A 'Low-Pass' filter serves to reduce 'Harmonics' which can be generated in overdriven, improperly adjusted or malfunctioning AMPLIFIER stages, either the actual Power Amplifier in a transmitter or an external Linear Power Amplifier. Consequently, it should be inserted as close as possible to the transceiver or amplifier if one is used. The HF Station block diagram begins with: Transceiver, Linear Amplifier, Low-Pass Filter, SWR Bridge, Antenna Switch...
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 'Low-Pass' filter serves to reduce 'Harmonics' which can be generated in overdriven, improperly adjusted or malfunctioning AMPLIFIER stages, either the actual Power Amplifier in a transmitter or an external Linear Power Amplifier. Consequently, it should be inserted as close as possible to the transceiver or amplifier if one is used. The HF Station block diagram begins with: Transceiver, Linear Amplifier, Low-Pass Filter, SWR Bridge, Antenna Switch...
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 'Low-Pass' filter serves to reduce 'Harmonics' which can be generated in overdriven, improperly adjusted or malfunctioning AMPLIFIER stages, either the actual Power Amplifier in a transmitter or an external Linear Power Amplifier. Consequently, it should be inserted as close as possible to the transceiver or amplifier if one is used. The HF Station block diagram begins with: Transceiver, Linear Amplifier, Low-Pass Filter, SWR Bridge, Antenna Switch...
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 'SWR Bridge' permits measuring the relative impedance match between the antenna system and the transceiver (SWR = Standing Wave Ratio). The HF Station block diagram begins with: Transceiver, Linear Amplifier, Low-Pass Filter, SWR Bridge, Antenna Switch...
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 'Antenna Switch' provides a convenient way to select a direct connection to an antenna, a connection through the 'Antenna Tuner' to other antennas or to the 'Dummy Load'. The HF Station block diagram begins with: Transceiver, Linear Amplifier, Low-Pass Filter, SWR Bridge, Antenna Switch, ...
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 'Antenna Tuner' provides variable impedance transformation: it can adapt the impedance of the antenna system (which changes with antenna dimensions and operating frequency) to the design impedance of the transceiver. The 'Antenna Tuner' permits using an antenna on a frequency or band other than the one for which it was designed.
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 'Dummy Load' (a resistor with a high power rating) dissipates RF energy as heat without radiating the RF on the air. Permits tests or adjustments without causing interference to other stations. The 'tuning process' refers to a manual procedure necessary for equipment with vacuum tube final Power Amplifiers where variable capacitors needed to be adjusted with each frequency change.
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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For example, on the 160 m band (1.8 MHz to 2.0 MHz), the band EDGES are 5% removed from the centre frequency of 1.9 MHz. On 80 m (3.5 MHz to 4.0 MHz), the edges are nearly 7% removed from the centre frequency of 3.75 MHz. On 20 m (14.0 MHz to 14.35 MHz), the edges are only 1.2% removed from the centre frequency of 14.175 MHz. Antennas present an acceptable standing wave ratio over a limited range of frequencies, the Antenna Tuner circumvents that limitation.
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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For example, on the 160 m band (1.8 MHz to 2.0 MHz), the band EDGES are 5% removed from the centre frequency of 1.9 MHz. On 80 m (3.5 MHz to 4.0 MHz), the edges are nearly 7% removed from the centre frequency of 3.75 MHz. On 20 m (14.0 MHz to 14.35 MHz), the edges are only 1.2% removed from the centre frequency of 14.175 MHz. Antennas present an acceptable standing wave ratio over a limited range of frequencies, the Antenna Tuner circumvents that limitation.
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 "modem" is a modulator/demodulator: a device which turn computer digital communications into audible tones and vice-versa. Driven by computer programs, the 'sound card' in a computer can readily emulate that function.
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 'Keyer' is an electronic circuit to which connects a 'Paddle'. The 'Keyer' issues dots and dashes in response to contact closures on the 'Paddle' by the operator. Dots and dashes are uniformly timed and spaced. The 'Paddle' relies on a side to side motion of the hand; it does not lead to fatigue as the traditional hand key does after a while.
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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Remember your transmitter block diagrams: the Microphone connects to the Speech Amplifier, the first stage in a voice transmitter.
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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Remember your transmitter block diagrams: the Microphone connects to the Speech Amplifier, the first stage in a voice transmitter.
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 'Dummy Load' (a resistor with a high power rating) dissipates RF energy as heat without radiating the RF on the air. Permits tests or adjustments without causing interference to other stations. The 'tuning process' (or 'loading') refers to a manual procedure necessary for equipment with vacuum tube final Power Amplifiers where variable capacitors needed to be adjusted.
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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VOX = "Voice Operated Transmit". VFO = "Variable Frequency Oscillator". [ the other two are beyond the scope of a Basic license. ]
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 'Speech Processor' makes for more average power being packed in the transmitted sideband. 'Speech processing' is raising the average amplitude of the audio input from the microphone closer to an acceptable peak value: i.e., make every passage of the spoken words equally loud. THE AVERAGE can be increased but not the PEAK. Too much speech processing leads to distortion and possibly driving the Linear Power Amplifier with too large a signal (overdriving).
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 'Speech Processor' makes for more average power being packed in the transmitted sideband. 'Speech processing' is raising the average amplitude of the audio input from the microphone closer to an acceptable peak value: i.e., make every passage of the spoken words equally loud. THE AVERAGE can be increased but not the PEAK. Too much speech processing leads to distortion and possibly driving the Linear Power Amplifier with too large a signal (overdriving).
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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Switching from receive to transmit supposes FOUR actions: disconnect the antenna from the receiver, connect the antenna to the transmitter, silence the receiver and activate the Power Amplifier in the transmitter. A 'Relay' (a multiple-contact electrically-driven switch) frequently performs the antenna changeover an the enabling/disabling of the transceiver sections.
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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Switching from receive to transmit supposes FOUR actions: disconnect the antenna from the receiver, connect the antenna to the transmitter, silence the receiver and activate the Power Amplifier in the transmitter. A 'Relay' (a multiple-contact electrically-driven switch) frequently performs the antenna changeover an the enabling/disabling of the transceiver sections.
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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Switching from receive to transmit supposes FOUR actions: disconnect the antenna from the receiver, connect the antenna to the transmitter, silence the receiver and activate the Power Amplifier in the transmitter. A 'Relay' (a multiple-contact electrically-driven switch) frequently performs the antenna changeover an the enabling/disabling of the transceiver sections.
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 'Dynamic Microphone' is built around a membrane, a voice coil and a magnet: sound waves cause the membrane to vibrate, the voice coil, attached to the membrane, moves in and out of a magnetic field thus producing a tiny electrical signal corresponding to the voice. Loudspeaker employ the reverse principle: an audio signal applied to the voice coil moves the membrane to reproduce sound waves.
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 'Antenna Tuner' permits using an antenna on a frequency or band other than the one for which it was designed. The 'SWR Meter' measures antenna system efficiency. The 'Low-Pass Filter' reduces 'Harmonic Radiation'. The 'High-Pass Filter' protects TV receivers from being overloaded by HF transmissions.
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 'Antenna Tuner' provides variable impedance transformation: it can adapt the impedance of a the antenna system (which changes with antenna dimensions and operating frequency) to the design impedance of the transceiver. The 'Antenna Tuner' permits using an antenna on a frequency or band other than the one for which it was designed.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
Tags: none