++++++++++++++++++ Good switching power supplies are hard to find. Even some of the "Ham Name Brand" rig companion power supplies were found to have a lot of noise. But, there are some quiet ones to be found. Biggist problem is that computer power supplies are cheap and plentiful but don't have the "quiet" requirements that Ham Tranceivers do.... See also Power Supplies ++++++++++++++++++ Date: Tue, 02 Apr 2002 05:47:20 -0500 To: "John McClain" From: Charles Greene Subject: Re: [Elecraft] Small 5 amp supplies? Cc: "K2" At 07:15 PM 4/1/2002 -0700, John McClain wrote: >Can recommend a very small 5 amp and electrically quiet supply that I >can use with the K2 when I travel? I would prefer a small switching >supply even though the manual warns against it because of noise. > >John, Morse Express www.MorseX.com sells a very fine, quiet, tiny 3 A switcher I use for my K2. Works very well. 73, Chas, W1CG ++++++++++++++++++++ From: "Don Brown" To: "Elecraft" Subject: Re: [Elecraft] Small 5 amp supplies? Date: Tue, 2 Apr 2002 08:24:42 -0600 Hi Look at: http://mouser.com/specsheets/55265U.pdf I haven't tried the 60 watt but the 45 watt power supply works and is ver= y quiet. These are laptop computer adaptors. The 12 volt will supply 5 am= ps and the 15 volt will supply 4 amps. The 15 volt is a better choice if = you have the internal battery option. Installing a 3 to 5 amp diode in se= ries will drop the voltage to 14.3 volts just about right for charging th= e battery. If you are thinking of adding the KP-100 look at the MFJ 25 amp switcher.= I have a Astron 25 amp switcher, a MFJ 25 amp switcher and a MFJ 45 amp = switcher. I like the MFJ's better than the Astron. They have lighted amp = and volt meters, a cigarette lighter socket on the front panel and can be= adjusted from the front panel from 9 to 15 volts. The MFJ comes with a s= chematic diagram. Astron does not provide diagrams and the voltage adjust= ment is internal requiring the cover to be removed. Looking at the schema= tic I can see why the MFJ's are so quiet. The supply runs in a resonate m= ode rather than a switching mode, supplying a high frequency sine wave to= the transformer so the high frequency hash is eliminated in the LC circu= it. The same as in a class C transmitter just at a much lower frequency. As usual I have no interest in Astron or MFJ - JMHO :-) Don Brown KD5NDB +++++++++++++++++++ From: "Ken Lotts" To: "K2" Date: Wed, 3 Apr 2002 05:42:47 -0700 Subject: [Elecraft] Switching noise "hash" story (was Radio Shack power supply) Interesting story about the Switching noise "hash".. I have six computers in my house.. I had never given any thought to the QRN I was picking up until one day I shut two of my servers off while I was listening to 40 mtrs on my K2. I had spectrogram running and was able to clearly see and hear what those computer were doing to my radio. The noise was a series of signals (possibly 12 or more) exactly 60 hz apart. They were very unstable and therefore drifted (all together) up and down at random.. My solution was to buy new power supplies from a discount computer store I found on the net.. BUT, when they arrived, I placed them in service and they both had a very pronounced 60 hz pulse noise that was worse than the hash! Luckily, I finally found some old power supplies from work and all has been quiet ever since. Ken aa7jc http://www.lotts.net/ken/ham ++++++++++++++++++++++++ From: "SHOAF,DAVID (HP-Cupertino,ex1)" To: "'elecraft at mailman.qth.net'" Date: Wed, 3 Apr 2002 09:36:42 -0800 Subject: [Elecraft] RE: Switching supplies, my experiences... Hello to all, Seems like the only subject with more dialog than switching power supplies is antennas...so, to add to the noise, here's my experience, Rick. I don't have a horror story as much as good old diagnosis and remedy. I first tried an Alinco switching supply with my Icom IC-706MkIIG and then with the Yaesu FT-817. This was their 25 amp version with the meter and auto plug in addition to 5-way binding posts - a nice little compact heatsinked case, too. I bought it knowing that birdies might be a problem depending on the filtering and radiated isloation designed into the unit and it had a little knob so that I could vary the switching frequency right from the front panel. Boy, that should have been a give-away! I was fortunate to have a **really** nice HP heavy duty regulated supply as my reference, too, which I knew worked perfectly. I got consistent hetrodynes all up and down the bands on both radios (I'm about half-way through my K2 right now so no comment there). I know it was the supply since I could tune around them with that knob on the supply. Tried all sorts of the normal ways of reducing the interference - grounding schemes, clip-on torroids, additional inline filtering, etc. No help and no significant change in the radio's behavoirs. So, I sold it back to where I bought it and got an 'analog' power supply, a 35 amp Astron in my case, but the brand is less imprortant than the design center of an 'old school' regulated supply. Bigger, runs hotter, less efficient, you bet, but its also dead quiet. So, my experience is to stay away from switching supplies unless there's no other option. BTW, Radio Shack has a 3 Amp non-switching regulated power supply with 5 way binding posts and an auto lighter socket for about $40 or so. I'm using it with the FT-817 and it, too, is dead quiet - does have a bit lower regulation, in terms of ripple, than the Astron but that's quibbling. At least I've eliminated that point of interference in my setup. Hope that helps, Rick. Cheers, David/KG6IRW +++++++++++++++++ Date: Wed, 03 Apr 2002 09:52:44 -0800 From: lhlousek Subject: [Elecraft] switching power supplies To: ricks at sherbtel.net Cc: elecraft list <> I have tried 7 or 8 different switchers from 1.5A wall warts, to little laptop bricks, to 30A shack supplies. Most work well in the shack with good grounds, remote coax fed antennas, etc. All, except one, have produced some noise when using field expedient antennas like end fed wires, close in dipoles, and whips with counterpoises, even those advertised as not producing noise. The noise is generally a broad band of hash that drifts into your QSO at the most inopportune time. The big Elpac switcher I have has never produced noise although it is a big as some comparable linear supplies. It is lighter. I built a little linear supply for my K1 based on an unregulated DC wallwart and low drop-out V-reg that has worked FB. For the K2 I use the Elpac or one of the less heinous among the small switchers. Lou W7DZN +++++++++++++++++ Date: Wed, 03 Apr 2002 12:36:30 -0700 To: From: Larry East Subject: [Elecraft] Switching Power Supplies I believe that the "trick" for successfully using a switching power supply is to keep the receiving antenna far away from the poser supply -- which is admittedly difficult in field operations -- since the hash is usually radiated rather than transmitted via the power cord. In the rare instance when hash reaches the receiver via the power cable from the supply to the receiver, wrapping several turns of the power cable thru a large 77- or 43-mix toroid as close as possible to the power supply should take care of the problem. I have used a Radio Shack 3A switcher and a small laptop switcher (modified to give 14V rather than 18V output) with my K2 and neither caused any problems when using an antenna outside of my house, or when using them in my motor home with an antenna mounted on the back of the vehicle. However, if I use an "indoor" antenna within a few feet of either power supply, I can hear an assortment of "birdies", "hash" and other bad stuff -- not very loud, but loud enough to be objectionable. So, as someone else mentioned, use an outside antenna and good grounding -- good ideas in any event. 72/73, Larry W1HUE/7 +++++++++++++++++++ Date: Wed, 03 Apr 2002 12:03:15 -0800 To: elecraft at mailman.qth.net From: peter gerba Subject: [Elecraft] Switchers Hi Crafters; I recently took my TS 930 out of service due to local high power (I mean HIGH) CBers getting into one of the IFs. A TS-850 replaced the 930 with few of the IF problems. I also noticed that the 850 had little trouble with the computer across the room.. I had all the covers off the machine for weeks as I evaluated some new boards. I had to turn the computer off when using the 930. I had power supply trouble here with the 850 last week and replaced the supply, with a Astron switcher, that was stored as a repeater back-up. I didn't notice any noise on the 850, but, my broadcast band radio didn't like the supply at all. I placed cores on the AC and DC outs from the supply with no improvement. I think the design of the supply and of the 850 made a good match. I've had serious problems with Lambda switching supplies and 2 meter transmiters getting into the supplys and shutting them down. No trouble with switchers on 1.2Ghz so far. pete +++++++++++++++++ From: "Dan Barker" To: "Elecraft" Subject: [Elecraft] switching power supplies Date: Wed, 3 Apr 2002 16:17:25 -0500 I find a 7 aH gel-cell makes a dandy filter. The thing even works (for a = time) unplugged. Dan / WG4S / K2 #2456 ... based on an unregulated DC wallwart and low drop-out V-reg = that has worked FB. +++++++++++++++++++ From: "bfollett" To: Date: Thu, 4 Apr 2002 07:46:04 -0700 Subject: [Elecraft] Switching P/S Horror Stories Gang: Rick, KC0OV asks about switching supply horror stories. I have tried several switchers all the way back to one of the first ham products, the Yaesu pancake for a 747. (15 years ago?) I had tested it at home, worked fine, took it on vacation, where I used a G5RV, and found horrible switching noise on all upper bands -- almost ruined the vacation. Since then, I have added several to the shack, including a very nice, 105-240V input 2.4A out for the K1 and FT817. My personal experience confirms one thought "Regardless of source, don't believe a thing about someone else's noise tests -- QST included". Sorry, there is no easy answer here -- other than to say, if you are using a long run of coax to your antenna, and have a good ground -- most everything will work. But if you run ladderline, are portable w/o ground, have a close by antenna like a MP-1, or run an end-fed with a Z match as I often do -- You had better run some tests before deciding to use a switcher! Personally, I carry the Int'l Power Sources CUP36-12-1, with 13.5V output, with me on all trips. I use it to charge the batts in the K1 or FT817. Depending upon antenna, and where I am on a specific band, I "may" be able to Xmit with it, but I don't expect too.... Its a great supply for "packing", about the size of a long cigarette pack. In summation, Rick is right -- "no guarantees". 73, Bob AB7ST ++++++++++++++++ Date: Tue, 2 Apr 2002 17:51:07 -0800 (PST) From: Claude To: qrp-l at lehigh.edu Subject: [123882] Power supply noise Don, Steve, and Bruce and others who have thought on my problem about the power supply noise my hat is off to you all...... I have been trying to find a solution for about 2 months and didn't want to bother anyone on the list with such a hard to answer question..... I use a battery for the circuit and no noise at all, but in the commerical supplies there is some annoying noise..... I am going to rebuild the regulator circuit that was an excellent tip. I am sure that that will fix the problem... What I was originally looking for was as Steve described to me was the "capacitor multiplier" circuit... I am glad that I asked.... Your answers got me on the right track.... THANK YOU ALL.... Claude WB4WHH in Virginia.... ++++++++++++++++++ Date: Wed, 3 Apr 2002 07:19:23 -0800 (PST) From: Claude To: qrp-l at lehigh.edu Subject: [123901] Re: Power supply noise Good morning Steve, That is a good question..... I have used commerical power supplies so long I didn't know the noise wasn't suppose to have been there... When my mail Astrin power Supply failed one morning I hooked up a DC battery pack and I couldn't believe the difference in how quiet the receiver was... After getting the Astron back on line I heard this much annoying background noise which I always thought was band conditions or some such thing.... I switch back to the battery pack and no noise !!!! Back to the power supply, noise.... The noise sounds like background noise, not at all noticeable on strong stations, but on extremly weak stations just above the noise line the noise being generated will cover them.... I tried other power supplies and have the same results, some a little more or less than others, but back to the battery pack "no noise".... It does it on all commerical radios too... I Broadcast Band DX also with car radios set up and tune the AM bands the noise appears there on these radios too... But the thing that got me was I didn't know the signal could have been any quieter.... But it is with the battery pack... I have tried all types of grounding, choke coils on the input leads and output leads, even more capacitance at the Power supply's output terminal, all of which hasn't got it as quiet as a battery pack yet... Maby I am wishfull thinking but I think the power supply circuits can be quieter.....I hope this provides further insight to this "new discovered" noise source when trying to copy super low border line signals.....????? Steve I really appreciate your feedback... Claude WB4WHH +++++++++++++++++ Date: Thu, 04 Apr 2002 09:53:18 -0800 From: lhlousek Subject: [Elecraft] Switching P/S Horror Stories To: elecraft at mailman.qth.net Based on the QST review I bought an Alinco 25A switcher. It's a very nice supply with adjustable voltage, voltage lock, meter, small size, etc. Works absolutely FB...except for 80m. It generates noise and birdies all over the 80m band. The noise bands are so closely spaced that it is difficult to find a quiet spot by adjusting the patented noise shifter knob and, once you do find a quiet spot, it doesn't last long because a band of noise or a birdy will come drifting into your QSO. This is with a coax fed outdoor antenna. Lou W7DZN +++++++++++++++++++ Reply-To: From: "Ron D' Eau Claire" To: Subject: RE: [Elecraft] Switching P/S Horror Stories Date: Thu, 4 Apr 2002 13:32:03 -0800 > I have had noise problems with switchers as well. What I want to > know is "why > is it so hard to filter/bypass these supplies to get rid of the noise?" > > I'm old enough to remember the advent of TVI and the development of TVI > suppression techniques for homebrew and commercial rigs. Why > can't we take a > similar approach to switching power supplies? > Vic, K2VCO Vic, you are right that it's a matter of shielding and filtering just like the old TVI issues with Ham transmitters in the 1950's - but the switching power supply is putting out r-f that is probably thousands of times more powerful than the harmonics from our old Ham rigs and we are using receivers that are probably thousands of times more sensitive than the old TV's. Take a 50 to 100 watt transmitter designed to produce broadband r-f right on top of the TV channels, then set it right next to the TV set and connect it to the TV with cables that depend upon filters to stop ALL of the r-f, and you will see just how unsuccessful the system would work to prevent TVI. That is essentially what we have with "switcher" power supplies in the shack and connected to the rig. I think that it's AMAZING that they have managed to make them as 'quiet' as they have. Ron AC7AC K2 # 1289 ++++++++++++++++++ From: "Don Brown" To: "Elecraft" Subject: Re: [Elecraft] Switching P/S Horror Stories Date: Thu, 4 Apr 2002 16:52:19 -0600 Hi It is possible to design a quiet power supply. Tektronix had a switching = power supply in all of their 7000 series scopes from the 1970's. Some of = these scopes had high gain amplifiers with bandwidths of up to 1 GHz in t= he same case as the switcher and you could not see any hint of the power = supply at any frequency. Switchers are noisy because they drive the power= transformer with a fast rise time square wave. It is very hard to filter= the harmonics of this square wave. The way Tektronix solved the problem = was to drive the power transformer with a ultrasonic sine wave. That way = there are no harmonics, only the fundamental frequency making the filter = design more straight forward. =20 The reason we are stuck with noisy power supplies is these supplies came = out of the computer industry and there is not a requirement for quiet sup= plies with computers as many of you know. There are some designs sold for ham use that use a variation of the Tektr= onix method. The MFJ switchers are one and I have been happy with them. I= can only hear a very low level of hash if I lay the antenna of a general= coverage receiver on top of the power supply at any frequency from broad= cast to 30 MHz. I have not noticed any hash on my K1 or K2 using the 45 a= mp or 25 amp version. MFJ's adds say no hash and it looks like they are r= ight. As usual no interest in MFJ or Tektronix just a customer Don Brown KD5NDB +++++++++++++++++ Reply-To: "Bob Lewis (AA4PB)" From: "Bob Lewis (AA4PB)" To: Subject: Re: [Elecraft] Switching P/S Horror Stories Date: Thu, 4 Apr 2002 22:11:50 -0500 The fact is that there have been quiet switching supplies built for years. The Icom IC-761 for example has a switching supply built right inside of it. The key is that its inside a completely shielded can with all leads entering or exiting via RFI filters. ++++++++++++++++++++ To: elecraft at mailman.qth.net Date: Fri, 5 Apr 2002 00:43:57 -0600 From: n4so at juno.com Subject: [Elecraft] Switching Power Supplies-RF Filtering Ideas for RFI filtering are from a QST article on building a Switching Power Supply. The basic principles of RF filtering would apply to any switching power supply. 1. Line voltage is EMI filtered and an additional noise filter for common-mode currents is used, following the first EMI filter. 2. The 13.8 V dc cables use Amidon FB-73-2401 ferrite beads, with six on each cable for a total of twelve beads. The output power cable filtering is completed by six bypass capacitors on the output leads. The ground is floating to reduce stray HF currents. 3. L3 is a noise absorber using a ferrite solenoid. 4. Between C3 and the power oscillator, Type-73 beads are used to absorb noise. L2 is a toroid choke, and absorbs most of the noise on the output side. Manfred Mornhinweg, XQ2FOD, A 13.8-V, 40-A Switching Power Supply, QST, December, 1998, p. 37-41. Ken Brown-N4SO Mobile, AL EM50tk Elecraft K-1 4 ele. monoband yagi N4SO at juno.com +++++++++++++++++ From: "Rick Shindley" To: "elecraft digest" Date: Fri, 5 Apr 2002 12:47:55 -0600 Subject: [Elecraft] switcher filtering >>I have had noise problems with switchers as well. What I want to know is "why >>is it so hard to filter/bypass these supplies to get rid of the noise?" >>I'm old enough to remember the advent of TVI and the development of TVI >>suppression techniques for homebrew and commercial rigs. Why can't we take a >>similar approach to switching power supplies? >>73, >>Vic, K2VCO >>Fresno CA The problem with many switchers is with limiting their common mode noise at the power line side. Common mode currents can turn into differential currents easily enough, depending on the application. These rf currents will appear on your radio ground wires thus making the chassis potential vary with the switcher noise. Add a grounded antenna and you'll have a mess on your hands! If the radio chassis is jumping around at some millivolt rf level caused by poor common mode noise limiting of a line-powered switcher, any stray capacitance to ground in your antenna or lead-in system will result in noise currents at the radio's antenna terminal! ARRGGGHHH! For safety reasons, UL and other agencies place limits on the amount of "leakage current" the supply represents from its line ("hot") input to ground. Filter designers must respect that limit so they are practically constrained to using filter caps from line to ground totalling less than 0.01 uF. They try make up for it by using large amounts of series inductance. The use of inductors adds cost and increases size. High-volume power supply makers avoid adding cost! Common mode filtering is more difficult to achieve than ordinary differential filtering due to the safety-limited C to ground. Designers use common mode-wound toroids to restrict those currents, but such inductors add size and cost, and they often aren't enough anyway. Switchers are not much more than a small box of compromises! The real-world solution is to restrict the use of switchers in sensitive radio environments, or use switchers designed to operate at frequencies far removed from the radio operating frequencies. Better to just to avoid them if you are having interference problems. Rick KC0OV K2 1360 +++++++++++++++++++ From: "Alex Turner" To: , "Vic Rosenthal" Cc: Subject: Re: [Elecraft] Switching P/S Horror Stories Date: Fri, 5 Apr 2002 16:00:12 -0500 John, I am having the same experience here. Had mine about a year now and am very satisfied with the performance,size ,etc.. I have one antenna fed with ladder line that interferes with everything else in the house, but I don't hear any thing from the power supply. Like you I just figured my luck had finally changed Alex N4BYJ ----- Original Message ----- From: To: "Vic Rosenthal" Cc: Sent: Friday, April 05, 2002 3:34 PM Subject: Re: [Elecraft] Switching P/S Horror Stories > > Wow. I guess I'm lucky. I run an SEC1223 switching supply with > absolutely NO noise that I can find. If I unplug the supply and run on > battery, no difference. This is with coax-fed outside antennas about > 130ft away. > > 73 de John - KC4KGU > K2 #2490 ++++++++++++++++++++ From: "N0SA" To: Date: Fri, 5 Apr 2002 15:07:57 -0600 Subject: [Elecraft] RE:switching power supplies I have an Astron 20 amp switcher that I have used for about 4 years and = have never noticed any noise on any of my radios. Larry N0SA ++++++++++++++++++++ From: "Reginald Mackey" To: Subject: Re: [Elecraft] RE:switching power supplies Date: Fri, 5 Apr 2002 13:56:29 -0800 I use a Astron ss25 for about 5 years with no apparent noise in my ts570 or ic706 or ten tec pegasus +++++++++++++++++++++ From: "Steve Jackson" To: Date: Sat, 6 Apr 2002 15:12:48 -0500 Subject: [Elecraft] Samlex 1223 "I use a Samlex SEC 1223 regulated DC power supply which has an output vol= tage of 13.8 VDC and an output current of 23 Amps continuous/25 Amps maxi= mum." Gee, so do I! I turned the '1223 up to 14.1 volts using its internal pot. (There are two pots, the other is the current limit and I forget which is which now, sorry). The SEC1223 is RF silent, AND easily runs the IC756/K2 station AND floats the K2 internal battery AND also the big SLA that is in the garage right under the shack (hooked up with 1/0 wire). If the AC goes away, the '1223 does not care that there's DC on its power pins. Interesting that the SEC1223 is frequently also the least expensive 20A supply around, availability is good, and support is excellent. I even tried a remote sense mod once, with full support from the design engineer himself, who (if memory serves) was in Vancouver BC - and I got him on the phone with a single call. (The mod didn't work.) My PS is mounted out of sight ... I did it by taking the lid off and drilling 4 holes into it, and then mounting the lid to the bottom of my shack table with short self-tapping screws. I then just re-mounted the supply chassis. Zero desktop footprint! I turned it on, and forgot it. 3 years that way so far, almost, and no problems. ++++++++++++++++++ Date: Sun, 07 Apr 2002 13:22:26 +0200 To: "Steve Jackson" , From: Eric Wosten Subject: Re: [Elecraft] Samlex 1223 and K1 RIT mod applicability At 03:12 PM 06/04/02 -0500, Steve Jackson wrote: >Two items in this message: > >#1 Someone wrote: >"I use a Samlex SEC 1223 regulated DC power supply which has an output vol= >tage of 13.8 VDC and an output current of 23 Amps continuous/25 Amps maxi= >mum." > >Gee, so do I! > >I turned the '1223 up to 14.1 volts using its internal pot. (There are two >pots, the other is the current limit and I forget >which is which now, sorry). > >The SEC1223 is RF silent, Hmm, funny, I owned the same model, but mine wasn't silent....worst on 80, less worse but still no good on the higher bands. It made even my AO40 downconverter (2.4 GHz to 144 MHz) unusable, spiking caused the mixer to go bazurk... Friend of mine also has this one, same problem. I've switched back to linear power supplies. 73 Eric PA3CEV K2#960 www.qsl.net/pa3cev ++++++++++++++++++