Hallicrafters SX-28
Encyclopedia
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
shortwave
Shortwave
Shortwave radio refers to the upper MF and all of the HF portion of the radio spectrum, between 1,800–30,000 kHz. Shortwave radio received its name because the wavelengths in this band are shorter than 200 m which marked the original upper limit of the medium frequency band first used...
communications receiver
Communications receiver
A communications receiver is a type of radio receiver used as a component of a radio communication link.-Features:Commercial communications receivers are characterised by high stability and reliability of performance, and are generally adapted for remote control and monitoring...
produced between 1940 and 1946 that saw wide use by amateur radio
Amateur radio
Amateur radio is the use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication...
, government and military services.
History
Hallicrafters
The Hallicrafters Company manufactured, marketed, and sold radio equipment beginning in 1932. The company was based in Chicago, Illinois, USA.-History:William J. Halligan founded his own radio manufacturing company in Chicago in late 1932...
announced the SX-28 "Super Skyrider", the result of a development effort by 12 staff engineer
Engineer
An engineer is a professional practitioner of engineering, concerned with applying scientific knowledge, mathematics and ingenuity to develop solutions for technical problems. Engineers design materials, structures, machines and systems while considering the limitations imposed by practicality,...
s and analysis of more than 600 reports that included input from U.S. government engineers, commercial users, and amateur radio operator
Amateur radio operator
An amateur radio operator is an individual who typically uses equipment at an amateur radio station to engage in two-way personal communications with other similar individuals on radio frequencies assigned to the amateur radio service. Amateur radio operators have been granted an amateur radio...
s. The SX-28's distinctive art deco
Art Deco
Art deco , or deco, is an eclectic artistic and design style that began in Paris in the 1920s and flourished internationally throughout the 1930s, into the World War II era. The style influenced all areas of design, including architecture and interior design, industrial design, fashion and...
styling was considered sleek and strikingly modern in 1940. The receiver's electronic circuit
Electronic circuit
An electronic circuit is composed of individual electronic components, such as resistors, transistors, capacitors, inductors and diodes, connected by conductive wires or traces through which electric current can flow...
utilized 15 vacuum tube
Vacuum tube
In electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...
s in a double preselection front end on the top four shortwave band
Electromagnetic spectrum
The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object....
s and single preselection on the lower two bands. The radio frequency
Radio frequency
Radio frequency is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals...
coverage was 550 kHz (0.55 MHz) to 43 MHz in six bands. Amplified
Amplifier
Generally, an amplifier or simply amp, is a device for increasing the power of a signal.In popular use, the term usually describes an electronic amplifier, in which the input "signal" is usually a voltage or a current. In audio applications, amplifiers drive the loudspeakers used in PA systems to...
AVC, a Lamb Noise Silencer, Calibrated bandspread, and Push-Pull audio output
Sound recording and reproduction
Sound recording and reproduction is an electrical or mechanical inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording technology are analog recording and digital recording...
were some of the features incorporated into the design. The SX-28 would become notable for its "high fidelity" audio together with high sensitivity, stability and selectivity, and good purchase value.
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. SX-28 and Hallicrafters S-27 and S-36 receivers were often rack mounted in British government listening posts and secret listening stations for monitoring German
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
and communications during the war such as Beaumanor Hall
Beaumanor Hall
Beaumanor Hall is a stately home with a park in the small village of Woodhouse on the edge of the Charnwood Forest, near the town of Loughborough in Leicestershire in the United Kingdom. It was built in 1845-7 by architect William Railton in Elizabethan style for the Herrick family. and is a Grade...
in the English Midlands
English Midlands
The Midlands, or the English Midlands, is the traditional name for the area comprising central England that broadly corresponds to the early medieval Kingdom of Mercia. It borders Southern England, Northern England, East Anglia and Wales. Its largest city is Birmingham, and it was an important...
where German and Italian
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
encrypted radio messages were intercepted and passed to Bletchley Park
Bletchley Park
Bletchley Park is an estate located in the town of Bletchley, in Buckinghamshire, England, which currently houses the National Museum of Computing...
for decoding. A number of the receivers were sent to Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
as a part of the Lend Lease Act, subsequently modified to accommodate Russian tubes. The Radio Intelligence Division (RID) of the U.S. Federal Communications Commission
Federal Communications Commission
The Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...
(FCC) and the Foreign Broadcast Information Service
Foreign Broadcast Information Service
Foreign Broadcast Information Service was an open source intelligence component of the Central Intelligence Agency's Directorate of Science and Technology. It monitored, translated, and disseminated within the U.S. government openly available news and information from media sources outside the...
also used them to monitor the airwaves for American intelligence agencies
Intelligence agency
An intelligence agency is a governmental agency that is devoted to information gathering for purposes of national security and defence. Means of information gathering may include espionage, communication interception, cryptanalysis, cooperation with other institutions, and evaluation of public...
in both mobile and fixed listening posts in the US. The typical fixed listening post had six SX-28 receivers and one S-27. After the war, the SX-28/28A continued to be used by the FCC in both mobile and fixed installations to monitor domestic radio transmitters.
Hallicrafters published that 50,000 SX-28 and SX-28A's had been built by the end of its production run in 1946, however the serial numbers appear to indicate a production figure of about half that amount, approximately 27,500 receivers. Many of the SX-28/28A's that exist today are in the hands of vintage amateur radio
Vintage amateur radio
Vintage amateur radio is a subset of the amateur radio hobby, considered a form of nostalgia much like antique car collecting, where enthusiasts collect, restore, preserve, build, and operate amateur radio equipment from bygone years, most notably those using vacuum tube technology.Popular modes of...
collectors and amateur radio operators.
The "Skyrider" name
Regenerative circuit
The regenerative circuit or "autodyne" allows an electronic signal to be amplified many times by the same vacuum tube or other active component such as a field effect transistor. It consists of an amplifying vacuum tube or transistor with its output connected to its input through a feedback...
sets. The "Super" was added with the introduction of the first Hallicrafters superheterodyne model, the S-4/ SX-4 in 1934. The last Hallicrafters sets to use Skyrider as part of the name were the SX-28A and the 1947 S-41 Skyrider Jr. receiver.
Specifications
- Frequency range: .55-1.6, 1.6-3, 3-5.8, 5.8-11, 11-21 and 21-43 MHz.
- Bandspread: 3.5-4, 7-7.3, 14-14.4 and 28-30 MHz.
- Voltages: 105-125 VAC 50/60 HzHertzThe hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....
- Coverage: 550 - 43000 kHz
- Readout: AnalogAnalog signalAn analog or analogue signal is any continuous signal for which the time varying feature of the signal is a representation of some other time varying quantity, i.e., analogous to another time varying signal. It differs from a digital signal in terms of small fluctuations in the signal which are...
- Modes: AMAmplitude modulationAmplitude modulation is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the strength of the transmitted signal in relation to the information being sent...
/CWContinuous waveA continuous wave or continuous waveform is an electromagnetic wave of constant amplitude and frequency; and in mathematical analysis, of infinite duration. Continuous wave is also the name given to an early method of radio transmission, in which a carrier wave is switched on and off...
- Selectivity: 6 positions
- Circuit: Single Conversion Superheterodyne
- Physical: 20.5x10x14.75" 75 Lbs. 521x254x375mm 34 kg
- Vacuum tubes: 6AB7 1st RF Amp, 6SK7 2nd RF Amp, 6SA7 Mixer, 6SA7 HF Osc, 6L7 1st IF ANL, 6SK7 2nd IF Amp, 6B8 AVC Amp, 6B8 2nd Detector/S Meter, 6AB7 Noise Amp, 6H6 Noise Rectifier, 6J5 BFO, 6SC7 1st Audio Amp, (2) 6V6GT Audio Amps and 5Z3 Rectifier
- Features: ¼" Headphone jack, S-Meter, Tone control, Phono input jack, Sensitivity and Bandspread controls, Dial lock, Speaker terminals, Flywheel Tuning, AVC ON/OFF switch, Dial lamps, Hinged top cover, Mute line, Bass switch, Standby switch, Antenna trimmer, Noise limiter
- Accessories: PM-23 Speaker
- New Price: $225–275
Variations
Variations and special versions of the SX-28 were produced over the years. During WWII, Hallicrafters continued to redesign portions of the SX-28 and, at the beginning of 1944, a major redesign to the receiver's front end prompted a designation change to SX-28A. The old front-end coils were replaced by smaller, Hi-Q Micro Set types that were mounted on removable chassis. The new coil design eliminated the majority of brass parts that were used in the early style coils. After WWII, Hallicrafters had nothing new to sell radio amateurs as they had devoted all design and manufacturing to the war effort, so they offered the SX-28A as a 1946 model. The last 4000 SX-28As built have "SX-28A" indicated on the front panel which is thought to have first appeared around November, 1945.
Specialty versions
- AN/GRR-2 - introduced in February 1944 became the U.S. Navy SX-28A, a ruggedized unit built for U.S. Army Signal Corps and U.S. Navy use. The AN/GRR-2 included a potted power transformer built by General Transformer Company, wax impregnated IF transformers and bandswitches, Korite dipped filter choke and audio output transformer, fungicide coating on the solder joints, and special heavy duty nylon insulated stranded hook-up wire in the wiring harnesses.
- FCC model - built for FCC monitoring posts where several receiving stations would be in operation. Each operator would be using earphones to prevent listening interference to an adjacent monitoring station. Since the audio requirements were minimal, the Push-Pull audio output 6V66V6The 6V6 is a beam-power tetrode, introduced by Radio Corporation of America RCA United States in late 1937, and still in use in niche applications.Similar to its predecessor the 6L6, the 6V6 was far more widely used...
s were replaced with a single-ended 6V6 audio output.
- SX-28U and SX-28AU - special order receivers with a dual primary power transformer for operation on either 120VAC or 240VAC.
- Canadian versions - sold by distributors like Rogers-MajesticRogers Vacuum Tube CompanyRogers Vacuum Tube Company was founded as "Standard Radio Manufacturing" in 1925 by Edward S. Rogers, Sr. to sell Rogers "Batteryless" radio using vacuum tube technology. It was later renamed Rogers Majestic Corporation Limited when Rogers merged his company with Majestic Corporation of Chicago...
in Canada. The Canadian Army also employed SX-28's among its communications networks.
General references
- de Hensler, Max. The Hallicrafters Story. Charleston, West Virginia: ARCA Press, 1988
- Moore, Raymond. Communications Receivers, Fourth Edition. La Belle, Florida: RSM Communications, 1997
- Osterman, Fred. Shortwave Receivers Past and Present. Reynoldsburg, Ohio: Universal Radio Research, 1998
- Dachis, Chuck. Radios by Hallicrafters. Atglen, Pennsylvania: Schiffer Books for Collectors, 1999
- SX-28 and SX-28A Manuals, VOLs. XII and XVI, Riders Perpetual Troubleshooting Manual
- AN/GRR-2 Manual, Army # TM-11-874, military SX-28A
- QSTQSTQST is a magazine for amateur radio enthusiasts, published by the American Radio Relay League . It is a membership journal that is included in membership with the ARRL. The publisher claims that circulation of QST in the United States is higher than all amateur radio-related publications in the...
, July,1940 to 1946 - ARRL Handbook 1946