- R-390A
The R-390A /URR is a general coverage HF
radio communications receiver designed byCollins Radio Company for theUS military .History
The R-390A
military shortwave radio receiver was the result of a project undertaken by theU. S. Army Signal Corps in 1954 to replace the existing R-390 receiver then in use. The R-390 had done its job so well that the Corps decided continued use of this type of receiver necessitated an improved, reduced-cost version.Originally built by Collins Radio Company in Cedar Rapids,
Iowa , the R-390A was designed by two teams. The mechanical team was led by Fred Johnson while the electronics team was overseen by Collins' Ernie Pappenfus, K6EZ. Besides Collins Radio, 12 other sub-contractors (includingMotorola , Stewart Warner,Stromberg Carlson , Capehart,Teledyne , and others) built R-390As until the last one rolled off the assembly line in 1984. Banks of these radios served the country in all branches of the US military. Additionally, they found service with theCIA andNSA to monitor communications from behind theIron Curtain . During theCold War years, the R-390A was so valued it was classified top secret, a security measure which remained in force until the mid-1960s. [http://www.r390a.com/html/history.htm R-390A History]Design
The R-390A is a general coverage radio receiver capable of receiving amplitude modulated, code, and
frequency shift keying signals. Its tuning range is from 500kilohertz to 32megahertz , in 32 one-megahertz bands. The circuit is thesuperheterodyne type, double conversion except on the lower bands where triple conversion is used. It employs 26vacuum tube s, a larger than normal count for most general-coverage receivers. The receiver weighs 85 pounds and can be operated on 120 volt or 240 volt supplies. It fits neatly into a standard 19 inch relay rack.Tuning of the R-390A's radio frequency and
intermediate frequency front end is synchronized by means of an ingenious mechanical system of racks, gears, and cams. When the front panel tuning controls are rotated, this system raises and lowersferrite slugs in and out of the receiver's tuning coils. This ensures that all front-end circuits are tracked, meaning all circuits are tuned to the correct frequency to maintain excellent selectivity and sensitivity. The receiver's construction is modular for easy servicing. Each major area of the receiver is contained in easily removable subassemblies, and these can be repaired or replaced as needs be. Though the R-390A is mechanically and electrically complex, alignment and servicing were designed to follow simplified procedures published by the Signal Corps.Use
The R-390A was deployed to most branches of the US military and remained in general use through the 1980s. The last major update to its documentation was in 1984. As the military procured newer receivers, many R-390As were released to surplus while others were destroyed. Some receivers were retained by the services, however, when they found that the R-390A's vacuum tube circuitry could easily survive an
electromagnetic pulse . There are reports, possibly apocryphal, that R-390A receivers are still in use aboardU. S. Navy submarines since the receiver can withstand the strongradio frequency fields found aboard ship.Many of the R-390As that exist today are in the hands of
vintage amateur radio collectors andamateur radio operators who contend that few modern solid state communications receivers can equal its performance. There is a wealth of information, both printed and electronic, devoted to R-390A restoration and maintenance, as the R-390A is widely considered an example of the best ofvacuum tube technology.ee also
*
ART 13 transmitter
*ARC-5
*BC-348
*BC-654
*Collins Radio
*Hammarlund super pro
*National HRO
*Vintage amateur radio References
General References
*Rippel, Chuck. "R-390A History" and "R-390A Overview". [http://www.R390A.com The R-390A/URR Home on the Web.] (9-11 January 2003)
*Couillard, L. W, "Cost Reduction Program for Radio Receivers R-390." Cedar Rapids, Iowa: Collins Radio Company, 1952
*United States Department of the Army, "Technical Manual TM-11-5820-358-35: Radio Receiver R-390A/URR." Washington, DC: Government Printing Office, 1961.
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