Hi Josh,

In my experience the bulk of radio interference comes in through the
antenna, which in most situations is the connecting cables. Filtering on
every wire, grounds that are really ground, good layout. Those will get
you 90 percent there. Shielding the box is harder than it seems and is
likely only a small factor in any immunity problems you might have.

You should sign up for a free subscription to In Compliance magazine.
Like most trade journals its purpose is to sell, but every issue has
some useful information.

Best regards,

Bob

On Fri, Jan 18, 2013, at 10:09 AM, Josh Koffman wrote:
> Hi all,
>=20
> For the project I mentioned in my other post, I'm considering making
> my own enclosure. I've become a bit better with that sort of simple
> mechanical design, and it would allow me to build in guards to prevent
> unwanted switch presses and protect cables and connectors a bit. This
> isn't anything really complex, just a bit more than a standard
> rectangular case.
>=20
> If I go this way, I'll have to use some sort of easily machinable
> material, such as nylon, delrin, or some kind of HDPE. No problems
> there, but since this device will be used with a radio nearby, I think
> it should be shielded to help prevent interference. As a result, I'm
> looking for ideas on how to shield the inside of a plastic enclosure.
> I have found a couple of sprays that are available locally, but I'm
> not sure which is more suited to my application.
>=20
> The first is MG Chemicals 838
> http://www.mgchemicals.com/products/protective-coatings/emi-rfi-shielding=
/total-ground-carbon-conductive-coating-838/
> This appears to be a carbon spray designed for shielding and creating
> conductive ESD free surfaces.
>=20
> The second is MG Chemicals 841
> http://www.mgchemicals.com/products/protective-coatings/emi-rfi-shielding=
/super-shield-nickel-841/
> This is a spray with nickel in it.
>=20
> I think the nickel spray would be better, but I'm not entirely sure.
> I'm also not sure how well either of those would stick to the plastics
> I'm looking at. Another option might be to try to adhere some aluminum
> foil to the inside surfaces of the enclosure.
>=20
> Any thoughts on which might be the more appropriate path to take?
> Alternative ideas are definitely welcome!

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