Today's Message Index:
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1. 06:24 AM - Re: Shield grounds (Eric M. Jones)
2. 06:52 AM - Re: Shield grounds (Robert L. Nuckolls, III)
3. 08:21 PM - Re: Handheld transceiver alternate antenna (jrevens)
Message 1
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Subject: | Re: Shield grounds |
Here is the ultimate authority on the subject:
http://eeeic.eu/proc/papers/55.pdf
Also see my attachment on the subject.
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=438765#438765
Attachments:
http://forums.matronics.com//files/dabbling_with_electricity_137.pdf
Message 2
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Subject: | Re: Shield grounds |
At 16:26 2015-02-25, you wrote:
><matronics.list@gmail.com>
>
>I thought I understood how shield grounds worked and how to
>implement them but now looking at a Garmin G3X. The garmin manual
>specifically has some of the shields terminated on both ends and
>grounded. some of the shields are only terminated and grounder on
>one end and the other is floating. So what is the proper
>termination of shields and what is the science behind the proper methods.
The 'shielding' feature of a conductor
wrapped about a central wire or collection
of wires is to break potential electro-static
coupling between said wires and any other
wires.
Wires inside a shield can be EITHER a potential
antagonist (like p-leads) or victim (audio
wires). Shielding allows potential victims and
antagonists to share the same wire bundles.
Since the shield is also a conductor, the system
designer may . . . and often does . . . use
the shield for both electro-static barrier
AND as some functional flow of energy from
one item to another. Obviously, in this
case BOTH ends of a shield may be terminated.
Sometimes, shielded wire is used as two conductor
cable and both ends of the shield are terminated
even if wires within the shielding are neither
potential victim or antagonist. I have used
shielded wire to build flying leads off an LED
annunciators to exploit the nice round characteristic
of the shielded wire versus say, an open twisted
pair. I have used shielded trios to wire a 4-conductor
power/control path even tho the shielding is
not REQUIRED . . . only handy.
When the shield is applied ONLY for a barrier
to electro-static coupling, the general practice
is to terminate ONE END only. Terminating the
other end may not be a bad idea but it is
unnecessary and offers a low risk for creating
a 'ground loop' that was not foreseen by the
installer . . . or perhaps event the system
designer.
Bottom line: Don't second guess the system
designer. Wire per installation instructions.
Bob . . .
Message 3
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Subject: | Re: Handheld transceiver alternate antenna |
My thanks to all... there was a lot more input than I thought there would be. Lots
of good information and ideas. I believe I like some sort of the patch cable
idea best... don't want any more antennas, devices and wiring than necessary.
I'll just do it like I did my T-18, 25 years ago, only (hopefully) a little
cleaner and more accessible.
John Evens
Thorp T-18 N71JE (built & flying)
Kitfox SS7 N27JE (building)
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=438792#438792
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