On Tue,12/29/2015 1:33 PM, W9RPM wrote:
Hi, I recently started having a problem on 30 meters with one computer
with Multiple Monitors jumping everything around on different screens,
and another computer shutting down. I have a couple of other computers
in the shack that are not affected.
Several thoughts, John. First, STUDY my tutorial on Power, Grounding,
and Bonding, and carefully implement every part of it.
http://k9yc.com/GroundingAndAudio.pdf Some of the advice you have
received from others is quite good, most notably to study the position
of your antennas with respect to your station.
Other advice has been quite bad - here's the right way.
1) ALL of the equipment that is part of your station should be powered
from the same AC outlet box, or from outlets whose grounds (the green
wires) have been bonded together at the outlet. Equipment, like
computers, that are NOT connected to your station can be fed from
different outlets.
2) ALL of the equipment that is part of your station should be bonded
chassis-to-chassis with short, fat copper. Bonding should follow the
paths of the interconnections, NOT to some common point, because that
common point makes the bonding path longer. For example, bond your
computer chassis to your rig. If there's an accessory box connected to
your rig, bond it to the rig. If it goes to the computer, bond it to the
computer. For laptops, you can usually find a chassis connection at a
DB-connector.
3) Bond ONE of those chassis points to your station ground (usually the
rig) to all other grounds in your home -- ground rod(s) where antennas
enter your shack, the main AC power system ground, CATV ground, Telco
ground, etc., and make sure that all of those grounds are bonded together.
4) Add multi-turn ferrite chokes to every cable that is connected to the
computer(s) with RFI issues. Start with the power supply and video cable
(if there is one), USB and RS232 cables, audio connections to your rig,
etc.
5) AC line filters are rarely of much value. If you do use one, make
sure that it is bonded to your station ground with short fat copper.
Yes, some of this differs from long-standing myths about "ground loops"
perpetuated by the ham community for decades. The tutorial clearly shows
why those myths are wrong. N0AX, who edits the ARRL Handbook and ARRL
Antenna Book, and who writes a column in QST adapted many of my
recommendations for his columns on grounding and bonding. HE "gets it."
73, Jim K9YC
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