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Author Topic: Your experinces/tips on supressing noise from portable power stations?  (Read 204 times)

KK4SUH

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The other day I picked up a small LFP-based power station for cheap.  Curious of what noise it spews out, I decided to power a receiver though the built-in inverter.  It spews out some nasty noise, particularly strong on the AM broadcast band and 80. Doesn't appear to be as bad on higher frequency bands.  There appears to be both conducted and radiated noise.  I plan on experimenting with an extension cord to place it further away to mitigate the radiated emissions.  I have a few split ferrite beads on hand, but It'll be a challenge getting multiple turns with an extension cord. Might have to shop for some larger ferrite beads.  There is a 12 volt output that may be a bit better behaved, but it is limited to 8 amps.

Powering a radio wasn't the primary reason for buying the unit, but it would be nice to suppress the noise enough to be usable for such a purpose.

Curious how others out there dealt with a similar situation.
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W9IQ

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Re: Your experinces/tips on supressing noise from portable power stations?
« Reply #1 on: November 07, 2022, 04:00:16 PM »

You should anticipate both differential and common mode noise. An LPF comprised of shunt capacitors and appropriate ferrite chokes is warranted. Something along the lines of this filter.

- Glenn W9IQ
« Last Edit: November 07, 2022, 04:03:50 PM by W9IQ »
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

K6AER

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Re: Your experinces/tips on supressing noise from portable power stations?
« Reply #2 on: November 07, 2022, 06:49:21 PM »

Magnetic sine wave generators make no RF noise.

Go spend $99 at Harbor Freight for their 900 watt 2 cycle special and enjoy.
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AI5BC

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Re: Your experinces/tips on supressing noise from portable power stations?
« Reply #3 on: November 07, 2022, 07:06:22 PM »

You got what you asked for, a cheap POS with using a modified sinewave Inverter. Now you get to spend bucks using ham-foolery filters and hocus pocus that will never work.

Just use a good quality 12-volt high-capacity Marine or RV battery to power your radio equipment. If you must have 120 VAC use a good quality True Sine Wave Inverter.
« Last Edit: November 07, 2022, 07:10:08 PM by AI5BC »
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KK4SUH

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Re: Your experinces/tips on supressing noise from portable power stations?
« Reply #4 on: November 07, 2022, 07:12:38 PM »

You should anticipate both differential and common mode noise. An LPF comprised of shunt capacitors and appropriate ferrite chokes is warranted. Something along the lines of this filter.

- Glenn W9IQ

Thanks for the info, I'll have to look into that more.
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KK4SUH

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Re: Your experinces/tips on supressing noise from portable power stations?
« Reply #5 on: November 07, 2022, 07:20:52 PM »

Magnetic sine wave generators make no RF noise.

Go spend $99 at Harbor Freight for their 900 watt 2 cycle special and enjoy.

Last I checked, the $99 special weed wacker generator is no longer carried by Hazard Fraught (but I've seen it sold under different branding elsewhere.)

Oh and AI5BC, it actually has a pure sine wave inverter (the unit is made by a name-brand in the power station market, EcoFlow.) 

I do have something that will produce absolutely no noise, a SLA battery (although it's a bit on the hefty side to move around.)  If it turns out to be too costly/finicky to get the little power station to play nice, it's no big deal. Just something that would be nice to have. Perhaps I should grab a 12 volt stand-alone LFP battery in the future when the SLA battery passes on.

« Last Edit: November 07, 2022, 07:34:48 PM by KK4SUH »
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W9IQ

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Re: Your experinces/tips on supressing noise from portable power stations?
« Reply #6 on: November 08, 2022, 04:22:49 AM »

Thanks for the info, I'll have to look into that more.

Just for clarity, this is only a conceptual reference if you need to filter 120 VAC. The capacitors and board layout would need to be appropriately upscaled from this 12 volt version.

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

KK4SUH

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Re: Your experinces/tips on supressing noise from portable power stations?
« Reply #7 on: November 08, 2022, 04:41:04 AM »

Thanks for the info, I'll have to look into that more.

Just for clarity, this is only a conceptual reference if you need to filter 120 VAC. The capacitors and board layout would need to be appropriately upscaled from this 12 volt version.

- Glenn W9IQ

Indeed, those caps would go bang pretty darn fast if 120 VAC was applied to them. Would need X and Y class capacitors.
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KK4SUH

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Re: Your experinces/tips on supressing noise from portable power stations?
« Reply #8 on: November 08, 2022, 07:38:10 AM »

I did try using some ferrite beads alone. That did next to nothing. Just for kicks, I decided to hook it up to my normal HF radio right though my switch mode power supply. Noise actually wasn't too bad. Only obvious noticeable difference was an increase in noise on the AM broadcast band (still need to do more though testing, I was just quickly sweeping though the bands.)  Perhaps the filtering in the switch mode power supply was also filtering a lot of crap out from the power station.

I've been browsing though Fleabay, and I saw quite a few AC input filters that are similar in design to the example Glenn posted. 
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W9IQ

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Re: Your experinces/tips on supressing noise from portable power stations?
« Reply #9 on: November 08, 2022, 07:46:39 AM »

The type of ferrite can make a huge difference. For the AM band, I would try type 75.

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

WA3SKN

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Re: Your experinces/tips on supressing noise from portable power stations?
« Reply #10 on: November 08, 2022, 03:15:59 PM »

If it is supposed to be a "pure sine wave inverter", I would ask Ecoflow their recommendations.

-Mike.
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