Abstract: A lockable bearing apparatus for permitting rotation of adjacent members such as parts of an antenna mounting structure, wherein the adjacent members define circular bearing flanges surrounded and received by a coupling that can be tightened or loosened to lock or release the adjacent members. The coupling comprises an annular member defining an annular inwardly opening recess for receiving the flanges, and the flanges engage one another and are angled with respect to one another such that the coupling engages the flanges and urges them axially toward one another when the coupling is tightened. Stabilizing means for maintaining orientation of the adjacent members during rotation is disclosed, as well as means for selectively rotating the adjacent members with respect to one another. In the preferred embodiment for providing an azimuth axis in an antenna mounting structure, inexpensive sheet metal components are connected by the bearing apparatus embodying the invention.

Abstract: A modular solar collector system for solar radiation with a collector assembly including a series of overlapping collector pans defining a common fluid flow channel therealong exposed to solar radiation down which a heat transfer fluid flows to be heated directly or indirectly by the solar radiation. The fluid flow channel is closed by a transparent cover, a supply header which distributes the heat transfer fluid over the fluid flow channel for flow down the channel under the force of gravity, and a return header to receive the heated fluid after passage down the channel for passage through a heat exchanger and recirculation. The disclosure also contemplates the method of fabrication and installation of the solar collector system.

Abstract: A modular solar collector system and method for solar radiation with a collector assembly defining a fluid flow channel therein exposed to solar radiation; a heat transfer fluid for flowing down the fluid flow channel to be heated directly or indirectly by the solar radiation where the heat transfer fluid has a fluid vapor pressure differential between the maximum and minimum temperatures to which said heat transfer fluid is exposed during flow down the fluid flow channel of less than about 0.3 psia and/or defines a wetting angle with respect to said solar radiation absorbing surface of less than about 50.degree.; and means for supplying the heat transfer fluid to the upper end of the channel for the flow of the heat transfer fluid down the channel under the force of gravity to heat the transfer fluid.