How to Eliminate Power Supply Birdies?
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I have an Alinco DM-330MVT power supply that has significant birdies on
160M. The power supply has a nice feature that allows you to move the birdies, which makes it obvious that the birdies are originating from the power supply. The birdies are at least 1 S-unit above the background noise. Here's what I've done to try to eliminate them: - added a filter connected to the DC output consisting of 4 toroid beads (type 77) in series on each side and 0.1 caps across the leads and from each lead to ground. I also have both leads going about 10 turns through a type 77 toroid to filter common mode birdies. - I've put 2 snap on type toroids on the AC line as well as wound the ac cord through a T200-1 toroid (which I had lying around) . - I shielded all of the power leads from the power supply to all of the equipment that it powers (mostly my K2, KAT100 and external speaker/amp), with the shields connected to both the power supply and the K2 chassis grounds. - I've moved the power supply away from my K2 (about 5' away). All of this seems to have absolutely no affect on the birdies. To add to the mystery, the birdies are there only when I have an antenna connected to the K2, so it would appear that the Power supply is radiating, but with all of the wires to it filtered and the DC lines shielded, where can it be radiating from - (as a test I put the whole power supply inside a metal file box and grounded that to no effect. So, can anyone explain this? Other than buying a new power supply, what do I do now? Except for the birdies on 160M, this is a nice power supply that's small enough to fit into an attaché case with my K2, KAT100, mic and key. Thanks. Bob W1SRB ______________________________________________________________ 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 |
Re: How to Eliminate Power Supply Birdies?
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Exactly why I sold mine. It is noisey and basically worthless to me.
Perhaps the newer ones work better. I am using other more recent switching supplies that don't give me any issues and they are a whole lot less expensive. 73, Bill K9YEQ -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Bob Sent: Monday, January 11, 2010 6:30 PM To: [hidden email] Subject: [Elecraft] How to Eliminate Power Supply Birdies? I have an Alinco DM-330MVT power supply that has significant birdies on 160M. The power supply has a nice feature that allows you to move the birdies, which makes it obvious that the birdies are originating from the power supply. The birdies are at least 1 S-unit above the background noise. Here's what I've done to try to eliminate them: - added a filter connected to the DC output consisting of 4 toroid beads (type 77) in series on each side and 0.1 caps across the leads and from each lead to ground. I also have both leads going about 10 turns through a type 77 toroid to filter common mode birdies. - I've put 2 snap on type toroids on the AC line as well as wound the ac cord through a T200-1 toroid (which I had lying around) . - I shielded all of the power leads from the power supply to all of the equipment that it powers (mostly my K2, KAT100 and external speaker/amp), with the shields connected to both the power supply and the K2 chassis grounds. - I've moved the power supply away from my K2 (about 5' away). All of this seems to have absolutely no affect on the birdies. To add to the mystery, the birdies are there only when I have an antenna connected to the K2, so it would appear that the Power supply is radiating, but with all of the wires to it filtered and the DC lines shielded, where can it be radiating from - (as a test I put the whole power supply inside a metal file box and grounded that to no effect. So, can anyone explain this? Other than buying a new power supply, what do I do now? Except for the birdies on 160M, this is a nice power supply that's small enough to fit into an attaché case with my K2, KAT100, mic and key. Thanks. Bob W1SRB ______________________________________________________________ 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 ______________________________________________________________ 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 |
Re: How to Eliminate Power Supply Birdies?
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I have the same supply and have never had any birdie problems with it
in 9+ years of use (although being antenna-challenged, I don't operate much on 160). In the QST reviews of switching supplies several years ago the Alinco did pretty well compared to most of the competition, but I suspect that some supplies are more prone to these issues than others. I solved most of my birdie issues by switching from a CRT to a LCD monitor on the shack computer. 73, Bob N7XY On Jan 11, 2010, at 5:32 PM, Bill K9YEQ wrote: > Exactly why I sold mine. It is noisey and basically worthless to me. > Perhaps the newer ones work better. I am using other more recent > switching > supplies that don't give me any issues and they are a whole lot less > expensive. > > > 73, > > Bill > K9YEQ > > > -----Original Message----- > From: [hidden email] > [mailto:[hidden email]] On Behalf Of Bob > Sent: Monday, January 11, 2010 6:30 PM > To: [hidden email] > Subject: [Elecraft] How to Eliminate Power Supply Birdies? > > I have an Alinco DM-330MVT power supply that has significant > birdies on > 160M. The power supply has a nice feature that allows you to move the > birdies, which makes it obvious that the birdies are originating > from the > power supply. The birdies are at least 1 S-unit above the > background noise. > Here's what I've done to try to eliminate them: > - added a filter connected to the DC output consisting of 4 toroid > beads > (type 77) in series on each side and 0.1 caps across the leads and > from each > lead to ground. I also have both leads going about 10 turns > through a type > 77 toroid to filter common mode birdies. > - I've put 2 snap on type toroids on the AC line as well as wound > the ac > cord through a T200-1 toroid (which I had lying around) . > - I shielded all of the power leads from the power supply to all of > the > equipment that it powers (mostly my K2, KAT100 and external speaker/ > amp), > with the shields connected to both the power supply and the K2 chassis > grounds. > - I've moved the power supply away from my K2 (about 5' away). > > All of this seems to have absolutely no affect on the birdies. > To add to > the mystery, the birdies are there only when I have an antenna > connected to > the K2, so it would appear that the Power supply is radiating, but > with all > of the wires to it filtered and the DC lines shielded, where can it be > radiating from - (as a test I put the whole power supply inside a > metal file > box and grounded that to no effect. > > So, can anyone explain this? Other than buying a new power > supply, what do > I do now? Except for the birdies on 160M, this is a nice power > supply that's > small enough to fit into an attaché case with my K2, KAT100, mic > and key. > > Thanks. > > Bob W1SRB > ______________________________________________________________ > 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 > > ______________________________________________________________ > 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 ______________________________________________________________ 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 |
Re: How to Eliminate Power Supply Birdies?
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The RFI is almost certainly common-mode and is being radiated by the AC
power cord -- and, by extension, the house AC wiring. Your typical store-bought "AC line filter" is a differential-mode device and will do nothing to abate common-mode currents. What you need is a common-mode choke on the AC input cord, installed as close to the power supply case as possible. You make a common-mode choke by obtaining a fairly large ferrite toroid and wrapping it with the AC line cord. (Then use an extension cord to reach the wall outlet.) Palomar Engineers and a couple of other vendors sell these, and they have info on their websites that will help you choose the best ferrite mixture for the frequency bands you're most concerned with. Or, you can do like I did, and ditch the switcher. Get a "big iron" power supply, like my Astron RS-70M. No birdies, no problems. :-) Bill W5WVO -------------------------------------------------- From: "Bob Nielsen" <[hidden email]> Sent: Monday, January 11, 2010 7:31 PM To: "elecraft List" <[hidden email]> Subject: Re: [Elecraft] How to Eliminate Power Supply Birdies? > I have the same supply and have never had any birdie problems with it > in 9+ years of use (although being antenna-challenged, I don't > operate much on 160). In the QST reviews of switching supplies > several years ago the Alinco did pretty well compared to most of the > competition, but I suspect that some supplies are more prone to these > issues than others. > > I solved most of my birdie issues by switching from a CRT to a LCD > monitor on the shack computer. > > 73, Bob N7XY > > On Jan 11, 2010, at 5:32 PM, Bill K9YEQ wrote: > >> Exactly why I sold mine. It is noisey and basically worthless to me. >> Perhaps the newer ones work better. I am using other more recent >> switching >> supplies that don't give me any issues and they are a whole lot less >> expensive. >> >> >> 73, >> >> Bill >> K9YEQ >> >> >> -----Original Message----- >> From: [hidden email] >> [mailto:[hidden email]] On Behalf Of Bob >> Sent: Monday, January 11, 2010 6:30 PM >> To: [hidden email] >> Subject: [Elecraft] How to Eliminate Power Supply Birdies? >> >> I have an Alinco DM-330MVT power supply that has significant >> birdies on >> 160M. The power supply has a nice feature that allows you to move the >> birdies, which makes it obvious that the birdies are originating >> from the >> power supply. The birdies are at least 1 S-unit above the >> background noise. >> Here's what I've done to try to eliminate them: >> - added a filter connected to the DC output consisting of 4 toroid >> beads >> (type 77) in series on each side and 0.1 caps across the leads and >> from each >> lead to ground. I also have both leads going about 10 turns >> through a type >> 77 toroid to filter common mode birdies. >> - I've put 2 snap on type toroids on the AC line as well as wound >> the ac >> cord through a T200-1 toroid (which I had lying around) . >> - I shielded all of the power leads from the power supply to all of >> the >> equipment that it powers (mostly my K2, KAT100 and external speaker/ >> amp), >> with the shields connected to both the power supply and the K2 chassis >> grounds. >> - I've moved the power supply away from my K2 (about 5' away). >> >> All of this seems to have absolutely no affect on the birdies. >> To add to >> the mystery, the birdies are there only when I have an antenna >> connected to >> the K2, so it would appear that the Power supply is radiating, but >> with all >> of the wires to it filtered and the DC lines shielded, where can it be >> radiating from - (as a test I put the whole power supply inside a >> metal file >> box and grounded that to no effect. >> >> So, can anyone explain this? Other than buying a new power >> supply, what do >> I do now? Except for the birdies on 160M, this is a nice power >> supply that's >> small enough to fit into an attaché case with my K2, KAT100, mic >> and key. >> >> Thanks. >> >> Bob W1SRB >> ______________________________________________________________ >> 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 >> >> ______________________________________________________________ >> 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 > > ______________________________________________________________ > 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 > ______________________________________________________________ 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 |
Re: How to Eliminate Power Supply Birdies?
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In reply to this post by Bob Nielsen-2
Switching supplies tend to have their worst noise problems on the low
bands because those are the lower (stronger) harmonics of the switching frequency and the noise filtering tends to be less effective at low frequencies. It sounds like the spurs are coming out the power line. If the Alinco supply does not already have a line module with built-in filter you might see if you can find a filtered module that would fit. For example, here's one I was looking at recently. ($12.58 in single quantity) http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=817-1499-ND It has a PI filter with 0.1 uF, 0.3 mH (2) and 2.2 nF (2) which ought to give 30 or 40 dB attenuation on 160 meters. Or you could search the Digi-Key site for separate line filters: <a href="http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=3408328&k=line%">http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=3408328&k=line% 20filter Al N1AL On Mon, 2010-01-11 at 18:31 -0800, Bob Nielsen wrote: > I have the same supply and have never had any birdie problems with it > in 9+ years of use (although being antenna-challenged, I don't > operate much on 160). In the QST reviews of switching supplies > several years ago the Alinco did pretty well compared to most of the > competition, but I suspect that some supplies are more prone to these > issues than others. > > I solved most of my birdie issues by switching from a CRT to a LCD > monitor on the shack computer. > > 73, Bob N7XY > > On Jan 11, 2010, at 5:32 PM, Bill K9YEQ wrote: > > > Exactly why I sold mine. It is noisey and basically worthless to me. > > Perhaps the newer ones work better. I am using other more recent > > switching > > supplies that don't give me any issues and they are a whole lot less > > expensive. > > > > > > 73, > > > > Bill > > K9YEQ > > > > > > -----Original Message----- > > From: [hidden email] > > [mailto:[hidden email]] On Behalf Of Bob > > Sent: Monday, January 11, 2010 6:30 PM > > To: [hidden email] > > Subject: [Elecraft] How to Eliminate Power Supply Birdies? > > > > I have an Alinco DM-330MVT power supply that has significant > > birdies on > > 160M. The power supply has a nice feature that allows you to move the > > birdies, which makes it obvious that the birdies are originating > > from the > > power supply. The birdies are at least 1 S-unit above the > > background noise. > > Here's what I've done to try to eliminate them: > > - added a filter connected to the DC output consisting of 4 toroid > > beads > > (type 77) in series on each side and 0.1 caps across the leads and > > from each > > lead to ground. I also have both leads going about 10 turns > > through a type > > 77 toroid to filter common mode birdies. > > - I've put 2 snap on type toroids on the AC line as well as wound > > the ac > > cord through a T200-1 toroid (which I had lying around) . > > - I shielded all of the power leads from the power supply to all of > > the > > equipment that it powers (mostly my K2, KAT100 and external speaker/ > > amp), > > with the shields connected to both the power supply and the K2 chassis > > grounds. > > - I've moved the power supply away from my K2 (about 5' away). > > > > All of this seems to have absolutely no affect on the birdies. > > To add to > > the mystery, the birdies are there only when I have an antenna > > connected to > > the K2, so it would appear that the Power supply is radiating, but > > with all > > of the wires to it filtered and the DC lines shielded, where can it be > > radiating from - (as a test I put the whole power supply inside a > > metal file > > box and grounded that to no effect. > > > > So, can anyone explain this? Other than buying a new power > > supply, what do > > I do now? Except for the birdies on 160M, this is a nice power > > supply that's > > small enough to fit into an attaché case with my K2, KAT100, mic > > and key. > > > > Thanks. > > > > Bob W1SRB > > ________ ______________________________________________________________ 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 |
Re: How to Eliminate Power Supply Birdies?
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In reply to this post by Bill VanAlstyne W5WVO
On Mon, 11 Jan 2010 20:05:10 -0700, Bill VanAlstyne W5WVO wrote:
>The RFI is almost certainly common-mode and is being radiated by the AC >power cord -- and, by extension, the house AC wiring. Yes, this is most common. >Your typical >store-bought "AC line filter" is a differential-mode device and will do >nothing to abate common-mode currents. What you need is a common-mode choke >on the AC input cord, installed as close to the power supply case as >possible. You make a common-mode choke by obtaining a fairly large ferrite >toroid and wrapping it with the AC line cord. Yes. >(Then use an extension cord to >reach the wall outlet.) Palomar Engineers and a couple of other vendors sell >these, and they have info on their websites that will help you choose the >best ferrite mixture for the frequency bands you're most concerned with. On my website, you will find MEASURED data for common mode chokes of 1-14 turns wound on 2.4-in toroids of Fair-Rite #31, #43, #61, #77, and #78 material. The common mode choke shown in Fig 30 is ideal for 160, 80, and 40M, and still pretty effective on 30M. The capacitor shown in the photo forms a differential filter with the leakage inductance of the choke, and is "icing on the cake." http://audiosystemsgroup.com/RFI-Ham.pdf The only part of Bill's advice that I disagree with is to purchase from vendors like Palomar or Amidon, who have been ripping off the ham community for decades with VERY high markups on ferrite parts (typically 4x-5x their cost). They get away with this by inventing new part number (for example, FT- 11, FT-240) for parts they buy from Fair-Rite, who is the actual manufacturer. Fair-Rite has many industrial distributors who sell for a lot less. Further, the so-called technical data I've seen on their websites is laughable -- lots of numbers, but none of them relevant. The above-referenced tutorial includes buying advice in Appendix One. In addition to common mode radiation from external wiring (the AC cord, the DC cables), it's also possible that wiring internal to the power supply is creating magnetic fields strong enough to be picked up by our antennas. Remember, we're listening for very weak signals, so even low levels of radiated trash bother us. That field is produced by current flowing in a loop, and magnetic fields are NOT well shielded by simply throwing some metal around them -- the shield must come very close to totally surrounding the field to be effective, and it needs to be thick enough (in terms of skin depth) to attenuate the field. This is a MAGNETIC field we're talking about, not an ELECTRIC field. Henry Ott's new book has an excellent discussion of RFI from switching power supplies, and how to avoid it. http://www.hottconsultants.com/ 73, Jim Brown 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 |
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