R-390A
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The R-390A /URR is a general coverage HF
radio Radio is the technology of communicating using radio waves. Radio waves are electromagnetic waves of frequency between 3  hertz (Hz) and 300  gigahertz (GHz). They are generated by an electronic device called a transmitter connec ...
communications receiver Communication is commonly defined as the transmission of information. Its precise definition is disputed and there are disagreements about whether unintentional or failed transmissions are included and whether communication not only transmit ...
designed by
Collins Radio Company Rockwell Collins, Inc. was a multinational corporation headquartered in Cedar Rapids, Iowa, providing avionics and information technology systems and services to government agencies and aircraft manufacturers. It was formed when the Collins Rad ...
for the
United States Armed Forces The United States Armed Forces are the Military, military forces of the United States. U.S. United States Code, federal law names six armed forces: the United States Army, Army, United States Marine Corps, Marine Corps, United States Navy, Na ...
.


History

The R-390A
military A military, also known collectively as armed forces, is a heavily armed, highly organized force primarily intended for warfare. Militaries are typically authorized and maintained by a sovereign state, with their members identifiable by a d ...
shortwave radio receiver A shortwave radio receiver is a radio receiver that can receive one or more shortwave bands, between 1.6 and 30 MHz. A shortwave radio receiver often receives other broadcast bands, such as FM radio, Longwave and Mediumwave. Shortwave radio receiv ...
was the result of a project undertaken by the
United States Army Signal Corps The United States Army Signal Corps (USASC) is a branch of the United States Army responsible for creating and managing Military communications, communications and information systems for the command and control of combined arms forces. It was ...
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. There are many references to the R390A in the open literature during this period; a picture of the receiver appeared in the May 1959 issue of '' QST''. The total production of the R-390A (as determined by the high serial numbers noted) is over 55,000 units. Initial production started in 1955 and ran through approximately 1970, and then was restarted in 1984 by Fowler Industries for Avondale Shipyards. Manufacturers and their approximate production numbers are: Companies which made spare modules, but not whole sets were Communications Systems Corp., Clavier Corp. and Hacking Labs.


Design

The R-390A is a general coverage radio receiver capable of receiving
amplitude modulated Amplitude modulation (AM) is a signal modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave. In amplitude modulation, the instantaneous amplitude of the wave is varied in proportion t ...
,
code In communications and information processing, code is a system of rules to convert information—such as a letter, word, sound, image, or gesture—into another form, sometimes shortened or secret, for communication through a communicati ...
, and
frequency shift keying Frequency-shift keying (FSK) is a frequency modulation scheme in which digital information is encoded on a carrier signal by periodically shifting the frequency of the carrier between several discrete frequencies. The technology is used for c ...
signals. Its tuning range is from to , in thirty-two bands. The circuit is the
superheterodyne A superheterodyne receiver, often shortened to superhet, is a type of radio receiver that uses frequency mixing to convert a received signal to a fixed intermediate frequency (IF) which can be more conveniently processed than the original car ...
type, double conversion above , below which triple conversion is used. It employs 23
vacuum tube A vacuum tube, electron tube, thermionic valve (British usage), or tube (North America) is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied. It ...
s, a larger than normal count for most general-coverage receivers. The receiver weighs and can be operated on 120-volt or 240-volt supplies. It fits neatly into a standard
19-inch rack A 19-inch rack is a standardized frame or enclosure for mounting multiple electronic equipment modules. Each module has a front panel that is wide. The 19 inch dimension includes the edges or ''ears'' that protrude from each side of the ...
. Tuning of the R-390A's radio frequency and
intermediate frequency In communications and electronic engineering, an intermediate frequency (IF) is a frequency to which a carrier wave is shifted as an intermediate step in Transmission (telecommunications), transmission or reception. The intermediate frequency is ...
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 lowers ferrite 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 An electromagnetic pulse (EMP), also referred to as a transient electromagnetic disturbance (TED), is a brief burst of electromagnetic energy. The origin of an EMP can be natural or artificial, and can occur as an electromagnetic field, as an ...
. There are reports, possibly apocryphal, that R-390A receivers are still in use aboard
U.S. Navy The United States Navy (USN) is the maritime service branch of the United States Department of Defense. It is the world's most powerful navy with the largest displacement, at 4.5 million tons in 2021. It has the world's largest aircraft ...
submarines A submarine (often shortened to sub) is a watercraft capable of independent operation underwater. (It differs from a submersible, which has more limited underwater capability.) The term "submarine" is also sometimes used historically or info ...
since the receiver can withstand the strong
radio frequency Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around . This is roughly between the u ...
fields found aboard ship. Many of the R-390As that exist today are in the hands of
vintage amateur radio Vintage amateur radio is a subset of amateur radio hobby where enthusiasts collect, restore, preserve, build, and operate amateur radio equipment from bygone years, such as those using vacuum tube technology. Popular modes of operation include spe ...
collectors and
amateur radio Amateur radio, also known as ham radio, is the use of the radio frequency radio spectrum, spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emer ...
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 of
vacuum tube A vacuum tube, electron tube, thermionic valve (British usage), or tube (North America) is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied. It ...
technology.


See also

* ART 13 transmitter *
ARC-5 The AN/ARC-5 Command Radio Set is a series of radio receivers, transmitters, and accessories carried aboard U.S. Navy aircraft during World War II and for some years afterward. It is described as "a complete multi-channel radio transmitting an ...
*
BC-348 The BC-348 is an American-made communications receiver, which was mass-produced during World War II for the U.S. Army Air Force. Under the joint Army-Navy nomenclature system, the receiver system became known as the AN/ARR-11. History The BC-3 ...
* BC-654 *
Collins Radio Rockwell Collins, Inc. was a multinational corporation headquartered in Cedar Rapids, Iowa, providing avionics and information technology systems and services to government agencies and aircraft manufacturers. It was formed when the Collins Radio ...
*
Hammarlund super pro The Hammarlund Super Pro was an United States, American-made radio communications receiver. History In March 1936, the Hammarlund Manufacturing Company initiated the first of the famous "Super-Pro" line, the SP-10 receiver, followed in January ...
*
National HRO The original National HRO was a 9-tube HF ( shortwave) general coverage communications receiver manufactured by the National Radio Company of Malden, Massachusetts, United States. History James Millen (amateur radio call sign W1HRX) in Massach ...
*
Vintage amateur radio Vintage amateur radio is a subset of amateur radio hobby where enthusiasts collect, restore, preserve, build, and operate amateur radio equipment from bygone years, such as those using vacuum tube technology. Popular modes of operation include spe ...
* 75A-4 and KWS-1


References


Further reading

*


External links

* Amateur radio receivers Military radio systems of the United States Military electronics of the United States Equipment of the United States Air Force Models of radios Telecommunications equipment Military equipment introduced in the 1950s {{Rockwell International