Re: Power Supply Box's

Re: Your suggestion of a compartmented box. I see nothing wrong with
this concept, but remember that only hindsight is 20:20. Problems
have a way of popping up.

I would make very sure that all of the box's components are very
solidly connected electrically. RF equipment is constructed with
bare metal contact and screws or other fasteners every inch or
so. Computer chassis use sheet metal techniques that have tight
fitting seams or fingers that pull the joint tight together. Modern
computer equipment operates at frequencies that are in microwave
range so you are designing an enclosure that would be usable for
radars or communications equipment in that range. Microwave
frequency energy can leak out of a crack that is less than 1/32" wide
and less than inch long. Forget the 12 inches mentioned by someone
above: microwaves radiate efficiently from antennae that are only a
fraction of an inch long (1/4 to 1/2 wavelength). Critical
components in such assemblies are often housed in separate cast metal
boxes inside the overall enclosure and they are connected with
shielded coax cables. These inner boxes are of cast construction for
closer fitting seams and often silver plated "finger stock" is used
around the entire length of the seam to ensure a good electronic seal.

And also attach a good ground. Not the regular electrical green wire
ground that is the same gauge as the power carrying wires, but one
that is at least several gauges BIGGER. Keep it as short as possible
and attach it to a regular ground rod (15 to 20 feet). Also route it
as LOW as possible, preferable along the floor (a wire in the air is
an antenna, not a ground).

Another consideration, possible contradictory to the above, is
cooling. You need adequate cooling for the electronics. Otherwise,
you will be repairing/replacing on a regular basis. Components that
generate the most heat are best located at the top, near an exhaust
vent. The cooler components can be located below. FanS would be
almost mandatory in an assembly like this and air flow around and
THROUGH all the components should be carefully considered. All the
openings, internal and external, should have metal screens to prevent
radiation and chips from passing through. Filters on the air intakes
may also be desirable to keep dust (abrasive) out. They need not be
fancy, but they should be finer than normal HVAC filters. Foam or
cloth could be used for fabricated filters. Or I am sure there are
many commercial products.

I probably forgot something.