| SCR-108 Radio Truck | |
|---|---|
 | |
| Type | Radio truck |
| Place of origin | United States |
| Service history | |
| In service | 1920-? |
| Used by | US Army |
| Wars | World War I ? |
| Production history | |
| Designed | 1919 |
| Manufacturer | White Motor Company |
| Variants | 1 |
| Specifications | |
| Mass | 1 1/2 ton |
| Length | 120 inches |
| Width | 64 inches |
| Height | 64 inches |
| Crew | 4 |
| Armor | none |
Main armament | none |
The SCR-108 Radio Truck was a Signal Corps Radio vehicle used by the United States Army during and after World War I for short range air-to-ground communications,
This truck was assigned to squadron headquarters in order to communicate with the SCR-68 airplane radio as well as the others in its class. eventually replaced by the SCR-197 mobile radio station. The van is described as having room for 3 operators and one squadron radio officer. One bench supports the SCR-67, SCR-54, and one amplifier with storage batteries held by clamps underneath the bench. on another bench is the SCR-79. a desk for the officer is installed with batteries underneath. a six volt circuit is provided for two lamps connected to storage batteries, and a 110 volt circuit with two lamps is provided if there is an external power source available.
(Note- all sets seem to have been upgraded to an A model)
The SCR-124 was evidently housed in a similar truck, and was assigned to division and Corps level headquarters. it carried the following components-
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 carrier frequency. It was long believed to have been invented by US engineer Edwin Armstrong, but after some controversy the earliest patent for the invention is now credited to French radio engineer and radio manufacturer Lucien Lévy. Virtually all modern radio receivers use the superheterodyne principle; except software-defined radios, which use direct sampling.
A vacuum tube, electron tube, valve, or tube, is a device that controls electric current flow in a high vacuum between electrodes to which an electric potential difference has been applied.
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 or reception. The intermediate frequency is created by mixing the carrier signal with a local oscillator signal in a process called heterodyning, resulting in a signal at the difference or beat frequency. Intermediate frequencies are used in superheterodyne radio receivers, in which an incoming signal is shifted to an IF for amplification before final detection is done.
A tetrode is a vacuum tube having four active electrodes. The four electrodes in order from the centre are: a thermionic cathode, first and second grids and a plate. There are several varieties of tetrodes, the most common being the screen-grid tube and the beam tetrode. In screen-grid tubes and beam tetrodes, the first grid is the control grid and the second grid is the screen grid. In other tetrodes one of the grids is a control grid, while the other may have a variety of functions.
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 so as 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 radio communications, a radio receiver, also known as a receiver, a wireless, or simply a radio, is an electronic device that receives radio waves and converts the information carried by them to a usable form. It is used with an antenna. The antenna intercepts radio waves and converts them to tiny alternating currents which are applied to the receiver, and the receiver extracts the desired information. The receiver uses electronic filters to separate the desired radio frequency signal from all the other signals picked up by the antenna, an electronic amplifier to increase the power of the signal for further processing, and finally recovers the desired information through demodulation.
The SCR-270 was one of the first operational early-warning radars. It was the U.S. Army's primary long-distance radar throughout World War II and was deployed around the world. It is also known as the Pearl Harbor Radar, since it was an SCR-270 set that detected the incoming raid about 45 minutes before the December 7, 1941, attack on Pearl Harbor commenced.
The term All American Five is a colloquial name for mass-produced, superheterodyne radio receivers that used five vacuum tubes in their design. These radio sets were designed to receive amplitude modulation (AM) broadcasts in the medium wave band, and were manufactured in the United States from the mid-1930s until the early 1960s. By eliminating a power transformer, cost of the units was kept low; the same principle was later applied to television receivers. Variations in the design for lower cost, shortwave bands, better performance or special power supplies existed, although many sets used an identical set of vacuum tubes.
Radio receiver design includes the electronic design of different components of a radio receiver which processes the radio frequency signal from an antenna in order to produce usable information such as audio. The complexity of a modern receiver and the possible range of circuitry and methods employed are more generally covered in electronics and communications engineering. The term radio receiver is understood in this article to mean any device which is intended to receive a radio signal in order to generate useful information from the signal, most notably a recreation of the so-called baseband signal which modulated the radio signal at the time of transmission in a communications or broadcast system.
The autodyne circuit was an improvement to radio signal amplification using the De Forest Audion vacuum tube amplifier. By allowing the tube to oscillate at a frequency slightly different from the desired signal, the sensitivity over other receivers was greatly improved. The autodyne circuit was invented by Edwin Howard Armstrong of Columbia University, New York, NY. He inserted a tuned circuit in the output circuit of the Audion vacuum tube amplifier. By adjusting the tuning of this tuned circuit, Armstrong was able to dramatically increase the gain of the Audion amplifier. Further increase in tuning resulted in the Audion amplifier reaching self-oscillation.
The SCR-299 was a U.S. Signal Corps mobile military communications unit used during World War II.
Survival radios are carried by ships and aircraft to facilitate rescue in an emergency. They are generally designed to transmit on international distress frequencies. Maritime systems have been standardized under the Global Maritime Distress Safety System.
The SCR-300 was a portable radio transceiver used by US Signal Corps in World War II. This backpack-mounted unit was the first radio to be nicknamed a "walkie talkie".
The BC-342 was a World War II U.S. Army Signal Corps high frequency radio receiver. It was used primarily as part of field installations such as the SCR-188A, but could be used with mobile sets such as the 2 1/2 ton mounted SCR-399. First designed at Fort Monmouth, New Jersey by the U.S. Army Signal Corps, it was built by various manufacturers including RCA. Many of the later units that are encountered today were manufactured by the Farnsworth Television and Radio Corporation of Fort Wayne, Indiana. Variants include the low frequency coverage BC-344 receiver, and the battery or dynamotor powered BC-312 receiver.
The SCR-68 was a military radiotelephone used by the US Army Signal Corps as an aircraft radio in the waning months of World War I. Due to its many problems, primarily its inability to communicate with other radios, like its ground component the SCR-67 or the larger truck mounted SCR-108, over large distances, the SCR-68 quickly became obsolete. Nonetheless, the SCR-68 was one of the first steps towards developing more effective messaging between pilots and commanders, even beyond military usage.
The SCR-508 radio was a mobile Signal Corps Radio used by the U.S. Army during World War II, for short range ground communications. The SCR-508 series radio represented the Army's commitment to both FM and crystal tuning, and was used extensively by armor and mechanized units. The turret bustle of late series light and medium tanks was designed around this radio.
A magnetoquasistatic field is a class of electromagnetic field in which a slowly oscillating magnetic field is dominant. A magnetoquasistatic field is typically generated by low-frequency induction from a magnetic dipole or a current loop. The magnetic near-field of such an emitter behaves differently from the more commonly used far-field electromagnetic radiation. At low frequencies the rate of change of the instantaneous field strength with each cycle is relatively slow, giving rise to the name "magneto-quasistatic". The near field or quasistatic region typically extends no more than a wavelength from the antenna, and within this region the electric and magnetic fields are approximately decoupled.
The SCR-54 was a tunable, portable crystal radio receiver used by the U. S. Army during World War I for fire control in conjunction with airplanes.
KFC was a Seattle, Washington AM radio station that was licensed from December 8, 1921 to January 23, 1923. The station was owned by the Northern Radio & Electric Company, however both its studio and transmitter were located at the Seattle Post-Intelligencer building, and the newspaper was responsible for most of its operations.
