If you use HNC connectors instead of BNC the center pin will
be protected, and will, I believe, disconnect before the
shield disengages. This will eliminate HV hazards on
disconnect
Cortland
__
Subject: Human exposure to microwave RF
Author: doug_fra...@atk.com (Doug Frazee) at internet
List-Post: emc-pstc@listserv.ieee.org
Date:12/16/96 9:29
I am looking for documents that discuss safe exposure levels to radiated
microwave RF energy in the 2-4 and 4-8 GHz frequency r
For what it is worth... I own GriD laptop computer whose
bottom casting is magnesium. GriD was famous for its
rugged, magnesium computers -- and they were sold worldwide.
I do recall an insulating plastic sheet between the board
and t
Doug,
The FCC Amateur Radio regs (Part 97) require that one operate on frequencies
authorized for the class of license issued, with a level of power authorized,
and that equipment meet certain technical standards with respect to spurious
emissions and construction. As long as a licensee is o
Charlie,
You write:
"So according to the standard, the required minimum number
of hosts in one. I believe that one is sufficient,
especially where you have no idea what computer the end user
will have.
Has anyone the status on immunity testing standards for
Europe? I understand 61000-4-2, 61000-4-3 and 61000-4-4 are
adopted, and 61000-4-5 and 6100-4-8, and 61000-4-11 yet to
become effective. Is this accurate?
Thanks,
My comments on Tony Frediksson's post are indented among his words.
It is indeed the case that testing in one representative host meets the
requirements. But the statement, "...of the PWBA manufacturer's choice so as to
ensure compliance of the PWBA with the entire population of hosts in which i
>> Is the (FCC A) data package acceptable as being compliant
>> with EN55022? That is, can I use that data set to support
>> my claim of compliance with EN55022?
I don't see why it _should_ be sufficient. For one thing,
the conducted
>> ... possible to FAIL the FCC limits but PASS the CISPR
limits. The question then becomeswhat next? Can I still
ship to US customers...
Doesn't that answer the question for you? I really don't
think you want
_Compliance Engineering_ for 1996 contains an article
discussing in detail the requirements for intentional
radiators in the US and Europe. Unfortunately, mention of
Japanese standards is limited to two short and uninformative
comparisons. The a
Jim,
I've used plywood, plastic and plywood/solid construction
where I've worked with good results. Particle board -- in
my opinion -- is NOT the best choice for anything that has
to bear a load.
You can easily ch
Nails versus dielectric fasteners has been debated for years now and I don't
think anyone has come up with a definitive rule. I know of two facilities that
use nails for their shelters without ill effects (there are probably more);
other folks prefer all-dielectric material. Whether you can get
>> I know that washing machine wringers pose a threat to some appendages of the
>> human body...
Printing presses and other industrial hazards may be dealt with by operator
safeguards and personal safety equipment (eg safety shoes)but the home will
always have to be treated differently. It re
Let's not go overboard here. This virus is widespread, and it is common to find
people who harbor it unknowingly. Files were distributed here to deal with it --
I understand they were made available by Microsoft -- and they work well. I now
have the Guide -- uninfected -- on a drive where I can
Rod,
I think you will have to make sure your tests (to Class A)
comply with the FCC Part 15 test setup (which differs
somewhat from CISPR-22 -- see ANSI C63.4) and also include
tests above 1 GHz if the equipment has clocks of 108 MHz o
Max,
You may be exciting a resonant cavity with the video card.
If you can identify cavity modes being set up you may be
able install straps to reroute current flow within the
cabinet away from vulnerable slot coupling. Alternatively,
Robert,
My experience has been that separating logic ground from the
D-sub shell on a plug-in card is not necessarily a good
idea. When you evaluate this card, please check it not only
on a system you know is a good performer for EMI,
A few additional comments:
Art Kampmeier:
>- A four year college degree in engineering?
> Product Safety is only a very small portion of the
> curriculum.
"Egon H. Varju" 8/28/96:
~Actually, four years is not enough. Most fresh engineering graduates are quite
~useless t
The question duly asked,
What meaning's then attached
When one says RFI's on hand,
Another's EMI is banned?
And why two experts, old and wise,
Cannot their terms in one comprise
This thing on which they both must toil;
Thanks for the word, Dave. I will know not to rely on the
printed material they supply, then. Sic transit tyrannosaurus,
right?
Cortland
__ Reply Separator _
Subject: Re: C-Tick mark
Author: Dave Perlmutter
Paul,
I too have looked at consumer grade equipment with an eye towards EMI
measurement. I have the ICOM R7000 (modified) and R7100, as well as Yupiteru
7100 and AOR AR8000 handheld scanners, plus the usual amateur radio handheld
transceivers, and I have made some use of all of these
Heber,
I have zero experience or training in X-ray technology
(aside form what's in the physics books about Coolidge
tubes) but I'd think you could quantify transparency as 10
log P1/P2 where P1 is tube power needed for a given flux
I will have to go back to my records, in which I have a copy of the
FCC's NPRM setting up Class A and B limits, but as I recall, limits were
established by reference to the response of radio and television users
to known levels of radio noise. Also, impulses of known energy and PRF
It does seem to be the case that commercial courses offered for EMI
prevention are developed by people with something to sell. Still, not
all are aimed at 11th hour solutions. Few people in the field really
favor this kind of fix. It isn't integrated with product esthetics
This is also my last day at my present location, though I'll continue
in the list from my Compuserve account while searching.
Part of the confusion, I think, is that the Rulemaking says labels shown
replace existing labels, without clearly discriminating between Class A and
Class B. It is not clear that the intent was only to replace the Class B
label, although the text is contains actions evidently meant to qualify a
Tony,
Radiated immunity tests set up a situation where only the unloaded
field is known. You're correct we cannot know for sure what is
actually getting into the EUT. If we had to know what current was
actually entering the ports we would need to monitor it real-
Nice post, Gabriel. I really liked the reminder that what we call
precision doesn't necessarily mean something. One dB is about 10
percent. That's not really very good -- but for RF it's about what we
can get, generally.
On the other hand, knowing the precise fr
Well, how to answer this? I would say that I feel sympathetic to his particular
problem, but I am not in favor of eliminating rules which exist to protect the
rest of us from side effects of products they sell.
Yes, stand
ar
ds can eliminate minor manufacturers, like the family computer business
While not losing sight of the reason why regulations exist,
let's also remember that if we don't participate in making
them, we can only complain afterwards about their impact. I
have participated in the FCC's comment process on several
occasio
Chris,
>> Here my natural cynicism comes out...
In this business we all get cynical.
>> The reduction in Electronic Fog in our universe is a secondary effect
Here we disagree. CISPR-12 was based on actual interference tests using real
people as subjects. The standard, which was
Chris,
The "blame" for standards can be assessed everywhere. But you posted:
>> ...how we stood by and let the power generating industry make the
>> consumer responsible for the supply quality.
The problem here is that the industry can't control what we hang on the line.
Remember Tungar
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