I'll agree with Brent, and others, the headaches of a metal room or the
metal studs et al, in a building are going to make you pull your hair out.
But there is an alternative to the parking lot. You may want to consider the
roof. The ground reference can be put up there as well, especially if you
are doing pre-compliance stuff. You don't have to give up parking space -
which is sure to irate somebody. The roof gets a little hot, but that only
gives you the opportunity to work in your cutoffs, and showing up to a
meeting with the suits dressed like this is always good for a laugh!
Gary
-----Original Message-----
From: Brent DeWitt [SMTP:[email protected]]
Sent: Friday, April 23, 1999 7:12 PM
To: Allen Tudor; [email protected]
Subject: RE: Precompliance Testing
Allen,
From bunches of years of designing and using sites, what I would
suggest is,
IMHO, use the money to reserve a large space in the parking lot free
of
obstacles. Current construction techniques in buildings use lots of
steel
"2x4s" for the walls and there will likely be steel in the floor
above you.
All of these contribute to resonances in the emissions measurements
that are
far too difficult to want to deal with. The best way to do radiated
measurements is to be a minimalist. Get as far away from any
structure as
you can, put down a simple hardware cloth ground plane and throw a
nylon
tent over the product if it rains.
Best regards,
Brent DeWitt
Datex-Ohmeda Medical
Louisville, CO
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]]On Behalf Of Allen Tudor
> Sent: Friday, April 23, 1999 1:27 PM
> To: [email protected]
> Subject: Precompliance Testing
>
>
> Our division is in the process of constructing a new building. I
> have been told that I will be given a room in which to make
> pre-compliance radiated emissions measurements. However, ferrite
> tiles or cones are out of the question (I have been told that I
> can hang "chicken-wire" on the walls if I want to).
>
> Even though I am restricted in how much money can be spent, I
> have the luxury of designing in features as the building is being
> constructed.
>
> At a bare minimum, I think we should lay sheet metal or grid-wire
> on the floor after the concrete is poured. This ground plane
> should be grounded at each corner by ground rods. I am thinking
> that if there is no steel framework near the room, this may
> provide fairly good results.
>
> I would appreciate any recommendations on other cheap features
> that I can design in while the building is under construction.
> Also, what is the minimum size the room should be? How about
> power wiring in the walls and in the ceiling. Should any
> measures be taken to prevent radiated energy from coupling into
> power wiring?
>
> Perfection is not the key issue here: repeatability is. We have
> a local certified lab that I can compare my measurements with.
> Once the room is complete, I can repeat my measurements at the
> certified lab and develop the necessary correction factors.
>
> By the way, my product is dc powered shelf-level telecom
equipment.
>
> Again, any advice will be appreciated.
>
> Thanks in advance.
>
>
> Allen Tudor, Compliance Engineer
> PairGain Technologies tel: (919)875-3382
> 2431-153 Spring Forest Rd. fax: (919)876-1817
> Raleigh, NC 27615 email:
> [email protected]
>
>
>
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