Westinghouse built an FD search radar designed to operate in the S-band at 2322 to 2670 MHz. The radar was designed to have a maximum range of 220 nautical miles and search to an altitude of 150,000 feet. System problems required several modifications at the test platform located at Crystal Springs, Mississippi. Once these problems were solved, the first of twenty units in the continental United States became operational at Charleston, Maine, in 1963. The last unit was installed at Bellefontaine, Ohio, a year later. In the early 1970s, AN/FPS-27 radar stations that had not been shutdown received a modification (solid state circuitry replacing vacuum tubes) that improved reliability and saved on maintenance costs.
Prototype AN/FPS-27, Crystal Springs, MS
Photo from old Westinghouse AN/FPS-27 booklet
From an email recieved from Bob Redding:
I believe the Crystal Springs picture is just as construction was being completed, before a lot of things had been painted. I think I remember that radome being painted sometime. That would probably been the second time. Also, in the picture, the road hadn't been paved. I believe the date of this picture must have been about 1958 or 1959.
I'm a little confused about the FPS-27A and B, too. The FPS-27 here in C. S., was an XW1, and it was retrofitted twice that I know of, but I don't know about the A's and B's. When I saw the "B" model mentioned on Gene's site, I wondered if maybe they had "solid stated" the receiving equipment on the top floor, and reduced the size. The "cut-away" picture that you sent, is missing the "monstrous" receivers, as I knew them. I don't see the GLA-8 either, as I knew it.
I remember there being 10 big receiver cabinets, with three vertical drawers each, all lined up in a row. Frankly, I'm a little "fuzzy" on the "receiver floor" since I never worked on them. Early on, I maintained the receiver modules, in a separate shop, but most of my years were spent on the transmitters.
I'm fairly sure that Havre, MT had the same model equipment as Klamath, CA and Miles City, MT, since they were installed at exactly the same time. I was scheduled to go to Havre, but I talked them into sending me to Miles City instead, which turned out to be a mistake. Maybe the Canadians could tell us what a "B" model is, since they kept the FPS-27's running a lot longer than the U. S. did.
From September, 1967 C&E Digest: Article on FPS-27 regulators