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Re: [RFI] Daisy chain vs Common Ground in Shack

To: jim@audiosystemsgroup.com, rfi@contesting.com
Subject: Re: [RFI] Daisy chain vs Common Ground in Shack
From: Sean Waite <waisean@gmail.com>
Date: Wed, 07 Jun 2017 21:55:54 +0000
List-post: <mailto:rfi@contesting.com>
Hi Jim,

I was hoping you might respond. I've read a lot of your slides and papers
and have started sharing them out (along with W1HIS's article on chokes)
when people ask about RFI. I saw that book, but wasn't sure if there was
much in there about RF grounding that wasn't already available on your
site. I may have to pick up a copy, I have a few other grounding questions
that it might answer.

Everything I've read of yours makes a lot of sense, the only reason I
questioned it was because it strays directly against conventional wisdom.
Considering how many hams consider RFI and grounding to be some sort of
magic, it's not terribly surprising that there is bad information out
there. Just today I saw a thread with someone recommending that when men
have to answer the "call of nature" that they go out and periodically water
the ground rod to increase the soil salinity and conductivity.

Is there ever a case where the star bond is the correct one? Is there an
evidence based counter to the methods you suggest? Given the thoroughness
of your research and the implied backing of the ARRL through NOAX's book,
it seems like daisy chaining really is the right way to go though. If I'm
reading your slides correctly, you recommend stripping the braid off of the
coax linking devices like the transceiver, tuner, and switches? Does this
remove the need for common mode chokes on the same pieces of coax?

It's taken me a few readthroughs of your material to digest it, and I had
everything in the shack disconnected anyway so it was a good time to redo
the ground.

The great part about this hobby is that there is always more learning to
do. Thanks for the reply,
Sean WA1TE

On Wed, Jun 7, 2017 at 5:19 PM Jim Brown <jim@audiosystemsgroup.com> wrote:

> Sean,
> In the new ARRL book on Grounding and Bonding, you will find me credited
> as a contributor,  you will find my methods cited, and you will find a
> link to the slides for my tutorial on the topic. The book is by Ward
> Silver, N0AX, who also edits the ARRL Handbook and Antenna Book.
> The primary my recommendation differs from prior "wisdom" on the topic
> is that the prior wisdom ignored the issue of leakage current from the
> AC power system, which is how power line "buzz" couples into equipment
> that is interconnected with other equipment. That prior wisdom depends
> on the fictional concept of a "ground loop" as the cause of that buzz,
> ignores the fact that the shield of audio cables between equipment
> creates a loop with a "star ground," and is ignorant of a widespread
> cause of both buzz and RFI called "The Pin One Problem."
> My method solves all of those problems, AND satisfies grounding and
> bonding requirements for RF and lightning protection.
> FACT -- the ONLY way in which a LOOP affects a system is if it is in a
> magnetic field (from a poorly shielded power transformer, or in a place
> with improper AC wiring). In both of those situations, the received
> noise will be pure 60 Hz (hum) not buzz (triplen harmonics of 60 Hz --
> 180, 360, 540, 720, etc).
> 73, Jim K9YC
> On Wed,6/7/2017 12:50 PM, Sean Waite wrote:
> > Hi everyone,
> >
> > I was reading through a lot of K9YC's articles on grounding and RFI. It
> > seems that he recommends daisy chaining ground together in the shack, and
> > then running a single cable from the last point out to the common house
> > ground. His reasoning seems sound (combined with choking off coax to
> > eliminate ground loops), but it goes against everything you hear about
> > station grounding.
> >
> > Is this the correct thing to do? Am I just misreading what he's writing?
> A
> > lot of RFI topics seem to be borderline magic in the ham community and
> I'm
> > trying to unravel the myth from reality.
> >
> > Thanks and 73,
> > Sean Waite, WA1TE
> > _______________________________________________
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> > RFI@contesting.com
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> >
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