[Elecraft] Mac Grounding

[Joe Subich, W4TV]

If you don't bond the computer chassis to the radio system
ground you stand a very good chance of blowing the USB
ports or your USB to serial interface in the event of a
nearby lightning strike.

Most amateur installations fail to properly bond the tower,
"ground stake" where the antenna feedlines and control lines
enter the shack and the power (utility) service entrance
grounds together.  Since the service entrance ground is
the power system "safety ground" any difference in the
ground potential between the RF system (antenna/tower) and
the safety (utility) ground will appear directly across the
USB devices.  Since the difference in potential can be many
hundred volts and the USB port/devices are 5V DC devices,
can see how quickly the devices can be damaged when one of
the "grounds" reverse biases the diodes in the devices <G>!

If you *don't* bond the computer chassis to the RF system
ground, disconnect *ALL* connections between the computer
and radio when you are not using them.

73,

    ... Joe, W4TV


On 4/11/2011 7:39 PM, Phil Hystad wrote:
> Follow up on some of this discussion...
>
> Any wiring made to an Apple computer that is not supported via
> standard cabling (e.g. USB, Firewire, etc., video, etc.) is not
> authorized and may violate the warranty.  This is essentially what
> it says in my iMac 24 user guide.  I did not quote it exactly since
> it is about 3 paragraphs long with really tiny print.
>
> As far as I know, I do not have an RFI problem in my shack and
> I am certainly not going to ground my computer (other then the
> grounding plug for the 120 volt AC connection) nor will I put
> a ground strap wire on my laptop.  I mean, does anyone really
> do that?
>
> But, like I said, I do not have any hum, buzz, or RFI that I
> know of and if I don't know of it it certainly does not bother me.
>
> peh
>
>
> On Apr 11, 2011, at 8:58 AM, Jim Brown wrote:
>
>> On 4/10/2011 2:29 PM, David Guernsey wrote:
>>> The radio is grounded of course, but the computer is not.
>>
>> EVERY piece of equipment in a ham shack should its chassis bonded to
>> every other chassis in the shack, and to your earth ground system. This
>> includes the computer.  Doing so will minimize problems with hum, buzz,
>> and RFI. It also tends to minimize lightning damage.
>>
>> A tutorial on this is part of http://audiosystemsgroup.com/RFI-Ham.pdf
>> and in
>>
>> http://audiosystemsgroup.com/HamInterfacing.pdf
>>
>> 73, Jim Brown K9YC
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