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Re: Conductive Paint


 

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Copper tape is one of the better ways to shield. Solderability is a feature you won¡¯t get with aqua-dag or silver-dag, and these paintable solutions are quite costly, meant more for small areas with difficult geometries. I prefer to not rely on the conductivity of the adhesives, but use solder bridges or wires to ensure continuity.?
There is one aspect you need to think about and that is the possibility that you may end up creating a slot antenna inadvertently; two conductive layers that don¡¯t touch and connect properly leaving a long gap can be trouble. I learned this lesson while working on a 70cm linear and there was what seemed like a minimal gap between aluminum panels. The glow from a nearby fluorescent tube should have us in, but nobody thought that far ahead. A simple continuity test won¡¯t reveal the gap either. Finger stock is a ¡®must¡¯ for this kind of structure when panels are removable.?
Before applying the tape, make sure that the surface is really clean. You can improve the rigidity of the tape layer by putting a piece of wire under the tape so as to form a small ridge in the tape when pressed down, which will reduce the tendency to buckle or curl up. Forming an X shape on the two diagonals will help to stop the corners from detaching on a larger flat segment.?

Good luck with the shielding tasks,
Roland AE6VL?

On Feb 9, 2025, at 11:11?AM, jerry-KF6VB via groups.io <jerry@...> wrote:

?On 2025-02-09 10:58, K9HZ wrote:
Have a look at msg #5998 from Chris Corcoran¡­ He shows a number of
plots that show the resistance of the coating. You can use that to
figure out the attenuation for the coating.
** Yeah, the attenuation for the cheap carbon stuff doesn't look too
good
around 20M.

I bought a roll of self-stick copper tape that claims that their
adhesive
is conductive.

I figure I can put that tape on the easy places, and then coat the
innards
- including the tape - with the carbon paint.

In principle, I like the fact that the carbon paint is *resistive*.
So it
should be able to attenuate EMI without necessarily having to be
grounded.

- Jerry

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