[RFI] Raspberry PI / Wall wart RFI

[Alex]

Hi David,

Check out Argon One power supplies on Amazon specifically for the Pi.

I've tried several power supplies that caused noise on the USB ports to the SDR's that were hanging off the RPi 3B and 4B. I replaced them with the Argon One wall warts. For a while I also used a linear power supply, until I found these. Now, my main interest right now is mainly VHF and up weak signal, so I don't hang out on HF as much anymore, but I don't think I ever heard any noise from these on HF and I have a pretty low noise floor. Perhaps I should check these power supplies with the IC-705 and see what they do.

The nice thing about these Argon One power supplies is that the output voltage is slightly higher than others (5.25V). This compensates nicely for the voltage drop caused by heavier loads on the Pi and prevents the low voltage indicator from coming on.

73,
--Alex KR1ST



On Apr 3, 2021, 9:05 AM, at 9:05 AM, David Gottschalk <dave at highredline.com> wrote:
>Thanks Jim.
>
>Some others have also already suggested a linear power supply. I'll
>probably try that, but I'm strongly considering just moving my antenna
>much
>further away from my house, so I can spend less time trying to kill
>RFI.
>
>On Fri, Apr 2, 2021 at 8:49 PM Jim Brown <jim at audiosystemsgroup.com>
>wrote:
>
>> That's because it's a switch-mode power supply. What voltage and
>> current?  Depending on that, it may be possible to re-purpose an old
>> linear wall wart. Also, study my tutorials on chasing and killing
>RFI.
>> They include specific advice on subbing the linear supply.
>>
>> Text:  http://k9yc.com/KillingReceiveNoise.pdf
>> Slides: http://k9yc.com/KillingRXNoiseVisalia.pdf
>>
>> 73, Jim K9YC
>>
>> On 4/2/2021 5:15 PM, David Gottschalk wrote:
>> > I'm wondering if anyone has had success finding a wall wart for a
>> Raspberry
>> > Pi that doesn't make horrific RFI on HF (or really any switch mode
>power
>> > supply that isn't noisy!)
>> >
>> > I recently discovered the wall wart for my Raspberry PI (that is
>mounted
>> > outside in a water proof enclosure for my 4G internet) is making S7
>level
>> > noise on 80m. Unfortunately, my 80m loop is currently pretty close
>to it.
>> > When the PI is battery powered, or off, it's S4 noise level here
>(This is
>> > in the middle of the day). 60m also seems to be severely affected
>as
>> well.
>> >
>> > I found this on Amazon, but it seems like it's more of a AC line
>> > conditioner, but might be worth a shot. Any feedback would be
>greatly
>> > appreciated.
>> >
>> >
>>
>https://www.amazon.com/iPower-Supply-International-Travel-Adapters/dp/B01GNNXP0Y?ref_=ast_sto_dp&th=1
>> >
>> > 73,
>> > David
>> > KN4ZKT
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>> >
>>
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