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Re: [RFI] House Ground

To: Robert Nobis <n7rjn@nobis.net>
Subject: Re: [RFI] House Ground
From: dalej <dj2001x@comcast.net>
Date: Wed, 16 Mar 2016 12:01:28 -0500
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
I have two iMacs, same deal with the PS.  I don't have any noise from either 
one.  My neighbors plasma TV I hear though.  

All the Apple products I've owned since 1988 never had an issue with RFI from 
any of them.

Dale, k9vuj



On 16, Mar 2016, at 11:55, Robert Nobis <n7rjn@nobis.net> wrote:

Cortland,

The MacMini is the also double insulated, although it has an internal power 
supply. More and more computer manufacturers are doing this.  However, it is 
not totally clear to me how one could realistically insulate (or isolate) the 
various I/O lines from such computers. For example USB ports or audio in/out 
lines. 

73,


Bob Nobis - N7RJN
n7rjn@nobis.net


> On Mar 16, 2016, at 09:13, Cortland Richmond <ka5s@earthlink.net> wrote:
> 
> On 3/16/2016 2:24 AM, Robert Nobis wrote:
>> Many modern, small profile, PCs have a built in power supply (switching) and 
>> are connected to the AC mains with a two wire cord/plug, without a “green 
>> wire”. My iMac and MacMini are like this as is my Microsoft Surface Pro 3.   
>> Per your step two, should these types of computers also be bonded to the 
>> radio with a heavy short braid?
> 
> See https://en.wikipedia.org/wiki/Appliance_classes#Class_II
> 
> My Surface Pro uses a double insulated, external power supply with a number 
> of agency safety marks. Bypassing double insulation with an external ground 
> wire is a bad idea, as that protection is also bypassed. It can also increase 
> radio interference.  Does this mean we can't filter signals going into and 
> out of such equipment? No it doesn't. We have to ensure that the signals we 
> want to filter are also insulated to the same degree as the equipment is.
> 
> Cortland Richmond
> KA5S
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