Foxhole radio

The maker of the first foxhole radio is unknown, but it was almost certainly invented by a soldier stationed at the Anzio beachhead during the stalemate of February – May 1944. One of the first newspaper articles about a foxhole radio ran in the New York Times on April 29, 1944. That radio was built by Private Eldon Phelps of Enid, Oklahoma, who later claimed to have invented the design. It was fairly crude, a razor blade stuck into a piece of wood acted as the detector, and the end of the antenna wire served as a cat whisker. He managed to pick up broadcasts from Rome and Naples. The idea spread across the beachhead and beyond. Toivo Kujanpaa built a receiver at Anzio and was able to receive German propaganda programs.{{citation There were also allied broadcasts available, from the 5th Army Mobile Radio Station and the BBC. American G.I.s in Italy would put several radios together. The G.I.s would listen at night near the front lines to phonograph records played on a radio station in Rome. One could typically hear a radio station on a foxhole radio if the station was within twenty five or thirty miles. In 1942, Lieutenant Colonel R. G. Wells—a prisoner of war in Japan—built a foxhole radio to get news about the international situation. "The whole POW camp craved news", according to Wells.{{citation ==Designs and operation==

which, along with the capacitance of the antenna forms a resonant circuit (tuned circuit) with the inductance of the coil, resonating at a specific resonant frequency. The coil has a high impedance at its resonant frequency, and passes radio signals from the antenna along to the detector, while at other frequencies it had a low impedance so signals at those frequencies passed through the coil to ground. By varying the inductance of the coil with a sliding contact arm, a crystal radio can be tuned to receive different frequencies. Most of these wartime sets did not have a sliding contact and were only built to receive one frequency, the frequency of the nearest broadcast station. The detector and earphones were connected in series, but across the coil, which applied the radio signal of the received radio station. The detector acted like a rectifier, allowing current to flow through it in only one direction, but in a non-linear way, extracting the audio modulation, which then passed through to the earphones. The earphones converted the audio signal to sound waves. Usually the earphones had to be scrounged or borrowed from the unit's communication officer. In one case a soldier, Richard Lucas, built earphones by binding four nails together with cloth then winding wire and dripping wax over the turns. After about ten layers of wire he placed it in a piece of bamboo. A tin can lid was placed over the coil of wire. The listener connected the improvised earphone to the foxhole radio and received three radio stations. The best listening was at night, according to Lucas. File:Homemade radio receiver with razorblade.JPG File:RBDiode.pdf File:50% FHR.jpg ==See also==