The external source will frequently be a wall socket where 120 volts AC is available. The blocks in a Regulated Power Supply: Input, Transformer, Rectifier, Filter, Regulator, Output.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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Prior to rectification with diodes, a transformer lowers or raises the voltage (to bring it closer to the desired output voltage). The blocks in a Regulated Power Supply: Input, Transformer, Rectifier, Filter, Regulator, Output.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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The 'Rectifier' (diodes) converts AC into 'pulsating DC' which is then smoothed out into pure DC by a 'Filter' (often simply a capacitor). The blocks in a Regulated Power Supply: Input, Transformer, Rectifier, Filter, Regulator, Output.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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The 'Rectifier' (diodes) converts AC into 'pulsating DC' which is then smoothed out into pure DC by a 'Filter' (often simply a capacitor). The blocks in a Regulated Power Supply: Input, Transformer, Rectifier, Filter, Regulator, Output.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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The pure DC available after the 'Filter' goes through the 'Regulator' which maintains a constant output voltage regardless of input variations or load changes. The blocks in a Regulated Power Supply: Input, Transformer, Rectifier, Filter, Regulator, Output.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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The 'Output' circuitry (fuses, meters, output terminals) connects to the 'Regulator'. The blocks in a Regulated Power Supply: Input, Transformer, Rectifier, Filter, Regulator, Output.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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In the car, the transceiver gets power from the car battery. In the home, a power supply provides the 12 volts DC necessary for the transceiver. From the car to the home, the prime difference is the source of voltage.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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A large percentage of modern transceivers are designed to work off 12 volts DC which is readily available from a car battery. To use a rig in the home, a 'Power Supply' is required: a 'Power Supply' combines a transformer, rectifier and filter to convert 120 volts AC down to 12 volts DC.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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key words: HIGH CURRENT. Receivers rarely draw more than 1 ampere at 12 VDC. A 100 watt transceiver (while on transmit) can draw 20 amperes at 12 VDC.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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key word: HUM. Remember the 'Power Supply' block diagram: a 'Rectifier' (diode) converts AC into 'pulsating DC'. A 'Filter' then turns the 'pulsating DC' into pure DC. If the 'Filter' is deficient, hum or buzzing will appear on the transmitted signal.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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A DIODE, vacuum tube or semiconductor, has two electrodes: Anode and Cathode. Electrons flow from Cathode to Anode in a forward-biased (i.e., a diode subjected to a voltage polarity which permits conduction) diode.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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A DIODE, vacuum tube or semiconductor, has two electrodes: Anode and Cathode. Electrons flow from Cathode to Anode in a forward-biased (i.e., a diode subjected to a voltage polarity which permits conduction) diode.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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Nominal household voltages have slowly come up since the early 20th century from 110 V, to 115 V, to 117 V, to 120 V. The current standard is 120 V and 240 V. 240 V is used for energy-hungry devices like water heaters, clothes dryers, electric ovens AND high-power linear amplifiers.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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Understand that DC power is brought to the radio over a pair of wires. Each wire must not drop more than 0.25 volt (half the given value) over 3 metres. Thus, the loss per metre must be below 0.08 volt. The run must be at least number 10 gauge. Voltage drops (E = R x I) at that current were computed for you from resistance value per unit length available from wire tables. [ # 14 = 1.63 mm (0.06 in.), # 12 = 2.05 mm (0.08 in.), # 10 = 2.59 mm (0.10 in.), # 8 = 3.26 mm (0.13 in.) ]
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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A car battery can deliver a hundred amperes or more into a short circuit; the voltage drop in any current-carrying wire and such large currents produce heat (P = E x I), enough heat to melt wire insulation and other plastics which abound in cars. Fuses close to the battery ensure excessive current is interrupted regardless of where the fault occurs over the DC power line to the radio.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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key word: HUM. Remember the 'Power Supply' block diagram: a 'Rectifier' (diode) converts AC into 'pulsating DC'. A 'Filter' then turns the 'pulsating DC' into pure DC. If the 'Filter' is deficient, hum or buzzing will appear on the transmitted signal.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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