Found this interesting receiver at the most recent Meriden, CT Hamfest last October, and since the price was right hauled it home with me. Why did it catch my eye? For starters, the construction is a dead giveaway that it is a commercial/mil-spec receiver of 1960s or so vintage. Second, the radio had no identifying markings, and no apparent evidence at first glance of being debadged. That is sometimes an identifier of equipment that saw clandestine service in its past life. Third, there was some circuit modules marked as “video converter” which had piqued my curiosity. Finally, if I was a little more awake that morning, I might have recognized the front panel as that of some variant of the Hammarlund SP600 which did see extensive government service. Regardless, it was a mil-spec HF receiver, probably a Black Radio, the price was right, and it was something you normally don’t see at a local hamfest. Once I got home, a Google image search found identical units, and identified it as being an NSA-issue R-1511/GR. Further Google searching discovered that a fellow hobbyist had scanned and uploaded the manual.
From what I discovered online, the R-1511/GR was developed for the National Security Agency in 1968, and was based on the Hammarlund SP600. It saw service until at least the mid 1980s, and based on my research appeared to be part of the AN/GSR-4 Store and Forward Environmental Collection System. With this system, wideband RF spectrum was recorded to magnetic tape for later analysis. While this is an easy task these days for any hobbyist with a PC, free software, and an SDR such as the Lime or HackRF One, the NSA was doing this in the 1960s.
Like a lot of gear at hamfests these days, this receiver was from a silent key’s estate, and its specific history, and that of the silent key, is uncertain. He was possibly in the ASA, NAVSECGRU, or maybe even USAFSS as they would have been the service members familiar with this system. Did this piece of gear listen to the Soviets, the Chinese, or someplace in Central or South America before retiring to civilian life in some former veteran’s ham shack? We’ll never know, but we can safely guess that it was interesting in a “behind the curtain” manner.
The frequency coverage of this radio goes up to the 6 Meter ham band (50-54 MHz.), and the SP600 is still a good performing receiver by today’s standards. This unit, when not being used for displays, is going to be parked on the center of the 6m beacon subband to monitor and record VHF propagation conditions.