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Re: [RFI] Quiet Shack PC Systems?

To: rfi@contesting.com
Subject: Re: [RFI] Quiet Shack PC Systems?
From: "Ian White, G3SEK" <G3SEK@ifwtech.co.uk>
Reply-to: "Ian White, G3SEK" <g3sek@ifwtech.co.uk>
Date: Fri, 26 Mar 2004 09:19:13 +0000
List-post: <mailto:rfi@contesting.com>
Jim Brown wrote:

If I'm not mistaken, CE compliance is written around the EN55103-1 and -2. The emissions standard is mandatory, however the susceptibility standard is essentially voluntary, since it simply requires that the manufacturer state the level of interfering signal to which the product is immune. Those levels vary from 1 mV/m to 10 mV/m.


That does not change the fact that by reciprocity, design techniques that minimize emissions will tend to minimize susceptibility. But it does NOT mean that other mechanisms that might not be involved in emissions might not be degrading susceptibility.

That's basically correct.

In some ways, the main virtue of mandatory CE compliance is that it forces product designers to *think* about EMC/RFI - to recognize the problem and get a grip on it. When they take that first big step, a big improvement in performance will usually follow.

Our experience in CE-land has generally been that compliant products are usually pretty reasonable; and that very, very bad products are probably non-compliant. The very bad ones are probably junk consumer imports, possibly the very same models that are imported into the USA.

Unfortunately there are some loopholes in the mandatory CE tests, which are letting through a few problems. At present there is no requirement to test products in standby mode, and radiation from some SMPSes (eg in some wide-screen TVs) is turning out to be much worse in standby than in full operation. Also there is no clear mandatory requirement to test for radiation from mains leads plugged into the *output* of devices such as "power savers".

The TV problem is rather unexpected, something that the designers probably never thought about. On the other hand, the power saver problem may have been a quite deliberate move to save on components. In both cases, the solution is to close the loophole... but that will take time.


-- 73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)

http://www.ifwtech.co.uk/g3sek
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