If you were building a microwave oven, though, what is the largest
aperture you would allow to seal the door or the window, for instance?
If you think you might ever run a generator in your shop, by the way, I
would put sheet rock on the ceiling (walls also) and fiberglass
insulation.
No, the foam panels are quite rigid, and they carry the weight of
each panel. Heavy aluminum foil is glued on each side, and over the edge
where the panels join. You leave at least a half inch gap all the way
around the edge to be sure they don't touch. Then you glue thin
paneling or hardboard to each side to protect the foam and foil. The
corners and edge joints are the secret, they hold everything together
and connect the inside and outside foils into a pair of separate but
continuous shields. Finally, you bring power in somewhere and bond the
two shields. You can make a pair of holes for air conditioning, as long
as you are careful to maintain the shielding with bronze screening. I'll
put plenty of pictures on my website as I build it. You can build a 12'
* 8' for well under a grand, as opposed to over 20 grand for a solid
aluminum booth.
Sheet rock if fairly heavy, so you paint the ceiling panels white, or
another light color.
A generator, as in Gasoline powered? It would be in a separate
building, by the automatic transfer switch.
According to an online calculator the wavelength for 76 Hz is
12,947,368.421 feet (2452 miles). The wavelength for 2450 Mhz,
incidentally, is 4.82 inches.
A simple steel box will stop 76 Hz.
I've always wondered, incidentally, if my
subwoofer would sound better if I built a room 1/4 wavelength long at
it's lowest frequency. I haven't done it yet, though :>
It would cause a resonance over a narrow range of frequencies and
sound like crap, unless all you want is a vibration that will shake the
walls apart.
Me too--3 years--U.S. Army. I've lost everything else over the years,
including all my year books, but I still have my DD214. I'm not sure
why. Maybe subconciously I wanted to make sure they didn't call me up
accidently :>
You can get full copies of your military records by applying to the
VA directly, or through your local Veterans Service Officer. A local
DAV post should have at least one, and sometimes the county government
has one, too. I have both, locally, and have had help from both at
different times.
--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.
Michael A. Terrell
Central Florida