cool to the touch and also been on for 3 hours. Zero issues with the noise level from either one. Absolutely beautiful quality for the video, makes the P3 SVGA come alive. Extremely low power consumption. 73, Gary KA1J > Hello Everyone. > I am running a Samsung 21 inch monitor on my Elecraft P3 SVGA. > I just found that when the monitor is on it adds 2 bars of noise to my > meter. > It is also turning off when I operate on certain bands. > Does anyone know of a good monitor to combat RFI and Noise. > I have had some local hams tell me to cut the power cable and run it from my > Astron and take out the switching power supply that came with the Samsung > monitor. > Any suggestions and thoughts are appreciated. Oh PS I do have a bunch of > beads on the cable from P3 to monitor and on the power cable. > > Thanks > Gerald > KC6CNN ______________________________________________________________ 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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I have 3 Acer monitors (one 19" square and two 23" wider screen). The
19" runs directly on 120VAC and the twp 23" ones have small switching mode power supplies that look like laptop supplies and put out 13.8/14 volts. The switcher supplies for these 2 monitors appear to be virtually noise free. At least I have not had any noise problems that I can attribute to them and they have been on the desk for several years now. My major noise source has always been the 7500 volt power lines that run across the South and West sides of my small city lot. Fortunately the utility company ran afoul of the FCC several years ago and they are very responsive to noise/interference calls. Jim - W0EB ______________________________________________________________ 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 thelastdb
May I encourage everyone to study the excellent work from Jim Brown, K9YC — he weighed in here and you’ll see his link below. I’m also taking his suggestion after careful study to replace the parallel zip line red-black cable with shielded twisted pair cable (18 AWG ) with the Anderson Power Poles connectors. The theory being that anything twisted will resist RFI while parallel cable invites it and generates it. A fist full of ferrites helps also. Getting surgical, but it really helps.
David A., KK6DA > On Apr 11, 2016, at 6:29 AM, Myron Schaffer <[hidden email]> wrote: > > One thing I have noticed over the years is that the near-field noise is present with most any modern electronics. The switching frequency is between 200-300kHz and can be easily sniffed with a pocket AM radio (harmonics of that fundamental switching frequency are easily spotted with an AM radio). When I bring my CCrane Pocket Radio in the near field at the operating position, I can’t tune in the semi-local 600 KCOL out of Greely, CO. If I back up a few feet the noise level drops considerably and the station is audible again. The CC Pocket Radio has a fairly good front end with somewhat good selectivity but is still overloaded with IBOC noise. > > I have battery chargers, an old Dell 1501 laptop, an external HD with switcher, the list goes on. Common mode noise and strong near-field noise is the bane of my ham radio existence in this RFI rich environment. > > Myron WV0H > Printed on Recycled Data > > From: Jim Brown > Sent: Monday, April 11, 2016 12:14 AM > To: [hidden email] > Subject: Re: [Elecraft] RFI resistant Monitor > > On Sun,4/10/2016 10:44 PM, KC6CNN wrote: >> I just found that when the monitor is on it adds 2 bars of noise to my >> meter. It is also turning off when I operate on certain bands. > > I had exactly that experience with a Samsung that W4UAT gave me because > it did that in his shack too. It also makes RF noise. The good news is > that not all Samsung monitors are RFI dogs. I have two recent model > Samsungs in my house and four in the shack. They are designed to run on > power supplies labeled 14VDC, and the supply they sell you is a > switching power supply that makes RF noise. I throw those power supplies > away, cut the attached power cable and attach red/black PowePoles, and > run them from either the 12V battery system in my shack or a small 12V > lead-acid cell that I float-charge from a linear 12V wall wart. > > I also use ferrite common mode chokes on both the video cable that runs > to the computer and the power supply cable "just in case" some RF trash > is conducted to those cables, which the cables could radiate. > > All that, and a lot more, is discussed in this "in progress" article for > the National Contest Journal. k9yc.com/KillingReceiveNoise.pdf > > 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] > > ______________________________________________________________ > 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] David Ahrendts [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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In reply to this post by Jim Sheldon
In the tutorial at the link posted, I wrote:
Evaluating Equipment For Noise: When someone tells you that XYZ equipment produces no noise on the ham bands because he can’t hear any noise in his radio, should you believe that the equipment is clean? NO! The equipment may be noisy but is not heard because it is being covered by other noise from the neighborhood. Figs 7 and 8 compare the daytime 80M spectra at K6GFJ in a San Jose residential neighborhood and K9YC 30 miles to the south in the Santa Cruz Mountains. The difference in the noise floor is 10 dB. And it’s certainly not dead quiet in the mountains, either – everything on the displays from both QTHs is noise from either switching power supplies or other electronic sources. Proximity to Antennas Is What Matters: Noise radiates from sources on wires that are connected to noise sources, and enters our receivers via our antennas. My SteppIR that’s up 120 ft and is 200 ft from the shack doesn’t hear much noise from the shack, but the 160M Tee vertical only 25 ft from the operating position does. When someone tells you that a particular model of internet router or video monitor sits next to his power amp and there’s no RFI, ask him how far it is from his antennas, not from his radio. 73, Jim K9YC On Mon,4/11/2016 7:43 AM, Jim Sheldon wrote: > The switcher supplies for these 2 monitors appear to be virtually > noise free. At least I have not had any noise problems that I can > attribute to them and they have been on the desk for several years now. > > My major noise source has always been the 7500 volt power lines that > run across the South and West sides of my small city lot. Fortunately > the utility company ran afoul of the FCC several years ago and they > are very responsive to noise/interference calls. ______________________________________________________________ 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 thelastdb
You'll find exactly these suggestions in the tutorial at the link I posted.
73, Jim K9YC On Mon,4/11/2016 6:29 AM, Myron Schaffer wrote: > > One thing I have noticed over the years is that the near-field noise > is present with most any modern electronics. The switching frequency > is between 200-300kHz and can be easily sniffed with a pocket AM radio > (harmonics of that fundamental switching frequency are easily spotted > with an AM radio). When I bring my CCrane Pocket Radio in the near > field at the operating position, I can’t tune in the semi-local 600 > KCOL out of Greely, CO. If I back up a few feet the noise level drops > considerably and the station is audible again. The CC Pocket Radio has > a fairly good front end with somewhat good selectivity but is still > overloaded with IBOC noise. > > I have battery chargers, an old Dell 1501 laptop, an external HD with > switcher, the list goes on. Common mode noise and strong near-field > noise is the bane of my ham radio existence in this RFI rich environment. > ______________________________________________________________ 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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