[Elecraft] Fwd: RE: K3S proper grounding?

[Fred Townsend]

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Jim Brown
Sent: Sunday, September 27, 2015 10:16 PM
To: Reflector Elecraft
Subject: [Elecraft] Fwd: RE: K3S proper grounding?



	

	

	

	

-----Original Message----- From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Jim Brown Sent: 
Sunday, September 27, 2015 3:49 PM To: elecraft at mailman.qth.net Subject: 
Re: [Elecraft] K3S proper grounding?

 > Often the requirements of one system will be at odds with other >
grounding requirements. For instance you generally want a high > impedance
for RFI issues and a very low impedance for lightning > grounds. One system
defeats the other so they really need to be separate systems. NO, NO, NO,
NO!

  [Fred Townsend] Well yes maybe. How do you bond a ferrite choke? Are not
all chokes high impedance at their intended useful frequency? I said
'system' not 'ground'.

[K9YC]

Huh? Chokes are used on SIGNAL lines, NOT on bonding conductors. A
fundamental requirement of bonding is that it be LOW IMPEDANCE, so, in
general, bonding conductors should not be choked. Further, lightning is NOT
a DC event, it is an RF event. It's an impulse, with broad energy peak
around 1 MHz.

[Fred Townsend] Correct on all scores
Jim I think you have tunnel vision on bonding. Jim as others suggested this
was really an EMI issue and I was addressing this as a system or EMI issue.
In this case chokes are appropriate for signal AND power cords containing
neutral. I don't believe anyone suggested chokes on bonding conductors.
However you suggested everything should be bonded and I merely asked how you
bond a choke.

Also the NEC as well as other codes prohibit tying neutral and safety (green
wire) together. Two cases I called out in my four different parts of the
system. So no you do not tie all grounds together.

Furthermore I think the whole issue of grounding is exacerbated by the
overuse and incorrect use of the word 'ground'. The Brits prefer to use the
word 'earth' which helps a little. I would prefer to bury the word 'ground'
and replace it with context appropriate words like 'signal common' but that
isn't common practice.

73,
Fred, AE6QL 

73, Jim K9YC

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