[OZAPRS] rf earth

[Damien Gardner Jnr]

On 27/04/2010, at 11:39 AM, Steven Heimann wrote:

> On Tue, 2010-04-27 at 02:05 +0100, Paul Mullins wrote:
> <snip lots>
>> NOW ANOTHER WORD OF WARNING.
>>
>> Only licensed people should play around with 240 volts mains, this  
>> is what
>> the law states, if you are competed I think that's the right word,  
>> you could
>> make a great earthing system, ALSO you need to keep the two system  
>> apart
>> easy said. Also beware of potential voltage differences on the two  
>> earthing
>> systems, As I said my RF earth is better than my mains earth, so be  
>> aware .
>>
> </snip>
>
> I would think that keeping the two earths separate creates a danger.
> The two earths will be connected through the case of your expensive
> radio gear.  If a spike comes down the mains (wire gets hit by
> lightning) these is a discharge path through your transceiver to the  
> RF
> earth which you have just said is better than your mains earth and  
> thus
> is a very attractive path for all those electrons.
>
> I am not sure what the best answer is, but creating the potential  
> for a
> potential difference between the two earths seems like a bad idea.

Yeah ditto, we were taught that your RF, Audio, and Mains earth/ 
grounds should *always* be bonded together..  Especially if you're  
running audio circuits between different electrical supply circuits..   
It was amazing how much earth buzz would appear just running FOH amps  
off a different circuit (but still form the same switchboard!) as your  
mixing desk...  Though that's going back 15 years now, maybe they're  
pushing something different now?

--DG


Damien Gardner Jnr
VK2TDG. Dip EE. GradIEAust
rendrag at rendrag.net -  http://www.rendrag.net/
--
We rode on the winds of the rising storm,
  We ran to the sounds of thunder.
We danced among the lightning bolts,
  and tore the world asunder
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