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Although the superheterodyne receiver is the most common receiver in use today [citation needed], the regenerative radio made the most out of very few parts. In World War II the regenerative circuit was used in some military equipment. An example is the German field radio "Torn.E.b". [34]
Hallicrafters founder Bill Halligan and his personal SX-28 depicted in a 1944 magazine ad. In July 1940, the Hallicrafters Company announced the SX-28 "Super Skyrider", the result of a development effort by 12 staff engineers and analysis of more than 600 reports that included input from U.S. government engineers, commercial users, and amateur radio operators.
Grundig Satellit 400 solid-state, digital shortwave receiver, c. 1986 [1]. Shortwave radio is radio transmission using radio frequencies in the shortwave bands (SW). There is no official definition of the band range, but it always includes all of the high frequency band (HF), which extends from 3 to 30 MHz (approximately 100 to 10 metres in wavelength).
The R-390A military shortwave radio receiver was the result of a project undertaken by the United States 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.
[6] [11] Before each radio left the factory, a technician custom calibrated a set of A, B, C, and D coils for that particular radio, a process that took nearly 4 hours. [12] Each of the four main sets of coils also had bandspread modes set by moving screws that limited the frequency range to 28–29.7, 14–14.4, 7–7.3, 3.5-4 MHz ...
Another first for portable radios was the unique dial scale used in the 1000 and later series of Trans-Oceanics. The 1000 was designed with a cylinder dial scale that would rotate with the band switch allowing only that particular band scale to show. [9] Zenith Royal 1000 All Transistor Trans-Oceanic Short Wave Portable Radio, circa 1957.
Shortwave bands are frequency allocations for use within the shortwave radio spectrum (the upper medium frequency [MF] band and all of the high frequency [HF] band). Radio waves in these frequency ranges can be used for very long distance (transcontinental) communication because they can reflect off layers of charged particles in the ionosphere and return to Earth beyond the horizon, a ...
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 receivers are often used by dedicated hobbyists called shortwave listeners.