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Re: [RFI] CHECK your grounds.

To: rfi@contesting.com
Subject: Re: [RFI] CHECK your grounds.
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Thu, 27 Jan 2011 09:17:46 -0800
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
On 1/27/2011 5:15 AM, Michael Coslo wrote:
> I've always thought that way too many things are called "ground".

YES, YES, YES, YES!  The use of the word "ground" to describe circuit 
common, or the chassis, causes MUCH confusion and leads to extensive 
muddy thinking.  That muddy thinking extends to WRONG questions in the 
exam pool, to WRONG admonitions by manufacturers in manuals for their 
equipment, and WRONG thinking about solutions to RFI. And all of these 
errors are pervasive throughout ham publications, including those from  

> I think that the main message that I take from Kurt's post is that when we 
> see what he has seen, you can bet that there will be other problems. They 
> need fixed.
> I recommend homeowners who can safely look at their wiring do so.

More good advice, including that from Paul, W9AC in another post in this 
thread. When I bought a 100 year old home in Chicago I rewired about 90% 
of it. In the week before I sold it, 20 years later, a wiring fault in 
the other 10% of it that I didn't get to a bad splice in the ceiling of 
a kitchen) caused a loss of power in that kitchen. It didn't cause a 
fire, but I had to get an electrician in to chase it down in time for 
the papers to be signed to close the sale.

I've found numerous problems in the 25 year old home that I bought here 
in California, everything from mis-wired outlets to the improperly 
grounded clothes dryer that Dale described yesterday, to improper 
connections between ground in the main house to ground in the 4-room 
building that houses my shack, and really stupid errors in grounding of 
the power system.   At the main service entrance to the house, the 
neutral was properly bonded to the chassis of the backbox, but there was 
no earth connection!  Rather the wire that SHOULD have been an earth 
connection ran about 40 feet to a water spigot for a garden hose, which 
was fed through the hose via PVC pipe. Ground was then carried to the 
second building, where there was another bond between neutral and ground 
(another no-no), and a ground wire that led from a sub-panel in the 
kitchen, up the wall, along the eaves, and back down to a ground rod. 
That was the only earth electrode I could find anywhere, and it was MUCH 
longer than it should have been.

I strongly agree with Paul's recommendations for shack wiring, but I'll 
take it a step further. In general, ALL equipment in the shack should be 
plugged directly into outlets that share the same green wire back to the 
panel, or to outlets mounted in steel backboxes that are bonded 
together. And I recommend installing enough outlets (using multi-gang 
back boxes) so that all equipment can be plugged directly into those 
outlets rather than into outlet strips.  The primary reason for all of 
this is minimizing hum and buzz when interconnecting computers and other 
audio gear to our rigs.

A single 20A circuit provides enough power to safely run at least two 
100W radios, a couple of computers, and a 500W power amp, and it could 
handle two of those amps in an SO2R or multi-single contest 
configuration (that is, with only one rig transmitting at a time).

  It's also good practice to increase the wire size by at least one 
gauge, especially if the run to the shack is fairly long. That's because 
the impulsive waveshape of the current drawn by power supplies for 
electronic equipment causes IR drop to be much greater than if the load 
current were a pure sine wave.

73, Jim Brown K9YC

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