[Amps] placement of RF choke bypass cap.

[la7sl Nils Petter]

Hi !
I have not followed this discussion closely...
But I have always believed that electrical currents can
and will be following any conductor...regardless of frequency...
And YES..I do know about skin effect....
In the case of a closed metal box..a shielded compartment...
the shielding property lies in the fact that electromagnetic fields
will be "converted" to electrical currents in the shielding metal..
and will therefore not penetrate the box and set up electrical
currents in inside conductors. But it will for sure generate an electrical
potential on both the inside and the outside of the box.
And RF currents in that shielding material can under certain circumstances
regenerate a em field inside the box... my teacher told me to be careful
in choosing "ground" points in shielded enclosures for this very reason.
Please excuse me for simplifying matters here.
Faraday and Maxwell may be good reading here.....
It is a fact that different mechanical layouts in RF circuits can and will 
lead
to different "return paths" in the circuit and this will alter resonant 
frequencies
among other things...
But I am getting old now...and what we considered "laws of nature" back then
may have changed since I was studying these things...
If so..I will be happy to learn about it !
Peter
----- Original Message ----- 
From: "Ian White GM3SEK" <gm3sek at ifwtech.co.uk>
To: <amps at contesting.com>
Sent: Thursday, March 25, 2010 8:19 AM
Subject: Re: [Amps] placement of RF choke bypass cap.


> DF3KV wrote:
>>
>>For the third or fourth time, you are talking about RADIATED RF energy,
>>i.e. an electromagnetic field. The discussion regarding the padder cap
>>under the chassis and the load cap above the chassis was about the flow
>>of electrical current - two different things.
>>
>
> This discussion is getting lost; we need to get back to that original
> question about the padder cap.
>
> Bill: please can you post photographs of "above" and "below" the
> chassis, so that other people can make their own judgement about the RF
> current path.
>
>
> -- 
>
> 73 from Ian GM3SEK
> http://www.ifwtech.co.uk/g3sek
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> http://lists.contesting.com/mailman/listinfo/amps
> 
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