Radiotelegraphy: U.S. Signal Corps |
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adjustments aerial alternating current amperes amplitude antenna ammeter reading antenna circuit antenna inductance armature binding post C₁ capacity changes charged closed circuit closed oscillating circuit cuit curve cycles per second damped desired wave length detector direct current direction discharge electrical electromagnetic electrostatic energy formula Fort Sam Houston fundamental wave length gasket gears ground hot-wire ammeter inch insulated kilowatt loading coil logarithmic decrement loosely coupled machine mast maximum microhenrys millihenry motor motor-generator natural logarithm number of turns open circuit operating chest oscillation transformer oscillations per second plates plug potential primary circuit quenched spark radiation radio pack set radiotelegraphy reactance receiving circuits receiving set resistance resonance rheostat secondary circuit sections shown in figure Signal Corps spark frequency spark gap speed spiral static switch telephones terminals tion transformer secondary transmitting tuning variable condenser variometer voltage voltmeter volts wattmeter watts wave meter wave train wire
Popular passages
Page 99 - I. and so on, finding the best combination for every 50 meters increase in wave length up to the limit of the set. LIMITATIONS OF SYSTEM OF CODING WAVE LENGTHS. It will be noted that there is one best wave for the set, namely, about 1,000 meters. From some experiments made recently at Fort Leavenworth it is concluded that it is safe to state that, up to about 75 miles over average land, the falling off of energy due to the use of the longest wave lengths will not be so great as to prevent the use...
Page 86 - It is of 2-kilowatts output and is carried on a two-chest pintle wagon, one chest with the engine and generator and the other with the transmitting and the receiving apparatus. The range of these sets varies from 75 to 800 miles, depending on favorable weather conditions, time of day or night, character of the land between the sets, etc. FORT SAM HOUSTON STATION SET. The following description of the Fort Sam Houston station is given as an illustration of the type of the 8 and 10 kilowatt sets installed...
Page 109 - By the use of these circuits, the electrical load on the machine is limited to the small one of the exciter field, except when the key is closed in sending. Experiments have shown that twice the output of the former machines can thus be obtained with practically no more tiring effects on the men than before. OPERATING CHEST. In this chest is mounted the transmitting and receiving apparatus, the diagram of which is shown in figure 79. To put the chest in condition for sending, connect the double contact...
Page 5 - BODIES sealing wax they will be attracted to it, and similarly if the rubbed sealing wax is brought near particles charged by the rubbed glass they will be attracted; but two bodies, both of which have been charged by either the glass or the wax, will repel each other. Hence like charges repel each other and unlike charges attract. The names positive (glass) and negative (sealing wax) have been given, respectively, to these charges. By...
Page 115 - The coil is variable only by sections, marked "100," "200," etc., the smaller numbers to be used at the shorter wave lengths and the larger ones at the longer wave lengths. The position of the secondary coil within the primary — that is, the coupling — is variable, and for the sake of convenience a scale is provided so as to be able to note the different adjustments. The coupling is closest when the secondary is inside the primary, in which case the scale reading is 0, and vice versa...
Page 97 - ... No. 2 back to the generator. The voltmeter is across the AC leads as shown. If the voltmeter shows voltage, but upon closing the key no spark takes place at the spark gap the snap switch in the primary circuit is probably open. The voltage, as indicated by the voltmeter, must never be more than 85. If it is desired to change the generator frequency (and the pitch of the note emitted), in order to secure greater selectivity for the set when working in the presence of other sets having about the...
Page 95 - The aerial used with this set should have a capacity of 0.0011 mf and a natural period 'of 450 meters. The following detailed notes on the circuits and operation of the set have been found useful as a result of actual work in the field : POWER CIRCUITS. Referring to connection diagram 75, it is seen that DC leads marked 3 And 4 go to both receiving switches in series.
Page 93 - ... apply to water-cooled gasoline engines in general apply in this case, and the principal points are briefly as follows: Before starting make sure — 1. That the water tank is full. 2. That all bearings have been oiled. 3. That the engine has sufficient lubricating oil by means of the stopcock on under part of crank case. If it drips when opened, there is sufficient oil. 4. That there is sufficient gasoline in the tank as indicated by the gauge on the front of the tank. 5. That the main switch...
Page 98 - and " Great " which throws the coils of this variometer from a parallel to a series connection or vice versa. This switch can only be moved to the right or left — to " Little " or to " Great " — when the index is directly opposite the dividing line between the red and the white divisions. Any attempt to throw this switch when the variometer coils are in any other position will only result in damage to the switch.
Page 114 - The receiving set consists of an inductively connected transformer with broadly tuned secondary circuits, as mentioned on page 73, galena, or other similar detector, high-resistance telephones, etc., provided with the necessary switches for tuning to different wave lengths. The primary circuit includes the antenna, primary coil, series condenser or not as may be needed, and counterpoise. The antenna is connected to the primary coil through switches which put into circuit a variable number of turns,...