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Re: [RFI] House Ground

To: David Winarsky <david@winarsky.com>
Subject: Re: [RFI] House Ground
From: dalej <dj2001x@comcast.net>
Date: Wed, 16 Mar 2016 14:21:43 -0500
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
I got a Macbook Pro here in the shack that makes three.  If the snap on device 
took care of it then I wouldn't worry about trying to ground the macbook.  You 
might do harm to the macbook and not fix anything more than you already have.  

Dale, k9vuj


On 16, Mar 2016, at 12:19, David Winarsky <david@winarsky.com> wrote:

I have a Macbook Pro sitting next to my Elecraft K3.  I have a USB cable going 
from the Macbook to the KAT500 tuner and found that I was getting RFI from the 
cable at various points on 20m.  I stuck 3 snap-on ferrites on the USB cable by 
the connector to the Macbook and that took care of it, however it did make me 
wonder if I should be bonding to computer.  It’s not clear how, however because 
there’s no easy connection to the chassis.

David
NY6W

> On Mar 16, 2016, at 10:01 AM, dalej <dj2001x@comcast.net> wrote:
> 
> 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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