[Hpsdr] Call for Comments - ALEX

[Henry Vredegoor]

Hi Chris, Ray, All,

This is what I meant.
Open up a piece of equipment and if there is any metal shielding used, it is
most probably tinned steel for this exact reason. 
(Use a magnet to test this.)
It will be even better if the steel is plated with a good conducting metal
like eg. copper (for the electric shielding).

Is there any data on how thick the aluminum shielding would have to be to
provide the same magnetic shielding as say 1 mm. thick steel plate?

I would even go a step further and would be shielding all the different
filter sections from each other; I would certainly mount some very decent
shielding between the transmitter filter board and the receiver filter
board(Duplex operation)
I do not think a single PCB board is enough shielding.

Remember we are dealing here with the most sensitive part of the receiver!

73's

Henry.

>    
> The aluminum box can effectively shield the electric field, but thin
> aluminum won't do much for the near field magnetic field component.
> 
> You need a material with a relatively high mu (permeability) 
> like steel
> or other ferromagnetic alloy to provide useful magnetic shielding. The
> thickness of the metal is also a key factor (thin metal is less
> effective than thicker metal).
> 
> See chapter 11 in Clayton Pauls 'Introduction to Electromagnetic
> Compatibility' for a good discussion of the topic.
> 
> -Ray  WB6TPU
> 
> 


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