While investigating a new transmitter building for WGCR, I found
that the reinforced, welded rebar sort of construction I wanted for RF
shielding was terribly expensive - on the order of $20,000 for just the
building. An alternative had to be found to fit our budget.
We found an unlikely solution; sea containers. A sea container is
like a semi-trailer without the wheels. In our case, we purchased two
refrigerated sea containers from a local container supplier for about
$1,000 each. These containers have a fascinating construction. The
outside has a heavy corrugated steel shell lined with four to six
inches of a high-efficiency insulation. The inside is protected with
16-gauge stainless-steel walls and a ribbed-aluminum floor.
For a foundation, a 12-inch-thick concrete slab was poured, and then
six 6-inch angle iron stilts were placed. Then, a plate was welded to
the top of each stilt to form a socket for each corner of the
containers to sit side by side. The containers were bolted through the
sockets to the foundation and then welded. The containers sit 4 feet
above the ground.
After the containers were set on the stilts, work began on the
electrical and ventilation systems. One container is used for the
transmitter and audio container with the electrical panels and entry,
and the other houses the generator and storage for tools and other
While the stainless-steel liner proved tough to drill, it also
proved to be an ideal mount for various electrical boxes, panels and
the generator transfer switch. All electrical, telephone, cable and RF
wiring were routed through a common hole in the transmitter container
and then bonded to the liner at point of entry. Heavy copper ground
straps were brazed to both containers' inner and outer shells as close
as possible to the point of entry and then bonded to the radial system
at the tower base. The solid metal enclosure has provided the ultimate
We also found, much to our surprise, that a negative pressure
ventilation system, properly ducted, has served very well and allows
the doors to seal properly, providing the best insulation for these
containers. Conventional wisdom for typical buildings dictates positive
pressure, but in this particular unconventional instance, negative
pressure seems to work better.
How well has this setup performed once we moved our transmitter in?
To say I am pleased with the result would be a major understatement, as
mysterious RF troubles I had before are now gone for good.