The 74A4 and KWS-1 is an amateur radio receiver and transmitter pair made by the Collins Radio Company of Cedar Rapids, Iowa that were introduced in 1955. They were designed to operate using the then new single-sideband (SSB) voice modulation as well as CW and AM modes. They were influential in popularizing SSB. [1]
The KWS-1 transmitter along with the 75A-4 receiver, together, cost over $2500 when new (equivalent to over $20,000 in 2012 dollars). Collins products at the time were considered 'top of the line'. Ham radio enthusiasts nicknamed the pair the "Gold Dust Twins", since they were unaffordable for most amateur radio enthusiasts when first introduced. [2]
Both radios used vacuum tubes and employed Collins innovations including mechanical filters and permeability tuned oscillators. [lower-alpha 1] The KWS-1 final amplifier use a pair of 4X150 power tubes and operated at a power input of one kilowatt, the maximum allowed under Federal Communications Commission (FCC) regulations at the time. The transmitter appearance matched the receiver, but its high voltage power supply was packaged in a separate pedestal. [3] [4]
In a 2006 review of the half-century-old 75A-4 [5] Stu Cohen wrote "Performance under all but extremely crowded band conditions is still excellent, and a 75A-4 will hold its own against almost any receiver. Under less crowded band conditions, the performance is superb."
In amateur radio, QRP operation refers to transmitting at reduced power while attempting to maximize one's effective range. QRP operation is a specialized pursuit within the hobby that was first popularized in the early 1920s. QRP operators limit their transmitted RF output power to 5 W or less regardless of mode.
In radio communications, single-sideband modulation (SSB) or single-sideband suppressed-carrier modulation (SSB-SC) is a type of modulation used to transmit information, such as an audio signal, by radio waves. A refinement of amplitude modulation, it uses transmitter power and bandwidth more efficiently. Amplitude modulation produces an output signal the bandwidth of which is twice the maximum frequency of the original baseband signal. Single-sideband modulation avoids this bandwidth increase, and the power wasted on a carrier, at the cost of increased device complexity and more difficult tuning at the receiver.
A regenerative circuit is an amplifier circuit that employs positive feedback. Some of the output of the amplifying device is applied back to its input to add to the input signal, increasing the amplification. One example is the Schmitt trigger, but the most common use of the term is in RF amplifiers, and especially regenerative receivers, to greatly increase the gain of a single amplifier stage.
In a radio receiver, a beat frequency oscillator or BFO is a dedicated oscillator used to create an audio frequency signal from Morse code radiotelegraphy (CW) transmissions to make them audible. The signal from the BFO is mixed with the received signal to create a heterodyne or beat frequency which is heard as a tone in the speaker. BFOs are also used to demodulate single-sideband (SSB) signals, making them intelligible, by essentially restoring the carrier that was suppressed at the transmitter. BFOs are sometimes included in communications receivers designed for short wave listeners; they are almost always found in communication receivers for amateur radio, which often receive CW and SSB signals.
Rockwell Collins 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 Company, facing financial difficulties, was purchased by Rockwell International in 1973. In 2001, the avionics division of Rockwell International was spun off to form the current Rockwell Collins, Inc., retaining its name.
The Hallicrafters Company manufactured, marketed, and sold radio equipment, and to a lesser extent televisions and phonographs, beginning in 1932. The company was founded by William J. Halligan and based in Chicago, Illinois, United States.
Arthur Andrews Collins was an American radio engineer and entrepreneur. He first gained national recognition as a teenager for significant advances in radio communication. He later founded his own radio engineering and manufacturing company in 1933, Collins Radio Co. Rapidly expanding during World War II, Collins Radio eventually grew into a Fortune 500 leader in avionics, telecommunication, and military, space and commercial radio communications. Collins and his company ultimately became pioneers in melding computer and communication technology. Widely considered a genius in electronics innovation, he shunned personal publicity and is relatively little known today, even within the electronics community.
The R. L. Drake Company is a manufacturer of electronic communications equipment located in Springboro, Ohio. It is also known for its line of equipment for amateur radio and shortwave listening, built in the 1950s through the 1980s. The company operates as a separate entity owned by Blonder Tongue Laboratories, Inc.
A radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna. Radio waves are electromagnetic waves with frequencies between about 30 Hz and 300 GHz. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating current, the antenna radiates radio waves. Transmitters are necessary parts of all systems that use radio: radio and television broadcasting, cell phones, wireless networks, radar, two way radios like walkie talkies, radio navigation systems like GPS, remote entry systems, among numerous other uses.
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 and receiving set providing communication and navigation facilities for aircraft. The LF-MF-HF components are designed to transmit and receive voice, tone-modulated, and continuous wave (cw) signals." Its flexible design provided AM radiotelephone voice communication and Modulated continuous wave (MCW) and Continuous wave (CW) Morse code modes, all of which are typical capabilities in other Navy aircraft communication sets of the period. It was an improvement of the Navy's ARA/ATA command set. Similar units designated SCR-274-N were used in U.S. Army aircraft. The Army set is based on the ARA/ATA, not the later AN/ARC-5. The ARA/ATA and SCR-274-N series are informally referred to as "ARC-5", despite small differences that render all three series incompatible. Like the AN/ARC-5, the ARA/ATA and SCR-274-N had AM voice communication and two-way MCW and CW Morse code capability.
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.
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 speaking over amplitude modulation (AM), and communicating using Morse code through continuous wave (CW) radiotelegraphy. Some enthusiasts have interest in owning, restoring and operating vintage military and commercial radio equipment such as those from 1940s to 1960s. Some undertake to construct their own gear, known in ham slang as homebrewing, using vintage parts and designs. A number of amateur radio clubs and organizations sponsor contests, events, and swap meets that cater to this specialized aspect of the hobby.
The AN/ART-13 was a radio transmitter manufactured by Collins Radio that found widespread use during and after World War II in military aircraft.
Homebrew is an amateur radio slang term for home-built, noncommercial radio equipment. Design and construction of equipment from first principles is valued by amateur radio hobbyists, known as "hams", for educational value, and to allow experimentation and development of techniques or levels of performance not readily available as commercial products. Some items can be home-brewed at similar or lower cost than purchased equivalents.
The Hammarlund Super Pro was an American-made radio communications receiver.
Swan Electronics was a manufacturer of amateur radio gear located in Oceanside, California, United States.
The R-390A /URR is a general coverage HF radio communications receiver designed by Collins Radio Company for the United States Armed Forces.
The Gold Dust Twins, the trademark for Fairbank's Gold Dust washing powder products, appeared in printed media as early as 1892. "Goldie" and "Dusty", the original Gold Dust Twins, were often shown doing household chores together. In general use since the early 1900s, the term has had popular use as a nickname on several occasions. The sobriquet, "Gold Dust Twins," is often used to describe two talented individuals working closely together for a common goal, especially in sports.
AMSAT-OSCAR 16, also known as AO-16 and PACSAT, is the in-orbit name designation of an amateur radio satellite of the OSCAR series. It was built by AMSAT and was launched on 22 January 1990 from Kourou, French Guiana on an Ariane 4 launch vehicle. It is in Sun synchronous low Earth orbit.