more at http://showbiz.quickfound.net/world_band_radio.html See also: an even better Morse Code hand sending training film, produced by the US Army in 1966: http://www.youtube.com/watch?v=vOqbjbzC9V8 "IMPORTANT PARTS OF THE TRANSMITTER, TENSION SPRING, ADJUSTING CONTACTS, AND ADJUSTING SPRINGS. ELEMENTS OF MORSE CODE, TIMING, AND PARTS OF BODY THAT FUNCTION WHEN TRANSMITTING CODE. IMPORTANCE OF CORRECT POSITION AND OPERATION." US Navy training film MN-2621B http://en.wikipedia.org/wiki/Morse_code ...Beginning in 1836, the American artist Samuel F. B. Morse, the American physicist Joseph Henry, and Alfred Vail developed an electrical telegraph system. This system sent pulses of electric current along wires which controlled an electromagnet that was located at the receiving end of the telegraph system. In 1837, William Cooke and Charles Wheatstone in England began using an electrical telegraph that also used electromagnets in its receivers. However, in contrast with any system of making sounds of clicks, their system used pointing needles that rotated above alphabetical charts to indicate the letters that were being sent. In 1841, Cooke and Wheatstone built a telegraph that printed the letters from a wheel of typefaces struck by a hammer. This machine was based on their 1840 telegraph and worked well; however, they failed to find customers for this system and only two examples were ever built. On the other hand, the three Americans' system for telegraphy, which was first used in about 1844, was designed to make indentations on a paper tape when electric currents were received. Morse's original telegraph receiver used a mechanical clockwork to move a paper tape. When an electrical current was received, an electromagnet engaged an armature that pushed a stylus onto the moving paper tape, making an indentation on the tape. When the current was interrupted, the electromagnet retracted the stylus, and that portion of the moving tape remained unmarked. The Morse code was developed so that operators could translate the indentations marked on the paper tape into text messages. In his earliest code, Morse had planned to only transmit numerals, and use a dictionary to look up each word according to the number which had been sent. However, the code was soon expanded by Alfred Vail to include letters and special characters, so it could be used more generally. Vail determined the frequency of use of letters in the English language by counting the movable type he found in the type-cases of a local newspaper in Morristown. The shorter marks were called "dots", and the longer ones "dashes", and the letters most commonly used were assigned the shorter sequences of dots and dashes... International Morse code today is most popular among amateur radio operators, where it is used as the pattern to key a transmitter on and off in the radio communications mode commonly referred to as "continuous wave" or "CW" to distinguish it from spark transmissions, not because the transmission was continuous. Other keying methods are available in radio telegraphy, such as frequency shift keying. The original amateur radio operators used Morse code exclusively, since voice-capable radio transmitters did not become commonly available until around 1920. Until 2003 the International Telecommunication Union mandated Morse code proficiency as part of the amateur radio licensing procedure worldwide. However, the World Radiocommunication Conference of 2003 made the Morse code requirement for amateur radio licensing optional. Many countries subsequently removed the Morse requirement from their licence requirements. Until 1991, a demonstration of the ability to send and receive Morse code at five words per minute (WPM) was required to receive an amateur radio license for use in the United States from the Federal Communications Commission. Demonstration of this ability was still required for the privilege to use the HF bands. Until 2000, proficiency at the 20 WPM level was required to receive the highest level of amateur license (Amateur Extra Class); effective April 15, 2000, the FCC reduced the Extra Class requirement to five WPM. Finally, effective on February 23, 2007, the FCC eliminated the Morse code proficiency requirements from all amateur radio licenses...

• published: 19 Feb 2012
• views: 88612