Ham Radio - What is the Noise Offset control for on your power supply?

Many power supplies have it, but what does it do? I show you the noise and how you can tune it away with this control.
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[@arthurcramer4958]

Thank you for this video. I have the same Alinco supply and had no idea what it did. Will try it tonight. 73!

[@rhythmstic]

Excellent video, its good to see how the interference works in real time and visually! Seems to me the trade off is wandering interference of a switched psu against the fan noise of a linear psu. I'm trying to decide betwixt the two and this video has been a godsend of clarity. Many thanks.

[@k2cjbradio]

I'll stick with my Astron R35 good ol fashioned linear supply. 😃

[@rpcomms1]

Hi Kevin great video its just shifting the clocking frequency of SMP,can resolve it sometimes but if your SMPS has not got it try these tips. Ive had recent great success getting down to the bottom of DC Isolated Switch Mode Power Supplies (SMPS) especially with HF and 2 way radio equipment. I know some SMP's dont offer this feature but have put a list together that i have validated 2 years or R&D working on SMP issues with noise,RFI,DC noise and AC induced on DC Lot of Mfr's dont stipulate certain rules with these new SMP,especially when it comes to 2 way radio! so I like to share what I have found and resolved both in radio field and Industrial electronics as a client and design team were having some great headaches with SMP used in modern equipment. This is what I found and validated all tests to ensure repeatability -It also solved our design team headaches after some long research done as very misleading info around about SMP's. 1.All modern DC isolated SMPS should never have the DC negative be bonded to EARTH potential,they have a balanced isolated output.This means by grounding the DC negative via equipment or by not knowing, you can create this issue quite easily. Mfr's done stress this enough in data sheets etc,as I found out. DC Noise RFI Noise EMI issues Other problems when using RF this was confirmed in controlled tests with test equipment hooked up to monitor the affects. THE PROBLEM-Most modern 2 way radios (99%) nowadays have the DC negative lead tied to the radios metal chassis\Internal PCB and antenna socket (older equipment if often floating case like cb radios and not tied to DC negative so not so much a issue using these)typical a S)-239 or N-Socket. When you plug your coax into a antenna system that has a grounded metal mast,antenna bracket connected to mast,and coax cable all hooked up. What happens is the outer braid of coax is now at EARTH potential,by plugging it into your radio your now creating a potential problem with Rule 1.You must not EARTH the DC negative side,which is exactly what your doing here. Resolve-Fibre glass mast so fully insulated, A metal mast EARTHED but has a top section fibre or plastic insulator to mount antenna on to insulate potentials ground plane wire connect to this point and have egg insulator so not to ground to EARTH potential. Or what ive found easier is a special fully isolated primary winding and secondary windy 1:1 voltage balun (not current balun) to help ensure fully isolated grounds potentials to stop any problems. If its a floating antenna ie a wire dipole then not an issue Link here of suitable isolator balun and help prevent your radio ground DC connecting up to your EARTH mast. Link tinyurl.com/y97lqxyr That can resolve a lot of problems from the start. STEP 2.Check your SMPS for AC induced on DC outputs Some poor quality SMP's I have noted suffer from AC voaltage floating on DC outputs in rare occassion To check,use a DVM on 100V AC range,ensure SMP has a load source on it to draw current put red lead to DC+terminal and Black lead to Frame of PSU (EARTH),read what DVM says on display if its reading a high AC voltage 2V AC or more, an easy fix is to fit extra capacitors filters if required. One capacitor from DC positive terminal to EARTH Another capacitor from DC negative terminal to EARTH this will cure 99% of AC on DC issue up to 30V DC rated outputs from a SMP capacitor specs 680nF 1000V 310VAC RS Part 871-2629 Updated 19-7-2017 Rev 2.00 Wurth Part 890334027006CS after fitting capacitors typical AC values are less than 1V AC or better STEP 3.AC line filters (additional)-I highly recommend fitting a extra 2 stage AC line filter to the mains input of SMPS not only does it stop nasty s getting into SMPS,but also prevents nastys getting back out thru mains via the SMP annd creating problems. Ones I recommend and very effective in tests EPCOS Mfr. Part No.B84115EB110 RS Stock No.213-7154 Rule 1 is the most important not grounding the DC negative to EARTH in most cases via your antenna metal mast that's EARTH'ed. In my case it was DC grounding issue in the product that flagged this issue up,then bulb moment with radio and antennas earthing masts etc came to me. There not a lot of really good valid information that's up to date on this subject with DC isolated supplies do's and dont's think that's why they get a bad name when used in radio circles. I now run all my HF,VHF,UHF equipment noise free using these rules and no problems anymore. Unfortunately my SMPS dont have the noise shift pot in them being Industrial grade styles in caged box,so thought I would share this advice to other's having similar issues where they haven't got this feature. Great vid Kev 73's Rob RP Comms UK.

[@rhythmstic]

Thanks, much needed info & insight.

[@CinematicTouchProductions]

Hi Kevin, it may be two years later but your video is still relevant today, as a novice just fresh getting my license I am looking for two new things a mobile radio and power supply, this happens to be one that I been looking at and with that noise that power supply produces that was enough to make me cross that unit off my list, its a shame because I thought it is a pretty nice looking unit but in need it to do more than look nice so, thanks to you I didn't end up getting annoyed.

[@cuban9splat]

I use an Astron RS-35M analog supply in the shack here because I have heard from other ham friends that the switching supplies can generate significant noise in the RF spectrum. I have actually heard the same noise before on the HF bands but did not know what was causing it until your video was posted. Thank you for another great video!. 73 DE K7RMJK Frank

[@KG5IF]

Kevin, I have the Alinco DM-330FX power supply and I have exactly the same issue with noise. Like you I can move the noise around but it eventually comes back. I have relegated the Alinco to my VHF/UHF FM rig. My Omni VII is powered my Astron RS-35M with no noise

[@jose-medero7746]

I have one, the way it works is like this, voltage ac have 60hz and other country’s 50hz, that’s off set cleans the noise on the ac line coming to be rectified from ac to dc.

[@loughkb]

No, it changes the oscillator frequency. In a switching power supply the incoming line frequency doesn't matter, an oscillator drives a power MOSFET into a transformer creating a higher frequency AC that is stepped up, and then rectified and regulated down. That oscillator being a square wave oscillator generates a lot of harmonics. The noise offset changes the frequency of the oscillator allowing you to move the noise away from the frequency you want to operate on.

[@1337flite]

Thanks - Im just waiting for my local regulating authority to issue my first entry level ham license and I'm looking at buying my first rig. No linear power supplies available in the country so I'm looking at swtitch mode supplies and sure enough the Alinco DM330 appears to be the same OEM supply as yours and as you say no-one talks about the Noise Offset swicth - so thanks, this has been hugely helpful.

[@cthoadmin7458]

You’ve convinced me Kevin, to stick with my linear PSU. Thanks for the info. 73 Tim.

[@denelson83]

But nowadays, the linear PSU's are getting harder to find. When I build my HF station, I will not be powering it from the grid at all. I will instead use a rather hefty LiFePO4 battery to power it, like what Bioenno makes.

[@ok1lad159]

I have the Alinco one and it never drifted like this. It stays on one frequency I set it on and sometimes moves like 100Hz or so, never more. Anyway... this is a good demonstration of the noise offset, I quite like that feature. 73 de OK9DHL

[@mgarza5157]

And now i know what that awful noise is. Thank you very much! Time to change to a linear power supply. I hope you enjoyed your time in and around Corpus. 73s de KG5PRT

[@jose-medero7746]

The application of filtering can be ac or dc. That shows different manufacturers applying the concept of what kind or where apply the filter. On the ac part or after been rectified has ac to dc voltage. Line noise or ripples on the voltage.

[@loughkb]

Yes but that does not apply in a switching power supply. The line voltage ripple or frequency does not matter. In a linear power supply, the line voltage ripple comes through the transformer. In a switching power supply there's a separate oscillator that drives into the transformer. At a different frequency from the line voltage.

[@N5ZY]

I have the Alinco DM-330MVT and if I monitor long enough I have a bird fly across the band (spectrum scope at 100 KHz wide) it crosses in one second. I always assumed it was just 'noise in the city' but I guess it is the Alinco. It always goes up the band, never down, never slows.. I always guessed it was neon light power supplies or grow lights at the nursery or something else.. With a 500 KHz wide scope I can see it cross in 2 seconds and 8 seconds later another bird chases the first.. but then in between them it's 12 minutes... But I did always think it was odd that it's on any band.

[@recumbentogiro26]

Thank You. Learning a little bit every day.

[@k2wo1]

Kevin, for what its worth, I have the Alinco version (DM-330FX) and I never see any noise from it except on 160M and on that band they don't move/shift at all. 73, George K2WO.

[@ojjenkins7110]

Hi Kevin. I have two Alinco DM-330MV'S and they are much more stable than the one you have and much quieter as well. I am not sure if they start at 21KC or not. I have a steady carrier at 42KC and 84KC that I can move around. Above that the carrier goes away real quick. Any noise that I have come across in the Ham bands is so weak I don't hear it. Once on 1917 while on a round table on AM I heard a real weak whistle that I finally moved away with the noise offset and it went away very fast with turning the little pot. I am very happy with my Alinco's and have been using them sitting "on top" of my TS-2000X since Dec 8 2010. The other one is on top of my IC-706MK2G with the same results which I don't use as much. Yes the linear supplies are quieter but when you move em like for field day, GRUNT :-) One hand with a good switcher :-) Happy Thanksgiving day. OJ kØOJ

[@dmb3428]

I had the tekpower TP30SWII that had the noise offset dial, it worked in moving the noise however 80/20m were pretty bad and needed tweaking of the knob quite often...annoying so got rid of it and tried a samlex 1235, not as bad but some noise is there and it doesnt have an offset knob. Im resisting getting a linear because they are huge and heavy plus not efficient but I might not have a choice with the Icom 7300

[@learnelectronics]

Kevin, I have the same supply and a 7300 also. I have never had that noise issue.

[@seekerinseattle4863]

Yo Kevin!: I vote along with some of the other commentators, maybe a follow up video, discussing how you might aleviate the problem. I suggest either or both torroids / additional filtering in the supply. Hopefully it won't be surface mount technology! Glad you mentioned the brand of power supply, (to avoid : ). Motor on guy! 73! seeker / Jeff WA7LFP

[@Al_Dente1]

I use my Astron 35Ms in the shack. I have a pair of Astron SS30s switchers for the field but never noticed any noise from them. I did not go looking for it so maybe it was there but not around my operating frequencies. They work fine for me, especially since I made a powerpole pigtail for their oddball power connector. I have heard that they made that connector to comply with a big contract that required UL approval so they had to use a covered terminal. It is the only model on which I have seen that terminal.

[@andycampbell5416]

Excellent vid cheers

[@KB5WQW]

I have a couple Jet Stream supplies with this feature. I never messed with it much because I really didn't know what it was for. I shall hafta try it out, now. Tnx es 73!

[@johnkershaw9575]

TGIF Your live stream was very successful.

[@DonDegidio]

Hi Kevin, I have the Samlex SEC-1235 35A power supply and have never heard a noise like that, although do not have a spectrum display to see if there is anything coming from the power supply. 73 WB3BJU

[@denelson83]

There should be a way for your transceiver to communicate with such a power supply so that the noise offset can be automatically retuned when you select a different frequency on your transceiver. But it would only work if the noise didn't drift in frequency as you demonstrate here. 73 VE7NDE

[@davidniemi4051]

Great video, now I know why I had been steered away from that genre of power supplies when I was getting my first HF radio with "you'd be happier with XXXXX model ...". While I still have a switching power supply I have never encountered that sort of noise. I also put snap on ferrite cores on each lead coming from the power supply,

[@firemandanobrien7894]

Thank you for all you great videos.

[@salat]

I'd stay away from those with a noise offset dial - there are SMPS which won't go for that cheap trick with the offset but do implement working filtering and produce almost no noise - e.g. Manson SPA-8230.

[@prabirdebnath5197]

You are just right - its a cheap trick way of controlling noise

[@anomaliamedia]

Many thanks !

[@alanread6596]

Very good video and informative now I know how to use it. 73's Alan in the UK

[@1949ala]

Very useful

[@scottrand7626]

Hi Kevin, Seen this before...Those noise tracings are a function of the oscilator frequency And Bandwidth... think pulse width modulation... are you charging your batteries??? maybe try without... best of luck in your adventure... WB0ZLX

[@andykeddie7602]

Hi Kevin, I have the Alinco version of that PSU, and have never had any noise generated by it, never used the noise offset on it. I did buy a 'Power Mite' 25A PSU, and had to return it, I just couldn't use it, it behaved exactly like yours, and I was tuning the noise offset more than the Yaesu's VFO, it was junk! M0KED.

[@ElectronicsUSA]

I call it a power supply "Noise Tornado" !! Perhaps a snap on ferrite core RF choke or two might help on the output line? 73 and GL!

[@RajaramSrinivasan59]

Very nicely explained! Thanks a ton.

[@flexairz]

Why not run that radio direct from the batteries and circumvent the power supply?

[@loughkb]

I do. I can parallel the power supply on the batts when I'm on shore power to take the load and charge the batts. This was for illustration purposes.

[@mohinderkaur6671]

Use battery or linear supply.

[@elvinpena8788]

My Xiegu G90 reacts the same way with my Pyramid power supply. Same noise interference. I am using a computer server power supply with no interference issues. the noise shows again when I power up the Pyramid P.S. with no load in same room.

[@artur8403]

I have alinco like on one picture. It's noisy. It says 15mV peak to peak but it's 200mVpp at 13V and 4A load. Scope shows ugly switching noise at many frequencies. My scope can't even calculate it because it's all over the place

[@rtgideon]

Thanks for the information Kevin. Live show tonite, Right! Randy.

[@MoTown44240]

@Randy Live show was Tuesday, 06 Nov and as John Kershaw indicates it was successful. I missed it too.

[@thuff3207]

Thank you for the video. I wonder if you could add a PLL circuit to lock it in place once you adjusted? Depending on how the switcher is built it might be possible.

[@johnkershaw9575]

Hi Kevin, have you thought of putting a curtain (insulated) across the front of the camper just behind the seats? Lots of cold through all that glass. I've also seen where folks will cut that silver insulation to fit the front and side windows. You can get them at Wal Mart. Will also help when it's heat out.

[@loughkb]

Yes, I have thick black-out curtains up already. Important for privacy too.

[@nelsonwalker7105]

i had no idea switching power supplies generated noise spikes like that. I have used a linear power supply for some years. I think I will switch to a linear supply.

[@loughkb]

Yeah, at their core a switching power supply is a square wave oscillator that's driving a MOSFET. And as you know square waves generate lots of harmonics. They generate a lot of noise. Those little wall warts that power devices throughout your house also generate a lot of noise on HF.

[@Travis141123]

The only problem I have with my Wouxun supply is mostly on 20 & 17 meters. Those bands are just full of spurs, with constant knob adjustment needed.

[@akellettsocal]

Excellent! Thank you.

[@jack002tuber]

I hope you plan a future video on how to filter this out for good! :-D Seems the logical next step

[@dannypind4440]

I have the Tekpower basically the same thing your running and i also have it running my icom 7300 but i do not get this noise at all... works great.

[@learnelectronics]

Same here, Tek Power, 7300 and no noise.

[@watsok]

After reading the comments of others who have similar switchers but not the drift, open the unit and see what parts were "optional" and did not get installed due to "value" engineering. Is the noise coming from the DC side or the AC input side? Good luck.

[@curtmyersk2cwm477]

Excellent, thank you...

[@jimrecord6505]

I just stay away from switching power supplies with such poor filtering that they need the noise adjustment. I have a linear supply at home and a MFJ switching supply in my motorhome. No switching noise!

[@DAVIDGREGORYKERR]

Have you got Adaptive Noise Filtering if so use it, Can you use a crystal locked PSU.

[@a_ham_like_me]

May be a silly question but don't you have a gas furnace built in to that RV? My 1992 Shasta has one built in. Thermostat on the wall and everything...works wonderfully. Perhaps yours doesn't have one?

[@loughkb]

Yes it does. Why burn the propane if I'm plugged in though.

[@dandruff7807]

Kevin.......As an experiment, can you use a small dc fan to blow air across the power supply's heat sink.

[@dandruff7807]

Or possibly add an additional heat sink with or without a fan.

[@loughkb]

It has a fan. It stays cool. At any rate, regardless of how much cooling you provide, there will be some shift in temperature of the internal components and drift.

[@MichaelLaferriere]

Does the noise settle down and stay in place after a while? Components warming up etc.?

[@loughkb]

Nope. It wanders as the load changes.

[@jakelemay7913]

Alinco - same thing.

[@kepkopke]

Watch from 3:00

[@DeeegerD]

Chilly? Sure lol. It's -4C here and it's been snowing for a day (Ottawa, Canada).

[@petertyrrell6690]

I converted a 500w atx smps to 13.8vdc and use it to power my 100watt rigs. My unit made the same noise as yours when I disconnected the power supply's negative output from ground. (It was the only part of my supply that was directly grounded). When I regrounded the negative output, the noise went away. Apparently some smps negative outputs are not directly grounded like mine but benefit from a 3.3uf 200vdc electrolytic from the floating negative to ground. Here is a great link regarding fixing smps noise ka7oei.blogspot.com/2014/08/completely-containing-switching-power.html?m=1

[@hrgft68]

I have the same unit Kevin, similar problem, not sure if it wanders but it certainly seems to find my operating frequency, going to order a linear supply, sure wish id never given my old Astron away :-( let us know if you find a fix,73 de VE7URL.

[@bobahlberg6360]

you can camp on the beach ..also drive all the way to Port Aransas

[@Dreamlgider]

I have a 65A watson switcher, it is pretty much unusable for radio. I have an allinco 35A also, it's very similar to yours. Rather anoying for radio. Any powersupply designed for hamradio should not have a 'noise offset'. Looking for a good 40A or more linear. , allinco 35a. It is

[@alanread6596]

Does this only happen on switch mode power supplies.

[@loughkb]

Generally, yes. The noise comes from the square wave being used to drive the step up, step down, and requlation circuits.

[@AlvinMcManus]

Very useful video. I learned a thing or two. 73 de KN6ZVI

[@robertk4vl412]

I had no idea where that was coming from. It doesn't bother me as long as it keeps moving.

[@M7XCB]

I've never liked pulse power supply like my home made 30 Amp Marchwood 30 Amp built in over volt protection

[@michaeledmonds3027]

Thanks so much for this video, I thought there was a problem with my PS. I wonder if there's a solution to the "wandering" issue?

[@samglaim4274]

Good info.... stay warm..... 73 :-)

[@wuxiaofan7953]

I have the same PS30SWV power supply, ...... and the same noise :-(

[@prabirdebnath5197]

Kevin the NOISE OFFSET Control in power supplies is a Deceiving way to get rid of NOISE -That should not be way to control noise. Rather, I would say its a wrong cheap attitude way to Control any Noise. The ideal way is to have Proper 2nd stage Filtration with Common mode choke and capacitor - BUT then the cost and real estate will increase substantially. I use CATALEYA CL350 - here is a link - THEY use very detailed FILTRATION both in the input and output - here us the link ceda-labz.com/assets/uploads/files/6f45b-SmpsCataloge_CL350_12.pdf

[@manoffaith2501]

So if a power supply has a noise offset control I will pass on that type power supply. 73 KE8NQL.

[@RamLaska]

Has anyone tried using an old server power supply instead? They're quite cheap and a lot of the hams in my local club swear by 'em.

[@daddy3d1972]

What radio is that?

[@loughkb]

Icom 7300

[@daddy3d1972]

@@loughkb thanks for the response

[@ri3cjoh]

"Makes AND Manufacturers?" :D

[@samiam5557]

I wonder if "they" offer a software download to "fix" this glitch?

[@charlesschindler1971]

Yo.....⚔️🇺🇸⚔️

[@ed-jf3xh]

Every 100 kcs for my radio shack power supply. One might wonder why they don't just clean up the ps in the first place. Save a buck, I guess.

[@edwingm8790]

aliens

[@TheRetiredtech]

I think my Mfj dies the same thing.

[@tom_olofsson]

Thanks for sharing.