Signedplaque: RECEIVER, RADIO R-390A/URR / PART NO. [blank] SERIAL NO. 53 / ELECTRONIC ASSISTANCE CORP. / RED BANK NEW JERSEY / 115/230VAC / 48-62~ 220W
on manual: HEADQUARTERS, DEPARTMENT OF THE ARMY, 16 JANUARY 1961.
FunctionA device that can be set to receive signals at a specific frequency.
The R390A/URR was a very successful radio receiver first developed for the Army by the Collins Radio Company in the mid-1950s. It continued to be produced by several companies including the Electronic Assistance Corp / Hammarlund until the 1984. Starting in the late 1960s, it was available for civilian use. It is reputed to be one of the finest receivers based on vacuum tube technology.
There exists very extensive documentation on the R390A/URR among enthusiasts online, including scanned operating manuals. A good website to start can be found here.
Historical AttributesThis particular instrument was used to receive high-frequency signals emitted by a sample during negative spin temperature experiments (see 2004-1-0412a,b,c, and 2004-1-0413).
ProvenanceUsed in Harvard's advanced undergraduate physics lab (Physics 191r) before coming to the collection.