I think you'll find that many of today's transceivers DO NOT have a low
resistance connection between the negative supply lead and chassis.
Larry N8LP
On 4/17/2018 5:37 PM, elecraft-requ...@mailman.qth.net wrote:
Message: 10
Date: Mon, 16 Apr 2018 22:39:44 -0700
From: Alan<n...@sonic.net>
To:elecraft@mailman.qth.net
Subject: Re: [Elecraft] Issue 12 re Astron Power Supply
Message-ID:<9141e52a-a64f-5174-1889-1e31ef365...@sonic.net>
Content-Type: text/plain; charset=utf-8; format=flowed
You're right. If all the devices run from the same 12V power supply and
they are all bonded together, then there is nothing to prevent some of
the transceiver return current flowing in the negative power supply
leads of the other devices. Hopefully the transceiver power leads use
much heavier wire so most of the current will flow in them. And if the
plus and minus leads are close together and tightly twisted then that
should reduce hum and noise coupling.
Ideally every device would have its own 12V power supply, each with
floating ground. Then there would be no "ground loop". (Sorry Jim, I
know you don't like that term.)
Alan N1AL
On 04/16/2018 10:22 PM, Vic Rosenthal wrote:
But I keep coming back to this: almost every device connected to the power
supply has V- connected to ground internally. So if you have, say, a keyer and
a transceiver running off the same supply, won?t some of the transceiver?s
current flow through the V- line to the keyer, to the case of the keyer via the
internal connection, to the station bonding, to the transceiver case and thence
to the transceiver V- input?
In short, don?t the accessories fed from the same PS as the transceiver do
exactly the same thing as the notorious black wire in the Astron?
Vic 4X6GP
On 16 Apr 2018, at 23:50, Jim Brown<j...@audiosystemsgroup.com> wrote:
Joe is right and George is WRONG. V- is NOT GROUND, it is the return for DC
power. Bonding V- to ground is a BAD idea -- that's why virtually all
pro-grade power supplies are built either without the bond or so that the bond
can easily be removed.
As to those who were confused by my advice -- I thought it was pretty plain.
Quite a few posts back, I posted a link to a detailed discussion of this on my
website. I published this around 2010-12. I urge those who are confused to
study it.
http://k9yc.com/PowerSupplyBondingAndAudioDistortion.pdf
My detailed advice on station grounding and bonding is the link below. Much of
it has been incorporated in Ward Silver's recent ARRL book on the topic, and is
referenced in the book. You can buy the book from ARRL, while the pdf on my
website is free. :) Joe and Don are right on in their understanding of the
NEC, the fundamentals of which I have been paid to teach to audio/video
professionals in workshops at conventions.
http://k9yc.com/GroundingAndAudio.pdf
73, Jim K9YC
On 4/16/2018 7:06 AM, Joe Subich, W4TV wrote:
On 2018-04-16 9:28 AM, George Danner wrote:
Re-Connect it!
DON'T CONNECT THAT WIRE BETWEEN V- AND CHASSIS CASE!
Unless you have a substantial*EXTERNAL GROUND CONNECTION*
between your station ground and the electrical system ground
rod, that connection between V- and chassis will bridge the
power system "safety" ground and the station grounding and
put your delicate and expensive equipment between two "grounds"
that can separate by many hundreds of volts in a lightning
event (or equipment failure).
We even used ring grounds around studio & transmitter building with
ground rods every 10' all cad-welded.
That is proper grounding and bonds all entry points together*OUTSIDE*
the building to prevent grounds from separating. It creates a common
"island" for everything inside the building. However, for the majority
of amateur stations which fail to properly bond the shields of all of
the coaxial cables entering the shack to the electrical system ground
*at the meter*, there is no "island" ... more like an isthmus across
the equipment.
73,
... Joe, W4TV
On 2018-04-16 9:28 AM, George Danner wrote:
Re-Connect it!
From a broadcaster (AM,FM & TV) was in South Florida (lightning capital of
North America).
The more massive the common (ground, bonding, whatever term you use) for the
connection between equipment and the power company ground connection the better.
We even used ring grounds around studio & transmitter building with ground rods
every 10' all cad-welded. This is probably over kill for a ham station; but think
as massive as you can.
Towers at 500' or above had 2 ring grounds and lots of ground rods.
The common for equipment interconnection is for safety first and the reduction
of voltage drops on the common lines that can transfer from one piece of
equipment to another (us old timers use the term ground loop - not PC any more).
73 George AI4VZ
-----Original Message----- From: Charlie T
"This greatly increases the chances for damages to station equipment and all other
electronic equipment in the household in event of a lightning event."
What is, disconnecting the wire or leaving it in place?
Your comment can be taken both ways.
73, Charlie k3ICH
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