[RFI] Daisy chain vs Common Ground in Shack
Roger (K8RI)
k8ri at rogerhalstead.com
Mon Jun 12 17:44:21 EDT 2017
Yup. I strip abt the last 3/4" of jacket and dielectric, twist the
braid tight onto the exposed center conductor, crimp a ring or spade
terminal onto the end and then coat the exposed braid with liquid
electrical tape. I often neglect the liquid tape in the den or shop as
they are temperature and humidity controlled. (If I remember to empty
the dehumidifiers.) Solder can be used at the terminal as there
shouldn't be a vibration or flexing problem.
73, Roger (K8RI)
On 6/8/2017 Thursday 8:50 AM, Sean Waite wrote:
>
> Hi Roger,
>
> What connectors do you use when running 8X as ground wire? Do you
> squeeze the stripped braid into a ring terminal?
>
> Sean WA1TE
>
>
> On Thu, Jun 8, 2017, 01:58 Roger (K8RI) <k8ri at rogerhalstead.com
> <mailto:k8ri at rogerhalstead.com>> wrote:
>
> I downloaded your tutorials a while back, but haven't read the one on
> grounding. It makes sense to me as using a common ground is installing
> two grounds of different lengths. One being the ground line to the
> common point (Not CPG) and the other being the coax shields in a Daisy
> Chain. For more than two items, the ground currents / paths, can be
> quite complex,
> In the shack, why not leave the coax in tact. That way the braid is
> protected except at the very ends. I strip the ends just far enough
> back to be able to crimp the connectors on. I coat any exposed braid
> from the jacket onto the end of the crimp-on connector. I've used
> RG8X
> and 8X-LL for some years. This allowed me to have the ground line very
> close to the lengths of the coax cables. I do not solder into the
> crimp-on. That works well in aircraft where soldered connections are
> prohibited due to vibration except in specific connectors.
>
> The recent common wisdom had me working on changing that, but now I'm
> going back to Daisy Chaining. Thanks for bringing it up, Sean and
> thanks
> Jim for the work on grounding.
>
> 73, Roger (K8RI)
>
> On 6/7/2017 Wednesday 9:08 PM, Jim Brown wrote:
> > On Wed,6/7/2017 2:55 PM, Sean Waite wrote:
> >> 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?
> >
> > There is FAR more to my tutorial (and to Ward's book) than how
> > equipment is bonded in the shack. ALL of it is important.
> >
> >> Is there an evidence based counter to the methods you suggest?
> >
> > Not that I know of. My recommendations, as well as Ward's, are
> based
> > on the total picture -- power, lightning, fire and personal safety,
> > audio, RFI, and all sorts of other systems.
> >
> >> 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?
> >
> > I don't know where you got that idea. The answer is NO. What I DO
> > recommend is using braid stripped from coax for indoor bonding. Ward
> > does NOT recommend that, because he feels that the copper is more
> > likely to oxidize when exposed to air (rather than remaining inside
> > the insulation provided by the coax jacket). When I use braid in
> that
> > manner, I usually enclose it in heat shrink to minimize that
> possibility.
> >
> >>
> >> 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.
> >
> > 73, Jim
> >>
> >> 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 at audiosystemsgroup.com <mailto:jim at audiosystemsgroup.com>
> >> <mailto:jim at audiosystemsgroup.com
> <mailto:jim at 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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> >>
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