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Switching Power Supply Headaches

Paul Veal (N0AH) on January 18, 2006
View comments about this article!

Switching Power Supplies - Are They Worth The Headaches?

I first started noticing RFI problems with my switching power supplies back in 1999. In particular, I was getting a raspy sound every 8-10KHz on the low bands and a little less on the high bands. . My Icom 756 scope showed a nice spike averaging about 10KHz apart thanks to the power switching supply.

Today, 4 switching supplies and 8 years later, the technology has not cured the problem. I still have the exact same noise using switching power supplies. But using my solid state Astron RS-50 rated at 13.8V and 50A, I just don't experience the same phenomenon. So if add the total weight of the 4 supplies I have, they are less heavy then the cumbersome solid state supply. So weight, space, and looks are all good reasons to get a switching power supply. But is it worth the noise headaches?

The most recent supply I purchased was the Alinco DM-330MV. It is rates at 32 amps and you can adjust the voltage from 0 - 16V. It is real fancy with a 10 amp lighter plug adapter and a solid case with heat fins. But all this is not why I bought it. I got it because it has a noise offset to move the noise from the frequency your on to somewhere else. That was the only thing of this awesome power supply that didn't work. No matter what I do with the noise offset, it has no effect on the noise. And my 756 Pro III. still can't suppress it.

If I were to rank the worst noise producer to the least, here's my list of what I have experienced. This does not include my original earth quake switching supply which is somewhere buried in the Burns, WY land-fill.:

Radio Shack Model # 22-510 -

At first, (2 minutes) it seemed ok. Then it got a life of its own. It created rampant noise that covered at least 25% of my bandwidth with wide noise spikes of 10-15KHz. Rated at 13.8V 25A.

Alinco DM-330MV-

When you buy something, and 80% of it works as advertised yet you bought it for the remaining 20% that's not working (noise shifter) it ends up a close tie with the Radio Shack model. Shame too. This power supply looks like it could survive anything. Spikes were every 15KHz, less frequency than most. But that doesn't help you inside the CW DX windows. Rated at 0-16V and 32 amps.

Samlex America SEC-1223-

The bandwidth of the noise spikes were less than the Radio Shack model, but just as frequent as the Radio Shack model. (Help)- Rated at 13.8V and 23A.

Astron SS-30-

I had great expectations with this supply as it has a 110V or 220V input voltage option. The wiring has to be changed inside the box to change input voltage but it works. You don't find anything in the manual on this but by calling Astron, you get the secret code on how to do it. (Is that just odd or what?) I needed it for my 3DA0 DX'pedition and visits to in-laws in France. Similar performance to the SEC-1223 but the noise spikes we're not as strong. However, they occurred at about the same spacing, in-between 8 to 10KKz apart.

Sure there a lot of variables with power supplies. Do they really deliver the amperage promised? Are they safe not to kick under your desk? Can you use them as boat anchors etc….but my question is why switching supplies have remained around the hobby as long as they've have. In my case, the light weight is just not worth the headaches with the rare exception of a DX'pedition, traveling, etc…What would you suggest to a new ham getting into the hobby on power supplies? Supplies are expensive. This might be a one time purchase for awhile.

Member Comments:
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Switching Power Supply Headaches  
by HA5RXZ on January 18, 2006 Mail this to a friend!
"What would you suggest to a new ham getting into the hobby on power supplies? Supplies are expensive".

Build one, but make it a standard linear supply. There are quite a few vendors out there who can supply a transformer, add to that a couple of meaty power transistors and a surplus high-value smoothing capacitor and you're almost there.

As for switched-mode PSUs, does ANYONE make a low noise model? I've always run linear supplies because of these problems. The biggest linear supply I ever saw was a four man lift but it supplied 13.80 volts at 150 amps and the output was squeaky clean.

Switching Power Supply Headaches  
by KC9ECI on January 18, 2006 Mail this to a friend!
I've used that Alinco switching supply for a couple of years now without issue.
Switching Power Supply Headaches  
by W4LGH on January 18, 2006 Mail this to a friend!
You know, I find one thing in your comment to be very interesting... a spike @ 10kc with every ss power supply you have tried. I personally thing your spikes are coming from somewhere else. True that switching power supplies can be noisey, and some more so than others, but just about EVERY DC device out there, now has a switch mode power supply, even the litte "wall warts" are switch mode now, and your 10kc spikes could be coming from one of them??

I personally own an SEC-1223, and found it to be very quiet, with only a little noise generated on one spot in the 80 meter band. I also run my shack off of an Astron SS-30M. Now this supply did become very noisey, and continued to get worse. I was ready to sell it, when I read an article about tightening the 4 circuit board screws, as they become lose and will generate noise. Sure enough they were lose, I tightened than and the noise went away. A few months later it came back, they were lose again. So this time I re-tightened, and soldered ground straps from each corner to the case. From that time on, have never heard the noise again.

So I would go looking around my house for something else generating that noise, especially after trying so many different supplies. And by the way that Radio Shack and SEC supply are the same supply, made by the same people. RS may have had the manufacture leave out some filtering to cut their cost (as they do with a lot of products)but who knows?

Good luck in finding your noise.... 73

de W4LGH - Alan
RE: Switching Power Supply Headaches  
by N3CRT on January 18, 2006 Mail this to a friend!
I too have a Samlex SEC 1223 and I think it does just fine like the other poster says. Only minimal noise in the 80m band. Have you tried switching off other things in your house? You would be suprised what kind of noise even the most simple devices will make.
Switching Power Supply Headaches  
by KI4NX on January 18, 2006 Mail this to a friend!
Hi Pablo,

I purchased an Icom PS-85 a couple of weeks ago. I didn't know about all the noise it made at the time. However, after checking I found this switching supply could be modified and really cleaned up. And after I made the changes, it's one nice, clean 13.8v supply for my HF radios. I also have an Astron 35A and a PS-125. I would like to mod the -125 but no schematic presently. You might take a look at to get some ideas about cleaning it up the ones you have.

73's de KZ4Y
Switching Power Supply Headaches  
by K2ANE on January 18, 2006 Mail this to a friend!
You can add the Diamond GZV4000 to the list. This supply is a buzzer every 50 to 60 khz from BC to 10 meters. I can only use it on FM on 10. But I can use it for 2 and 440 SSB & FM, however that is rare in my operating, which is little consolation to me.

Yes, one can't beat iron.

de K2ANE/2
Switching Power Supply Headaches  
by KB1GMX on January 18, 2006 Mail this to a friend!
Short and sweet. It isn't the power supply.

Reason, none of the supplies for a lot of years uses
a switching speed under 40Khs or higher. Higher switching speeds mean smaller transfomers and most are
much higher than even 40khz.

So that means to things. Likely if you replace the
PS with a battery you will still hear the noise. And
the source is NOT the PS.

Your hearing the noise becuase the PS allows you to turn on the radio. However I severely doubt the source is
the PS.

I'd start looking for other sources. Likely its a bunch of things in you area.

RE: Switching Power Supply Headaches  
by AB0TA on January 18, 2006 Mail this to a friend!
Some switchers may have problems, granted. I have used the Astron SS-30M switcher for several years now with the ICOM 756 PRO II without any problems.
RE: Switching Power Supply Headaches  
by KC0NPF on January 18, 2006 Mail this to a friend!

go swipe the battery out of your car, hook up the rig and tune around listening for your 10khz noise. if it was the power supply, it's now gone. if it was something else, perhaps related to noise the supply put back into the wall current? it should also be gone. If you still see the noise, wait until the wife is out of the house, then flip your "main" circut breaker, kill everything in the house while running off the battery. if that doesn't kill the noise, I don't know what will.

also: use the linear power supply to power the rig, then plug the switcher into the same circut (i'm not sure if it should be loaded down) and see if you get your noise back. if so, you've got a crude BPL system figure out how to make it transmit data, then sell it to a consumer market ::grin:: (or not...)

just a couple ideas,

73 de KC0NPF
RE: Switching Power Supply Headaches  
by K9NW on January 18, 2006 Mail this to a friend!
I've had my SS30 for almost 7 years and haven't noticed any problems. I can fit the SS30 along with my IC746 in a normal sized, regulation carry-on which makes things very nice when I'm schlepping off to a DX spot. Couldn't ever imagine traveling and dealing with the extra weight of something like a 35 or 50 series model.

You mentioned something about changing the wiring inside the box, and a secret code, when changing from 110v to 220v. My SS30 has a little red switch on the back to change voltages. Interesting...maybe yours is an earlier generation?

I know a few others that use and like the Samlex unit.


73, Mike K9NW
RE: Switching Power Supply Headaches  
by K5DVW on January 18, 2006 Mail this to a friend!
Two comments..

1. Get your antenna away from your power supply, or whatever is generating the noise, and it'll greatly reduce your noise reception. My antenna is 100ft from my house and I don't have a serious RFI problem. I have a few minor things I can receive, but it's not annoying and it's not from my ham switching supplies. I have two switching supplies constantly on, an Alinco and an ICOM.

2. I have an Alinco DM-330MV and the noise mover function works as advertised. I tested it out with a wire laid on top of the power supply as an antenna.

No doubt about it, old analog supplies are great in some respects, but when you have to buy a couple that can supply 30 amps each, that's a lot of iron sitting on the table.

RE: Switching Power Supply Headaches  
by LNXAUTHOR on January 18, 2006 Mail this to a friend!
- a big ditto on the SS30! excellent supply and quiet... i also like the gauges (although i wish they were backlit)

- btw, the earlier Radio Shack PS is a Samlex 1223 - no difference except in lettering on the case
RE: Switching Power Supply Headaches  
by AD5X on January 18, 2006 Mail this to a friend!
I've been using the MFJ-4125 switcher with absolutley no problems. This power supply has heavy internal filtering on both the AC input and DC outputs. They even scraped the paint off the case where the covers come together to ensure good case grounds all around. You can see the filtering in the internal photos I took of this unit when I added PowerPoles to the rear of the power supply. This info is in the "Equipment Modification" section on my website (

Phil - AD5X
Switching Power Supply Headaches  
by K0KTB on January 18, 2006 Mail this to a friend!
I have been using the IOTA model which puts out 55 amps. It has no noise and is perfectly quiet. Look up Iota Engineering. It also doubles as a battery charger and will float batteries. Excellent unit and works without any noise.

RE: Switching Power Supply Headaches  
by WA8MEA on January 18, 2006 Mail this to a friend!
Believe it or not, I had a "Mighty Fine Junk" power supply that had a bare minimum of "hash", except on the AM broadcast band. It worked better than some of the so-called finer supplies you mentioned above.

Your plight was also my plight years ago. And it wasn't about the expense of getting a "real" power supply that was holding me back. Those "real" supplies could hum/buzz better than my electric chain saw! I was getting disgruntled at all supplies.

Finally opted for a Sears marine battery and one of their "smart chargers" that shut down after reaching peak charge. Ran a lot of my qrp and VHF stuff with that battery. Added a second Sears marine battery in parallel years later, to get enough amps to run my HF rigs.

73, Bill - WA8MEA
Switching Power Supply Headaches  
by KU4UV on January 18, 2006 Mail this to a friend!
And yet MFJ failed to make the list, how did that happen? I personally would never use a switching supply, but that's just me. I would rather deal with the extra weight of my trusty Astron RS-20A than have to fool with the noise across the spectrum. Until someone can make a switching supply that is noise-free, I'll stick with the old standby.

RE: Switching Power Supply Headaches  
by AA4PB on January 18, 2006 Mail this to a friend!
All switching supplies generate some noise unless they have extensive shielding. The solution is generally to get the antenna away from the power supply. This is the primary variable that causes some stations to have problems while others don't. I have an Astron switcher sitting directly above the radio and never hear any noise from it. My antennas are located well away from the shack.
RE: Switching Power Supply Headaches  
by K5UJ on January 18, 2006 Mail this to a friend!
<<<But using my solid state Astron RS-50 rated at 13.8V and 50A, I just don't experience the same phenomenon. So if add the total weight of the 4 supplies I have, they are less heavy then the cumbersome solid state supply.>>>

All ur supplies are solid state. Does anyone edit these articles?

Switching p.s. have become an industry standard. Even broadcast gear uses them now. There was a problem in the 1990s with them not being filtered well but that is no longer an issue. I'll probably never buy a linear supply again. What is a problem is cheap imported supplies in consumer appliances that have no filtering.
RE: Switching Power Supply Headaches  
by K0BG on January 18, 2006 Mail this to a friend!
I have an MFJ 4126 switching PS, and I have not had any problems with it in any respect. I can hear the supply in my receiver, but is far below the point of worry. It has run 24/7 for nearly 4 years and has never hiccuped. Considering it cost just $99, I think I got a bargain.

If I had to buy another one today, it would not be a linear supply. Fact is now, even the proverbial wall warts are changing over to switch designs.

Alan, KōBG
Switching Power Supply Headaches  
by N0AH on January 18, 2006 Mail this to a friend!
I get the spikes in France, Africa, Wyoming and Colorado- I have used a portable short wave radio and I can not find any significant ambient RF noise source. I have used the supplies on Icom's 756, 756 Pro and Pro III. Also on a FT-847. I wish it was that simple- But maybe it is. Will keep looking.
RE: Switching Power Supply Headaches  
by KG6AMW on January 18, 2006 Mail this to a friend!
I've had the Astron SS-30M in my shack for 6 year and its on 24/7. No interference no problems, its perfect.
RE: Switching Power Supply Headaches  
by W3JJH on January 18, 2006 Mail this to a friend!
Let me preface my comments with a bit of background information. I started out in the recording and broadcasting industries, so I'm very familiar with keeping spurious signals out of gear. I'm now working as a consultant designing switching power supplies for sensitive instruments at Goddard Space Flight Center.

1. Linear power supplies are relatively easy to design, usually quiet, and inefficient. It's a no-brainer for an engineer to take the ap note for a 723 and kludge together something like Astron sells.

2. Switching supplies are harder to design, but if they're done correctly, switchers will outperform linears in every way--including noise performance. Great attention to detail is required. There's the rub. The switching supply for a piece of consumer electronics will not make it into the marketplace without being able to pass the FCC's Part 15 requirements. The potential liability for the manufacturer is too great to risk selling a defective product. And, although it doesn't relate to EMC per se, consumer products will be safety agency listed also. It's rare to see a supply in the amateur radio market with a safety agency bug (UL, ETL, MET, etc.) or and FCC Part 15 compliance statement.

3. I have a couple of the aforementioned Alinco supplies in my shack. They cause absolutely no problems. Neither my Omni VI, my FT-817, my Argonaut V, my HRO-500, nor my son's IC-746 can hear them.
Switching Power Supply Headaches  
by WA7NCL on January 18, 2006 Mail this to a friend!
Test with a battery to make sure the noise spikes really come from the supply.

Carefully check the frequency that the noise spikes repeat at. A frequency of 15750 Hz (15.75KHz) is the Horiz sweep of a TV. Many new big screen TVs are very noisey. With a little research on internet, you can find the sweep frequencies of Computer mons running in the various modes. If I recall, the computer mons run more in the 20 plus KHz range.

Lastly, if it isn't the supply, make a Faraday Loop out of coax. You can search the internet and find sites on how to build them. You can use the loop and a portable RX (I use my K2 with internal batt.) to find the noise source.

good luck
RE: Switching Power Supply Headaches  
by N3JWN on January 18, 2006 Mail this to a friend!
If you are really technically interstersed in the basic and problems of the Switch mode Power supplies to involved to get into here go to Google and lookup Switching Power Supplies.
Supplies Switching-Mode Power Supply Design
Power supply circuit design problems, solutions, tutorials, tips, and resources. A website about power supply design for power supply designers.
This site is dedicated to switching-mode power supply circuit designers. Here you will find solutions to the most difficult problems facing you as a power supply designer, a tutorial that places power supply design problems in context, and resources that aid in your power supply design tasks. If you are a first-time visitor you will want to read this page as an orientation. If you have been here before (thank you for coming back), use the menu on the right to find the power supply design information you need.

The biggest Problem with the Switch mode Power Supplies on the market cheap for the average experimenter or Ham Radio is that not only are they cheap!! But there made too cheep and this is why so many people have trouble. So many burdes, EMI, RFI problems.. In the first place they should be in an RF tight Box double or triple shield with bonded grounded, with toroid core, chokes and ferrite beads on all input and out put Leads. the Manufactures donít even have the average RF input line filter that all of you home computers have in that black plastics covered 110 volt input plug is a metal box RF proof to the line cord to Keep any oscillation off the 110vac line (nice antenna by the way) Iíve installed these on radio shack and many other Switch mode supplies to get rid of the RFI problems and double shielded the circuitry bonded all to ground with wide copper strapping or braid!! You know single wiring just wonít do for RFI SHIELDING.Farad beads on input and output wiringÖÖ This has done the trick for me!! The manufactures could do it reasonably but it will add to the cost!!! A couple of the manufactures have gone as far as variable freq input adjust from 15 to 40 KHZ so you can tune out the RF interference in your HF receiver rig!!! I canít remember the 2 manufactures that have these on the market right now!! QST ran a comparison of most of the switchers that were on the market a couple of years ago very good article but I just canít find in at the present!!
Basic switching supplies work by rectifying doubling and filtering the 110 vac and feeding it to a switching transistor by saturating it and driving the high voltage with a square wave or something that looks like an over driven sign wave with the peak chopped off and there by also creating many, MANY harmonics!! They tap off this 180 volts or so to run an oscillator which is circuitry guarded by feed back optical isolators that usually monitor the highest currant in the supply in the case of computers the 5, 2.5 volt lines or in our case the single output 12 volts with crowbar and short circuit protection by loosing (short) or buy loading the 12volts down you loose the feed back to the oscillator their by shutting down the high voltage switching and killing the supply with out damage to components. This is very basic. Most of the repair problems ( I've worked on switchers for over 30 years) are in capacitors, shorted output diodes and open chokes. Pick off resistore ( feed thet 7-12volt low voltage supply that runs just the oscillator) usually 220K OHM 1/2 watt should be replaced with 2 watt reastors... they have lasted for 10-15 years by doing this!! But for the most part right out of the box are the cheaply manufacturing..... Sometimes proximity and lead dress along with the addition of the shielding and the RFI protectionÖ
So basically Switchers are very nice light and portable but we will have to pay more for a quality power supply.. If we let the manufactures know what we demand!! If we donít complain they wonít know but Iíve personally repaired and worked on all the power supplies listed and have eliminated almost all RFI problemsÖ If you read about the design of Switchers perhaps youíll see some of the design problems!...... dampened oscillation adding longer input and long output leads to RFI shielding in the input yielding the power supply inopeasable so I would say they took the cheapest, easiest design or either the cheapest components or both!!!!! Like they say you get what you Pay for or perhaps were notÖ. Anyway be CAUTIONED on working on these supplies as you can see High Voltage are present you need a good sola transformer and a variac. Good test equipment and good common sense safety precautions to work on these !!!Please be cautious and safe !! If you donít know what you are doing then please donít do it!! I hope this will help!!
thanks have fun Dick / n3jwn
RE: Switching Power Supply Headaches  
by W3NRL on January 18, 2006 Mail this to a friend!
I have been using Alinco DM-330MV ( i have 2 ) for the past 2 years without any noise or problems what so ever.
Switching Power Supply Headaches  
by N0AH on January 18, 2006 Mail this to a friend!
If Alinco put a NOISE OFFSET on their DM-330MV, is that an admission that these supplies make noise? It is why I bought it and I can't make a better point. It is a selling point for them when you call to inquire about buying a switching power supply. Seriously, call them or a dealer nearby. I got my advice from HRO here in Denver.

I'm not saying any of the suggestions/comments made here are wrong. This is not a black and white issue.

I'm sure that there are dozen of variables to consider. Many already well thought out and listed here in this forum.

In fact, I did go back this morning and tried the supplies again. I did notice noise spikes we're a bit further apart on some of the supplies as some suggested. But with the noise spikes varying by model, what outside noise source would do that?

I think the temperature of the supplies also has something to do with the fact that the noise spikes can move around. Thus, the Alinco noise off-set on their DM-330MV. And an explanation for the Radio Shack model 2 minute wonder performance.

I appreciate the unput, but again I'd like to refer you back to the noise offset of Alinco supply to prove a point. And the fact that placement and distance and magnitude of the interference changes with supplies used.

Using 4 switching supplies compared to one solid state supply is a good test to check for outside sources.

Using the solid-state supply, my problems go away-

Trust me, I'm hoping it is something else- Or if any one wants one of these switching supplies, make me an offer and I'll ship it to you-

I'm glad those of you lucky enough to have your switching supply work es FB. Continued success.
RE: Switching Power Supply Headaches  
by N3JWN on January 18, 2006 Mail this to a friend!
I Whole Hartley agree with W3JJH's comments he's saying what I wanted to say in a more succinct way. Very good............ way to go bill didnt read any before I wrote mine..........Later Dick / n3jwn
Switching Power Supply Headaches  
by K2GW on January 18, 2006 Mail this to a friend!
Remember that lots of hams have different interests. For portable and emergency operations, the light weight of a switcher is a significant advantage

I have both types. I use a linear Astron RS-30 to power the shack at home and a switching Astron SS-30 in my go kit. Both are quiet on HF, but the switcher is a lot easier to carry around! And of course, the 50 percent of US hams who don't operate on HF won't be bothered by any HF noise. ;-)


Gary, K2GW
RE: Switching Power Supply Headaches  
by K7TCE on January 18, 2006 Mail this to a friend!
I've had an Icom PS-85 (extremely noisy) and currently have the Samlex 1223. With the Samlex, I did the ZL2DF mod, and it's still noisy on 80/75 meters. I moved the Samlex 1223 to my go kit, it works perfectly for my 50 watt 2-meter portable station. For the HF rigs I use the faithful RS-20M and VS-20M heavy metal power supplies. My next purchase will be a large RV battery with a small charger, then I'll have *no* noise and no worry about surges and power outages.
RE: Switching Power Supply Headaches  
by NI0C on January 18, 2006 Mail this to a friend!
I've never used switching supplies on my radios for the exact reasons you specify. There are just too many uncontrollable noise sources in our radio environments to be dealing with, so why take chances by putting one in the shack ? It's also a good idea to keep your antennas far enough away from the shack so they don't pick up noise from other devices, including PC's. This also generally makes it easier to comply with FCC regulations concerning RF safety.

Chuck NI0C
RE: Switching Power Supply Headaches  
by K3WQ on January 18, 2006 Mail this to a friend!
I agree with some of the other posters who say it could be something else in your home. The worst source of noise in my home is an "Ionic Breeze" air cleaner. It generates a drifting, raspy noise that can completely wipe out 5kHz segments throughout the HF bands. Most of the time, all I need to do is walk down to the bed room and turn it off. If that doesn't work, the next thing I do is turn of the computer monitor, which is right next to the rig.

-Davem K3WQ
Switching Power Supply Headaches  
by WI8W on January 18, 2006 Mail this to a friend!
My take on switching power suplies is this.

All computers have a switching power supply.

I lost a $3500 internet server to a 29 cent component in it's power supply. Fried motherboard, hard drives and network cards.

Do you really want to take a chance with your radio connected to one?
RE: Switching Power Supply Headaches  
by K8MHZ on January 18, 2006 Mail this to a friend!
You may be surprised to find out that some very strong PS noise can come from places other than your own QTH.

For an experiment, shut all the AC power in your house down, even to the point of turning off the main breaker. Now go around and un-plug all the UPSs that should be beeping and turn them off too. Now power your rig up with a 12 volt battery and give a listen.

I also found that much noise can be abated by making your grounding system more effecient. I used to connect my ground rods to my bus with about 10 feet of #4 copper. The weather broke for a couple days so I punched a hole in the basement wall right behind my ground bus so now only 20 inches or so of wire is the path to where it enters the earth, underground, and then is connected to the ground rod. I would say that my noise level went down almost 6 dB.

I hear the same type of sound that you describe on the HF bands. I used to think that it was some sort of PS noise. I now am pretty sure it isn't because a friend of mine hears them at the same places in the bands that I do and he lives almost 10 miles away. They are also present when I shut the AC down and run off 12 VDC. (Noisy batteries?)

A REAL fun experiment is to fire up the rig when your power is out from storms. If you can listen when a large area is without power you may be surprised to hear less of some noise and more of another...that from noisy ignition systems on generators.

After have been through enough of the above to know for sure you have a noisy PS, there is still hope. It should be possible to add a few components, either interally or externally, to quiet the PS down.

Every dB you can cut the noise floor down is the same as gaining that dB in the signal you intend to recieve. My best success has been to minimize the length of exposed grounding conductor while maximizing the surface area of said conductor.

Try 12 VDC and see if there is a difference. Also, thouroghly check to make sure your grounding system is not acting like an antenna.

Good Luck


Mark K8MHZ
RE: Switching Power Supply Headaches  
by K3AN on January 18, 2006 Mail this to a friend!
My concern with any power supply is transient voltage spikes or a failure that causes an overvoltage. I'd hate for a $100 supply to take out my much more valuable radio. To minimize that risk, I've used a filtered, regulated homebrew battery charger and a deep-cycle battery to power my station for at least the last 15 years. If the regulator fails, the battery will absorb the excess voltage for at least a few minutes. In that time I should be able to notice the slow voltage rise on the expanded scale voltmeter (also homebrew) that sits next to the radio, and shut everything down.

As a side benefit, there are no switching transients, and I've got emergency capability to operate for at least some period of time during a power outage.
RE: Switching Power Supply Headaches  
by AA4PB on January 18, 2006 Mail this to a friend!
Linear power supplies can also fail. I lost a repeater due to a $1 pass transistor shorting in an Astron linear supply. Yes, they have over-voltage protection but the SCR also opened.

Personally, I don't think the chance of a damaging failure is any more prevelent with a good switching design than it is with a linear design.
RE: Switching Power Supply Headaches  
by WA1RNE on January 18, 2006 Mail this to a friend!

Have you checked the unobvious?

>> i.e. a high impedance ground path between the power supply chassis under test and the mains earth ground - or possibly from the rig to earth ground?

If so, any leakage currents from the switchers could just circulate between the supply and the rig, or coupled by adjacent wiring to the rig instead of running to a common earth ground.

Linears don't have to deal with leakage currents from HF switching circuits so that's never an issue with a properly designed supply.

Could be as simple as a bad duplex wall receptacle or some other related earth ground issue at the station or at the main breaker/fuse panel.

Given the generally positive feedback from others using switchers, you have to figure the cause may be similar to what I've suggested.

Chris, WA1RNE
RE: Switching Power Supply Headaches  
by VE3GNU on January 18, 2006 Mail this to a friend!
My Icom IC-PS20 Switching unit mated with the Icom 740 transceiver was purchased in Nov. '82. Both have been in operation since then and have never let me down---but then remember when they were built!---a sound testimonial to the quality of gear available at that time---but then look what it cost me---$1546.98 Can.---still have the receipt---but no 'headaches'.
RE: Switching Power Supply Headaches  
by WB2WIK on January 18, 2006 Mail this to a friend!
N0AH, all the supplies you refer to, including the switch mode ones, are "solid state," so you ought to use a different term to discuss the non-switchers: They are "linear" power supplies, as opposed to switch-mode.

No way any modern switch mode power supply would be operating anywhere near a 10 kHz switch frequency. Not 20 kHz, either. Most operate at at least 70 kHz, and in the past few years, higher.

I've used all the switch mode power supplies you refer to, including the Alinco, and have never noticed any RFI from any of them in the amateur HF spectrum. Down below the amateur HF spectrum -- yes. I can hear the Alinco, and even the very good Astron SS30, down at 500 kHz and such, but I'm normally not listening there.

The SMPS's I have, if they radiate any RFI I can detect, do so in intervals of the switch frequency, 70 kHz or higher.

I suspect you have some other things going on, and possibly even intermodulation of RFI pulses that are conducted through the power mains. This is actually pretty common. In my household alone there are probably 100 switch mode power supplies that are "always" powered ON, whether we're using them or not, and whether we're home or not. As long as the AC mains doesn't fail, they're running. In our seven television sets, five PCs, numerous CD/DVD players, telephones and answering machines, Nintendo and Sony games...hell, even my sprinkler system is powered by a "cube" switch mode power supply.

A possible Solution  
by K0BG on January 18, 2006 Mail this to a friend!
This maybe a little off subject, but not by much.

I have been plagued with an off and on noise source since moving into this house new, about 5 years ago. Several times I thought I have found it. I even traced one to a heating pad at a neighbor who didn't even know it was plugged in. But until I purchased a model 852 noise receiver from MFJ (it was half the cost of building one), and started looking really hard for it. I found it three blocks from my house. Why it was quiet between the sources, is a mystery. Once the power company replaced one transformer, and a lightening arrester, the noise stopped and has stayed that way.

I have a new one now that a neighbor installed a swimming pool. Without the noise receiver, I would have never located it. The pool company was was impressed enough, they bought one! Turns out it is the ozone generator, and a new shielded one it on its way. Other than the 259B, it has been the most rewarding gear I've ever purchased.

Alan, KōBG
RE: Switching Power Supply Headaches  
by W9WHE-II on January 18, 2006 Mail this to a friend!
Switchers have another problem - repair.
Your typical switcher is not nearly as easy to troubleshoot and repair as your typical linear supply. So when/if it fails, the average techy ham (not appliance operator) can troubleshoot and fix a linear supply. As for a switcher, you better plan on sending it in and getting a bill close to what a new one costs.

As for the Alinco DVM, great looker, but mine can't hold its voltage steady at 24 amps, let alone its rated 32!

Switching Power Supply Headaches  
by NE0P on January 18, 2006 Mail this to a friend!
I have had an Astron SS30, Diamond GZV4000, and a Samlex SE1330, and haven't had problems with any of them. I now have an Astron RS50A and haven't noticed the noise floor dropping any when I replaced a switching PS with it. Now the switching PS in my 27 inch GE television is another story. I wish my 3 year old would hurry up and break that TV so we can get another.
Switching Power Supply Headaches  
by KC7ULI on January 18, 2006 Mail this to a friend!
W3JJH replied with a lot of what I would say about switchmode supplies. I am a power applications engineer with a major semiconductor manufacturer and we specialize in switchmode converters -- they are my bread and butter. So here are my observations about switchers in general:

1) They are not going to go away. Too many advantages to list vs. linear supplies. (Linears on the other hand, may someday go away -- see the next comment)
2) The Feds will mandate switchers for energy conservation in almost everything made in the next few years so get used to the idea. This is the next step beyond "Energy Star".
3) If you have switching noise issues with your supply it is probably because you bought to a price point, not to a quality point. More expensive switchers usually have more and better shielding, multi-sided shielded boards with real ground plane, etc. Not to mention the better magnetics, smaller current paths for reduced spiking and EMI, better filter capacitors with lower effective series inductance, etc. Bargain switchers are not usually well designed.
4) Linear supplies can be less reliable than switchers due to the heat associated with linear mode operation. Heat kills electronics and properly designed switchers produce less heat. Anectdotes aside, linears can take out expensive equipment just as surely as a failed switcher.
5) Frequencies are going up so that component sizes and costs will come down. Your PC probably uses a 4 phase DC/DC switcher operating at about 1.2MHz or higher and supplying 1.2V at 120Amps to your CPU (12V in, 1.2V out, for example). Each phase switches at 300KHz. This will go up to about 500KHz in the not too distant future. These supplies are not the source of noise eminating from your PC, in all likelihood. That comes from your monitor or in the video circuits in general.
6) Most switching noise issues from these supplies have reasonable solutions, including adding some additional ferrite filtering on AC and DC lines in and out, better grounding, better lead trim and dressing, additional capacitive filtering, etc. This may take some time to implement, but it is a satisfying process when it works for you.

Switching power supplies are a good solution. They are not perfect, but an oscillating regulator in a linear supply isn't a perfect thing either. Good switchers are great, and mediocre switchers are really pretty darn good. Your main PC supply is a mediocre switcher and costs have been driven so low in these that they should really not work as well as they do. But they do work and they have been refined and refined over a long time frame. Most of these are really clean enough to use near your transceiver without a problem.

Switchers are a fact of life and just because you think you are using a linear to keep your rig clean, be aware that somewhere, near your shack is a switcher. If it is making noise that you can detect, fix it or replace it. The suggestion made by K0GB to use a noise RX to detect offending sources, is superb. As BPL comes into our lives, this tool may be a necessity for us all.

73 to all and happy new year.


RE: Switching Power Supply Headaches  
by AA4PB on January 18, 2006 Mail this to a friend!
Switchers have another problem - repair
That is an issue. Many of the mfgs don't even provide a schematic or parts list on their web sites for the switchers. Linear supplies do follow the KISS method so it is something to consider if you don't need small and light weight.
RE: Switching Power Supply Headaches  
by N6AJR on January 18, 2006 Mail this to a friend!
How many folks are using Icom ps 125 ?? these have run my Icom rigs for years, with no noise.. HMMMM
Switching Power Supply Headaches  
by K7VO on January 18, 2006 Mail this to a friend!
I will join both Alans, Alison, Steve, and everyone else who has said your problem is not the switching power supply. I have had no problems with the Astron SS-10 I currently use and I also had the Samlex and found it to be noise free on the ham bands I use (40m and above). I had the Radio Shack one as well and my complaint with it was the incredibly loud fan that was on all the time, not RFI. I also have a linear supply in the shack (Kenwood PS-20) and there is no difference in noise (or lack thereof) between the Astron switcher and the Kenwood linear supply.

The main reason I like the Astron better than the Samlex is that it can be easily switched between 110 and 220V AC input for travel. The Astron SS-10 is one of the smallest, lightest 10A supplies out there and as I don't run anything that requires more current than that it serves my needs well.

look elsewhere when experiencing these "probl  
by KZ1X on January 18, 2006 Mail this to a friend!
Pretty much 80% of the problems of switching supply noise I've run into is in shacks with end-fed or (even worse) indoor or other compromise antennas.

The other 20% is conducted emissions due to insufficient low frequency reactance in the supply's power line filter.

My Samlex PS1223 jams the AM BCB, only on some frequencies, and only on my end-fed. Since it is the float charger for my 300 AH battery, I simply reach over and turn it off for a while when I need "real quiet." The batteries can run the whole shack for over a week ....
RE: Switching Power Supply Headaches  
by W6TH on January 18, 2006 Mail this to a friend!

I have absolutely no problems with my Samlex, Radio Shack or the MFJ Switching Power Supplies.

However my noise generated on my ham radio is from my monitor of the computer, a smaller amount of noise from the computer itself.

Every ten Kc/s you hear may be from a horizontal oscillator of some sort or from your television.

Compared to my linear power supply, the Tripp Lite model PR 20, one is as good as the other.

Buy American.

73, W6TH.

RE: Switching Power Supply Headaches  
by W5HTW on January 18, 2006 Mail this to a friend!
Ten years ago, when I bought the original Icom 706 and the PS-85 power supply, I learned "there's no free lunch." Switchers are supposed to be lightweight and reliable. Took me under a week to realize the PS-85 was a radio transmitter on its own, and did not need the 706 to work DX. The interference was roughly every 17 khz from BCB into 2 meters, though it dropped below S6 on 2 meters. On 40 CW, the switcher was S9 plus 30 db. CW operation was completely impossible. Around 10 meters, the PS-85 was S9.

Icom admitted finally that it was a defective power supply (not my specific one, but the PS-85 in general) and I traded it back to them for an Icom 2000H 2 meter rig. Sure I lost money, but I had had the PS85 back to them twice and they certified it was operating according to design.

By the time it arrived back at my home after its second trip to Bellevue, I had purchased an MFJ linear 35 amp power supply. That unit has remained on the desk (or under it) for nine years now, and all I have done to it is clean the fan once in a while.

I do agree, though, if I could have moved the antenna further way, perhaps 3/4 mile or so, it would probably have been better.

Switching Power Supply Headaches  
by K0RGR on January 18, 2006 Mail this to a friend!
I have both in my shack, in fact, I think I have the same Radio Shack unit powering a two meter rig and I have looked for HF noise from it and haven't found any - but it is not powering the HF rig, either (it is about 8 feet away).

In my home, I used my FT-817 with a little sniffer loop ( a small wire loop on the end of a piece of coax) to find a wall wart that was causing S9+++ noise on all the lower HF bands.

Ultimately, I purchased a brute-force line filter like those they use on industrial equipment from Digi-Key, and wired it into the AC line for my station. The resultant quiet was unbelievable! I had heard of other OT's doing this, but had never tried it before - what a difference! I never dreamed that the typical residential powerline was so polluted, but with the stuff we plug into them today, I imagine they have to be.

Many vendors carry these things. I've seen them pre-assembled in nice boxes with breakers and multiple outlets, too, and they shouldn't break the bank.

Obviously they won't cure a truly noisy power supply, but it will probably eliminate other noise, and that may be why mine doesn't bother me - the input AC is cleaner to start with.
RE: Switching Power Supply Headaches  
by AA4PB on January 18, 2006 Mail this to a friend!
I believe the original PS-85 came in dead last on the ARRL lab testing of switching power supplies. I understand the later units are much improved. I wouldn't condem all switching power supplies based on an early PS-85.
RE: Switching Power Supply Headaches  
by KC8VWM on January 18, 2006 Mail this to a friend!
I also found that much noise can be abated by making your grounding system more effecient.


Switching Power Supply Headaches  
by W0FEN on January 18, 2006 Mail this to a friend!
I have my ICOM PS125 plugged into a SOLA ferroresonant transformer that sits below the operating desk. I use it to keep line voltage spikes out of the rig and computer. If you are not familiar with this device it regulates the AC output to a 1% pure sine wave at exactly 117 VAC. Yes it hums but, I have very little noise and no spikes in my shack. The one I use is a 500 VA unit. I also have a 1 KVA one in the garage that I use on Field Day to ensure that the generator doesn't go astray and fry my big $$$$$ rig. I would recommend one for each Field Day operation. I bought mine at a hamfast for $25 each.
RE: Switching Power Supply Headaches  
by K2WH on January 18, 2006 Mail this to a friend!
"I first started noticing RFI problems with my switching power supplies back in 1999. In particular, I was getting a raspy sound every 8-10KHz on the low bands and a little less on the high bands. . My Icom 756 scope showed a nice spike averaging about 10KHz apart thanks to the power switching supply.

Today, 4 switching supplies and 8 years later, the technology has not cured the problem. I still have the exact same noise using switching power supplies."

Wait a minute, let me get this straight. You put up with this noise for 7 years! Am I correct or did you type in error? If you actually put up with his for this amount of time you deserve no sympathy from anyone and certainly not a head scratching article like this one.

Something new every day. No wonder they call them amateurs.


RE: Switching Power Supply Headaches  
by WA6CDE on January 18, 2006 Mail this to a friend!
I used to use a standard astron power supply ... linear... then I built my own for higher power... wow talk about heating abilities... keeps your feet warm no doubt but, then when we went traveling... we decided to go with a switching power supply... and we were impressed... but, not only is the Semtec a good one.. 1000 of yeasu owneres cant be wrong... as that is what they use... also... Check AES they know... but, we found some other interesting things...

First off the weight... ouch... lift one of them boat anchor linear supplys.. and you need to visit the weight room to work up to lifting them... (astron has a problem with its steel case making a humming noise... and just can't seem to fix it on the 30's and 50's which are linear ones...) putting lots of books on it seemed to help... putting half a dozen more screws in did too.. but, it still hums from the magnetics of the transformer... and you know that has to come from somewhere...

Which leads us into the second reason we now use a Switching power supply... cost... not of the unit but, of the power it consumes... my Astron SS30M uses half the elect bill power that the linear 35 did... It was real reflective in the power bill when only the PS were on when we were away...

The linear 35 uses about twice as much just sitting their as the SS30M does... according the watt meter... on the power line... now add to this the amperage needed to run the radios... and the switching one starts using more power... the 35 does also.. but when you get to the max output of both... strange they seem to draw about the same from the wall...

So if you use the max power... then its more efficent to use the linear one... if not the switching is better...

As to noise... a few good torid beeds in a few good places will make the Switching power supply about as quiet as a church mouse on sunday... I recomend that you look at the hombuilt 40 amp one and see his output filtering he developed (listed in the ARRL book) or go on the internet and look him up... as he also has good design for filtering... of the switching power supply...

But, almost every computer has them... for effecent use of power... and almost all the new radios are coming out with them... again to keep the power drain down... but, there is nothing like a linear power supply for pure DC... provided you pour some concrete pad to support its weight... and have lots of money to pay the power company with... grin...

Good luck in making your decision... as to which to get... for travel I use the switching... at home I use the switiching... both for the power saving and when traveling the weight...(about 1/3 a linear)
Switching Power Supply Headaches  
by W7DDD on January 18, 2006 Mail this to a friend!
Try the Diamond SS-330W. Great unit. Runs cold. No RFI/EMI. No noise. Could not be happier.
RE: Switching Power Supply Headaches  
by K1EJA on January 18, 2006 Mail this to a friend!
Hey guys, look at the suggestions and mods on how to make these work well . Move the antenna system away from the supply, just move it around ..hmm how far do I place it? Provide a better ground system. Easy if I lived in the basement. , but drilling holes through the walls to make a ground system better.. ? Buy an AC line Filter? Apply more shielding to the unit?. Use ferrite chokes, etc. At this point, I think the original post is answered.
I have an Alinco 330MVT.. (with a NOISE offset knob). Above 14 MHZ it is great, but below 14 MHZ the birdies crept up and forget the broadcast band. So if it's a supply that works well only under ideal conditions, then..I opt for the linear supply. I tried to like this supply. It's physically well designed and lightweight, but after six months of frustration, I decided to go with a "linear" Astron and everything is relatively quiet on all bands. I Know it's heavy, but hey I don't have to move the antenna.
If I buy quality HF transceiver, I don't want to try to find just a frequency where the switcher isn't signing or have try all of the modifications.. The 330MV seems to have excellent reviews for some, just didn't work for me.

Switching Power Supply Headaches  
by W4KPA on January 18, 2006 Mail this to a friend!
I've had an MFJ-4125 for several years. If it has a hash problem, I can't hear it.

This thread is so long that I'm not sure if anybody has mentioned this, but in January 2000, QST published a side-by-side comparison of several switching supplies, including including spectral displays of the outputs. It included the Samlex 1223 (lots of broadband noise), the Astron SS-30 (pretty quiet), and the MFJ-4225 (also pretty quiet). There were also proprietary supplies from Kenwood, Icom, and Yaesu, but I don't remember off hand how they fared.

Based on that, I went out and bought the MFJ-4125, keeping my fingers crossed that the technology was similar to the one QST reviewed. I never checked that out, but the supply has been more than acceptable. I've carried on a lot of trips in my luggage or brief case.

Which brings me to my final point: I probably wouldnt use the switcher to replace my two big Astron 35-As in my home station. But, when you need a compact supply, a switcher is hard to beat.
RE: Switching Power Supply Headaches  
by K6AER on January 18, 2006 Mail this to a friend!
Iíve read through all the postings and only one ham mentioned the location of your antenna. This might be the location of you noise input. All switchers generate noise. It is just a matter of path propagation. Every switcher has a level of RFI output and as many have mentioned the performance of RFI shielding and switch band noise is much improved in current designs. The one area you did not mention is the location of your antenna, feed line and general station orientation. Using open wire feeder near a switch mode power supply will surely pick up switch mode transient noise. Using a battery will eliminate the power supply suspect but there are many other emitters of transient noise. Computers, monitors, heating controls, DVD players, TVís, radios, stereos, room light controls, stoves, refrigerators, washers and dryers, and any device that plugs into a wall socket. Did I mention cell bphone chargers?

Put your station on a battery and turn off the AC feed at the panel to the house. If the noise disappears the source is in the home, if it doesnít it might be from outside the home.
RE: Switching Power Supply Headaches  
by KC2MMI on January 18, 2006 Mail this to a friend!
<<Build one, but make it a standard linear supply. There are quite a few vendors out there who can supply a transformer,>>

Can you recommend a source for one? From what I've seen they're going to run $75++ and shipping will bump that over a hundred very quickly.

At which point the phrase "economically unfeasible" starts coming to mind. I've actually got all the rest built (25+ years ago) but never ran across a nice high capacity transformer (say, 18V 25A rated secondary) in all that time, so I've been living with one that saturates out much faster than that.
Switching Power Supply Headaches  
by KB9YUR on January 19, 2006 Mail this to a friend!
I've been running the Astron SS-30M for nearly five years now with no problems or RFI powering
an Icom 275H. Having an APC SU1000NET UPS ahead of the unit helps with line noise and
voltage/spike issues.
RE: Switching Power Supply Headaches  
by AD5X on January 19, 2006 Mail this to a friend!
... but never ran across a nice high capacity transformer (say, 18V 25A rated secondary)...

MFJ sells a transformer (part number 406-3800) which has a secondary rating of 18V at 30A. Price is $35.

Phil - AD5X
Switching Power Supply Headaches  
by AI2IA on January 19, 2006 Mail this to a friend!
By and use a good switching power supply. Don't push it close to its limits for extended periods of time. Put it in a clean, dry location and use good housekeeping. Give it adequate cooling space. Keep it dust free by keeping it clean and gently blowing away any dust built up outside and inside. Keep it away from RF sources. Ground it, and check it from time to time. I have done this for years and my switching power supply units have been every bit as dependable as my rigs, and some being older and well used, are even more dependable.
Switching Power Supply Headaches  
by K4HPP on January 19, 2006 Mail this to a friend!
I have had two DM330MV almost since the day they hit the market. I have used them with the TS2000, IC706MK2G, IC-756PRO, IC-756PROlll, IC-7000, K-1, and KX-1. There has never been a hint of noise associated with the Alinco supplies with any of these rigs. The only place I can find switching noise is below 500KHz in the LW aircraft beacon band. The noise pulse shift control works as advertised to shift this pulse several KHz off of the listening frequency. Nowhere above the BC band can I find even trace evidence of power supply generated noise all the way to 470 MHz. This would suggest that the "10 KHz" spaced noise that is being reported is coming from some other source.
RE: Switching Power Supply Benifits  
by WA6CDE on January 19, 2006 Mail this to a friend!
One thing else I forgot to mention was that the Astron 35 and most other transformer linear PS will only work with 60 cyc 120 v ac power... something that is only common in the US... while the Astron SS-30M will work on just about any frequency power from 120-220 volts when set for voltage only... thus you can use it over in europe and other places ... when you go field day hopping... it doesn't care about the line frequency... and if the generator isn't quite up to snuff on the gas your feeding it... so the RPM is down and the frequency is off...

I havn't tried the SS on one of the new hondas that use a switching power supply/DC voltage for power... Such as the EU-2000... Some have said that the Astron SS doesn't like it.. but, others have said.. works fine..

Just a note to add to the pile...

73's GM
Switching Power Supply Headaches  
by K3YD on January 19, 2006 Mail this to a friend!
I own an Astron SS-30 and have noted only 2 noise spikes with mine. One is in the AM-BCB, the other on the high end of 15 meters. I find the fan noise from my supply far more bothersome than the RF noise. At home, where size/weight is no issue, I use an RM-35M linear supply. Going portable? Then I'll accept the little bit of noise from my switching supply. The little 8# box is a lot easier to carry.

Since you have noise every 10 KHz with all of the switching supplies, I'd recommend some detective work. Try listening on a dummy load to determine if the noise is coming in the 13.8 V. line, or being radiated. Try operating the radio independent of mains (i.e., car or marine battery) and repeat the Dummy Load test. Those experiments may give you some ideas. GL es 73!
RE: Switching Power Supply Headaches  
by KL7IPV on January 19, 2006 Mail this to a friend!
I bought an Astron SS-20 a few years ago and noticed noise on my HF gear right away. I never thought the noise was from the PS but looked everywhere else. After months of noise and no luck finding the source, I unplugged the PS and used a battery to power the HF rig. When the noise was not there I looked to the PS. After verifying the noise source to be the SS PS, I called Astron. They told me to place a cap between the Pos & Neg posts and ground the neg term post inside the box. I did as told and the noise is gone and has remained quiet for years of solid use. If you call Astron and ask them about yours, maybe the simple fix I made will correct the problem. Good luck.
Switching Power Supply Headaches  
by N0AH on January 19, 2006 Mail this to a friend!
So what it comes down to is that very few of us in this sample have no problems. OK. That's cool-

The Alinco DM-330MV has a noise offset. Hummmm....

I think most NB controls and switching supplies have one thing in common, one is suppose to supress noise, the other is not suppose to create it. Get's opinionated fast.


Thanks to those of you who have made great suggestions, informative comments, and private emails in attempts to address the subject-

RE: Switching Power Supply Headaches  
by K8KAS on January 19, 2006 Mail this to a friend!
I know no one builds anything anymore, but have you ever heard of a filter? Yes I have an SEC 1223 and it had some switching noise on the DC bus. I looked on the Internet and yes there was a cure noted in an article by a Ham. A simple filter made of about 8 small toroid cores (type 43) and a pair of .1 mfd caps.
The cores were slid over the positive and negitive leads and the caps were across the input to the leads and then the output. No noise even on 75 meters. Took me about 15 min and cost me about 5 bucks.
RE: Switching Power Supply Headaches  
by WB9NJB on January 19, 2006 Mail this to a friend!
After four years of constant use, I have never observed any noise with the Alinco supply. It has performed as advertised, and I would recommend it without hesitation. It drives an FT1000MP, and several other UHF/VHF rigs.
RE: Switching Power Supply Headaches  
by N3JJA on January 19, 2006 Mail this to a friend!
I have an Alinco DM-330, Astron SS-30, and an Icom PS-125 (came with the 746Pro).

Except for an ocassional noise artifact on 75m phone from the Alinco (the offset control DOES work, BTW) I've got absolutley no noise from any SMPS in my shack. I get more crap from the power lines and the 57-inch Sony HDTV projection set.

You've either got a black cloud over you, or (as others have suggested) you've got something else going on that's not obvious.

I find it hard to believe that anyone could have that many defective SMPS.
RE: Switching Power Supply Headaches  
by G3RZP on January 20, 2006 Mail this to a friend!
My main bitch with SMPS is that in my experience, failure results in a chain reaction leading to handfuls of dead parts!

The worst one I ever encountered for RFI was a Toshiba one for the XYL's first laptop. Despite FCC certifcation on it (for what that's worth), the RFI was so bad you couldn't even listen to an FM radio in the same room.
Switching Power Supply Headaches  
by N2JSO on January 20, 2006 Mail this to a friend!
The cheap switcher that was in my PC produced S9+ hash at intervals all through the HF bands. It produced broadband noise that made 160m and 80m completely unusable. I replaced with a less cheap PS, and the RF noise from my PC vanished.

My PS-125 came free with my 746Pro. As far as I can tell, it produces no RF noise. However, it has a very audible whistle/hiss that comes from the transformer. I tracked the noise down by holding one end of a rubber tube to my ear, and passing the other end near various components inside the PS. I should send it back to Icom. But, it was free, and I'm using my old linear supply - a Yaesu FP-301D, with a nice built in speaker and clock.
RE: Switching Power Supply Headaches  
by AD5TD on January 20, 2006 Mail this to a friend!
Been using the RadioShack, and an MFJ adjustable for over 2 years WITHOUT any of your problems. I like them.
RE: Switching Power Supply Headaches  
by W9AC on January 20, 2006 Mail this to a friend!
> "At first, (2 minutes) it seemed ok. Then it got a life of its own. It created rampant noise that covered at least 25% of my bandwidth with wide noise spikes of 10-15KHz. Rated at 13.8V 25A."


For the past few years, I have been ridding my shack of switch-mode power supplies at every opportunity. The only non-linear supply left in the shack is a 48V Lambda switcher for my GPS-based frequency standard and the internal switcher in my ICOM IC-7800. The Lambda is the only switching supply I will allow by choice. My ICOM-7800 does use a switch-mode power supply and it does generate some noise, but through the use of these supplies, I have had to re-think my shack's AC power distribution.

120V for my shack is now fed from isolated-ground outlets, home-run back to the load center. Moreover, I run a pair of Tripp-Lite 1KVA 1:1 isolation transformers -- one for general shack power distribution and the other for the ICOM 7800. With this arrangement, I've been able to minimize the spray of RFI/EMI emanating from other house-hold switching supplies into the shack AC line.

Other switch-mode power supplies are in the home and it has become a real battle in keeping them tame. During the past year, I have had intense noise coming from the power supplies feeding my home LAN router, my home theatre's subwoofer, and various laptop PCs.

No doubt the switchers are efficient, but unless you're constantly prepared to do battle with these supplies, try to use linear supplies where you can.

Switching Power Supply Headaches  
by N5YPJ on January 20, 2006 Mail this to a friend!
Have used the Radio Shack Model # 22-510 for two years now, no problems on my IC-728 or IC-V8000.
Switching Power Supply Headaches  
by W2RAC on January 20, 2006 Mail this to a friend!
I have been using a Astron SS-30M for 4 Years and never had a seconds trouble with it. Even when I accidently short the contacts, INSTANT shutdown. I rarly hear the fan, but with 3 pcs and a dozen rigs/scanners in the room I would hope not too.

My Astron RS-35M is now the backup and been in storage since I got my SS-30M.

Richard W2RAC
RE: Switching Power Supply Headaches  
by NS6Y_ on January 20, 2006 Mail this to a friend!
I'd say, put that puppy on a Spectrum Analyzer and take a look, then.... decide!
RE: Switching Power Supply Headaches  
by K8CXM on January 21, 2006 Mail this to a friend!
If you are looking for 'hash' from switching power supplies and you have a PC in your shack, check it and all it's attached devices. I had a Dlink DI-604, a small wired router that was 8 feet from gear and it caused all kinds of hash. I finally replaced it wirh a wireless Linksys which so far is perfect.
RE: Switching Power Supply Headaches  
by VE7ALQ on January 21, 2006 Mail this to a friend!
I use an Alinco DM-330MVT with my Icom ic-706mkiiG I operate 40 and 30 meters CW as well as 2 meters FM. What is this noise that you are referring to? It seems to be absent from my configuration.
RE: Switching Power Supply Headaches  
by K8RBW on January 21, 2006 Mail this to a friend!
I have a variety of switching and linear power supplies. At my condo in Wisconsin I have the RS, Samlex, MFJ and Astron switching supplies. I experienced much the same problem as you and thought I was going crazy. I replaced them with an Ainco linear supply, but to no avail. Then I built the portable battery power pack described by Phil, AD5X, for the SG-2020 and the problem still persisted. It also disappeared when I drove the mobile away from buiding. I later hauled the SG-2020 with battery pack into my neigbor's unit (they're sweethearts who support me in the face of antenna restrictions) and found the problem in the switching supply in their TV. When they left for Florida this year they disconnected all their appliances and the problem disappeared. As a number of people have said, look elsewhere and you may find the source of the problem.
de Dick, K8RBW
RE: Switching Power Supply Headaches  
by WA2ZDY on January 21, 2006 Mail this to a friend!
I too have the SS30 and experience absolutely zero RFI from it on any HF band. I'm using it with my Kenwood TS480 and a linear loaded dipole in the attic ten feet over the shack. If this power supply was generating RFI, I'd hear it. It's not.

RE: A possible Solution  
by W4VR on January 21, 2006 Mail this to a friend!
For the past 5 years I've been using transformerless power supplies to power radios and amplifiers and never had any problems with interference. Is it possible the ones you purchased were lemons? You must be "lucky Pierre."
Switching Power Supply Headaches  
by N0AH on January 21, 2006 Mail this to a friend!

Just look in the most recent 2006 MFJ Catalog, page 23. Both switching supplies listed, MFJ-4225MV and the MFJ-4245MV have big bold red letters stating "NO RF HASH!"

Same for their MFJ-4125. But this time the have the No RF Hash underlined!!!!!

My God, using MFJ to make a point? World ending now-Over..............

RE: Switching Power Supply Headaches  
by W5ONV on January 21, 2006 Mail this to a friend!
I have used the Astron SS-30M for 6 years now.I have intentionally looked for noise on all bands and I can not find any to tell about.Very clean. 73, Jim
PS: Do you think that MFJ would lie to us or use false advertisment about their products? ya,right. Hi,Hi !!
Switching Power Supply Headaches  
by W5SSC on January 22, 2006 Mail this to a friend!
I have a Ten Tec 963 switching power supply providing power to my Ten Tec Jupiter HF rig and have never heard any noise emanating from the 963 power supply.
I also have a Diamond QZV 4000 switching supply and have nothing but praise for it's performance. I have no issues whatsoever from my switching power supplies. W5SSC Scott Chamlee
RE: Switching Power Supply Headaches  
by WX4O on January 22, 2006 Mail this to a friend!
I also have the MFJ 4125 and it's been in use a couple
of years with no problems at all. No hash, no spikes.
MFJ does sell some good things and I think this is one
of them.
RE: Switching Power Supply Headaches  
by WA6CDE on January 22, 2006 Mail this to a friend!
their are only two sources for a switching power supply to send noise out of it through... one is the line in.. the other is the line out... both areas should be filtered so as not to emitt noise...

If you look at the schematic of the MFJ and others you will see they take great pains to make sure both ends of the supply is filtered... You can see this also in the ARRL handbooks 40 amp switching power supply... where the use of ferite beeds around the output wire changes the noise into no noise... by filtering it. Making sure the shield is around it and attached properly is also a must to keep the osc'ltions from being heard no matter which kind of supply you have...

While each kind of supply has its merrits and faults... each has it place. Some have said they like the old linear supply at home.. while other use both one at home and one on the road for weight and convience.

If I were to select just one.. I think I would go with the switching supply... and while it has more parts in it... it does seem to be much more efficent probably why the computer people went that way... after all think of the millions of computers that are all fired up and making the powerplants run... if the powersupply weren't effecent... how much more power would be needed to supply the fleet??... and how much more it would cost you at home to go on line???...

Their reliability have come a long way since the old ones of yester year... and they are still improving them to make them more efficent and use less power while still meeting the design loads... You can't take a old Lamda power supply and compair it to todays... its apples and oranges...

And while its much easier to use the old linear supply and make one.. (less parts) one will find that they draw about twice as much power... thus if you go with the bean counters... the pay back in the switching power supply is less than 6 months.. over the linear consumption.

Most of the new radio manufactures have gone to the switching power supply also.. Yeasu had it for their 757 and icom has now gone to it also... (No more conserns about line frequency power... one supply does it all kinda thing)

Its all about how much power cost these day to play...

As to protection... the switching probably has more than a linear's fused supply would...

But,... thats what makes the world go round... each to their own choice... the bottom line is which one do you like... to run your radios etc...
Switching Power Supply Headaches  
by KC8Y on January 22, 2006 Mail this to a friend!
I've used my Astron RS-20A (about 15-years old) on both, of my 2-M rigs...had the Icom 2100H (sold), and now the Icom IC-V8000...never any trouble with the PS...I use the Icom IC-736 [has internal PS] xcvr for HF; and it, also
never gives me trouble...must be that I have good-luck all-away round
RE: Switching Power Supply Headaches  
by G3RZP on January 23, 2006 Mail this to a friend!
The Icom IC 251 had a switching PSU some 20+ years ago. Mine has proved reliable (touch wood!) and quiet, even on the HF rig sitting next to it on the bench. It certainly can be done.

But if I want a supply for me, and I have the transformer, rectifiers, transistors, electrolytics etc in the junk box, (and you should see my piles of such things) I'm far too mean to buy a SMPS.
RE: Switching Power Supply Headaches  
by KD7QX on January 23, 2006 Mail this to a friend!
I recently purchased a Daiwa SS-330W ($149 shipped at VIS) and it is absolutely silent on both the rigs I use (Yaesu 757GX and TenTec Argosy). I, too, was hesitant to risk the potential noise of a switching supply, but the Daiwa's small size and light weight lets me pack it along for trips much more easily than a linear supply, so I took the plunge. So far I'm very happy with the purchase.
RE: Switching Power Supply Headaches  
by DD3LY on January 23, 2006 Mail this to a friend!
Just to mention another trade mark: I use two Emtron EPS-20ST switching power supplies. I have NO hash at all, never had with these. These are switching power supplies from some elder design, just capable 8A continuous operation 15A intermittent (3 minutes, with 50% duty cycle) 20A peak but this is enough for my 100W transceiver for SSB or CW. At the moment Emtron sells these supplies new for just 78.ooUSD (see, but surely you can find them used on ham trade meetings.
RE: Switching Power Supply Headaches  
by KE5GLK on January 25, 2006 Mail this to a friend!
I too run the IOTA 55 power supply. It isn't pretty but it is built like a tank and no noise. By the way, it's built to deliver a constant 55-amp load at full duty cycle 24x7. Lastly, they are extremely reasonable concerning price.
Switching Power Supply Headaches  
by K6XT on January 28, 2006 Mail this to a friend!
I use the Astron SS-25 and SS-30. No HF noise from either one. My IC765 has a built in switcher as well, no noise from it. That 10KHz-spaced noise from various supplies in various locations is extraordinarily suspicious. Good luck!
73 Art
RE: Switching Power Supply Headaches  
by W5CMP on February 1, 2006 Mail this to a friend!
my gzv supply made noise also but i plug it in to my ups and now the noise is gone. you could try this if you have a ups. plus my ps 125 no 746 pro did the same thing.plug it in ups and noise is gone.
73 from mike
RE: Switching Power Supply Headaches  
by KE4DRN on February 1, 2006 Mail this to a friend!

we powered our fd digital station with
the compact honda generator and the ss-30
astron supply, no problems. Two other
fd stations were powered with a larger
honda series EU model and no trouble there.
The gensets were properly gounded.

I also have an Lambda Vega model
switching supply, no problems using it.

73 james
RE: Switching Power Supply Headaches  
by HP1KL on February 2, 2006 Mail this to a friend!
I also have an MFJ 4126 switching PS and I have not had any problems whatsoever. It works like a charm and allows me to move the radio around, especially on weekends when we go to our mountain retreat.

The way I have my portable set-up is: A Kenwood TS-50, an MFJ-971 manual antenna tuner on top of the radio, and the MFF 4126 PS on top of that. I use heavy plastic ties to keep all three together as one piece, easy to pack and carry. Notice the proximity of the radio-PS, but I have had to hash problems. I also like the 110-220 input, which is great for travel to Southern Cone countries or Europe.

73's - Tony-HP1KL
Switching Power Supply Headaches  
by KB7UXE on February 8, 2006 Mail this to a friend!
ok, one thing bothers me, yes, some of you have problems with switchers, some don't.
I believe this to be true. But, the one factor seemed NOT to be mentioned is: the noise is frequency spicific.
that is, above 80m noise significantly drops.
On mine 10m on up, you just don't hear it.
but on 80m, it's very annoying and basicly rendered the hf useless. This is with 5 different brands including two Radio shack 25amp, Pyramid PSV-200,sudo IOTA and an Astron ss-30m. The best so far has been the Astron ss-30m, while not as bad, it's still there. I called Astron this morning 949-458-7277, the tech suggested:
remove cover,
1,make sure screws tight in 4 corners on pc board
2, look for L5 L4, If L4 & L5 are present,
3, Add 16V 2200 mfg & .1mfg parrell @ output.

I would assume some eirly production units did not have the 2 inductors L4 & L5.

Ok, so off to RS to buy some caps. finkers crossed.
Like previousy mentioned, for get e-mail to astron corp. It either bounces or no answer.
Simply call direct.949-458-7277.
Once on the phone, responce was fast and spicific.

kb7uxe at comcast dot net
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