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Re: [RFI] Raspberry PI / Wall wart RFI

To: rfi@contesting.com
Subject: Re: [RFI] Raspberry PI / Wall wart RFI
From: N4ZR <n4zr@comcast.net>
Date: Fri, 2 Apr 2021 22:30:39 -0400
List-post: <mailto:rfi@contesting.com>
Jameco has a bunch of 5 and 12-volt linear wall warts for quite reasonable prices.  For example, their 5V unregulated 800 ma wall wart is $3.90, and a 12V 2 amp unit is $13.95.  There are a lot in between.

73, Pete N4ZR
Check out the new Reverse Beacon Network
web server at <http://beta.reversebeacon.net>.
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On 4/2/2021 8:49 PM, Jim Brown 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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