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Re: [RFI] [Amps] Amp causing RFI

To: rfi@contesting.com
Subject: Re: [RFI] [Amps] Amp causing RFI
From: donovanf@starpower.net
Date: Wed, 5 Feb 2020 00:09:18 -0500 (EST)
List-post: <mailto:rfi@contesting.com>
DANGER 
DANGER 
DANGER 


Mark's advice should not be copied by anyone who respects their lives 
and the lives of anyone living in or visiting their shack or home. 


The ground wire in AC wiring provides a low resistance path back 
to the circuit breaker through a low resistance wire normally carrying 
very low current. Cutting the third wire significantly degrades the 
performance and reliability of the circuit breaker protecting electrical 
equipment on that branch circuit. 


I have never encountered an RFI related problem that traces back 
to the ground wire in an AC power cord. In the very unlikely event 
that you actually need to break this path, the only safe approach is 
an AC isolation transformer. This approach is sometimes needed in 
very large industrial facilities where low level signals are interconnect 
equipment racks separated by hundreds of feet. 


73 
Frank 
W3LPL 


From: Mark Schoonover [mailto:mark@ka6wke.net] 
Sent: Tuesday, February 4, 2020 8:26 PM 
To: Tim Duffy 
Cc: jim@audiosystemsgroup.com; Amps 
Subject: Re: [Amps] Amp causing RFI 



There can be two paths to ground. One from the back of your equipment to the 
station ground then back to house ground. The other path is from the ground in 
the outlet back to breaker box to house ground then back to station ground. 
That creates a large loop depending on how much AC wiring involved. 



I use several of those three prong to two prong AC adapters to break the path 
in the AC ground leaving just one path to ground through station ground. All 
chassis grounds are connected to AC ground so electrical safety isn't 
compromised. Really cleaned up a lot of noise with my station. 



The main video about RFI on my website I drew it out on a whiteboard. It's 
about 2/3 of the video. 

73! Mark KA6WKE 

Website: https://www.ka6wke.net 



On Tue, Feb 4, 2020, 16:32 Tim Duffy <k3lr@k3lr.com> wrote: 

Hello Mark, 

I am confused. What does a connection to earth ground have to do with ground 
loops? 

73 
Tim K3LR 

-----Original Message----- 
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Mark Schoonover 
Sent: Monday, February 3, 2020 11:04 PM 
To: jim@audiosystemsgroup.com 
Cc: Amps 
Subject: Re: [Amps] Amp causing RFI 

On Mon, Feb 3, 2020 at 7:57 PM Jim Brown <jim@audiosystemsgroup.com> wrote: 

> On 2/3/2020 7:48 PM, Alek Petkovic wrote: 
> > ndeed. It has also helped me and most ham friends I know on numerous 
> > occasions. 
> > 
> > Adding a few shallow buried wires to the ground rod has also worked well 
> > for me. 
> 
> Balderdash. The earth is not a sump into which noise, RFI, and other 
> trash is poured. Comments like this bring to mind the infinite number of 
> monkeys and typewriters producing Shakespeare. 
> 
> 73, Jim K9YC 
> 
> 
What having a decent ground does is eliminate the possibility of ground 
loops provided the ground is lifted from the third pin of the AC plug. I 
did a comprehensive RFI video on the subject and show how ground loops can 
happen and what to do to eliminate them. Quite possibly the #1 cause of 
RFI. You can watch the video in the link below. 
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