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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