[CQ-Contest] Optical and galvanic isolation

[Dallas and Lucy]

I don't have any issue with that explanation.  It's the "single point 
ground" that very few stations actually have.  It's an extremely complex and 
expensive process and not understood by most.  It is normally discussed in 
terms of lightning protection, but common mode rejection is another issue 
that is applicable.

Dallas W3PP
>
>>Single point ground?  I don't believe this exists for even a modestly
>>equipped station.  Please identify where you think the single point is.
>
> ------------ REPLY  ------------
>
> The single point is at the wall outlet box for your AC wiring. This is
> where all your power supply and chassis grounds should come together.
> Please excuse me for using the word "ground", an old habit. "Common"
> would be more accurate.
>
> What you want to avoid is having one chassis "grounded" at one wall
> outlet and another chassis "grounded" at another. That is what leads
> to ground loop currents and thereby to hum in your audio.
>
> Bill, W6WRT
>