Ops – should be cheapo depo, not cheapo dopeJ
From: Dward [mailto:dw...@atcb.com]
Sent: Saturday, June 19, 2010 2:55 PM
To: 'k...@earthlink.net'; 'EMC-PSTC@LISTSERV.IEEE.ORG'
Subject: RE: [PSES] EMC Performance Changing With Age Of Product
Seems to be the old scenario of:
1 – know exactly
Seems to be the old scenario of:
1 – know exactly what your device does, test it till it breaks, find out
just what it can do and can’t do – expensive – but you end up with a
superior product far above the average – a rock solid device.
2 – assume your product is OK, but test just a little more t
Tuppence from my corner... Once upon at time at Wang Labs, we noticed
emissions performance improved after transportation vibe tests. I attributed
this to having scraped surface oxidation off mating surfaces of shielding
chassis'. A reasonable inference could be made that over time oxides might
bu
COTS equipment is not likely to work just out of the box.
Significant additions and re-work will be needed to meet MIL-SPEC.
or find a purpose built PC for that environment.
It would be about 10x the $ of COTS gear. Just because they can get it.
-
Bill
In the event of a national emergency,
In this application, the PC has to meet an RE limit which is numerically
tighter than CISPR, plus the limit has to be met at one meter, not three
meters. I am thinking that in order to meet the mil RE limit, it may be
necessary to apply mil tactics, such as low impedance, not low resistance,
bonds
On Fri, 18 Jun 2010 16:04:37 -0700,
"Brian O'Connell" wrote:
> what is a "standards-receptive" directive ?
I guess what you mentioned is the directives for which
harmonised standards will be used for presumption of conformity.
In the following pages, six directives other than the new approach
In message <01cb0f3a$a0dd5250$d600a...@tamuracorp.com>, dated Fri,
18 Jun 2010, Brian O'Connell writes:
>what is a "standards-receptive" directive ?
Please give more context.
--
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
John Woodgate, J M Woodgate and Associates
The USB connector is small and uses relatively thin gauge metal, so you
can't get values as low as for large braid shields or other more massive
grounds. Tens of milliohms is certainly adequate from an EMI standpoint.
Really low ground impedances are required when there are lightning
requirements
Was doing some troubleshooting on a PC with a metal case and found the USB
shells had bonds to case ground on the order of several tens of milliohms.
Is this common practice? I was looking for single digit milliohm values
indicative of a faying surface type bond. Application was a militarized PC.
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