[RFI] [Amps] Amp causing RFI

Wed Feb 5 00:59:37 EST 2020

Hi Mark, 

You misunderstand how short circuits to ground trip a circuit breaker. 
Lets examine just a simple case. 

Lets suppose you cut the ground wire in the AC power cord connecting 
your DC power supply to your AC power outlet. If a short circuit 
develops from the hot side of the AC power line to the metal case of 
your power supply -- perhaps a short circuit in a power transformer or a 
short circuited capacitor -- the metal case of the power supply is now 
energized at 125 volts AC. Death could result. 

Now if the ground wire had not been cut, the ground wire provides 
a path back to the neutral wire in your circuit breaker box. The same 
short circuit condition I described in the paragraph above will trip 
the circuit breaker. 

73 
Frank 
W3LPL 

----- Original Message -----

From: "Mark Schoonover" <mark at ka6wke.net> 
To: donovanf at starpower.net 
Cc: "RFI" <rfi at contesting.com>, "Amps" <amps at contesting.com> 
Sent: Wednesday, February 5, 2020 5:43:59 AM 
Subject: Re: [RFI] [Amps] Amp causing RFI 

Actually reviewing the wiring diagram for a standard breaker box and the ground wire isn't attached to a circuit breaker at all. 

https://www.do-it-yourself-help.com/circuit-breaker-wiring-diagrams.html 

73! Mark KA6WKE 

Website: https://www.ka6wke.net 

On Tue, Feb 4, 2020, 21:25 Mark Schoonover < mark at ka6wke.net > wrote: 

Frank, 

FINALLY someone actually explains why what I've done is wrong. It's an easy remedy to put things back. I'll also update my video and remove this advice. 

73! Mark KA6WKE 

Website: https://www.ka6wke.net 

On Tue, Feb 4, 2020, 21:09 < donovanf at starpower.net > wrote: 

<blockquote>

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 at ka6wke.net ] 
Sent: Tuesday, February 4, 2020 8:26 PM 
To: Tim Duffy 
Cc: jim at 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 at 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 at contesting.com ] On Behalf Of Mark Schoonover 
Sent: Monday, February 3, 2020 11:04 PM 
To: jim at audiosystemsgroup.com 
Cc: Amps 
Subject: Re: [Amps] Amp causing RFI 

On Mon, Feb 3, 2020 at 7:57 PM Jim Brown < jim at 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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</blockquote>